When a SP handler is activated, memory is allocated to hold the
MESSAGE_TEXT for the condition that caused the activation.
The problem was that this memory was allocated on the MEM_ROOT belonging
to the stored program. Since this MEM_ROOT is not freed until the
stored program ends, a stored program that causes lots of handler
activations can start using lots of memory. In 5.1 and earlier the
problem did not exist as no MESSAGE_TEXT was allocated if a condition
was raised with a handler present. However, this behavior lead to
a number of other issues such as Bug#23032.
This patch fixes the problem by allocating enough memory for the
necessary MESSAGE_TEXTs in the SP MEM_ROOT when the SP starts and
then re-using this memory each time a handler is activated.
This is the 5.5 version of the patch.
******
This patch fixes the following bugs:
- Bug#5889: Exit handler for a warning doesn't hide the warning in
trigger
- Bug#9857: Stored procedures: handler for sqlwarning ignored
- Bug#23032: Handlers declared in a SP do not handle warnings generated
in sub-SP
- Bug#36185: Incorrect precedence for warning and exception handlers
The problem was in the way warnings/errors during stored routine execution
were handled. Prior to this patch the logic was as follows:
- when a warning/an error happens: if we're executing a stored routine,
and there is a handler for that warning/error, remember the handler,
ignore the warning/error and continue execution.
- after a stored routine instruction is executed: check for a remembered
handler and activate one (if any).
This logic caused several problems:
- if one instruction generates several warnings (errors) it's impossible
to choose the right handler -- a handler for the first generated
condition was chosen and remembered for activation.
- mess with handling conditions in scopes different from the current one.
- not putting generated warnings/errors into Warning Info (Diagnostic
Area) is against The Standard.
The patch changes the logic as follows:
- Diagnostic Area is cleared on the beginning of each statement that
either is able to generate warnings, or is able to work with tables.
- at the end of a stored routine instruction, Diagnostic Area is left
intact.
- Diagnostic Area is checked after each stored routine instruction. If
an instruction generates several condition, it's now possible to take a
look at all of them and determine an appropriate handler.
Essentially, the problem is that safemalloc is excruciatingly
slow as it checks all allocated blocks for overrun at each
memory management primitive, yielding a almost exponential
slowdown for the memory management functions (malloc, realloc,
free). The overrun check basically consists of verifying some
bytes of a block for certain magic keys, which catches some
simple forms of overrun. Another minor problem is violation
of aliasing rules and that its own internal list of blocks
is prone to corruption.
Another issue with safemalloc is rather the maintenance cost
as the tool has a significant impact on the server code.
Given the magnitude of memory debuggers available nowadays,
especially those that are provided with the platform malloc
implementation, maintenance of a in-house and largely obsolete
memory debugger becomes a burden that is not worth the effort
due to its slowness and lack of support for detecting more
common forms of heap corruption.
Since there are third-party tools that can provide the same
functionality at a lower or comparable performance cost, the
solution is to simply remove safemalloc. Third-party tools
can provide the same functionality at a lower or comparable
performance cost.
The removal of safemalloc also allows a simplification of the
malloc wrappers, removing quite a bit of kludge: redefinition
of my_malloc, my_free and the removal of the unused second
argument of my_free. Since free() always check whether the
supplied pointer is null, redudant checks are also removed.
Also, this patch adds unit testing for my_malloc and moves
my_realloc implementation into the same file as the other
memory allocation primitives.
This patch:
- Moves all definitions from the mysql_priv.h file into
header files for the component where the variable is
defined
- Creates header files if the component lacks one
- Eliminates all include directives from mysql_priv.h
- Eliminates all circular include cycles
- Rename time.cc to sql_time.cc
- Rename mysql_priv.h to sql_priv.h
When values of different types are compared they're converted to a type that
allows correct comparison. This conversion is done for each comparison and
takes some time. When a constant is being compared it's possible to cache the
value after conversion to speedup comparison. In some cases (large dataset,
complex WHERE condition with many type conversions) query might be executed
7% faster.
A test case isn't provided because all changes are internal and isn't visible
outside.
The behavior of the Item_cache is changed to cache values on the first request
of cached value rather than at the moment of storing item to be cached.
A flag named value_cached is added to the Item_cache class. It's set to TRUE
when cache holds the value of the last stored item.
Function named cache_value() is added to the Item_cache class and derived classes.
This function actually caches the value of the saved item.
