LOCK_THREAD_COUNT

When using the performance schema file io instrumentation in MySQL 5.5,
a thread would loop forever inside lf_pinbox_put_pins, when disconnecting.
It would also hold LOCK_thread_count while doing so, effectively killing the
server.

The root cause of the loop in lf_pinbox_put_pins() is a leak of LF_PINS,
when used with the filename_hash LF_HASH table in the performance schema.

This fix contains the following changes:

1)
Added the missing call to lf_hash_search_unpin(), to prevent the leak.

2)
In mysys/lf_alloc-pin.c, there was some extra debugging code
(MY_LF_EXTRA_DEBUG) written to detect precisely this kind of issues,
but it was never used.
Replaced MY_LF_EXTRA_DEBUG with DBUG_OFF, so that leaks similar to this one
can be always detected in regular debug builds.

3)
Backported the fix for the following bug, from 5.6 to 5.5:
Bug#13417446 - 63339: INCORRECT FILE PATH IN PEFORMANCE_SCHEMA ON WINDOWS

Analysis:
-------------------------------
According to the Manual
(http://dev.mysql.com/doc/refman/5.1/en/identifier-case-sensitivity.html):
"Column, index, stored routine, and event names are not case sensitive on any
platform, nor are column aliases."

In other words, 'lower_case_table_names' does not affect the behaviour of 
those identifiers.

On the other hand, trigger names are case sensitive on some platforms,
and case insensitive on others. 'lower_case_table_names' does not affect
the behaviour of trigger names either.

The bug was that SHOW statements did case sensitive comparison
for stored procedure / stored function / event names.

Fix:
Modified the code so that comparison in case insensitive for routines 
and events for "SHOW" operation.

As part of this commit, only fixing the test failures due to the actual code fix.

Change the type of purge_sys_t::n_pages_handled and purge_sys_t::handle_limit
to ulonglong from ulint. On a 32 bit system doing ~700 deletes per second the
counters can overflow in ~3.5 months, if they are 32 bit.

Approved by Jimmy Yang over IM.

Analysis:
-------------------------------
According to the Manual
(http://dev.mysql.com/doc/refman/5.1/en/identifier-case-sensitivity.html):
"Column, index, stored routine, and event names are not case sensitive on any
platform, nor are column aliases."

In other words, 'lower_case_table_names' does not affect the behaviour of 
those identifiers.

On the other hand, trigger names are case sensitive on some platforms,
and case insensitive on others. 'lower_case_table_names' does not affect
the behaviour of trigger names either.

The bug was that SHOW statements did case sensitive comparison
for stored procedure / stored function / event names.

Fix:
Modified the code so that comparison in case insensitive for routines 
and events for "SHOW" operation.

rb://942
approved by: Marko Makela

We don't need to scan LRU for dropping AHI entries when DROPing a table.
AHI entries are already removed when we free up extents for the btree.

Manually resolved conflicts in ".bzr-mysql/default.conf" (tree name)
and in "storage/innodb_plugin" (does not belong into 5.5).

solve a conflict in ".bzr-mysql/default.conf".

to mysql-5.5

rb://979 approved by Marko

conflict in "sql/filesort.cc" solved manually.

Problem:

Field_set::val_str in case of an empty SET value
returned a String with str_length==0 and Ptr==0,
which is not expected by some pieces of the code.

Fix:
      
Returning an empty string with str_length==0 and Ptr=="",
like Field_enum does.

  Doing this for Sayantan whose VPN is not working ATM

The test case must insert all the records using a single transaction. Otherwise the test 
case takes more than 15 minutes and will time out in pb2 and mtr.  

FROM BUFFER POOL

rb://975
approved by: Marko Makela

There is a race in lock_validate() where we try to access a page
without ensuring that the tablespace stays valid during the operation
i.e.: it is not deleted. This patch tries to fix that by using an
existing flag (the flag is renamed to make it's name more generic
in line with it's new use).

rb://976
approved by: Marko Makela

Add an assertion to ensure that string overflow is not happening.
Pointed by Coverity analysis.

IN OS_THREAD_EQ

rb://977
approved by: Marko Makela

rw_lock::writer_thread field contains the thread id of current x-holder
or wait-x thread. This field is un-initialized at lock creation and is
written to for the first time when an attempt is made to x-lock.

Current code considers ::writer_thread as valid memory region only when
the lock is held in x-mode (or there is an x-waiter). This is an
overkill and it generates valgrind warnings.

The fix is to consider ::writer_thread as valid memory region once it
has been written to.

Reasoning:
==========
The ::writer_thread can be safely considered valid because:

* We only ever do comparison with current calling threads id.
* We only ever do comparison when ::recursive flag is set
* We always unset ::recursive flag in x-unlock
* Same thread cannot be unlocking and attempting to lock at the same
time
* thread_id recycling is not an issue because before an id is recycled
the thread must leave innodb meaning it must release all locks meaning
it must unset ::recursive flag.

Pre-requisite patch.
Add end-of-file marker to 5.5 version of errmsg-utf8.txt.

AND SAVEPOINT.
      
The bug was introduced by the patch for bug#11766752. This patch sets too
strong condition on XA state for SAVEPOINT statement that disallows its
execution during XA transaction. But since the statement SAVEPOINT doesn't
imply implicit commit we can allow its handling during XA transaction.

The patch explicitly check for transaction state against states XA_NOTR
and XA_ACTIVE for which the handling of statement SAVEPOINT for XA
transaction is allowed.

mysql-test/t/xa.test:
  Testcase was adjusted for bug#13737343. Now SAVEPOINT is allowed for XA
  transactions in ACTIVE state.

Updated code comments according to reviewers requests.

We are trying to sort a lot of text/blob fields, 
so the buffer is indeed too small.
Memory available = thd->variables.sortbuff_size = 262144
min_sort_memory = param.sort_length*MERGEBUFF2 = 292245
So the decision to abort the query is correct.

filesort() calls my_error(), the error is reported.
But, since we have DELETE IGNORE ... the error is converted to a warning by
THD::raise_condition

filesort currently expects an error to be recorded in the THD diagnostics
area.
If we lift this restriction (remove the assert) we end up in the familiar
void Protocol::end_statement()
  default:
    DBUG_ASSERT(0);

The solution seems to be to call my_error(ME_FATALERROR) in filesort,
so that the error is propagated as an error rather than a warning.


mysql-test/r/filesort_debug.result:
  New test case.
mysql-test/t/filesort_debug.test:
  New test case.

               ENOUGH - CONCAT() HACKS. ALSO WRONG
               ERROR MESSAGE WHILE TRYING TO CREATE
               A VIEW ON A NON EXISTING DATABASE

PROBLEM:
The first part of the problem is concluded as not a
bug, as 'concat' is not a reserved word and it is
completely valid to create a view with the name
'concat'.

The second issue is, while trying to create a view on
a non existing database, we are not giving a proper error
message.

FIX:
We have added a check for the database existence while
trying to create a view. This check would give an error
as 'unknown database' when the database does not exist.

This patch is a backport of the patch for Bug#13601606


mysql-test/r/view.result:
  Added test case result of Bug#12626844
mysql-test/t/view.test:
  Added test case for Bug#12626844
sql/sql_view.cc:
  Added a check for database existence in mysql_create_view

Automerging from mysql-5.1.

Adding missing sync_slave_with_master to the test case.