WL#1700 - Properly count key_blocks_used and key_blocks_current.

Introduced a new free blocks list. Free blocks are now re-used before
new blocks are allocated from the pool. There is a new status variable 
which can be queried by "show status like key_blocks_unused".


include/keycache.h:
  WL#1700 - Properly count key_blocks_used and key_blocks_current.
  free_block_list is the new free blocks list. It is implemented like a stack (LIFO).
  blocks_unused holds the number of never used blocks plus the number of blocks in the free list.
  Removed the variable global_blocks_used, as it was always the same as blocks_used.
mysql-test/r/key_cache.result:
  WL#1700 - Properly count key_blocks_used and key_blocks_current.
  Inserted some commands which show how key_blocks_used and key_blocks_unused work.
mysql-test/t/key_cache.test:
  WL#1700 - Properly count key_blocks_used and key_blocks_current.
  Inserted some commands which show how key_blocks_used and key_blocks_unused work.
mysys/mf_keycache.c:
  WL#1700 - Properly count key_blocks_used and key_blocks_current.
  Introduced a new free blocks list. The introductory comment says it all (I hope).
  Removed the variable global_blocks_used, as it was always the same as blocks_used.
sql/mysqld.cc:
  WL#1700 - Properly count key_blocks_used and key_blocks_current.
  The blocks_unused count can be queried by "show status like key_blocks_unused".
  Removed the variable global_blocks_used, as it was always the same as blocks_used.
  Introduced SHOW_KEY_CACHE_CONST_LONG for status variables that
  must not be modified (i.e. flushed to zero).
sql/sql_show.cc:
  WL#1700 - Properly count key_blocks_used and key_blocks_current.
  Introduced SHOW_KEY_CACHE_CONST_LONG for status variables that
  must not be modified (i.e. flushed to zero).
sql/sql_test.cc:
  WL#1700 - Properly count key_blocks_used and key_blocks_current.
  Removed the variable global_blocks_used, as it was always the same as blocks_used.
sql/structs.h:
  WL#1700 - Properly count key_blocks_used and key_blocks_current.
  Introduced SHOW_KEY_CACHE_CONST_LONG for status variables that
  must not be modified (i.e. flushed to zero).

1 files changed, 12 insertions, 0 deletions

diff --git a/mysql-test/t/key_cache.test b/mysql-test/t/key_cache.test
index 2bf5cdbcf6f..ca846a31def 100644
--- a/mysql-test/t/key_cache.test
+++ b/mysql-test/t/key_cache.test
@@ -66,6 +66,10 @@ set global keycache1.key_buffer_size=1024*1024;
 create table t1 (p int primary key, a char(10)) delay_key_write=1;
 create table t2 (p int primary key, i int, a char(10), key k1(i), key k2(a));
 
+show status like 'key_blocks_used';
+show status like 'The below may fail on 64-bit systems (ingo)';
+show status like 'key_blocks_unused'; # This may fail on 64-bit systems (ingo)
+
 insert into t1 values (1, 'qqqq'), (11, 'yyyy');
 insert into t2 values (1, 1, 'qqqq'), (2, 1, 'pppp'),
                       (3, 1, 'yyyy'), (4, 3, 'zzzz');
@@ -75,6 +79,10 @@ select * from t2;
 update t1 set p=2 where p=1;
 update t2 set i=2 where i=1;
 
+show status like 'key_blocks_used';
+show status like 'The below may fail on 64-bit systems (ingo)';
+show status like 'key_blocks_unused'; # This may fail on 64-bit systems (ingo)
+
 cache index t1 key (`primary`) in keycache1;
 
 explain select p from t1;
@@ -133,6 +141,10 @@ cache index t3 in keycache2;
 cache index t1,t2 in default;
 drop table t1,t2,t3;
 
+show status like 'key_blocks_used';
+show status like 'The below may fail on 64-bit systems (ingo)';
+show status like 'key_blocks_unused'; # This may fail on 64-bit systems (ingo)
+
 # Cleanup
 # We don't reset keycache2 as we want to ensure that mysqld will reset it
 set global keycache2.key_buffer_size=0;