Inconsistent behavior of session variable max_allowed_packet 
(and net_buffer_length); only assignment to the global variable 
has any effect, without this being obvious to the user.
      
The patch for Bug#22891 is backported to 5.0, making the two
session variables read-only. As this is a backport to GA 
software, the error used when trying to assign to the read-
only variable is ER_UNKNOWN_ERROR. The error message is the 
same as in 5.1+.

mysql-test/t/variables.test:
  Tests are changed to account for the new semantics, and assignment to the read-only variables is added to test 
  the emission of the correct error message.
sql/set_var.cc:
  Both max_allowed_packet and net_buffer_length are changed 
  to be of type sys_var_thd_ulong_session_readonly. ER_UNKNOWN_ERROR is used to indicate an attempt to assign 
  to an instance of a read-only variable.
sql/set_var.h:
  Class sys_var_thd_ulong_session_readonly is added.

The problem: described in the bug report.
The fix:
--increase buffers where it's necessary
  (buffers which are used in stxnmov)
--decrease buffer lengths which are used


client/mysql.cc:
  --increase buffers where it's necessary
    (buffers which are used in stxnmov)
  --decrease buffer lengths which are used
    as argument for strxnmov function
sql/ha_ndbcluster.cc:
  --increase buffers where it's necessary
    (buffers which are used in stxnmov)
  --decrease buffer lengths which are used
    as argument for strxnmov function
sql/ha_ndbcluster_binlog.cc:
  --increase buffers where it's necessary
    (buffers which are used in stxnmov)
  --decrease buffer lengths which are used
    as argument for strxnmov function
sql/handler.cc:
  --increase buffers where it's necessary
    (buffers which are used in stxnmov)
  --decrease buffer lengths which are used
    as argument for strxnmov function
sql/log.cc:
  --increase buffers where it's necessary
    (buffers which are used in stxnmov)
  --decrease buffer lengths which are used
    as argument for strxnmov function
sql/mysqld.cc:
  removed unnecessary line
sql/parse_file.cc:
  --increase buffers where it's necessary
    (buffers which are used in stxnmov)
  --decrease buffer lengths which are used
    as argument for strxnmov function
sql/sql_acl.cc:
  --increase buffers where it's necessary
    (buffers which are used in stxnmov)
  --decrease buffer lengths which are used
    as argument for strxnmov function
sql/sql_base.cc:
  --increase buffers where it's necessary
    (buffers which are used in stxnmov)
  --decrease buffer lengths which are used
    as argument for strxnmov function
sql/sql_db.cc:
  --increase buffers where it's necessary
    (buffers which are used in stxnmov)
  --decrease buffer lengths which are used
    as argument for strxnmov function
sql/sql_delete.cc:
  --increase buffers where it's necessary
    (buffers which are used in stxnmov)
  --decrease buffer lengths which are used
    as argument for strxnmov function
sql/sql_partition.cc:
  --increase buffers where it's necessary
    (buffers which are used in stxnmov)
  --decrease buffer lengths which are used
    as argument for strxnmov function
sql/sql_rename.cc:
  --increase buffers where it's necessary
    (buffers which are used in stxnmov)
  --decrease buffer lengths which are used
    as argument for strxnmov function
sql/sql_show.cc:
  --increase buffers where it's necessary
    (buffers which are used in stxnmov)
  --decrease buffer lengths which are used
    as argument for strxnmov function
sql/sql_table.cc:
  --increase buffers where it's necessary
    (buffers which are used in stxnmov)
  --decrease buffer lengths which are used
    as argument for strxnmov function
sql/sql_view.cc:
  --increase buffers where it's necessary
    (buffers which are used in stxnmov)
  --decrease buffer lengths which are used
    as argument for strxnmov function

The problem was that a pthread.h header used by gcc did not
declare the pthread_setscheprio, yet the function is implemented
by the function is implemented, causing a autoconf check to pass
and compilation with C++ to fail. The solution is to add a
autoconf check to ensure that the function is properly declared.

configure.in:
  Check that the pthread_setschedprio is declared.

Large transactions and statements may corrupt the binary log if the size of the
cache, which is set by the max_binlog_cache_size, is not enough to store the
the changes.

In a nutshell, to fix the bug, we save the position of the next character in the
cache before starting processing a statement. If there is a problem, we simply
restore the position thus removing any effect of the statement from the cache.
Unfortunately, to avoid corrupting the binary log, we may end up loosing changes
on non-transactional tables if they do not fit in the cache. In such cases, we
store an Incident_log_event in order to stop the slave and alert users that some
changes were not logged.

Precisely, for every non-transactional changes that do not fit into the cache,
we do the following:
  a) the statement is *not* logged
  b) an incident event is logged after committing/rolling back the transaction,
  if any. Note that if a failure happens before writing the incident event to
  the binary log, the slave will not stop and the master will not have reported
  any error.
  c) its respective statement gives an error

For transactional changes that do not fit into the cache, we do the following:
  a) the statement is *not* logged
  b) its respective statement gives an error

To work properly, this patch requires two additional things. Firstly, callers to
MYSQL_BIN_LOG::write and THD::binlog_query must handle any error returned and
take the appropriate actions such as undoing the effects of a statement. We
already changed some calls in the sql_insert.cc, sql_update.cc and sql_insert.cc
modules but the remaining calls spread all over the code should be handled in
BUG#37148. Secondly, statements must be either classified as DDL or DML because
DDLs that do not get into the cache must generate an incident event since they
cannot be rolled back.

