There is an optimization of DISTINCT in JOIN::optimize()
which depends on THD::used_tables value. Each SELECT statement
inside SP resets used_tables value(see mysql_select()) and it
leads to wrong result. The fix is to replace THD::used_tables
with LEX::used_tables.
mysql-test/r/sp.result:
test case
mysql-test/t/sp.test:
test case
sql/sql_base.cc:
THD::used_tables is replaced with LEX::used_tables
sql/sql_class.cc:
THD::used_tables is replaced with LEX::used_tables
sql/sql_class.h:
THD::used_tables is replaced with LEX::used_tables
sql/sql_insert.cc:
THD::used_tables is replaced with LEX::used_tables
sql/sql_lex.cc:
THD::used_tables is replaced with LEX::used_tables
sql/sql_lex.h:
THD::used_tables is replaced with LEX::used_tables
sql/sql_prepare.cc:
THD::used_tables is replaced with LEX::used_tables
sql/sql_select.cc:
THD::used_tables is replaced with LEX::used_tables
In sql_class.cc, 'row_count', of type 'ha_rows', was used as last argument for
ER_TRUNCATED_WRONG_VALUE_FOR_FIELD which is
"Incorrect %-.32s value: '%-.128s' for column '%.192s' at row %ld".
So 'ha_rows' was used as 'long'.
On SPARC32 Solaris builds, 'long' is 4 bytes and 'ha_rows' is 'longlong' i.e. 8 bytes.
So the printf-like code was reading only the first 4 bytes.
Because the CPU is big-endian, 1LL is 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x01
so the first four bytes yield 0. So the warning message had "row 0" instead of
"row 1" in test outfile_loaddata.test:
-Warning 1366 Incorrect string value: '\xE1\xE2\xF7' for column 'b' at row 1
+Warning 1366 Incorrect string value: '\xE1\xE2\xF7' for column 'b' at row 0
All error-messaging functions which internally invoke some printf-life function
are potential candidate for such mistakes.
One apparently easy way to catch such mistakes is to use
ATTRIBUTE_FORMAT (from my_attribute.h).
But this works only when call site has both:
a) the format as a string literal
b) the types of arguments.
So:
func(ER(ER_BLAH), 10);
will silently not be checked, because ER(ER_BLAH) is not known at
compile time (it is known at run-time, and depends on the chosen
language).
And
func("%s", a va_list argument);
has the same problem, as the *real* type of arguments is not
known at this site at compile time (it's known in some caller).
Moreover,
func(ER(ER_BLAH));
though possibly correct (if ER(ER_BLAH) has no '%' markers), will not
compile (gcc says "error: format not a string literal and no format
arguments").
Consequences:
1) ATTRIBUTE_FORMAT is here added only to functions which in practice
take "string literal" formats: "my_error_reporter" and "print_admin_msg".
2) it cannot be added to the other functions: my_error(),
push_warning_printf(), Table_check_intact::report_error(),
general_log_print().
To do a one-time check of functions listed in (2), the following
"static code analysis" has been done:
1) replace
my_error(ER_xxx, arguments for substitution in format)
with the equivalent
my_printf_error(ER_xxx,ER(ER_xxx), arguments for substitution in
format),
so that we have ER(ER_xxx) and the arguments *in the same call site*
2) add ATTRIBUTE_FORMAT to push_warning_printf(),
Table_check_intact::report_error(), general_log_print()
3) replace ER(xxx) with the hard-coded English text found in
errmsg.txt (like: ER(ER_UNKNOWN_ERROR) is replaced with
"Unknown error"), so that a call site has the format as string literal
4) this way, ATTRIBUTE_FORMAT can effectively do its job
5) compile, fix errors detected by ATTRIBUTE_FORMAT
6) revert steps 1-2-3.
The present patch has no compiler error when submitted again to the
static code analysis above.
It cannot catch all problems though: see Field::set_warning(), in
which a call to push_warning_printf() has a variable error
(thus, not replacable by a string literal); I checked set_warning() calls
by hand though.
See also WL 5883 for one proposal to avoid such bugs from appearing
again in the future.
The issues fixed in the patch are:
a) mismatch in types (like 'int' passed to '%ld')
b) more arguments passed than specified in the format.
This patch resolves mismatches by changing the type/number of arguments,
not by changing error messages of sql/share/errmsg.txt. The latter would be wrong,
per the following old rule: errmsg.txt must be as stable as possible; no insertions
or deletions of messages, no changes of type or number of printf-like format specifiers,
are allowed, as long as the change impacts a message already released in a GA version.
If this rule is not followed:
- Connectors, which use error message numbers, will be confused (by insertions/deletions
of messages)
- using errmsg.sys of MySQL 5.1.n with mysqld of MySQL 5.1.(n+1)
could produce wrong messages or crash; such usage can easily happen if
installing 5.1.(n+1) while /etc/my.cnf still has --language=/path/to/5.1.n/xxx;
or if copying mysqld from 5.1.(n+1) into a 5.1.n installation.
When fixing b), I have verified that the superfluous arguments were not used in the format
in the first 5.1 GA (5.1.30 'bteam@astra04-20081114162938-z8mctjp6st27uobm').
Had they been used, then passing them today, even if the message doesn't use them
anymore, would have been necessary, as explained above.
include/my_getopt.h:
this function pointer is used only with "string literal" formats, so we can add
ATTRIBUTE_FORMAT.
mysql-test/collections/default.experimental:
test should pass now
sql/derror.cc:
by having a format as string literal, ATTRIBUTE_FORMAT check becomes effective.
sql/events.cc:
Change justified by the following excerpt from sql/share/errmsg.txt:
ER_EVENT_SAME_NAME
eng "Same old and new event name"
ER_EVENT_SET_VAR_ERROR
eng "Error during starting/stopping of the scheduler. Error code %u"
sql/field.cc:
ER_TOO_BIG_SCALE 42000 S1009
eng "Too big scale %d specified for column '%-.192s'. Maximum is %lu."
ER_TOO_BIG_PRECISION 42000 S1009
eng "Too big precision %d specified for column '%-.192s'. Maximum is %lu."
ER_TOO_BIG_DISPLAYWIDTH 42000 S1009
eng "Display width out of range for column '%-.192s' (max = %lu)"
sql/ha_ndbcluster.cc:
ER_OUTOFMEMORY HY001 S1001
eng "Out of memory; restart server and try again (needed %d bytes)"
(sizeof() returns size_t)
sql/ha_ndbcluster_binlog.cc:
Too many arguments for:
ER_GET_ERRMSG
eng "Got error %d '%-.100s' from %s"
Patch by Jonas Oreland.
sql/ha_partition.cc:
print_admin_msg() is used only with a literal as format, so ATTRIBUTE_FORMAT
works.
sql/handler.cc:
ER_OUTOFMEMORY HY001 S1001
eng "Out of memory; restart server and try again (needed %d bytes)"
(sizeof() returns size_t)
sql/item_create.cc:
ER_TOO_BIG_SCALE 42000 S1009
eng "Too big scale %d specified for column '%-.192s'. Maximum is %lu."
ER_TOO_BIG_PRECISION 42000 S1009
eng "Too big precision %d specified for column '%-.192s'. Maximum is %lu."
'c_len' and 'c_dec' are char*, passed as %d !! We don't know their value
(as strtoul() failed), but they are likely big, so we use INT_MAX.
'len' is ulong.
sql/item_func.cc:
ER_WARN_DATA_OUT_OF_RANGE 22003
eng "Out of range value for column '%s' at row %ld"
ER_CANT_FIND_UDF
eng "Can't load function '%-.192s'"
sql/item_strfunc.cc:
ER_TOO_BIG_FOR_UNCOMPRESS
eng "Uncompressed data size too large; the maximum size is %d (probably, length of uncompressed data was corrupted)"
max_allowed_packet is ulong.
sql/mysql_priv.h:
sql_print_message_func is a function _pointer_.
sql/sp_head.cc:
ER_SP_RECURSION_LIMIT
eng "Recursive limit %d (as set by the max_sp_recursion_depth variable) was exceeded for routine %.192s"
max_sp_recursion_depth is ulong
sql/sql_acl.cc:
ER_PASSWORD_NO_MATCH 42000
eng "Can't find any matching row in the user table"
ER_CANT_CREATE_USER_WITH_GRANT 42000
eng "You are not allowed to create a user with GRANT"
sql/sql_base.cc:
ER_NOT_KEYFILE
eng "Incorrect key file for table '%-.200s'; try to repair it"
ER_TOO_MANY_TABLES
eng "Too many tables; MySQL can only use %d tables in a join"
MAX_TABLES is size_t.
