Function key_cache_insert

mysys/mf_keycache.c:2732–2947

*/

int key_cache_insert(KEY_CACHE *keycache,
                     File file, my_off_t filepos, int level,
                     uchar *buff, uint length)
{
  int error= 0;
  DBUG_ENTER("key_cache_insert");
  DBUG_PRINT("enter", ("fd: %u  pos: %lu  length: %u",
               (uint) file,(ulong) filepos, length));

  if (keycache->key_cache_inited)
  {
    /* Key cache is used */
    reg1 BLOCK_LINK *block;
    uint read_length;
    uint offset;
    int page_st;
    my_bool locked_and_incremented= FALSE;

    /*
      When the keycache is once initialized, we use the cache_lock to
      reliably distinguish the cases of normal operation, resizing, and
      disabled cache. We always increment and decrement
      'cnt_for_resize_op' so that a resizer can wait for pending I/O.
    */
    keycache_pthread_mutex_lock(&keycache->cache_lock);
    /*
      We do not load index data into a disabled cache nor into an
      ongoing resize.
    */
    if (!keycache->can_be_used || keycache->in_resize)
	goto no_key_cache;
    /* Register the pseudo I/O for the next resize. */
    inc_counter_for_resize_op(keycache);
    locked_and_incremented= TRUE;
    /* Loaded data may not always be aligned to cache blocks. */
    offset= (uint) (filepos % keycache->key_cache_block_size);
    /* Load data in key_cache_block_size increments. */
    do
    {
      /* Cache could be disabled or resizing in a later iteration. */
      if (!keycache->can_be_used || keycache->in_resize)
	goto no_key_cache;
      /* Start loading at the beginning of the cache block. */
      filepos-= offset;
      /* Do not load beyond the end of the cache block. */
      read_length= length;
      set_if_smaller(read_length, keycache->key_cache_block_size-offset);
      KEYCACHE_DBUG_ASSERT(read_length > 0);

      /* The block has been read by the caller already. */
      keycache->global_cache_read++;
      /* Request the cache block that matches file/pos. */
      keycache->global_cache_r_requests++;
      block= find_key_block(keycache, file, filepos, level, 0, &page_st);
      if (!block)
      {
        /*
          This happens only for requests submitted during key cache