WL#775 "Add status variable identifying binlog_cache_size shortage"

Added two status variables: 
  binlog_cache_use - counts number of transactions that used somehow
    transaction temporary binary log.
  binlog_cache_disk_use - counts number of transactions that required
    disk I/O for storing info in this this binary log.

3 files changed, 31 insertions, 3 deletions

diff --git a/sql/handler.cc b/sql/handler.cc
index 38b95424637..ddf2e68db47 100644
--- a/sql/handler.cc
+++ b/sql/handler.cc
@@ -405,6 +405,16 @@ int ha_commit_trans(THD *thd, THD_TRANS* trans)
 	my_b_tell(&thd->transaction.trans_log))
     {
       mysql_bin_log.write(thd, &thd->transaction.trans_log, 1);
+      statistic_increment(binlog_cache_use, &LOCK_status);
+      if (thd->transaction.trans_log.disk_writes != 0)
+      {
+        /* 
+          We have to do this after addition of trans_log to main binlog since
+          this operation can cause flushing of end of trans_log to disk. 
+        */
+        statistic_increment(binlog_cache_disk_use, &LOCK_status);
+        thd->transaction.trans_log.disk_writes= 0;
+      }
       reinit_io_cache(&thd->transaction.trans_log,
 		      WRITE_CACHE, (my_off_t) 0, 0, 1);
       thd->transaction.trans_log.end_of_file= max_binlog_cache_size;
@@ -492,10 +502,23 @@ int ha_rollback_trans(THD *thd, THD_TRANS *trans)
          Update the binary log with a BEGIN/ROLLBACK block if we have cached some
          queries and we updated some non-transactional table. Such cases should
          be rare (updating a non-transactional table inside a transaction...).
+         Count disk writes to trans_log in any case.
       */
-      if (unlikely((thd->options & OPTION_STATUS_NO_TRANS_UPDATE) &&
-                   my_b_tell(&thd->transaction.trans_log)))
-        mysql_bin_log.write(thd, &thd->transaction.trans_log, 0);
+      if (my_b_tell(&thd->transaction.trans_log))
+      {
+        if (unlikely(thd->options & OPTION_STATUS_NO_TRANS_UPDATE))
+          mysql_bin_log.write(thd, &thd->transaction.trans_log, 0);
+        statistic_increment(binlog_cache_use, &LOCK_status);
+        if (thd->transaction.trans_log.disk_writes != 0)
+        {
+          /* 
+            We have to do this after addition of trans_log to main binlog since
+            this operation can cause flushing of end of trans_log to disk. 
+          */
+          statistic_increment(binlog_cache_disk_use, &LOCK_status);
+          thd->transaction.trans_log.disk_writes= 0;
+        }
+      }
       /* Flushed or not, empty the binlog cache */
       reinit_io_cache(&thd->transaction.trans_log,
                       WRITE_CACHE, (my_off_t) 0, 0, 1);
diff --git a/sql/mysql_priv.h b/sql/mysql_priv.h
index 4fd41b7bd66..a979ef137ae 100644
--- a/sql/mysql_priv.h
+++ b/sql/mysql_priv.h
@@ -791,6 +791,7 @@ extern ulonglong log_10_int[20];
 extern ulonglong keybuff_size;
 extern ulong refresh_version,flush_version, thread_id,query_id,opened_tables;
 extern ulong created_tmp_tables, created_tmp_disk_tables, bytes_sent;
+extern ulong binlog_cache_use, binlog_cache_disk_use;
 extern ulong aborted_threads,aborted_connects;
 extern ulong delayed_insert_timeout;
 extern ulong delayed_insert_limit, delayed_queue_size;
diff --git a/sql/mysqld.cc b/sql/mysqld.cc
index d602c44c8f9..308f50c3eb0 100644
--- a/sql/mysqld.cc
+++ b/sql/mysqld.cc
@@ -297,6 +297,7 @@ ulong select_range_check_count, select_range_count, select_scan_count;
 ulong select_full_range_join_count,select_full_join_count;
 ulong specialflag=0,opened_tables=0,created_tmp_tables=0,
       created_tmp_disk_tables=0;
+ulong binlog_cache_use= 0, binlog_cache_disk_use= 0;
 ulong max_connections,max_used_connections,
       max_connect_errors, max_user_connections = 0;
 ulong thread_id=1L,current_pid;
@@ -4719,6 +4720,8 @@ The minimum value for this variable is 4096.",
 struct show_var_st status_vars[]= {
   {"Aborted_clients",          (char*) &aborted_threads,        SHOW_LONG},
   {"Aborted_connects",         (char*) &aborted_connects,       SHOW_LONG},
+  {"Binlog_cache_disk_use",    (char*) &binlog_cache_disk_use,  SHOW_LONG},
+  {"Binlog_cache_use",         (char*) &binlog_cache_use,       SHOW_LONG},
   {"Bytes_received",           (char*) &bytes_received,         SHOW_LONG},
   {"Bytes_sent",               (char*) &bytes_sent,             SHOW_LONG},
   {"Com_admin_commands",       (char*) &com_other,		SHOW_LONG},
@@ -5013,6 +5016,7 @@ static void mysql_init_variables(void)
   filesort_merge_passes= select_range_check_count= select_range_count= 0;
   select_scan_count= select_full_range_join_count= select_full_join_count= 0;
   specialflag= opened_tables= created_tmp_tables= created_tmp_disk_tables= 0;
+  binlog_cache_use=  binlog_cache_disk_use= 0;
   max_used_connections= slow_launch_threads = 0;
   max_sort_char= 0;
   mysqld_user= mysqld_chroot= opt_init_file= opt_bin_logname = 0;