sql/sql_binlog.cc:
ER_UNKNOWN_ERROR
eng "Unknown error"
sql/sql_class.cc:
ER_TRUNCATED_WRONG_VALUE_FOR_FIELD
eng "Incorrect %-.32s value: '%-.128s' for column '%.192s' at row %ld"
WARN_DATA_TRUNCATED 01000
eng "Data truncated for column '%s' at row %ld"
sql/sql_connect.cc:
ER_HANDSHAKE_ERROR 08S01
eng "Bad handshake"
ER_BAD_HOST_ERROR 08S01
eng "Can't get hostname for your address"
sql/sql_insert.cc:
ER_WRONG_VALUE_COUNT_ON_ROW 21S01
eng "Column count doesn't match value count at row %ld"
sql/sql_parse.cc:
ER_WARN_HOSTNAME_WONT_WORK
eng "MySQL is started in --skip-name-resolve mode; you must restart it without this switch for this grant to work"
ER_TOO_HIGH_LEVEL_OF_NESTING_FOR_SELECT
eng "Too high level of nesting for select"
ER_UNKNOWN_ERROR
eng "Unknown error"
sql/sql_partition.cc:
ER_OUTOFMEMORY HY001 S1001
eng "Out of memory; restart server and try again (needed %d bytes)"
sql/sql_plugin.cc:
ER_OUTOFMEMORY HY001 S1001
eng "Out of memory; restart server and try again (needed %d bytes)"
sql/sql_prepare.cc:
ER_OUTOFMEMORY HY001 S1001
eng "Out of memory; restart server and try again (needed %d bytes)"
ER_UNKNOWN_STMT_HANDLER
eng "Unknown prepared statement handler (%.*s) given to %s"
length value (for '%.*s') must be 'int', per the doc of printf()
and the code of my_vsnprintf().
sql/sql_show.cc:
ER_OUTOFMEMORY HY001 S1001
eng "Out of memory; restart server and try again (needed %d bytes)"
sql/sql_table.cc:
ER_TOO_BIG_FIELDLENGTH 42000 S1009
eng "Column length too big for column '%-.192s' (max = %lu); use BLOB or TEXT instead"
sql/table.cc:
ER_NOT_FORM_FILE
eng "Incorrect information in file: '%-.200s'"
ER_COL_COUNT_DOESNT_MATCH_PLEASE_UPDATE
eng "Column count of mysql.%s is wrong. Expected %d, found %d. Created with MySQL %d, now running %d. Please use mysql_upgrade to fix this error."
table->s->mysql_version is ulong.
sql/unireg.cc:
ER_TOO_LONG_TABLE_COMMENT
eng "Comment for table '%-.64s' is too long (max = %lu)"
ER_TOO_LONG_FIELD_COMMENT
eng "Comment for field '%-.64s' is too long (max = %lu)"
ER_TOO_BIG_ROWSIZE 42000
eng "Row size too large. The maximum row size for the used table type, not counting BLOBs, is %ld. You have to change some columns to TEXT or BLOBs"
result set when SQLEXCEPTION is active.
The problem was in a hackish THD::no_warnings_for_error attribute.
When it was set, an error was not written to Warning_info -- only
Diagnostics_area state was changed. That means, Diagnostics_area
might contain error state, which is not present in Warning_info.
The user-visible problem was that in some cases SHOW WARNINGS
returned empty result set (i.e. there were no warnings) while
the previous SQL statement failed. According to the MySQL
protocol errors must be presented in warning list.
The main idea of this patch is to remove THD::no_warnings_for_error.
There were few places where it was used:
- sql_admin.cc, handling of REPAIR TABLE USE_FRM.
- sql_show.cc, when calling fill_schema_table_from_frm().
- sql_show.cc, when calling fill_table().
The fix is to either use internal-error-handlers, or to use
temporary Warning_info storing warnings, which might be ignored.
This patch is needed to fix Bug 11763162 (55843).
of service in prepared statements).
sql/sql_prepare.cc:
At mysql_stmt_get_longdata(): instead of pushing an internal
error handler (as done in 5.1-tree) we save, set and restore
the statement's diagnostics area and warning info.
The problem was that server didn't check resulting size of prepared
statement argument which was set using mysql_send_long_data() API.
By calling mysql_send_long_data() several times it was possible
to create overly big string and thus force server to allocate
memory for it. There was no way to limit this allocation.
The solution is to add check for size of result string against
value of max_long_data_size start-up parameter. When intermediate
string exceeds max_long_data_size value an appropriate error message
is emitted.
We can't use existing max_allowed_packet parameter for this purpose
since its value is limited by 1GB and therefore using it as a limit
for data set through mysql_send_long_data() API would have been an
incompatible change. Newly introduced max_long_data_size parameter
gets value from max_allowed_packet parameter unless its value is
specified explicitly. This new parameter is marked as deprecated
and will be eventually replaced by max_allowed_packet parameter.
Value of max_long_data_size parameter can be set only at server
startup.
mysql-test/t/variables.test:
Added checking for new start-up parameter max_long_data_size.
sql/item.cc:
Added call to my_message() when accumulated string exceeds
max_long_data_size value. my_message() calls error handler
that was installed in mysql_stmt_get_longdata before call
to Item_param::set_longdata.
The error handler then sets state, last_error and last_errno
fields for current statement to values which correspond to
error which was caught.
sql/mysql_priv.h:
Added max_long_data_size variable declaration.
sql/mysqld.cc:
Added support for start-up parameter 'max_long_data_size'.
This parameter limits size of data which can be sent from
client to server using mysql_send_long_data() API.
sql/set_var.cc:
Added variable 'max_long_data_size' into list of variables
displayed by command 'show variables'.
sql/sql_prepare.cc:
Added error handler class Set_longdata_error_handler.
This handler is used to catch any errors that can be
generated during execution of Item_param::set_longdata().
Source code snippet that makes checking for statement's state
during statement execution is moved from Prepared_statement::execute()
to Prepared_statement::execute_loop() in order not to call
set_parameters() when statement has failed during
set_long_data() execution. If this hadn't been done
the call to set_parameters() would have failed.
tests/mysql_client_test.c:
A testcase for the bug #56976 was added.
- Removed files specific to compiling on OS/2
- Removed files specific to SCO Unix packaging
- Removed "libmysqld/copyright", text is included in documentation
- Removed LaTeX headers for NDB Doxygen documentation
- Removed obsolete NDB files
- Removed "mkisofs" binaries
- Removed the "cvs2cl.pl" script
- Changed a few GPL texts to use "program" instead of "library"
--Bug#52157 various crashes and assertions with multi-table update, stored function
--Bug#54475 improper error handling causes cascading crashing failures in innodb/ndb
--Bug#57703 create view cause Assertion failed: 0, file .\item_subselect.cc, line 846
--Bug#57352 valgrind warnings when creating view
--Recently discovered problem when a nested materialized derived table is used
before being populated and it leads to incorrect result
We have several modes when we should disable subquery evaluation.
The reasons for disabling are different. It could be
uselessness of the evaluation as in case of 'CREATE VIEW'
or 'PREPARE stmt', or we should disable subquery evaluation
if tables are not locked yet as it happens in bug#54475, or
too early evaluation of subqueries can lead to wrong result
as it happened in Bug#19077.
Main problem is that if subquery items are treated as const
they are evaluated in ::fix_fields(), ::fix_length_and_dec()
of the parental items as a lot of these methods have
Item::val_...() calls inside.
We have to make subqueries non-const to prevent unnecessary
subquery evaluation. At the moment we have different methods
for this. Here is a list of these modes:
1. PREPARE stmt;
We use UNCACHEABLE_PREPARE flag.
It is set during parsing in sql_parse.cc, mysql_new_select() for
each SELECT_LEX object and cleared at the end of PREPARE in
sql_prepare.cc, init_stmt_after_parse(). If this flag is set
subquery becomes non-const and evaluation does not happen.
2. CREATE|ALTER VIEW, SHOW CREATE VIEW, I_S tables which
process FRM files
We use LEX::view_prepare_mode field. We set it before
view preparation and check this flag in
::fix_fields(), ::fix_length_and_dec().
Some bugs are fixed using this approach,
some are not(Bug#57352, Bug#57703). The problem here is
that we have a lot of ::fix_fields(), ::fix_length_and_dec()
where we use Item::val_...() calls for const items.
3. Derived tables with subquery = wrong result(Bug19077)
The reason of this bug is too early subquery evaluation.
It was fixed by adding Item::with_subselect field
The check of this field in appropriate places prevents
const item evaluation if the item have subquery.
The fix for Bug19077 fixes only the problem with
convert_constant_item() function and does not cover
other places(::fix_fields(), ::fix_length_and_dec() again)
where subqueries could be evaluated.
Example:
CREATE TABLE t1 (i INT, j BIGINT);
INSERT INTO t1 VALUES (1, 2), (2, 2), (3, 2);
SELECT * FROM (SELECT MIN(i) FROM t1
WHERE j = SUBSTRING('12', (SELECT * FROM (SELECT MIN(j) FROM t1) t2))) t3;
DROP TABLE t1;
4. Derived tables with subquery where subquery
is evaluated before table locking(Bug#54475, Bug#52157)
Suggested solution is following:
-Introduce new field LEX::context_analysis_only with the following
possible flags:
#define CONTEXT_ANALYSIS_ONLY_PREPARE 1
#define CONTEXT_ANALYSIS_ONLY_VIEW 2
#define CONTEXT_ANALYSIS_ONLY_DERIVED 4
-Set/clean these flags when we perform
context analysis operation
-Item_subselect::const_item() returns
result depending on LEX::context_analysis_only.
If context_analysis_only is set then we return
FALSE that means that subquery is non-const.
As all subquery types are wrapped by Item_subselect
it allow as to make subquery non-const when
it's necessary.
mysql-test/r/derived.result:
test case
mysql-test/r/multi_update.result:
test case
mysql-test/r/view.result:
test case
mysql-test/suite/innodb/r/innodb_multi_update.result:
test case
mysql-test/suite/innodb/t/innodb_multi_update.test:
test case
mysql-test/suite/innodb_plugin/r/innodb_multi_update.result:
test case
mysql-test/suite/innodb_plugin/t/innodb_multi_update.test:
test case
mysql-test/t/derived.test:
test case
mysql-test/t/multi_update.test:
test case
mysql-test/t/view.test:
test case
sql/item.cc:
--removed unnecessary code
sql/item_cmpfunc.cc:
--removed unnecessary checks
--THD::is_context_analysis_only() is replaced with LEX::is_ps_or_view_context_analysis()
sql/item_func.cc:
--refactored context analysis checks
sql/item_row.cc:
--removed unnecessary checks
sql/item_subselect.cc:
--removed unnecessary code
--added DBUG_ASSERT into Item_subselect::exec()
which asserts that subquery execution can not happen
if LEX::context_analysis_only is set, i.e. at context
analysis stage.
