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.
This patch:
- Moves all definitions from the mysql_priv.h file into
header files for the component where the variable is
defined
- Creates header files if the component lacks one
- Eliminates all include directives from mysql_priv.h
- Eliminates all circular include cycles
- Rename time.cc to sql_time.cc
- Rename mysql_priv.h to sql_priv.h
given an already connected MYSQL handle
mysql_real_connect() did not check whether the MYSQL connection
handler was already connected and connected again even if so.
Now a CR_ALREADY_CONNECTED error is returned.
We cann connect() in a non-blocking mode to be able to specify a
non-standard timeout.
The problem was that we did not fetch the status from the
non-blocking connect(). We assumed that poll() would not return
a POLLIN flag if the connect failed. But on some platforms this
is not true.
After a successful poll() we do now retrieve the status value
from connect() with getsockopt(...SO_ERROR...). Now we do know
if (and how) the connect failed.
The test case for my investigation was rpl.rlp_ssl1 on an
Ubuntu 9.04 x86_64 machine. Both, IPV4 and IPV6 were active.
'localhost' resolved first for IPV6 and then for IPV4. The
connection over IPV6 was blocked. rpl.rlp_ssl1 timed out
as it did not notice the failed connect(). The first read()
failed, which was interpreted as a master crash and the
connection was tried to reestablish with the same result
until the retry limit was reached.
With the fix, the connect() problem is immediately recognized,
and the connect() is retried on the second resolution for
'localhost', which is successful.
Rename client_last_error to last_error and client_last_errno to last_errno
to not break connectors which use the internal net structure for error handling.
cause ROLLBACK of statement", part 1. Review fixes.
Do not send OK/EOF packets to the client until we reached the end of
the current statement.
This is a consolidation, to keep the functionality that is shared by all
SQL statements in one place in the server.
Currently this functionality includes:
- close_thread_tables()
- log_slow_statement().
After this patch and the subsequent patch for Bug#12713, it shall also include:
- ha_autocommit_or_rollback()
- net_end_statement()
- query_cache_end_of_result().
In future it may also include:
- mysql_reset_thd_for_next_command().
(Mostly in DBUG_PRINT() and unused arguments)
Fixed bug in query cache when used with traceing (--with-debug)
Fixed memory leak in mysqldump
Removed warnings from mysqltest scripts (replaced -- with #)
there was two problems about charsets in embedded server
1. mysys/charset.c - defined there default_charset_info variable is
modified by both server and client code (particularly when
--default-charset option is handled)
In embedded server we get two codelines modifying one variable.
I created separate default_client_charset_info for client code
2. mysql->charset and mysql->options.charset initialization isn't
properly done for embedded server - necessary calls added
There actually was 3 different problems -
hash_user_connections wasn't cleaned
one strdupped database name wasn't freed
and stmt->mem_root wasn't cleaned as it was
replased with mysql->field_alloc for result
For the last one - i made the library using stmt's
fields to store result if it's the case.
now mysql_server_init is called from mysql_init with fake parameters
mysql_once_init code included to mysql_server_init.
embedded-specific initialization is in init_embedded_server function
WL#604 Privileges in embedded library
code added to check privileges in embedded library
NO_EMBEDDED_ACCESS_CHECKS macros inserted in code so we can exclude
access-checking parts. Actually we now can exclude these parts from
standalone server as well. Do we need it?
Access checks are disabled in embedded server by default. One should
edit libmysqld/Makefile manually to get this working.
We definitely need the separate configure for embedded server
embedded library
I decided to get rid of #define mysql_some_function in mysql.h
It puzzles users and makes problems with dynamic libraries
Finally, there are only two functions left, that are covered with
the #define-s and it won't hurt performance at all
Prepared statements in embedded server
Several changes in library code with two goals:
to make mysql_prepare_stmt working in embedded server
to get rid of #define mysql_interface_func mysql->methods->interface_func
in user's interface
mysql_fetch_length fixed for embedded library. Now data length is stored
before the data. Pointers in row still points to the data so you have to
get *(uint*)(data_ptr - sizeof(uint)) to get data length
