MYSQLD.
DESCRIPTION
===========
Crash occurs when daemon_example plugin is uninstalled
immediately after its installed. This can be reproduced
by installing and uninstalling the plugin repeatedly.
ANALYSIS
========
The daemon_example_plugin_deinit() function of the daemon
example plugin calls pthread_cancel() but doesn't wait for
the worker thread to actually complete before deallocating
the data buffer and closing the file that it writes to.
This is causing SEGFAULT!
FIX
===
Added a pthread_join() to wait for the thread to complete
before doing the cleanup work.
Removed a stray 'x' variable from the example code.
NOTE
====
Have made an entry in .opt file as given below:
--plugin-dir=$DAEMONEXAMPLE_DIR
This is done so that the program takes plugin directory as
../<dbg>/plugin/daemon_example/ instead of
../lib/plugin/
Bug#17959689: MAKE GCC AND CLANG GIVE CONSISTENT COMPILATION WARNINGS
Bug#18313717: ENABLE -WERROR IN MAINTANER MODE WHEN COMPILING WITH CLANG
Bug#18510941: REMOVE CMAKE WORKAROUNDS FOR OLDER VERSIONS OF OS X/XCODE
Backport from mysql-5.6 to mysql-5.5
The assertion happens when: (i) the master and slave are configured to
use the semisync plugin; (ii) the DBA disables semisync on the master;
(iii) and he also unsets the option to wait for slaves ACK even if the
semisync slave count reaches 0 during the waiting period. This
combination of factors makes the server run into an assertion as soon
as the last semisync slave disconnects and its dump thread exits.
The root of the problem is the fact that when the dump thread
disconnects and calls the observer hook transmit_stop, which ends up
calling ReplSemiSyncMaster::remove_slave, there is no check whether
the master has already disabled semisync or not. If it has, the then a
second call to the switch_off member function must be avoided.
The quick fix is to avoid calling switch_off if the DBA has disabled
the semisync plugin interactively on the master. Also, the switch_off
member function should only be called if the plugin has not been
switched off already. This is basically the pattern throughout the
rest of the semisync plugin and no other calls seem vulnerable to
similar crashes/assertions.
(This a backport of the patch to 5.5, which is also vulnerable.)
RPL_SEMI_SYNC_MASTER_ENABLED OFF.
Problem:
=======
If master is waiting for a reply from slave, at this time
set global rpl_semi_sync_master_enabled=OFF, the master
server will crash.
Analysis:
========
When master is waiting for a reply from slave, at this time
if semi sync is switched off on master, during switch off if
active transactions are present the transactions will be
cleared and "active_tranxs_" variable will be set to NULL.
When the waiting master connection finds that semi sync is
switched of it tries to access "active_tranxs_" without
checking if the transaction list exists or not. Accessing
NULL transaction list causes the crash.
Fix:
===
A check has been added to see a valid list exists before
accessing the "active_tranxs_".
This patch changes the plugin configuration file format to make it
easier to add new plugins and remove complexity. It also adds more
information when plugin configuration file reads fail.
This patch adds a new client utility that enables or disables plugin
features. The utility disables or enables a plugin using values (name,
soname, and symbols) provided via a configuration file by the same name.
For example, to ENABLE the daemon_example plugin, the utility will read
the daemon_example.ini configuration file and use the values contained to
enable or disable the plugin.
The types mysql_event_general/mysql_event_connection are
being cast to the incompatible type mysql_event. The way
mysql_event and the other types are designed are prone to
strict aliasing violations and can break things depending
on how compilers optimizes this code.
This patch fixes audit interface, so it confirms to strict-
aliasing rules. It introduces incompatible changes to audit
interface:
- mysql_event type has been removed;
- event_class has been removed from mysql_event_generic and
mysql_event_connection types;
- st_mysql_audit::event_notify() second argument is event_class;
- st_mysql_audit::event_notify() third argument is event of type
(const void *).
"Writing Audit Plugins" section of manual should be updated:
http://dev.mysql.com/doc/refman/5.5/en/writing-audit-plugins.html
Due to how the server checks for option names the name of the
plugin "socket_peercred" collides with the existing server side
option "socket".
Renamed the plugin from "socket_peercred" to "auth_socket" to
avoid the name clash.
The autotools-based build system has been superseded and
is being removed in order to ease the maintenance burden on
developers tweaking and maintaining the build system.
In order to support tools that need to extract the server
version, a new file that (only) contains the server version,
called VERSION, is introduced. The file contents are human
and machine-readable. The format is:
MYSQL_VERSION_MAJOR=5
MYSQL_VERSION_MINOR=5
MYSQL_VERSION_PATCH=8
MYSQL_VERSION_EXTRA=-rc
The CMake based version extraction in cmake/mysql_version.cmake
is changed to extract the version from this file. The configure
to CMake wrapper is retained for backwards compatibility and to
support the BUILD/ scripts. Also, a new a makefile target
show-dist-name that prints the server version is introduced.
connectors plugins
Implemented changes needed to keep the client plugin API compatible with
the existing plugins :
1. Provided an options() client plugin API to let the application pass
options to the plugin after loading it
2. Added "License" (const char *) to specify the client plugin's license
3. Added "mysql_api" as a placeholder that the client library can use
to pass function pointers to the plugin so that the plugin can call the
C lib back.
4. Updated the existing client plugins to comply with the API change.
5. Added more detailed error message generation for Windows.
Introduce a MySQL maintainer/developer mode that enables
a set of warning options for the C/C++ compiler. This mode
is intended to help improve the overall quality of the code.
The warning options are:
C_WARNINGS="-Wall -Wextra -Wunused -Wwrite-strings -Werror"
CXX_WARNINGS="$C_WARNINGS -Wno-unused-parameter"
Since -Wall is essentially a moving target, autoconf checks
are not run with warning options enabled, in particualr -Werror.
This decision might be revisited in the future. The patch also
fixes a mistake in the makefiles, where automake CXXFLAGS would
be set to CFLAGS.
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.
Fix various mismatches between function's language linkage. Any
particular function that is declared in C++ but should be callable
from C must have C linkage. Note that function types with different
linkages are also distinct. Thus, if a function type is declared in
C code, it will have C linkage (same if declared in a extern "C"
block).
(make relies GNU extentions). The patch was partially
backport from 6.0.
Original comment:
bug#30708: make relies GNU extensions. Now that we no longer use
BitKeeper we can safely remove the SCCS handling with no loss of
functionality.