--Item_subselect::const_item()
Return FALSE if LEX::context_analysis_only is set.
It prevents subquery evaluation in ::fix_fields &
::fix_length_and_dec at context analysis stage.
sql/item_subselect.h:
--removed unnecessary code
sql/mysql_priv.h:
--Added new set of flags.
sql/sql_class.h:
--removed unnecessary code
sql/sql_derived.cc:
--added LEX::context_analysis_only analysis intialization/cleanup
sql/sql_lex.cc:
--init LEX::context_analysis_only field
sql/sql_lex.h:
--New LEX::context_analysis_only field
sql/sql_parse.cc:
--removed unnecessary code
sql/sql_prepare.cc:
--removed unnecessary code
--added LEX::context_analysis_only analysis intialization/cleanup
sql/sql_select.cc:
--refactored context analysis checks
sql/sql_show.cc:
--added LEX::context_analysis_only analysis intialization/cleanup
sql/sql_view.cc:
--added LEX::context_analysis_only analysis intialization/cleanup
Fixed the references to security_ctx->priv_user
to be real char * pointers instead of a C array name reference.
This is somehow important for some 3d party
dtrace replacements
Problem: Extended characters outside of ASCII range where not displayed
properly in SHOW PROCESSLIST, because thd_info->query was always sent as
system_character_set (utf8). This was wrong, because query buffer
is never converted to utf8 - it is always have client character set.
Fix: sending query buffer using query character set
@ sql/sql_class.cc
@ sql/sql_class.h
Introducing a new class CSET_STRING, a LEX_STRING with character set.
Adding set_query(&CSET_STRING)
Adding reset_query(), to use instead of set_query(0, NULL).
@ sql/event_data_objects.cc
Using reset_query()
@ sql/log_event.cc
Using reset_query()
Adding charset argument to set_query_and_id().
@ sql/slave.cc
Using reset_query().
@ sql/sp_head.cc
Changing backing up and restore code to use CSET_STRING.
@ sql/sql_audit.h
Using CSET_STRING.
In the "else" branch it's OK not to use
global_system_variables.character_set_client.
&my_charset_latin1, which is set in constructor, is fine
(verified with Sergey Vojtovich).
@ sql/sql_insert.cc
Using set_query() with proper character set: table_name is utf8.
@ sql/sql_parse.cc
Adding character set argument to set_query_and_id().
(This is the main point where thd->charset() is stored
into thd->query_string.cs, for use in "SHOW PROCESSLIST".)
Using reset_query().
@ sql/sql_prepare.cc
Storing client character set into thd->query_string.cs.
@ sql/sql_show.cc
Using CSET_STRING to fetch and send charset-aware query information
from threads.
@ storage/myisam/ha_myisam.cc
Using set_query() with proper character set: table_name is utf8.
@ mysql-test/r/show_check.result
@ mysql-test/t/show_check.test
Adding tests
during EXPLAIN
Before the patch, send_eof() of some subclasses of
select_result (e.g., select_send::send_eof()) could
handle being called after an error had occured while others
could not. The methods that were not well-behaved would trigger
an ASSERT on debug builds. Release builds were not affected.
Consider the following query as an example for how the ASSERT
could be triggered:
A user without execute privilege on f() does
SELECT MAX(key1) INTO @dummy FROM t1 WHERE f() < 1;
resulting in "ERROR 42000: execute command denied to user..."
The server would end the query by calling send_eof(). The
fact that the error had occured would make the ASSERT trigger.
select_dumpvar::send_eof() was the offending method in the
bug report, but the problem also applied to other
subclasses of select_result. This patch uniforms send_eof()
of all subclasses of select_result to handle being called
after an error has occured.
mysql-test/r/not_embedded_server.result:
Added test for BUG#54812
mysql-test/t/not_embedded_server.test:
Added test for BUG#54812
sql/sql_class.cc:
send_eof() of all subclasses of select_result can now handle being
called after an error has occured.
sql/sql_insert.cc:
send_eof() of all subclasses of select_result can now handle being
called after an error has occured.
Also fix call to abort() in select_create::send_eof(), which was supposed to abort the result set, not terminate the server. This call to abort() should have been changed when the function was renamed from abort_result_set() but was forgotten. New test case added by BUG#54812 covered this line and terminated server.
sql/sql_prepare.cc:
send_eof() of all subclasses of select_result can now handle being
called after an error has occured.
sql/sql_update.cc:
send_eof() of all subclasses of select_result can now handle being
called after an error has occured.
structure buffer).
This is a follow-up for WL#4435. The bug actually existed not only
MYSQL_TYPE_DATETIME type. The problem was that Item_param::set_value()
was written in an assumption that it's working with expressions, i.e.
with basic data types.
There are two different quick fixes here:
a) Change Item_param::make_field() -- remove setting of
Send_field::length, Send_field::charsetnr, Send_field::flags and
Send_field::type.
That would lead to marshalling all data using basic types to the client
(MYSQL_TYPE_LONGLONG, MYSQL_TYPE_DOUBLE, MYSQL_TYPE_STRING and
MYSQL_TYPE_NEWDECIMAL). In particular, that means, DATETIME would be
sent as MYSQL_TYPE_STRING, TINYINT -- as MYSQL_TYPE_LONGLONG, etc.
That could be Ok for the client, because the client library does
reverse conversion automatically (the client program would see DATETIME
as MYSQL_TIME object). However, there is a problem with metadata --
the metadata would be wrong (misleading): it would say that DATETIME is
marshaled as MYSQL_TYPE_DATETIME, not as MYSQL_TYPE_STRING.
b) Set Item_param::param_type properly to actual underlying field type.
That would lead to double conversion inside the server: for example,
MYSQL_TIME-object would be converted into STRING-object
(in Item_param::set_value()), and then converted back to MYSQL_TIME-object
(in Item_param::send()).
The data however would be marshalled more properly, and also metadata would
be correct.
This patch implements b).
There is also a possibility to avoid double conversion either by clonning
the data field, or by storing a reference to it and using it on Item::send()
time. That requires more work and might be done later.
bug #57006 "Deadlock between HANDLER and FLUSH TABLES WITH READ
LOCK" and bug #54673 "It takes too long to get readlock for
'FLUSH TABLES WITH READ LOCK'".
The first bug manifested itself as a deadlock which occurred
when a connection, which had some table open through HANDLER
statement, tried to update some data through DML statement
while another connection tried to execute FLUSH TABLES WITH
READ LOCK concurrently.
What happened was that FTWRL in the second connection managed
to perform first step of GRL acquisition and thus blocked all
upcoming DML. After that it started to wait for table open
through HANDLER statement to be flushed. When the first connection
tried to execute DML it has started to wait for GRL/the second
connection creating deadlock.
The second bug manifested itself as starvation of FLUSH TABLES
WITH READ LOCK statements in cases when there was a constant
stream of concurrent DML statements (in two or more
connections).
This has happened because requests for protection against GRL
which were acquired by DML statements were ignoring presence of
pending GRL and thus the latter was starved.
This patch solves both these problems by re-implementing GRL
using metadata locks.
Similar to the old implementation acquisition of GRL in new
implementation is two-step. During the first step we block
all concurrent DML and DDL statements by acquiring global S
metadata lock (each DML and DDL statement acquires global IX
lock for its duration). During the second step we block commits
by acquiring global S lock in COMMIT namespace (commit code
acquires global IX lock in this namespace).
Note that unlike in old implementation acquisition of
protection against GRL in DML and DDL is semi-automatic.
We assume that any statement which should be blocked by GRL
will either open and acquires write-lock on tables or acquires
metadata locks on objects it is going to modify. For any such
statement global IX metadata lock is automatically acquired
for its duration.
The first problem is solved because waits for GRL become
visible to deadlock detector in metadata locking subsystem
and thus deadlocks like one in the first bug become impossible.
The second problem is solved because global S locks which
are used for GRL implementation are given preference over
IX locks which are acquired by concurrent DML (and we can
switch to fair scheduling in future if needed).
Important change:
FTWRL/GRL no longer blocks DML and DDL on temporary tables.
Before this patch behavior was not consistent in this respect:
in some cases DML/DDL statements on temporary tables were
blocked while in others they were not. Since the main use cases
for FTWRL are various forms of backups and temporary tables are
not preserved during backups we have opted for consistently
allowing DML/DDL on temporary tables during FTWRL/GRL.
Important change:
This patch changes thread state names which are used when
DML/DDL of FTWRL is waiting for global read lock. It is now
either "Waiting for global read lock" or "Waiting for commit
lock" depending on the stage on which FTWRL is.
Incompatible change:
To solve deadlock in events code which was exposed by this
patch we have to replace LOCK_event_metadata mutex with
metadata locks on events. As result we have to prohibit
DDL on events under LOCK TABLES.
This patch also adds extensive test coverage for interaction
of DML/DDL and FTWRL.
