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.

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.

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.

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.

times (ie: 2:16:20).

statements missed from general log

A FLUSH LOGS is added to ensure that the log info hits
the file before attempting to process.