Item_cache_xxx::store functions now only store item to be cached and set
value_cached flag to FALSE.
Item_cache_xxx::val_xxx functions are changed to call cache_value function
prior to returning cached value if value_cached is FALSE.
The Arg_comparator::set_cmp_func function now calls cache_converted_constant
to cache constants if they need a type conversion.
The Item_cache::get_cache function is overloaded to allow setting of the
cache type.
The cache_converted_constant function is added to the Arg_comparator class.
It checks whether a value can and should be cached and if so caches it.
Bug 33983 (Stored Procedures: wrong end <label> syntax is accepted)
The server used to crash when REPEAT or another control instruction
was used in conjunction with labels and a LEAVE instruction.
The crash was caused by a missing "pop" of handlers or cursors in the
code representing the stored program. When executing the code in a loop,
this missing "pop" would result in a stack overflow, corrupting memory.
Code generation has been fixed to produce the missing h_pop/c_pop
instructions.
Also, the logic checking that labels at the beginning and the end of a
statement are matched was incorrect, causing Bug 33983.
End labels, when used, must match the label used at the beginning of a block.
cause ROLLBACK of statement", part 1. Review fixes.
Do not send OK/EOF packets to the client until we reached the end of
the current statement.
This is a consolidation, to keep the functionality that is shared by all
SQL statements in one place in the server.
Currently this functionality includes:
- close_thread_tables()
- log_slow_statement().
After this patch and the subsequent patch for Bug#12713, it shall also include:
- ha_autocommit_or_rollback()
- net_end_statement()
- query_cache_end_of_result().
In future it may also include:
- mysql_reset_thd_for_next_command().
After adding an index the <VARBINARY> IN (SELECT <BINARY> ...)
clause returned a wrong result: the VARBINARY value was illegally padded
with zero bytes to the length of the BINARY column for the index search.
(<VARBINARY>, ...) IN (SELECT <BINARY>, ... ) clauses are affected too.
When innodb detects a deadlock it calls ha_rollback_trans() to rollback the
main transaction. But such action isn't allowed from inside of triggers and
functions. When it happen the 'Explicit or implicit commit' error is thrown
even if there is no commit/rollback statements in the trigger/function. This
leads to the user confusion.
Now the convert_error_code_to_mysql() function doesn't call the
ha_rollback_trans() function directly but rather calls the
mark_transaction_to_rollback function and returns an error.
The sp_rcontext::find_handler() now doesn't allow errors to be caught by the
trigger/function error handlers when the thd->is_fatal_sub_stmt_error flag
is set. Procedures are still allowed to catch such errors.
The sp_rcontext::find_handler function now accepts a THD handle as a parameter.
The transaction_rollback_request and the is_fatal_sub_stmt_error flags are
added to the THD class. The are initialized by the THD class constructor.
Now the ha_autocommit_or_rollback function rolls back main transaction
when not in a sub statement and the thd->transaction_rollback_request
is set.
The THD::restore_sub_statement_state function now resets the
thd->is_fatal_sub_stmt_error flag on exit from a sub-statement.
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
Before this fix,
- a runtime error in a statement in a stored procedure with no error handlers
was properly detected (as expected)
- a runtime error in a statement with an error handler inherited from a non
local runtime context (i.e., proc a with a handler, calling proc b) was
properly detected (as expected)
- a runtime error in a statement with a *local* error handler was executed
as follows :
a) the statement would succeed, regardless of the error condition, (bug)
b) the error handler would be called (as expected).
The root cause is that functions like my_messqge_sql would "forget" to set
the thread flag thd->net.report_error to 1, because of the check involving
sp_rcontext::found_handler_here().
Failure to set this flag would cause, later in the call stack,
in Item_func::fix_fields() at line 190, the code to return FALSE and consider
that executing the statement was successful.
With this fix :
- error handling code, that was duplicated in different places in the code,
is now implemented in sp_rcontext::handle_error(),
- handle_error() correctly sets thd->net.report_error when a handler is
present, regardless of the handler location (local, or in the call stack).
A test case, bug8153_subselect, has been written to demonstrate the change
of behavior before and after the fix.
Another test case, bug8153_function_a, as also been writen.
This test has the same behavior before and after the fix.
This test has been written to demonstrate that the previous expected
result of procedure bug18787, was incorrect, since select no_such_function()
should fail and therefore not produce a result.
The incorrect result for bug18787 has the same root cause as Bug#8153,
and the expected result has been adjusted.
