Coding style: classes start with a capital letter.
Rename some classes related to parsing:
create_field -> Create_field
foreign_key -> Foreign_key
key_part_spec -> Key_part_spec
If a stored function or a trigger was killed it had aborted but no error
was thrown. This allows the caller statement to continue without a notice.
This may lead to a wrong data being inserted/updated to/deleted as in such
cases the correct result of a stored function isn't guaranteed. In the case
of triggers it allows the caller statement to ignore kill signal and to
waste time because of re-evaluation of triggers that always will fail
because thd->killed flag is still on.
Now the Item_func_sp::execute() and the sp_head::execute_trigger() functions
check whether a function or a trigger were killed during execution and
throws an appropriate error if so.
Now the fill_record() function stops filling record if an error was reported
through thd->net.report_error.
Bug#21483 "Server abort or deadlock on INSERT DELAYED with another
implicit insert"
Also fixes and adds test cases for bugs:
20497 "Trigger with INSERT DELAYED causes Error 1165"
21714 "Wrong NEW.value and server abort on INSERT DELAYED to a
table with a trigger".
Post-review fixes.
Problem:
In MySQL INSERT DELAYED is a way to pipe all inserts into a
given table through a dedicated thread. This is necessary for
simplistic storage engines like MyISAM, which do not have internal
concurrency control or threading and thus can not
achieve efficient INSERT throughput without support from SQL layer.
DELAYED INSERT works as follows:
For every distinct table, which can accept DELAYED inserts and has
pending data to insert, a dedicated thread is created to write data
to disk. All user connection threads that attempt to
delayed-insert into this table interact with the dedicated thread in
producer/consumer fashion: all records to-be inserted are pushed
into a queue of the dedicated thread, which fetches the records and
writes them.
In this design, client connection threads never open or lock
the delayed insert table.
This functionality was introduced in version 3.23 and does not take
into account existence of triggers, views, or pre-locking.
E.g. if INSERT DELAYED is called from a stored function, which,
in turn, is called from another stored function that uses the delayed
table, a deadlock can occur, because delayed locking by-passes
pre-locking. Besides:
* the delayed thread works directly with the subject table through
the storage engine API and does not invoke triggers
* even if it was patched to invoke triggers, if triggers,
in turn, used other tables, the delayed thread would
have to open and lock involved tables (use pre-locking).
* even if it was patched to use pre-locking, without deadlock
detection the delayed thread could easily lock out user
connection threads in case when the same table is used both
in a trigger and on the right side of the insert query:
the delayed thread would not release locks until all inserts
are complete, and user connection can not complete inserts
without having locks on the tables used on the right side of the
query.
Solution:
These considerations suggest two general alternatives for the
future of INSERT DELAYED:
* it is considered a full-fledged alternative to normal INSERT
* it is regarded as an optimisation that is only relevant
for simplistic engines.
Since we missed our chance to provide complete support of new
features when 5.0 was in development, the first alternative
currently renders infeasible.
However, even the second alternative, which is to detect
new features and convert DELAYED insert into a normal insert,
is not easy to implement.
The catch-22 is that we don't know if the subject table has triggers
or is a view before we open it, and we only open it in the
delayed thread. We don't know if the query involves pre-locking
until we have opened all tables, and we always first create
the delayed thread, and only then open the remaining tables.
This patch detects the problematic scenarios and converts
DELAYED INSERT to a normal INSERT using the following approach:
* if the statement is executed under pre-locking (e.g. from
within a stored function or trigger) or the right
side may require pre-locking, we detect the situation
before creating a delayed insert thread and convert the statement
to a conventional INSERT.
* if the subject table is a view or has triggers, we shutdown
the delayed thread and convert the statement to a conventional
INSERT.
The following type conversions was done:
- Changed byte to uchar
- Changed gptr to uchar*
- Change my_string to char *
- Change my_size_t to size_t
- Change size_s to size_t
Removed declaration of byte, gptr, my_string, my_size_t and size_s.
Following function parameter changes was done:
- All string functions in mysys/strings was changed to use size_t
instead of uint for string lengths.
- All read()/write() functions changed to use size_t (including vio).
- All protocoll functions changed to use size_t instead of uint
- Functions that used a pointer to a string length was changed to use size_t*
- Changed malloc(), free() and related functions from using gptr to use void *
as this requires fewer casts in the code and is more in line with how the
standard functions work.
- Added extra length argument to dirname_part() to return the length of the
created string.
- Changed (at least) following functions to take uchar* as argument:
- db_dump()
- my_net_write()
- net_write_command()
- net_store_data()
- DBUG_DUMP()
- decimal2bin() & bin2decimal()
- Changed my_compress() and my_uncompress() to use size_t. Changed one
argument to my_uncompress() from a pointer to a value as we only return
one value (makes function easier to use).