Performance of new and old global read lock implementations
in sysbench tests were compared. There were no significant
difference between new and old implementations.
mysql-test/include/check_ftwrl_compatible.inc:
Added helper script which allows to check that a statement is
compatible with FLUSH TABLES WITH READ LOCK.
mysql-test/include/check_ftwrl_incompatible.inc:
Added helper script which allows to check that a statement is
incompatible with FLUSH TABLES WITH READ LOCK.
mysql-test/include/handler.inc:
Adjusted test case to the fact that now DROP TABLE closes
open HANDLERs for the table to be dropped before checking
if there active FTWRL in this connection.
mysql-test/include/wait_show_condition.inc:
Fixed small error in the timeout message. The correct name
of variable used as parameter for this script is "$condition"
and not "$wait_condition".
mysql-test/r/delayed.result:
Added test coverage for scenario which triggered assert in
metadata locking subsystem.
mysql-test/r/events_2.result:
Updated test results after prohibiting event DDL operations
under LOCK TABLES.
mysql-test/r/flush.result:
Added test coverage for bug #57006 "Deadlock between HANDLER
and FLUSH TABLES WITH READ LOCK".
mysql-test/r/flush_read_lock.result:
Added test coverage for various aspects of FLUSH TABLES WITH
READ LOCK functionality.
mysql-test/r/flush_read_lock_kill.result:
Adjusted test case after replacing custom global read lock
implementation with one based on metadata locks. Use new
debug_sync point. Do not disable concurrent inserts as now
InnoDB we always use InnoDB table.
mysql-test/r/handler_innodb.result:
Adjusted test case to the fact that now DROP TABLE closes
open HANDLERs for the table to be dropped before checking
if there active FTWRL in this connection.
mysql-test/r/handler_myisam.result:
Adjusted test case to the fact that now DROP TABLE closes
open HANDLERs for the table to be dropped before checking
if there active FTWRL in this connection.
mysql-test/r/mdl_sync.result:
Adjusted test case after replacing custom global read lock
implementation with one based on metadata locks. Replaced
usage of GRL-specific debug_sync's with appropriate sync
points in MDL subsystem.
mysql-test/suite/perfschema/r/dml_setup_instruments.result:
Updated test results after removing global
COND_global_read_lock condition variable.
mysql-test/suite/perfschema/r/func_file_io.result:
Ensure that this test doesn't affect subsequent tests.
At the end of its execution enable back P_S instrumentation
which this test disables at some point.
mysql-test/suite/perfschema/r/func_mutex.result:
Ensure that this test doesn't affect subsequent tests.
At the end of its execution enable back P_S instrumentation
which this test disables at some point.
mysql-test/suite/perfschema/r/global_read_lock.result:
Adjusted test case to take into account that new GRL
implementation is based on MDL.
mysql-test/suite/perfschema/r/server_init.result:
Adjusted test case after replacing custom global read
lock implementation with one based on MDL and replacing
LOCK_event_metadata mutex with metadata lock.
mysql-test/suite/perfschema/t/func_file_io.test:
Ensure that this test doesn't affect subsequent tests.
At the end of its execution enable back P_S instrumentation
which this test disables at some point.
mysql-test/suite/perfschema/t/func_mutex.test:
Ensure that this test doesn't affect subsequent tests.
At the end of its execution enable back P_S instrumentation
which this test disables at some point.
mysql-test/suite/perfschema/t/global_read_lock.test:
Adjusted test case to take into account that new GRL
implementation is based on MDL.
mysql-test/suite/perfschema/t/server_init.test:
Adjusted test case after replacing custom global read
lock implementation with one based on MDL and replacing
LOCK_event_metadata mutex with metadata lock.
mysql-test/suite/rpl/r/rpl_tmp_table_and_DDL.result:
Updated test results after prohibiting event DDL under
LOCK TABLES.
mysql-test/t/delayed.test:
Added test coverage for scenario which triggered assert in
metadata locking subsystem.
mysql-test/t/events_2.test:
Updated test case after prohibiting event DDL operations
under LOCK TABLES.
mysql-test/t/flush.test:
Added test coverage for bug #57006 "Deadlock between HANDLER
and FLUSH TABLES WITH READ LOCK".
mysql-test/t/flush_block_commit.test:
Adjusted test case after changing thread state name which
is used when COMMIT waits for FLUSH TABLES WITH READ LOCK
from "Waiting for release of readlock" to "Waiting for commit
lock".
mysql-test/t/flush_block_commit_notembedded.test:
Adjusted test case after changing thread state name which is
used when DML waits for FLUSH TABLES WITH READ LOCK. Now we
use "Waiting for global read lock" in this case.
mysql-test/t/flush_read_lock.test:
Added test coverage for various aspects of FLUSH TABLES WITH
READ LOCK functionality.
mysql-test/t/flush_read_lock_kill-master.opt:
We no longer need to use make_global_read_lock_block_commit_loop
debug tag in this test. Instead we rely on an appropriate
debug_sync point in MDL code.
mysql-test/t/flush_read_lock_kill.test:
Adjusted test case after replacing custom global read lock
implementation with one based on metadata locks. Use new
debug_sync point. Do not disable concurrent inserts as now
InnoDB we always use InnoDB table.
mysql-test/t/lock_multi.test:
Adjusted test case after changing thread state names which
are used when DML or DDL waits for FLUSH TABLES WITH READ
LOCK to "Waiting for global read lock".
mysql-test/t/mdl_sync.test:
Adjusted test case after replacing custom global read lock
implementation with one based on metadata locks. Replaced
usage of GRL-specific debug_sync's with appropriate sync
points in MDL subsystem. Updated thread state names which
are used when DDL waits for FTWRL.
mysql-test/t/trigger_notembedded.test:
Adjusted test case after changing thread state names which
are used when DML or DDL waits for FLUSH TABLES WITH READ
LOCK to "Waiting for global read lock".
sql/event_data_objects.cc:
Removed Event_queue_element::status/last_executed_changed
members and Event_queue_element::update_timing_fields()
method. We no longer use this class for updating mysql.events
once event is chosen for execution. Accesses to instances of
this class in scheduler thread require protection by
Event_queue::LOCK_event_queue mutex and we try to avoid
updating table while holding this lock.
sql/event_data_objects.h:
Removed Event_queue_element::status/last_executed_changed
members and Event_queue_element::update_timing_fields()
method. We no longer use this class for updating mysql.events
once event is chosen for execution. Accesses to instances of
this class in scheduler thread require protection by
Event_queue::LOCK_event_queue mutex and we try to avoid
updating table while holding this lock.
sql/event_db_repository.cc:
- Changed Event_db_repository methods to not release all
metadata locks once they are done updating mysql.events
table. This allows to keep metadata lock protecting
against GRL and lock protecting particular event around
until corresponding DDL statement is written to the binary
log.
- Removed logic for conditional update of "status" and
"last_executed" fields from update_timing_fields_for_event()
method. In the only case when this method is called now
"last_executed" is always modified and tracking change
of "status" is too much hassle.
sql/event_db_repository.h:
Removed logic for conditional update of "status" and
"last_executed" fields from Event_db_repository::
update_timing_fields_for_event() method.
In the only case when this method is called now "last_executed"
is always modified and tracking change of "status" field is
too much hassle.
sql/event_queue.cc:
Changed event scheduler code not to update mysql.events
table while holding Event_queue::LOCK_event_queue mutex.
Doing so led to a deadlock with a new GRL implementation.
This deadlock didn't occur with old implementation due to
fact that code acquiring protection against GRL ignored
pending GRL requests (which lead to GRL starvation).
One of goals of new implementation is to disallow GRL
starvation and so we have to solve problem with this
deadlock in a different way.
sql/events.cc:
Changed methods of Events class to acquire protection
against GRL while perfoming DDL statement and keep it
until statement is written to the binary log.
Unfortunately this step together with new GRL implementation
exposed deadlock involving Events::LOCK_event_metadata
and GRL. To solve it Events::LOCK_event_metadata mutex was
replaced with a metadata lock on event. As a side-effect
events DDL has to be prohibited under LOCK TABLES even in
cases when mysql.events table was explicitly locked for
write.
sql/events.h:
Replaced Events::LOCK_event_metadata mutex with a metadata
lock on event.
sql/ha_ndbcluster.cc:
Updated code after replacing custom global read lock
implementation with one based on MDL. Since MDL subsystem
should now be able to detect deadlocks involving metadata
locks and GRL there is no need for special handling of
active GRL.
sql/handler.cc:
Replaced custom implementation of global read lock with
one based on metadata locks. Consequently when doing
commit instead of calling method of Global_read_lock
class to acquire protection against GRL we simply acquire
IX in COMMIT namespace.
sql/lock.cc:
Replaced custom implementation of global read lock with
one based on metadata locks. This step allows to expose
wait for GRL to deadlock detector of MDL subsystem and
thus succesfully resolve deadlocks similar to one behind
bug #57006 "Deadlock between HANDLER and FLUSH TABLES
WITH READ LOCK". It also solves problem with GRL starvation
described in bug #54673 "It takes too long to get readlock
for 'FLUSH TABLES WITH READ LOCK'" since metadata locks used
by GRL give preference to FTWRL statement instead of DML
statements (if needed in future this can be changed to
fair scheduling).
Similar to old implementation of acquisition of GRL is
two-step. During the first step we block all concurrent
DML and DDL statements by acquiring global S metadata lock
(each DML and DDL statement acquires global IX lock for
its duration). During the second step we block commits by
acquiring global S lock in COMMIT namespace (commit code
acquires global IX lock in this namespace).
