now do no initializations for the --help.
Do it for --verbose --help though.
per-file comments:
sql/mysqld.cc
Bug#30025 Mysqld prints out warnings/errors being run with --no-defaults --help
quit with the help message at once as --help was given
The fix is to:
- introduce ORACLE_WELCOME_COPYRIGHT_NOTICE define to have a single place
to specify copyright notice;
- replace custom copyright notices with ORACLE_WELCOME_COPYRIGHT_NOTICE
in programs.
Quoting from the bug report:
The pstack library has been included in MySQL since version
4.0.0. It's useless and should be removed.
Details: According to its own documentation, pstack only works
on Linux on x86 in 32 bit mode and requires LinuxThreads and a
statically linked binary. It doesn't really support any Linux
from 2003 or later and doesn't work on any other OS.
Before this fix, the server could crash during shutdown,
due to race conditions, that occured when killing the server.
In particular, the performance schema instrumentation handle,
PSI_server, and the performance schema itself would be cleaned up
too soon, causing race conditions with a running kill server thread.
The specifics of the race condition found are that:
the main thread executing "PSI_server= NULL" can cause crashes in
other threads still running, which are executing
"if (PSI_server != NULL) PSI_server->xxx()"
as part of the performance schema instrumentation.
While the bug was reported for the kill server thread,
in theory the same crash could happen with the signal thread,
as found by code analysis.
The correct fix would be to only shutdown the performance schema
and set PSI_server to NULL after every other thread is guaranteed
to be completed, including the kill_server_thread.
However, due to the existing mysqld server design, this is not the case.
See in particular bug number 56666.
The work around used to fix this race condition is to simply not
perform the call to shutdown_performance_schema() when the server exits,
and to keep the PSI_server pointer unchanged.
This will cause memory leaks to be reported by tools like valgrind,
but no memory leak actually happen because the process is about to exit().
As a result, the file mysql-test/valgrind.supp has been updated
to filter out these false positive messages.
This code has been tested with running in a loop the following
tests in parallel, which have been known to fail with race conditions
in the past:
- rpl_change_master
- binlog_max_extension
- events_restart
- rpl_heartbeat_basic
and no crash of test failure has been seen with the changed code.
thread-specific variables weren't set when we load error message files.
per-file comments:
libmysqld/lib_sql.cc
Bug#53251 mysql_library_init fails on second execution with embedded library
we need to call my_thread_init() once more. Normally it's called at the my_init()
stage but that doesn't happen on the second my_init() call.
sql/derror.cc
Bug#53251 mysql_library_init fails on second execution with embedded library
use default errors for the embedded server.
sql/mysqld.cc
Bug#53251 mysql_library_init fails on second execution with embedded library
unregister server errors in clean_up(). Without it the error list contains
that on the second mysql_server_init() which is not good.
sql/set_var.cc
Bug#53251 mysql_library_init fails on second execution with embedded library
sys_var::cleanup() call instead of the destructor
sql/set_var.h
Bug#53251 mysql_library_init fails on second execution with embedded library
sys_var::cleanup() introduced instead of the destructor
sql/sys_vars.h
Bug#53251 mysql_library_init fails on second execution with embedded library
Sys_var_charptr::cleanup() implemented
Before this fix, the ha_read_last_count status variable was defined and
updated internally, for never exposed as a system variable.
This fix exposes the system variable as "Handler_read_last",
for completness of the Handler_read_* system variables interface.
Adjusted tests results accordingly.
temp table
This patch introduces two key changes in the replication's behavior.
Firstly, it reverts part of BUG#51894 which puts any update to temporary tables
into the trx-cache. Now, updates to temporary tables are handled according to
the type of their engines as a regular table.
Secondly, an unsafe mixed statement, (i.e. a statement that access transactional
table as well non-transactional or temporary table, and writes to any of them),
are written into the trx-cache in order to minimize errors in the execution when
the statement logging format is in use.
Such changes has a direct impact on which statements are classified as unsafe
statements and thus part of BUG#53259 is reverted.
TABLES <list> WITH READ LOCK are incompatible".