- Changed type of 'pack_data' argument to packfrm() to avoid casts.
- Changed in readfrm() and writefrom(), ha_discover and handler::discover()
the type for argument 'frmdata' to uchar** to avoid casts.
- Changed most Field functions to use uchar* instead of char* (reduced a lot of
casts).
- Changed field->val_xxx(xxx, new_ptr) to take const pointers.
Other changes:
- Removed a lot of not needed casts
- Added a few new cast required by other changes
- Added some cast to my_multi_malloc() arguments for safety (as string lengths
needs to be uint, not size_t).
- Fixed all calls to hash-get-key functions to use size_t*. (Needed to be done
explicitely as this conflict was often hided by casting the function to
hash_get_key).
- Changed some buffers to memory regions to uchar* to avoid casts.
- Changed some string lengths from uint to size_t.
- Changed field->ptr to be uchar* instead of char*. This allowed us to
get rid of a lot of casts.
- Some changes from true -> TRUE, false -> FALSE, unsigned char -> uchar
- Include zlib.h in some files as we needed declaration of crc32()
- Changed MY_FILE_ERROR to be (size_t) -1.
- Changed many variables to hold the result of my_read() / my_write() to be
size_t. This was needed to properly detect errors (which are
returned as (size_t) -1).
- Removed some very old VMS code
- Changed packfrm()/unpackfrm() to not be depending on uint size
(portability fix)
- Removed windows specific code to restore cursor position as this
causes slowdown on windows and we should not mix read() and pread()
calls anyway as this is not thread safe. Updated function comment to
reflect this. Changed function that depended on original behavior of
my_pwrite() to itself restore the cursor position (one such case).
- Added some missing checking of return value of malloc().
- Changed definition of MOD_PAD_CHAR_TO_FULL_LENGTH to avoid 'long' overflow.
- Changed type of table_def::m_size from my_size_t to ulong to reflect that
m_size is the number of elements in the array, not a string/memory
length.
- Moved THD::max_row_length() to table.cc (as it's not depending on THD).
Inlined max_row_length_blob() into this function.
- More function comments
- Fixed some compiler warnings when compiled without partitions.
- Removed setting of LEX_STRING() arguments in declaration (portability fix).
- Some trivial indentation/variable name changes.
- Some trivial code simplifications:
- Replaced some calls to alloc_root + memcpy to use
strmake_root()/strdup_root().
- Changed some calls from memdup() to strmake() (Safety fix)
- Simpler loops in client-simple.c
- In some cases, flow control optimization implemented in sp::optimize
removes hreturn instructions, causing SQL exception handlers to:
* never return
* execute wrong logic
- This patch overrides default short cut optimization on hreturn instructions
to avoid this problem.
The issue found with bug 25411 is due to the function skip_rear_comments()
which damages the source code while implementing a work around.
The root cause of the problem is in the lexical analyser, which does not
process special comments properly.
For special comments like :
[1] aaa /*!50000 bbb */ ccc
since 5.0 is a version older that the current code, the parser is in lining
the content of the special comment, so that the query to process is
[2] aaa bbb ccc
However, the text of the query captured when processing a stored procedure,
stored function or trigger (or event in 5.1), can be after rebuilding it:
[3] aaa bbb */ ccc
which is wrong.
To fix bug 25411 properly, the lexical analyser needs to return [2] when
in lining special comments.
In order to implement this, some preliminary cleanup is required in the code,
which is implemented by this patch.
Before this change, the structure named LEX (or st_lex) contains attributes
that belong to lexical analysis, as well as attributes that represents the
abstract syntax tree (AST) of a statement.
Creating a new LEX structure for each statements (which makes sense for the
AST part) also re-initialized the lexical analysis phase each time, which
is conceptually wrong.
With this patch, the previous st_lex structure has been split in two:
- st_lex represents the Abstract Syntax Tree for a statement. The name "lex"
has not been changed to avoid a bigger impact in the code base.
- class lex_input_stream represents the internal state of the lexical
analyser, which by definition should *not* be reinitialized when parsing
multiple statements from the same input stream.
This change is a pre-requisite for bug 25411, since the implementation of
lex_input_stream will later improve to deal properly with special comments,
and this processing can not be done with the current implementation of
sp_head::reset_lex and sp_head::restore_lex, which interfere with the lexer.
This change set alone does not fix bug 25411.
streamline the event worker thread work flow and try to eliminate
possibilities for memory corruptions that might have been
lurking in previous (complicated) code.
This patch:
* removes Event_job_data::compile that was never used
* cleans up Event_job_data::execute to minimize juggling with
thread context and eliminate unneded code paths
* Implements Security_context::change/restore_security_context
to be able to re-use these methods in all stored programs
This is to maybe fix Bug#27733 "Valgrind failures in
remove_table_from_cache".
Review comments applied.
when there are no up-to-date system tables to support it:
- initialize the scheduler before reporting "Ready for connections".