Item_func_spatial_collection::val_str
        
When the concatenation function for geometry data collections
reads the binary data it was not rigorous in checking that there
is data available, leading to invalid reads and crashes.
Fixed by making checking stricter.


mysql-test/r/gis.result:
  Bug#44684: Test result
mysql-test/t/gis.test:
  Bug#44684: Test case
sql/item_geofunc.cc:
  Bug#44684: fix(es)
  - Check that there are 4 bytes available for type code.
  - Check that there is at least one point available for linestring.
  - Check that there are at least 2 points in a polygon and
    data for all the points.

This patch corrects a misstake in the test case for bug patch 43658.

There was a race in the test case when the thread id was retrieved from the processlist.
The result was that the same thread id was signalled twice and one thread id wasn't
signalled at all.

The affected platforms appears to be limited to linux.

mysql-test/r/query_cache_debug.result:
  There was a race in the test case when the thread id was retrieved from the processlist.
  The result was that the same thread id was signalled twice and one thread id wasn't
  signalled at all.
mysql-test/t/query_cache_debug.test:
  There was a race in the test case when the thread id was retrieved from the processlist.
  The result was that the same thread id was signalled twice and one thread id wasn't
  signalled at all.

with gcc 4.3.2
      
Compiling MySQL with gcc 4.3.2 and later produces a number of 
warnings, many of which are new with the recent compiler
versions.
                  
This bug will be resolved in more than one patch to limit the
size of changesets. This is the second patch, fixing more
of the warnings.

This is a backport of BUG#43076.

      
The assertion in String::copy was added in order to avoid
valgrind errors when the destination was the same as the source.
Eased restriction to allow for the case when str == NULL.


mysql-test/r/func_set.result:
  Bug#45168: Test result
mysql-test/t/func_set.test:
  Bug#45168: Test case
sql/item_strfunc.cc:
  Bug#45168: Code cleanup and grammar correction in comment
sql/sql_string.cc:
  Bug#45168: Fix

to a test file that guarantees the presence of partition code

Early patch submitted for discussion.

It is possible for more than one thread to enter the condition
in query_cache_insert(), but the condition predicate is to
signal one thread each time the cache status changes between
the following states: {NO_FLUSH_IN_PROGRESS,FLUSH_IN_PROGRESS,
TABLE_FLUSH_IN_PROGRESS}

Consider three threads THD1, THD2, THD3

   THD2: select ... => Got a writer in ::store_query
   THD3: select ... => Got a writer in ::store_query
   THD1: flush tables => qc status= FLUSH_IN_PROGRESS;
                      new writers are blocked.
   THD2: select ... => Still got a writer and enters cond in
                       query_cache_insert
   THD3: select ... => Still got a writer and enters cond in
                       query_cache_insert
   THD1: flush tables => finished and signal status change.
   THD2: select ... => Wakes up and completes the insert.
   THD3: select ... => Happily waiting for better times. Why hurry?

This patch is a refactoring of this lock system. It introduces four new methods:
   Query_cache::try_lock()
   Query_cache::lock()
   Query_cache::lock_and_suspend()
   Query_cache::unlock()

This change also deprecates wait_while_table_flush_is_in_progress(). All threads are
queued and put on a conditional wait. On each unlock the queue is signalled. This resolve
the issues with left over threads. To assure that no threads are spending unnecessary
time waiting a signal broadcast is issued every time a lock is taken before a full
cache flush.

mysql-test/r/query_cache_debug.result:
  * Added test case for bug43758
mysql-test/t/query_cache_debug.test:
  * Added test case for bug43758
sql/sql_cache.cc:
  * Replaced calls to wait_while_table_flush_is_in_progress() with
    calls to try_lock(), lock_and_suspend() and unlock().
  * Renamed enumeration Cache_status to Cache_lock_status.
  * Renamed enumeration items to UNLOCKED, LOCKED_NO_WAIT and LOCKED.
    If the LOCKED_NO_WAIT lock type is used to lock the query cache, other
    threads using try_lock() will fail to acquire the lock.
    This is useful if the query cache is temporary disabled due to 
    a full table flush.
sql/sql_cache.h:
  * Replaced calls to wait_while_table_flush_is_in_progress() with
    calls to try_lock(), lock_and_suspend() and unlock().
  * Renamed enumeration Cache_status to Cache_lock_status.
  * Renamed enumeration items to UNLOCKED, LOCKED_NO_WAIT and LOCKED.
    If the LOCKED_NO_WAIT lock type is used to lock the query cache, other
    threads using try_lock() will fail to acquire the lock.
    This is useful if the query cache is temporary disabled due to 
    a full table flush.