Note that unlike in old implementation acquisition of
protection against GRL in DML and DDL is semi-automatic.
We assume that any statement which should be blocked by GRL
will either open and acquires write-lock on tables or acquires
metadata locks on objects it is going to modify. For any such
statement global IX metadata lock is automatically acquired
for its duration.
To support this change:
- Global_read_lock::lock/unlock_global_read_lock and
make_global_read_lock_block_commit methods were changed
accordingly.
- Global_read_lock::wait_if_global_read_lock() and
start_waiting_global_read_lock() methods were dropped.
It is now responsibility of code acquiring metadata locks
opening tables to acquire protection against GRL by
explicitly taking global IX lock with statement duration.
- Global variables, mutex and condition variable used by
old implementation was removed.
- lock_routine_name() was changed to use statement duration for
its global IX lock. It was also renamed to lock_object_name()
as it now also used to take metadata locks on events.
- Global_read_lock::set_explicit_lock_duration() was added which
allows not to release locks used for GRL when leaving prelocked
mode.
sql/lock.h:
- Renamed lock_routine_name() to lock_object_name() and changed
its signature to allow its usage for events.
- Removed broadcast_refresh() function. It is no longer needed
with new GRL implementation.
sql/log_event.cc:
Release metadata locks with statement duration at the end
of processing legacy event for LOAD DATA. This ensures that
replication thread processing such event properly releases
its protection against global read lock.
sql/mdl.cc:
Changed MDL subsystem to support new MDL-based implementation
of global read lock.
Added COMMIT and EVENTS namespaces for metadata locks. Changed
thread state name for GLOBAL namespace to "Waiting for global
read lock".
Optimized MDL_map::find_or_insert() method to avoid taking
m_mutex mutex when looking up MDL_lock objects for GLOBAL
or COMMIT namespaces. We keep pre-created MDL_lock objects
for these namespaces around and simply return pointers to
these global objects when needed.
Changed MDL_lock/MDL_scoped_lock to properly handle
notification of insert delayed handler threads when FTWRL
takes global S lock.
Introduced concept of lock duration. In addition to locks with
transaction duration which work in the way which is similar to
how locks worked before (i.e. they are released at the end of
transaction), locks with statement and explicit duration were
introduced.
Locks with statement duration are automatically released at the
end of statement. Locks with explicit duration require explicit
release and obsolete concept of transactional sentinel.
* Changed MDL_request and MDL_ticket classes to support notion
of duration.
* Changed MDL_context to keep locks with different duration in
different lists. Changed code handling ticket list to take
this into account.
* Changed methods responsible for releasing locks to take into
account duration of tickets. Particularly public
MDL_context::release_lock() method now only can release
tickets with explicit duration (there is still internal
method which allows to specify duration). To release locks
with statement or transaction duration one have to use
release_statement/transactional_locks() methods.
* Concept of savepoint for MDL subsystem now has to take into
account locks with statement duration. Consequently
MDL_savepoint class was introduced and methods working with
savepoints were updated accordingly.
* Added methods which allow to set duration for one or all
locks in the context.
sql/mdl.h:
Changed MDL subsystem to support new MDL-based implementation
of global read lock.
Added COMMIT and EVENTS namespaces for metadata locks.
Introduced concept of lock duration. In addition to locks with
transaction duration which work in the way which is similar to
how locks worked before (i.e. they are released at the end of
transaction), locks with statement and explicit duration were
introduced.
Locks with statement duration are automatically released at the
end of statement. Locks with explicit duration require explicit
release and obsolete concept of transactional sentinel.
* Changed MDL_request and MDL_ticket classes to support notion
of duration.
* Changed MDL_context to keep locks with different duration in
different lists. Changed code handling ticket list to take
this into account.
* Changed methods responsible for releasing locks to take into
account duration of tickets. Particularly public
MDL_context::release_lock() method now only can release
tickets with explicit duration (there is still internal
method which allows to specify duration). To release locks
with statement or transaction duration one have to use
release_statement/transactional_locks() methods.
* Concept of savepoint for MDL subsystem now has to take into
account locks with statement duration. Consequently
MDL_savepoint class was introduced and methods working with
savepoints were updated accordingly.
* Added methods which allow to set duration for one or all
locks in the context.
sql/mysqld.cc:
Removed global mutex and condition variables which were used
by old implementation of GRL.
Also we no longer need to initialize Events::LOCK_event_metadata
mutex as it was replaced with metadata locks on events.
sql/mysqld.h:
Removed global variable, mutex and condition variables which
were used by old implementation of GRL.
sql/rpl_rli.cc:
When slave thread closes tables which were open for handling
of RBR events ensure that it releases global IX lock which
was acquired as protection against GRL.
sql/sp.cc:
Adjusted code to the new signature of lock_object/routine_name(),
to the fact that one now needs specify duration of lock when
initializing MDL_request and to the fact that savepoints for MDL
subsystem are now represented by MDL_savepoint class.
sql/sp_head.cc:
Ensure that statements in stored procedures release statement
metadata locks and thus release their protectiong against GRL
in proper moment in time.
Adjusted code to the fact that one now needs specify duration
of lock when initializing MDL_request.
sql/sql_admin.cc:
Adjusted code to the fact that one now needs specify duration
of lock when initializing MDL_request.
sql/sql_base.cc:
- Implemented support for new approach to acquiring protection
against global read lock. We no longer acquire such protection
explicitly on the basis of statement flags. Instead we always
rely on code which is responsible for acquiring metadata locks
on object to be changed acquiring this protection. This is
achieved by acquiring global IX metadata lock with statement
duration. Code doing this also responsible for checking that
current connection has no active GRL by calling an
Global_read_lock::can_acquire_protection() method.
Changed code in open_table() and lock_table_names()
accordingly.
Note that as result of this change DDL and DML on temporary
tables is always compatible with GRL (before it was
incompatible in some cases and compatible in other cases).
- To speed-up code acquiring protection against GRL introduced
m_has_protection_against_grl member in Open_table_context
class. It indicates that protection was already acquired
sometime during open_tables() execution and new attempts
can be skipped.
- Thanks to new GRL implementation calls to broadcast_refresh()
became unnecessary and were removed.
- Adjusted code to the fact that one now needs specify duration
of lock when initializing MDL_request and to the fact that
savepoints for MDL subsystem are now represented by
MDL_savepoint class.
sql/sql_base.h:
Adjusted code to the fact that savepoints for MDL subsystem are
now represented by MDL_savepoint class.
Also introduced Open_table_context::m_has_protection_against_grl
member which allows to avoid acquiring protection against GRL
while opening tables if such protection was already acquired.
sql/sql_class.cc:
Changed THD::leave_locked_tables_mode() after transactional
sentinel for metadata locks was obsoleted by introduction of
locks with explicit duration.
sql/sql_class.h:
- Adjusted code to the fact that savepoints for MDL subsystem
are now represented by MDL_savepoint class.
- Changed Global_read_lock class according to changes in
global read lock implementation:
* wait_if_global_read_lock and start_waiting_global_read_lock
are now gone. Instead code needing protection against GRL
has to acquire global IX metadata lock with statement
duration itself. To help it new can_acquire_protection()
was introduced. Also as result of the above change
m_protection_count member is gone too.
* Added m_mdl_blocks_commits_lock member to store metadata
lock blocking commits.
* Adjusted code to the fact that concept of transactional
sentinel was obsoleted by concept of lock duration.
- Removed CF_PROTECT_AGAINST_GRL flag as it is no longer
necessary. New GRL implementation acquires protection
against global read lock automagically when statement
acquires metadata locks on tables or other objects it
is going to change.
sql/sql_db.cc:
Adjusted code to the fact that one now needs specify duration
of lock when initializing MDL_request.
sql/sql_handler.cc:
Removed call to broadcast_refresh() function. It is no longer
needed with new GRL implementation.
Adjusted code after introducing duration concept for metadata
locks. Particularly to the fact transactional sentinel was
replaced with explicit duration.
sql/sql_handler.h:
Renamed mysql_ha_move_tickets_after_trans_sentinel() to
mysql_ha_set_explicit_lock_duration() after transactional
sentinel was obsoleted by locks with explicit duration.
sql/sql_insert.cc:
Adjusted code handling delaying inserts after switching to
new GRL implementation. Now connection thread initiating
delayed insert has to acquire global IX lock in addition
to metadata lock on table being inserted into. This IX lock
protects against GRL and similarly to SW lock on table being
inserted into has to be passed to handler thread in order to
avoid deadlocks.
sql/sql_lex.cc:
LEX::protect_against_global_read_lock member is no longer
necessary since protection against GRL is automatically
taken by code acquiring metadata locks/opening tables.
sql/sql_lex.h:
LEX::protect_against_global_read_lock member is no longer
necessary since protection against GRL is automatically
taken by code acquiring metadata locks/opening tables.
sql/sql_parse.cc:
- Implemented support for new approach to acquiring protection
against global read lock. We no longer acquire such protection
explicitly on the basis of statement flags. Instead we always
rely on code which is responsible for acquiring metadata locks
on object to be changed acquiring this protection. This is
achieved by acquiring global IX metadata lock with statement
duration. This lock is automatically released at the end of
statement execution.
- Changed implementation of CREATE/DROP PROCEDURE/FUNCTION not
to release metadata locks and thus protection against of GRL
in the middle of statement execution.