Stored procedure execution sometimes placed the address of auto variables
in the list of Item changes to undo in THD::rollback_item_tree_changes().
This could cause stack corruption.
Also added comments, and fixing some coding style (mostly in comments too).
There are no functional changes, so no tests or documentation needed.
(This was originally part of a bugfix, but it was decided to not include this
in that patch; instead it's done separately.)
Make the distinction between "exception conditions" and "completion
conditions" (warning and "no data") as defined by the standard. The latter
should not terminate a routine if no handler is found in the lexical scope.
according to the standard.
The idea is to use Field-classes to implement stored routines
variables. Also, we should provide facade to Item-hierarchy
by Item_field class (it is necessary, since SRVs take part
in expressions).
The patch fixes the following bugs:
- BUG#8702: Stored Procedures: No Error/Warning shown for inappropriate data
type matching;
- BUG#8768: Functions: For any unsigned data type, -ve values can be passed
and returned;
- BUG#8769: Functions: For Int datatypes, out of range values can be passed
and returned;
- BUG#9078: STORED PROCDURE: Decimal digits are not displayed when we use
DECIMAL datatype;
- BUG#9572: Stored procedures: variable type declarations ignored;
- BUG#12903: upper function does not work inside a function;
- BUG#13705: parameters to stored procedures are not verified;
- BUG#13808: ENUM type stored procedure parameter accepts non-enumerated
data;
- BUG#13909: Varchar Stored Procedure Parameter always BINARY string (ignores
CHARACTER SET);
- BUG#14161: Stored procedure cannot retrieve bigint unsigned;
- BUG#14188: BINARY variables have no 0x00 padding;
- BUG#15148: Stored procedure variables accept non-scalar values;
Search the chain of sp_rcontexts recursively for handlers. If one is found,
it will be detected in the sp_head::execute() method at the corresponding
level.
Replaced the dumb in-handler/not-in-handler check with a proper recursion
check of handlers being executed.
(Re-commit in a different tree, to make push possible.)
cursor is interpreted latin1 character and Bug#9819 "Cursors: Mysql Server
Crash while fetching from table with 5 million records."
A fix for a possible memory leak when fetching into an SP cursor
in a long loop.
The patch uses a common implementation of cursors in the binary protocol and
in stored procedures and implements materialized cursors.
For implementation details, see comments in sql_cursor.cc
and Bug#12297 SP crashes the server if data inserted inside a lon loop
Third commit attempt. With fixes to the issues, showed up after full rebuild and
tests on other hosts.
Fixed valgrind complaints. This fixes the memory leak problems for
procedured, and partially for functions. There's still a leak involving
results from functions that turned out to be too involved, so it will be
fixed separately.
Simple optimization for 2 argument usage to function of variable arguments
Fix stack overrun when using 1+1+1+1+1+1+1+....
Update crash-me results for 5.0
Don't call post_open if pre_open() fails (optimization)
Memory leak in locally evalutated expressions during SP execution fixed by
reusing allocated item slots when possible.
Note: No test case added, since the test is a stress test that tries to make
the machine to run out of memory.
Second attempt, now tested with debug build, valgrind build, max (optimized)
build, with and without --debug, --vagrind and --ps-protocol.
Errors in trigger and view test with --debug in debug build where present
before this patch, and likewise for valgrind warnings for view test in
valgrind build with --ps-protocol.
Memory leak in locally evalutated expressions during SP execution fixed by
reusing allocated item slots when possible.
Note: No test case added, since the test is a stress test that tries to make
the machine to run out of memory.
and some SP-related cleanups.
- We don't have separate stage for calculation of list of tables
to be prelocked and doing implicit LOCK/UNLOCK any more.
Instead we calculate this list at open_tables() and do implicit
LOCK in lock_tables() (and UNLOCK in close_thread_tables()).
Also now we support cases when same table (with same alias) is
used several times in the same query in SP.
- Cleaned up execution of SP. Moved all common code which handles
LEX and does preparations before statement execution or complex
expression evaluation to auxilary sp_lex_keeper class. Now
all statements in SP (and corresponding instructions) that
evaluate expression which can contain subquery have their
own LEX.
Lots of small fixes to multi-precision-math path
Give Note for '123.4e'
Added helper functions type 'val_string_from_real()
Don't give warnings for end space for string2decimal()
Changed storage of values for SP so that we can detect length of argument without strlen()
Changed interface for str2dec() so that we must supple the pointer to the last character in the buffer