This ensures that warnings, if any, are printed before "Ready for
connections", and this message is not mangled.
- do not abort the scheduler if there are no system tables
- check the tables once at start up, remember the status and disable
the scheduler if the tables are not up to date.
If one attempts to use the scheduler with bad tables,
issue an error message.
- clean up the behaviour of the module under LOCK TABLES and pre-locking
mode
- make sure implicit commit of Events DDL works as expected.
- add more tests
Collateral clean ups in the events code.
This patch fixes Bug#23631 Events: SHOW VARIABLES doesn't work
when mysql.event is damaged
execution breaks replication.
When a stored routine is executed, we switch current
database to the database, in which the routine
has been created. When the stored routine finishes,
we switch back to the original database.
The problem was that if the original database does not
exist (anymore) after routine execution, we raised an error.
The fix is to report a warning, and switch to the NULL database.
the lexer API which internally uses unsigned char variables to
address its state map. The implementation of the lexer should be
internal to the lexer, and not influence the rest of the code.
thd->options' OPTION_STATUS_NO_TRANS_UPDATE bit was not restored at the end of SF() invocation, where
SF() modified non-ta table.
As the result of this artifact it was not possible to detect whether there were any side-effects when
top-level query ends.
If the top level query table was not modified and the bit is lost there would be no binlogging.
Fixed with preserving the bit inside of thd->no_trans_update struct. The struct agregates two bool flags
telling whether the current query and the current transaction modified any non-ta table.
The flags stmt, all are dropped at the end of the query and the transaction.
TABLE ... WRITE".
Memory and CPU hogging occured when connection which had to wait for table
lock was serviced by thread which previously serviced connection that was
killed (note that connections can reuse threads if thread cache is enabled).
One possible scenario which exposed this problem was when thread which
provided binlog dump to replication slave was implicitly/automatically
killed when the same slave reconnected and started pulling data through
different thread/connection.
The problem also occured when one killed particular query in connection
(using KILL QUERY) and later this connection had to wait for some table
lock.
This problem was caused by the fact that thread-specific mysys_var::abort
variable, which indicates that waiting operations on mysys layer should
be aborted (this includes waiting for table locks), was set by kill
operation but was never reset back. So this value was "inherited" by the
following statements or even other connections (which reused the same
physical thread). Such discrepancy between this variable and THD::killed
flag broke logic on SQL-layer and caused CPU and memory hogging.
This patch tries to fix this problem by properly resetting this member.
There is no test-case associated with this patch since it is hard to test
for memory/CPU hogging conditions in our test-suite.
Before this fix, the parser would accept illegal code in SQL exceptions
handlers, that later causes the runtime to crash when executing the code,
due to memory violations in the exception handler stack.
The root cause of the problem is instructions within an exception handler
that jumps to code located outside of the handler. This is illegal according
to the SQL 2003 standard, since labels located outside the handler are not
supposed to be visible (they are "out of scope"), so any instruction that
jumps to these labels, like ITERATE or LEAVE, should not parse.
The section of the standard that is relevant for this is :
SQL:2003 SQL/PSM (ISO/IEC 9075-4:2003)
section 13.1 <compound statement>,
syntax rule 4
<quote>
The scope of the <beginning label> is CS excluding every <SQL schema
statement> contained in CS and excluding every
<local handler declaration list> contained in CS. <beginning label> shall
not be equivalent to any other <beginning label>s within that scope.
</quote>
With this fix, the C++ class sp_pcontext, which represent the "parsing
context" tree (a.k.a symbol table) of a stored procedure, has been changed
as follows:
- constructors have been cleaned up, so that only building a root node for
the tree is public; building nodes inside a tree is not public.
- a new member, m_label_scope, indicates if a given syntactic context
belongs to a DECLARE HANDLER block,
- label resolution, in the method find_label(), has been changed to
implement the restriction of scope regarding labels used in a compound
statement.
The actions in the parser, when parsing the body of a SQL exception handler,
have been changed as follows:
- the implementation of an exception handler (DECLARE HANDLER) now creates
explicitly a new sp_pcontext, to isolate the code inside the handler from
the containing compound statement context.
- registering exception handlers as a result occurs in the parent context,
see the rule sp_hcond_element
- the code in sp_hcond_list has been cleaned up, to avoid code duplication
In addition, the flags IN_SIMPLE_CASE and IN_HANDLER, declared in sp_head.h
have been removed, since they are unused and broken by design (as seen with
Bug 19194 (Right recursion in parser for CASE causes excessive stack usage,
limitation), representing a stack in a single flag is not possible.
Tests in sp-error have been added to show that illegal constructs are now
rejected.
Tests in sp have been added for code coverage, to show that ITERATE or LEAVE
statements are legal when jumping to a label in scope, inside the body of
an exception handler.