- Adjusted code to the fact that one now needs specify duration
of lock when initializing MDL_request and to the fact that
savepoints for MDL subsystem are now represented by
MDL_savepoint class.
sql/sql_prepare.cc:
Adjusted code to the to the fact that savepoints for MDL
subsystem are now represented by MDL_savepoint class.
sql/sql_rename.cc:
With new GRL implementation there is no need to explicitly
acquire protection against GRL before renaming tables.
This happens automatically in code which acquires metadata
locks on tables being renamed.
sql/sql_show.cc:
Adjusted code to the fact that one now needs specify duration
of lock when initializing MDL_request and to the fact that
savepoints for MDL subsystem are now represented by
MDL_savepoint class.
sql/sql_table.cc:
- With new GRL implementation there is no need to explicitly
acquire protection against GRL before dropping tables.
This happens automatically in code which acquires metadata
locks on tables being dropped.
- Changed mysql_alter_table() not to release lock on new table
name explicitly and to rely on automatic release of locks
at the end of statement instead. This was necessary since
now MDL_context::release_lock() is supported only for locks
for explicit duration.
sql/sql_trigger.cc:
With new GRL implementation there is no need to explicitly
acquire protection against GRL before changing table triggers.
This happens automatically in code which acquires metadata
locks on tables which triggers are to be changed.
sql/sql_update.cc:
Fix bug exposed by GRL testing. During prepare phase acquire
only S metadata locks instead of SW locks to keep prepare of
multi-UPDATE compatible with concurrent LOCK TABLES WRITE
and global read lock.
sql/sql_view.cc:
With new GRL implementation there is no need to explicitly
acquire protection against GRL before creating view.
This happens automatically in code which acquires metadata
lock on view to be created.
sql/sql_yacc.yy:
LEX::protect_against_global_read_lock member is no longer
necessary since protection against GRL is automatically
taken by code acquiring metadata locks/opening tables.
sql/table.cc:
Adjusted code to the fact that one now needs specify duration
of lock when initializing MDL_request.
sql/table.h:
Adjusted code to the fact that one now needs specify duration
of lock when initializing MDL_request.
sql/transaction.cc:
Replaced custom implementation of global read lock with
one based on metadata locks. Consequently when doing
commit instead of calling method of Global_read_lock
class to acquire protection against GRL we simply acquire
IX in COMMIT namespace.
Also adjusted code to the fact that MDL savepoint is now
represented by MDL_savepoint class.
In case of outer join and emtpy WHERE conditon
'always true' condition is created for WHERE clasue.
Later in mysql_select() original SELECT_LEX WHERE
condition is overwritten with created cond.
However SELECT_LEX condition is also used as inital
condition in mysql_select()->JOIN::prepare().
On second execution of PS modified SELECT_LEX condition
is taken and it leads to crash.
The fix is to restore original SELECT_LEX condition
(set to NULL if original cond is NULL) in
reinit_stmt_before_use().
HAVING clause is fixed too for safety reason
(no test case as I did not manage to think out
appropriate example).
mysql-test/r/ps.result:
test case
mysql-test/t/ps.test:
test case
sql/sql_prepare.cc:
restore original SELECT_LEX condition
(set to NULL if original cond is NULL) in
reinit_stmt_before_use()
'CREATE TABLE IF NOT EXISTS ... SELECT' behaviour
BUG#47132, BUG#47442, BUG49494, BUG#23992 and BUG#48814 will disappear
automatically after the this patch.
BUG#55617 is fixed by this patch too.
This is the 5.5 part.
It implements:
- 'CREATE TABLE IF NOT EXISTS ... SELECT' statement will not insert
anything and binlog anything if the table already exists.
It only generate a warning that table already exists.
- A couple of test cases for the behavior changing.
Fix a regression (due to a typo) which caused spurious incorrect
argument errors for long data stream parameters if all forms of
logging were disabled (binary, general and slow logs).
sql/sql_prepare.cc:
Add a missing logical NOT operator.
Fix a regression (due to a typo) which caused spurious incorrect
argument errors for long data stream parameters if all forms of
logging were disabled (binary, general and slow logs).
mysql-test/t/mysql_client_test.test:
Save the status of the slow_log.
sql/sql_prepare.cc:
Add a missing logical NOT operator.
tests/mysql_client_test.c:
Disable all query logs when running C tests. Fixes a omission
when, slow log should have been disabled too.
Run test case for Bug#54041 with query logs enabled and disabled.
Remove dead and unused code.
Update to reflect the code review requests.
include/thr_lock.h:
Remove declarations for THR_LOCK_OWNER,
added along with the patch for sensitive cursors.
mysys/thr_lock.c:
Remove support for multiple thr_lock requestors
per THD.
sql/lock.cc:
Revert the patch that added support for sensitive cursors.
sql/sp_rcontext.cc:
Updated the use of mysql_open_cursor().
sql/sql_class.cc:
Move the instance of Server_side_cursor
from class Prepared_statement to class Statement.
sql/sql_class.h:
Move the isntance of Server_side_cursor
from class Prepared_statement to class
Statement.
Remove multiple lock_ids of thr_lock.
sql/sql_cursor.cc:
Remove Sensitive_cursor implementation.
sql/sql_cursor.h:
Remove declarations for sensitive cursors.
sql/sql_prepare.cc:
Move the declaration of instance of Server_side_cursor
from class Statement to class Prepared_statement,
where it's used.
sql/sql_select.cc:
Remove sensitive cursor support.
sql/sql_select.h:
Remove sensitive cursor support.
sql/sql_union.cc:
Remove sensitive cursor support.
This patch also fixes Bug#55452 "SET PASSWORD is
replicated twice in RBR mode".
The goal of this patch is to remove the release of
metadata locks from close_thread_tables().
This is necessary to not mistakenly release
the locks in the course of a multi-step
operation that involves multiple close_thread_tables()
or close_tables_for_reopen().
On the same token, move statement commit outside
close_thread_tables().
Other cleanups:
Cleanup COM_FIELD_LIST.
Don't call close_thread_tables() in COM_SHUTDOWN -- there
are no open tables there that can be closed (we leave
the locked tables mode in THD destructor, and this
close_thread_tables() won't leave it anyway).
Make open_and_lock_tables() and open_and_lock_tables_derived()
call close_thread_tables() upon failure.
Remove the calls to close_thread_tables() that are now
unnecessary.
Simplify the back off condition in Open_table_context.
Streamline metadata lock handling in LOCK TABLES
implementation.
Add asserts to ensure correct life cycle of
statement transaction in a session.
Remove a piece of dead code that has also become redundant
after the fix for Bug 37521.
mysql-test/r/variables.result:
Update results: set @@autocommit and statement transaction/
prelocked mode.
mysql-test/r/view.result:
A harmless change in CHECK TABLE <view> status for a broken view.
If previously a failure to prelock all functions used in a view
would leave the connection in LTM_PRELOCKED mode, now we call
close_thread_tables() from open_and_lock_tables()
and leave prelocked mode, thus some check in mysql_admin_table() that
works only in prelocked/locked tables mode is no longer activated.
mysql-test/suite/rpl/r/rpl_row_implicit_commit_binlog.result:
Fixed Bug#55452 "SET PASSWORD is replicated twice in
RBR mode": extra binlog events are gone from the
binary log.
mysql-test/t/variables.test:
Add a test case: set autocommit and statement transaction/prelocked
mode.
sql/event_data_objects.cc:
Simplify code in Event_job_data::execute().
Move sp_head memory management to lex_end().
sql/event_db_repository.cc:
Move the release of metadata locks outside
close_thread_tables().
Make sure we call close_thread_tables() when
open_and_lock_tables() fails and remove extra
code from the events data dictionary.
Use close_mysql_tables(), a new internal
function to properly close mysql.* tables
in the data dictionary.
Contract Event_db_repository::drop_events_by_field,
drop_schema_events into one function.
When dropping all events in a schema,
make sure we don't mistakenly release all
locks acquired by DROP DATABASE. These
include locks on the database name
and the global intention exclusive
metadata lock.
sql/event_db_repository.h:
Function open_event_table() does not require an instance
of Event_db_repository.
sql/events.cc:
Use close_mysql_tables() instead of close_thread_tables()
to bootstrap events, since the latter no longer
releases metadata locks.
sql/ha_ndbcluster.cc:
- mysql_rm_table_part2 no longer releases
acquired metadata locks. Do it in the caller.
sql/ha_ndbcluster_binlog.cc:
Deploy the new protocol for closing thread
tables in run_query() and ndb_binlog_index
code.
sql/handler.cc:
Assert that we never call ha_commit_trans/
ha_rollback_trans in sub-statement, which
is now the case.
sql/handler.h:
Add an accessor to check whether THD_TRANS object
is empty (has no transaction started).
sql/log.cc:
Update a comment.
sql/log_event.cc:
Since now we commit/rollback statement transaction in
mysql_execute_command(), we need a mechanism to communicate
from Query_log_event::do_apply_event() to mysql_execute_command()
that the statement transaction should be rolled back, not committed.
Ideally it would be a virtual method of THD. I hesitate
to make THD a virtual base class in this already large patch.
Use a thd->variables.option_bits for now.
Remove a call to close_thread_tables() from the slave IO
thread. It doesn't open any tables, and the protocol
for closing thread tables is more complicated now.
Make sure we properly close thread tables, however,
in Load_data_log_event, which doesn't
follow the standard server execution procedure
with mysql_execute_command().
@todo: this piece should use Server_runnable
framework instead.
