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Simple binary cache optimizations

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- Don't call my_chsize() for small (less than 64K) binary log tmp files
- Don't flush cache to disk on reset.
This commit is contained in:
Monty 2017-04-07 10:08:20 +03:00 • committed by Alexander Barkov
parent 1bcfa14e26
commit 0177a9c74a
1 changed files with 20 additions and 18 deletions
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38
sql/log.cc
View file

@ -61,6 +61,8 @@
#define MAX_LOG_BUFFER_SIZE 1024
#define MAX_TIME_SIZE 32
#define MY_OFF_T_UNDEF (~(my_off_t)0UL)
/* Truncate cache log files bigger than this */
#define CACHE_FILE_TRUNC_SIZE 65536
#define FLAGSTR(V,F) ((V)&(F)?#F" ":"")
@ -313,24 +315,19 @@ public:
void reset()
{
compute_statistics();
truncate(0);
if(cache_log.file != -1)
bool cache_was_empty= empty();
bool truncate_file= (cache_log.file != -1 &&
my_b_write_tell(&cache_log) > CACHE_FILE_TRUNC_SIZE);
truncate(0,1); // Forget what's in cache
if (!cache_was_empty)
compute_statistics();
if (truncate_file)
my_chsize(cache_log.file, 0, 0, MYF(MY_WME));
changes_to_non_trans_temp_table_flag= FALSE;
status= 0;
incident= FALSE;
before_stmt_pos= MY_OFF_T_UNDEF;
/*
The truncate function calls reinit_io_cache that calls
my_b_flush_io_cache which may increase disk_writes. This breaks
the disk_writes use by the binary log which aims to compute the
ratio between in-memory cache usage and disk cache usage. To
avoid this undesirable behavior, we reset the variable after
truncating the cache.
*/
cache_log.disk_writes= 0;
DBUG_ASSERT(empty());
}
@ -437,11 +434,16 @@ private:
*/
void compute_statistics()
{
if (!empty())
statistic_increment(*ptr_binlog_cache_use, &LOCK_status);
if (cache_log.disk_writes != 0)
{
statistic_increment(*ptr_binlog_cache_use, &LOCK_status);
if (cache_log.disk_writes != 0)
statistic_increment(*ptr_binlog_cache_disk_use, &LOCK_status);
#ifdef REAL_STATISTICS
statistic_add(*ptr_binlog_cache_disk_use,
cache_log.disk_writes, &LOCK_status);
#else
statistic_increment(*ptr_binlog_cache_disk_use, &LOCK_status);
#endif
cache_log.disk_writes= 0;
}
}
@ -470,7 +472,7 @@ private:
It truncates the cache to a certain position. This includes deleting the
pending event.
*/
void truncate(my_off_t pos)
void truncate(my_off_t pos, bool reset_cache=0)
{
DBUG_PRINT("info", ("truncating to position %lu", (ulong) pos));
if (pending())
@ -478,7 +480,7 @@ private:
delete pending();
set_pending(0);
}
reinit_io_cache(&cache_log, WRITE_CACHE, pos, 0, 0);
reinit_io_cache(&cache_log, WRITE_CACHE, pos, 0, reset_cache);
cache_log.end_of_file= saved_max_binlog_cache_size;
}