The problem was that FLUSH TABLES <list> WITH READ LOCK
which was issued when other connection has acquired global
read lock using FLUSH TABLES WITH READ LOCK was blocked
and has to wait until global read lock is released.
This issue stemmed from the fact that FLUSH TABLES <list>
WITH READ LOCK implementation has acquired X metadata locks
on tables to be flushed. Since these locks required acquiring
of global IX lock this statement was incompatible with global
read lock.
This patch addresses problem by using SNW metadata type of
lock for tables to be flushed by FLUSH TABLES <list> WITH
READ LOCK. It is OK to acquire them without global IX lock
as long as we won't try to upgrade those locks. Since SNW
locks allow concurrent statements using same table FLUSH
TABLE <list> WITH READ LOCK now has to wait until old
versions of tables to be flushed go away after acquiring
metadata locks. Since such waiting can lead to deadlock
MDL deadlock detector was extended to take into account
waits for flush and resolve such deadlocks.
As a bonus code in open_tables() which was responsible for
waiting old versions of tables to go away was refactored.
Now when we encounter old version of table in open_table()
we don't back-off and wait for all old version to go away,
but instead wait for this particular table to be flushed.
Such approach supported by deadlock detection should reduce
number of scenarios in which FLUSH TABLES aborts concurrent
multi-statement transactions.
Note that active FLUSH TABLES <list> WITH READ LOCK still
blocks concurrent FLUSH TABLES WITH READ LOCK statement
as the former keeps tables open and thus prevents the
latter statement from doing flush.
Fix warnings flagged by the new warning option -Wunused-but-set-variable
that was added to GCC 4.6 and that is enabled by -Wunused and -Wall. The
option causes a warning whenever a local variable is assigned to but is
later unused. It also warns about meaningless pointer dereferences.
compiler problem
GCC-style inline assembly is not supported by the Sun Studio
compilers prior to version 12.
Added a check for the Sun Studio version to avoid using
_FPU_GETCW() / _FPU_SETCW() when inline assembly is
unsupported. This can lead to some differences in floating
point calculations on Solaris 8/x86 which, however, is not worth
bothering with Sun-style assembly .il templates.
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.
Apart strict-aliasing warnings, fix the remaining warnings
generated by GCC 4.4.4 -Wall and -Wextra flags.
One major source of warnings was the in-house function my_bcmp
which (unconventionally) took pointers to unsigned characters
as the byte sequences to be compared. Since my_bcmp and bcmp
are deprecated functions whose only difference with memcmp is
the return value, every use of the function is replaced with
memcmp as the special return value wasn't actually being used
by any caller.
There were also various other warnings, mostly due to type
mismatches, missing return values, missing prototypes, dead
code (unreachable) and ignored return values.
DATABASE with open HANDLER"
Remove LOCK_create_db, database name locks, and use metadata locks instead.
This exposes CREATE/DROP/ALTER DATABASE statements to the graph-based
deadlock detector in MDL, and paves the way for a safe, deadlock-free
implementation of RENAME DATABASE.
Database DDL statements will now take exclusive metadata locks on
the database name, while table/view/routine DDL statements take
intention exclusive locks on the database name. This prevents race
conditions between database DDL and table/view/routine DDL.
(e.g. DROP DATABASE with concurrent CREATE/ALTER/DROP TABLE)
By adding database name locks, this patch implements
WL#4450 "DDL locking: CREATE/DROP DATABASE must use database locks" and
WL#4985 "DDL locking: namespace/hierarchical locks".
The patch also changes code to use init_one_table() where appropriate.
The new lock_table_names() function requires TABLE_LIST::db_length to
be set correctly, and this is taken care of by init_one_table().
This patch also adds a simple template to help work with
the mysys HASH data structure.
Most of the patch was written by Konstantin Osipov.
POSIX requires that a signal handler defined with sigaction()
is not reset on delivering a signal unless SA_NODEFER or
SA_RESETHAND is set. It is therefore unnecessary to redefine
the handler on signal delivery on platforms where sigaction()
is used without those flags.