Remove an unnecessary call to mysql_unlock_tables().
sql/rpl_rli.cc:
Update Relay_log_info::slave_close_thread_tables()
to follow the new close protocol.
sql/set_var.cc:
Remove an unused header.
sql/slave.cc:
Remove an unnecessary call to
close_thread_tables().
sql/sp.cc:
Remove unnecessary calls to close_thread_tables()
from SP DDL implementation. The tables will
be closed by the caller, in mysql_execute_command().
When dropping all routines in a database, make sure
to not mistakenly drop all metadata locks acquired
so far, they include the scoped lock on the schema.
sql/sp_head.cc:
Correct the protocol that closes thread tables
in an SP instruction.
Clear lex->sphead before cleaning up lex
with lex_end to make sure that we don't
delete the sphead twice. It's considered
to be "cleaner" and more in line with
future changes than calling delete lex->sphead
in other places that cleanup the lex.
sql/sp_head.h:
When destroying m_lex_keeper of an instruction,
don't delete the sphead that all lex objects
share.
@todo: don't store a reference to routine's sp_head
instance in instruction's lex.
sql/sql_acl.cc:
Don't call close_thread_tables() where the caller will
do that for us.
Fix Bug#55452 "SET PASSWORD is replicated twice in RBR
mode" by disabling RBR replication in change_password()
function.
Use close_mysql_tables() in bootstrap and ACL reload
code to make sure we release all metadata locks.
sql/sql_base.cc:
This is the main part of the patch:
- remove manipulation with thd->transaction
and thd->mdl_context from close_thread_tables().
Now this function is only responsible for closing
tables, nothing else.
This is necessary to be able to easily use
close_thread_tables() in procedures, that
involve multiple open/close tables, which all
need to be protected continuously by metadata
locks.
Add asserts ensuring that TABLE object
is only used when is protected by a metadata lock.
Simplify the back off condition of Open_table_context,
we no longer need to look at the autocommit mode.
Make open_and_lock_tables() and open_normal_and_derived_tables()
close thread tables and release metadata locks acquired so-far
upon failure. This simplifies their usage.
Implement close_mysql_tables().
sql/sql_base.h:
Add declaration for close_mysql_tables().
sql/sql_class.cc:
Remove a piece of dead code that has also become redundant
after the fix for Bug 37521.
The code became dead when my_eof() was made a non-protocol method,
but a method that merely modifies the diagnostics area.
The code became redundant with the fix for Bug#37521, when
we started to cal close_thread_tables() before
Protocol::end_statement().
sql/sql_do.cc:
Do nothing in DO if inside a substatement
(the assert moved out of trans_rollback_stmt).
sql/sql_handler.cc:
Add comments.
sql/sql_insert.cc:
Remove dead code.
Release metadata locks explicitly at the
end of the delayed insert thread.
sql/sql_lex.cc:
Add destruction of lex->sphead to lex_end(),
lex "reset" method called at the end of each statement.
sql/sql_parse.cc:
Move close_thread_tables() and other related
cleanups to mysql_execute_command()
from dispatch_command(). This has become
possible after the fix for Bug#37521.
Mark federated SERVER statements as DDL.
Next step: make sure that we don't store
eof packet in the query cache, and move
the query cache code outside mysql_parse.
Brush up the code of COM_FIELD_LIST.
Remove unnecessary calls to close_thread_tables().
When killing a query, don't report "OK"
if it was a suicide.
sql/sql_parse.h:
Remove declaration of a function that is now static.
sql/sql_partition.cc:
Remove an unnecessary call to close_thread_tables().
sql/sql_plugin.cc:
open_and_lock_tables() will clean up
after itself after a failure.
Move close_thread_tables() above
end: label, and replace with close_mysql_tables(),
which will also release the metadata lock
on mysql.plugin.
sql/sql_prepare.cc:
Now that we no longer release locks in close_thread_tables()
statement prepare code has become more straightforward.
Remove the now redundant check for thd->killed() (used
only by the backup project) from Execute_server_runnable.
Reorder code to take into account that now mysql_execute_command()
performs lex->unit.cleanup() and close_thread_tables().
sql/sql_priv.h:
Add a new option to server options to interact
between the slave SQL thread and execution
framework (hack). @todo: use a virtual
method of class THD instead.
sql/sql_servers.cc:
Due to Bug 25705 replication of
DROP/CREATE/ALTER SERVER is broken.
Make sure at least we do not attempt to
replicate these statements using RBR,
as this violates the assert in close_mysql_tables().
sql/sql_table.cc:
Do not release metadata locks in mysql_rm_table_part2,
this is done by the caller.
Do not call close_thread_tables() in mysql_create_table(),
this is done by the caller.
Fix a bug in DROP TABLE under LOCK TABLES when,
upon error in wait_while_table_is_used() we would mistakenly
release the metadata lock on a non-dropped table.
Explicitly release metadata locks when doing an implicit
commit.
sql/sql_trigger.cc:
Now that we delete lex->sphead in lex_end(),
zero the trigger's sphead in lex after loading
the trigger, to avoid double deletion.
sql/sql_udf.cc:
Use close_mysql_tables() instead of close_thread_tables().
sql/sys_vars.cc:
Remove code added in scope of WL#4284 which would
break when we perform set @@session.autocommit along
with setting other variables and using tables or functions.
A test case added to variables.test.
sql/transaction.cc:
Add asserts.
sql/tztime.cc:
Use close_mysql_tables() rather than close_thread_tables().
to write into a closed socket
sql/protocol.cc:
Protocol::flush modified: set thd->main_da.can_overwrite_status= TRUE
before call to net_flush() in order to prevent crash on assert in case
of socket write failure, reset it to FALSE when net_flush() returned;
Protocol::send_fields modified: return from method with error if call to
my_net_write(), proto.write() or write_eof_packet() failed.
sql/sql_cache.cc:
Query_cache::send_result_to_client modified: call to
thd->main_da.disable_status() only if write to socket
was successful.
sql/sql_cursor.cc:
Materialized_cursor::fetch modified: leave method if call to
result->send_data() failed.
sql/sql_prepare.cc:
send_prep_stmt() modified: call to thd->main_da.disable_status()
only if thd->protocol_text.send_fields() completed successfully.
The problem was that a user could supply supply data in chunks
via the COM_STMT_SEND_LONG_DATA command to prepared statement
parameter other than of type TEXT or BLOB. This posed a problem
since other parameter types aren't setup to handle long data,
which would lead to a crash when attempting to use the supplied
data.
Given that long data can be supplied at any stage of a prepared
statement, coupled with the fact that the type of a parameter
marker might change between consecutive executions, the solution
is to validate at execution time each parameter marker for which
a data stream was provided. If the parameter type is not TEXT or
BLOB (that is, if the type is not able to handle a data stream),
a error is returned.
sql/sql_prepare.cc:
Before converting the parameter data stream, check the type
compatibility.
tests/mysql_client_test.c:
Add test case.
strict aliasing violations.
One somewhat major source of strict-aliasing violations and
related warnings is the SQL_LIST structure. For example,
consider its member function `link_in_list` which takes
a pointer to pointer of type T (any type) as a pointer to
pointer to unsigned char. Dereferencing this pointer, which
is done to reset the next field, violates strict-aliasing
rules and might cause problems for surrounding code that
uses the next field of the object being added to the list.
The solution is to use templates to parametrize the SQL_LIST
structure in order to deference the pointers with compatible
types. As a side bonus, it becomes possible to remove quite
a few casts related to acessing data members of SQL_LIST.
sql/handler.h:
Use the appropriate template type argument.
sql/item.cc:
Remove now-unnecessary cast.
sql/item_subselect.cc:
Remove now-unnecessary casts.
sql/item_sum.cc:
Use the appropriate template type argument.
Remove now-unnecessary cast.
sql/mysql_priv.h:
Move SQL_LIST structure to sql_list.h
Use the appropriate template type argument.
sql/sp.cc:
Remove now-unnecessary casts.
sql/sql_delete.cc:
Use the appropriate template type argument.
Remove now-unnecessary casts.
sql/sql_derived.cc:
Remove now-unnecessary casts.
sql/sql_lex.cc:
Remove now-unnecessary casts.
sql/sql_lex.h:
SQL_LIST now takes a template type argument which must
match the type of the elements of the list. Use forward
declaration when the type is not available, it is used
in pointers anyway.
sql/sql_list.h:
Rename SQL_LIST to SQL_I_List. The template parameter is
the type of object that is stored in the list.
sql/sql_olap.cc:
Remove now-unnecessary casts.
sql/sql_parse.cc:
Remove now-unnecessary casts.
sql/sql_prepare.cc:
Remove now-unnecessary casts.
sql/sql_select.cc:
Remove now-unnecessary casts.
sql/sql_show.cc:
Remove now-unnecessary casts.
sql/sql_table.cc:
Remove now-unnecessary casts.
sql/sql_trigger.cc:
Remove now-unnecessary casts.
sql/sql_union.cc:
Remove now-unnecessary casts.
sql/sql_update.cc:
Remove now-unnecessary casts.
sql/sql_view.cc:
Remove now-unnecessary casts.
sql/sql_yacc.yy:
Remove now-unnecessary casts.
storage/myisammrg/ha_myisammrg.cc:
Remove now-unnecessary casts.
transactional SELECT and ALTER TABLE ... REBUILD PARTITION".
The goal of this patch is to decouple type of metadata
lock acquired for table by open_tables() from type of
table-level lock to be acquired on it.
To achieve this we change approach to how we determine what
type of metadata lock should be acquired on table to be open.
Now instead of inferring it at open_tables() time from flags
and type of table-level lock we rely on that type of metadata
lock is properly set at parsing time and is not changed
further.
sql/ha_ndbcluster.cc:
Now one needs to properly initialize table list element's
MDL_request object before calling mysql_rm_table_part2().
sql/lock.cc:
lock_table_names() no longer initializes table list elements'
MDL_request objects. Now proper initialization of these
requests is a responsibility of the caller.
sql/lock.h:
Removed MYSQL_OPEN_TAKE_UPGRADABLE_MDL flag which became
unnecessary. Thanks to the fact that we don't reset type of
requests for metadata locks between re-executions we now can
figure out that upgradable locks are requested by simply
looking at their type which were set in the parser. As result
this flag became redundant.
sql/mdl.h:
Added version of new operator which simplifies allocation of
MDL_request objects on a MEM_ROOT.
sql/sp_head.cc:
Added comment explaining why it is OK to infer type of
metadata lock to request from type of table-level lock
for prelocking.
Added enum_mdl_type argument to sp_add_to_query_tables()
to simplify its usage in trigger implementation.
sql/sp_head.h:
Added enum_mdl_type argument to sp_add_to_query_tables()
to simplify its usage in trigger implementation.
sql/sql_base.cc:
- open_table_get_mdl_lock():
Preserve type of MDL_request for table list element which
was set in the parser by creating MDL_request objects on
memory root if MYSQL_OPEN_FORCE_SHARED_MDL or
MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL flag were specified.
Thanks to this and to the fact that we no longer reset
type of requests for metadata locks between re-executions
we no longer need to acquire exclusive metadata lock on
table to be created in a special way. This lock is acquired
by code handling acquiring of upgradable locks.
Also changed signature/calling convention for this function
to simplify its usage.
- Accordingly special lock strategy for table list elements
which was used for such locks became unnecessary and was
removed. Other strategies were renamed.
- Since we no longer have guarantee that MDL_request object
which were not satisfied due to lock conflict belongs to
table list element Open_table_context class and its methods
were extended to remember pointer to MDL_request which has
caused problem at request_backoff_action() time and use it
in recover_from_failed_open(). Similar approach is used
for cases when problem from which we need to recover is
not related to MDL but to the table itself. In this case
we store pointer to the element of table list.
- Changed open_tables()/open_tables_check_upgradable_mdl()/
open_tables_acquire_upgradable_mdl() not to rely on
MYSQL_OPEN_TAKE_UPGRADABLE_MDL flag to understand when
upgradable metadata locks should be acquired and not to
infer type of MDL lock from type of table-level lock.
Instead we assume that type of MDL to be acquired was set
in the parser (we can do this as type of MDL_request is
no longer reset between re-executions).
sql/sql_class.h:
Since we no longer have guarantee that MDL_request object
which were not satisfied due to lock conflict belongs to
table list element Open_table_context class and its methods
were extended to remember pointer to MDL_request which has
caused problem at request_backoff_action() time and use it
in recover_from_failed_open(). Similar approach is used
for cases when problem from which we need to recover is
not related to MDL but to the table itself. In this case
we store pointer to the element of table list.
sql/sql_db.cc:
Now one needs to properly initialize table list element's
MDL_request object before calling mysql_rm_table_part2()
or mysql_rename_tables().
sql/sql_lex.cc:
st_select_lex/st_select_lex_node::add_table_to_list() method
now has argument which allows specify type of metadata lock
to be requested for table list element being added.
sql/sql_lex.h:
- st_select_lex/st_select_lex_node::add_table_to_list()
method now has argument which specifies type of metadata
lock to be requested for table list element being added.
This allows to explicitly set type of MDL lock to be
acquired for a DDL statement in parser. It is also more
future-proof than inferring type of MDL request from type
of table-level lock.
- Added Yacc_state::m_mdl_type member which specifies which
type of metadata lock should be requested for tables to be
added to table list by a grammar rule in cases when the same
rule is used in several statements requiring different kinds
of metadata locks.
sql/sql_parse.cc:
- st_select_lex::add_table_to_list() method now has argument
which specifies type of metadata lock to be requested for
table list element being added. This allows to explicitly
set type of MDL lock to be acquired for a DDL statement in
parser. It is also more future-proof than inferring type of
MDL request from type of table-level lock.
- EXCLUSIVE_DOWNGRADABLE_MDL lock strategy has a new name -
OTLS_DOWNGRADE_IF_EXISTS.
- Adjusted LOCK TABLES implementation to the fact that we no
longer infer type of metadata lock to be acquired from table
level lock and that type of MDL request is set at parsing.
And thus MYSQL_OPEN_TAKE_UPGRADABLE_MDL flag became
unnecessary.
sql/sql_prepare.cc:
TABLE_LIST's lock strategy SHARED_MDL was renamed to OTLS_NONE
as now it means that metadata lock should not be changed during
call to open_table() (if it has been already acquired) and is
also used for exclusive metadata lock.
sql/sql_show.cc:
st_select_lex::add_table_to_list() method now has argument
which specifies type of metadata lock to be requested for
table list element being added.
sql/sql_table.cc:
- Adjusted mysql_admin_table()'s code to the fact that
open_tables() no longer determines what kind of metadata
lock should be obtained basing on type of table-level
lock and flags. Instead type of metadata lock for table
to be open should be set before calling open_tables().
- Changed mysql_alter_table() code to the facts:
a) that now it is responsibility of caller to properly
initalize MDL_request in table list elements before calling
lock_table_names()
b) and that MYSQL_OPEN_TAKE_UPGRADABLE_MDL is no longer
necessary since type of metadata lock to be obtained
at open_tables() time is set during parsing.
- Changed code of mysql_recreate_table() to properly set
type of metadata and table-level lock to be obtained
by mysql_alter_table() which it calls.
sql/sql_trigger.cc:
Instead of relying on MYSQL_OPEN_TAKE_UPGRADABLE_MDL flag to
force open_tables() to take an upgradable lock we now specify
exact type of lock to be taken when constructing table list
element for table to be open for CREATE/DROP TRIGGER.
sql/sql_view.cc:
We no longer use TABLE_LIST::EXCLUSIVE_MDL strategy to force
open_tables() to take an exclusive metadata lock on view to
be created. Instead we rely on parser setting proper type of
metadata lock to request and open_tables() acquiring it.
This became possible thanks to the fact that we no longer
reset type of MDL_request between statement re-executions.
sql/sql_yacc.yy:
Instead of inferring type of MDL_request for table to be
open from type of table-level lock and flags passed to
open_tables() we now explicitly specify them at parsing.
This became possible thanks to the fact that we no longer
reset type of MDL_request between statement re-executions.
In future this should allow to decouple type of metadata
lock from type of table-level lock.
The only exception to this approach is statements implemented
through mysql_admin_table() which re-uses same table list
element several times with different types of table-level
and metadata locks.
We now also properly initialize MDL_request objects for table
list elements which are later passed to lock_table_names()
function.
sql/table.cc:
Do not reset type of MDL_request between statement
re-executions. This became unnecessesary as we no longer
change type of MDL_request residing in table list element.
In its turn this change allows to set type of MDL_request
only once - at parsing time.
sql/table.h:
Got rid of TABLE_LIST::EXCLUSIVE_MDL lock strategy.
Now we can specify that we need to acquire exclusive lock
on table to be processed by open_tables() through setting
an appropriate type of MDL_request at parsing time (this
became possible thanks to the fact that we no longer reset
types of MDL_request's belonging to table list elements
between statement re-execution).
Strategy SHARED_MDL was renamed to OTLS_NONE as now it
means that metadata lock should not be changed during call
to open_table() (if it has been already acquired) and is
also used for exclusive metadata lock.
Strategy EXCLUSIVE_DOWNGRADABLE_MDL was renamed to
OTLS_DOWNGRADE_IF_EXISTS.
Item_hex_string::Item_hex_string
The status of memory allocation in the Lex_input_stream (called
from the Parser_state constructor) was not checked which led to
a parser crash in case of the out-of-memory error.
The solution is to introduce new init() member function in
Parser_state and Lex_input_stream so that status of memory
allocation can be returned to the caller.
mysql-test/r/error_simulation.result:
Added a test case for bug #42064.
mysql-test/t/error_simulation.test:
Added a test case for bug #42064.
mysys/my_alloc.c:
Added error injection code for the regression test.
mysys/my_malloc.c:
Added error injection code for the regression test.
mysys/safemalloc.c:
Added error injection code for the regression test.
sql/event_data_objects.cc:
Use the new init() member function of Parser_state and check
its return value to handle memory allocation failures.
sql/mysqld.cc:
Added error injection code for the regression test.
sql/sp.cc:
Use the new init() member function of Parser_state and check
its return value to handle memory allocation failures.
sql/sql_lex.cc:
Moved memory allocation from constructor to the separate init()
member function.
Added error injection code for the regression test.
sql/sql_lex.h:
Moved memory allocation from constructor to the separate init()
member function.
sql/sql_parse.cc:
Use the new init() member function of Parser_state and check
its return value to handle memory allocation failures.
sql/sql_partition.cc:
Use the new init() member function of Parser_state and check
its return value to handle memory allocation failures.
sql/sql_prepare.cc:
Use the new init() member function of Parser_state and check
its return value to handle memory allocation failures.
sql/sql_trigger.cc:
Use the new init() member function of Parser_state and check
its return value to handle memory allocation failures.
sql/sql_view.cc:
Use the new init() member function of Parser_state and check
its return value to handle memory allocation failures..
sql/thr_malloc.cc:
Added error injection code for the regression test.
