buf0buf.c

这是linux下运行的mysql软件包,可用于linux 下安装 php + mysql + apach 的网络配置

pool if it is found there. */

ibool
buf_page_peek_if_search_hashed(
/*===========================*/
			/* out: TRUE if page hash index is built in search
			system */
	ulint	space,	/* in: space id */
	ulint	offset)	/* in: page number */
{
	buf_block_t*	block;
	ibool		is_hashed;

	mutex_enter_fast(&(buf_pool->mutex));

	block = buf_page_hash_get(space, offset);

	if (!block) {
		is_hashed = FALSE;
	} else {
		is_hashed = block->is_hashed;
	}

	mutex_exit(&(buf_pool->mutex));

	return(is_hashed);
}

/************************************************************************
Returns TRUE if the page can be found in the buffer pool hash table. NOTE
that it is possible that the page is not yet read from disk, though. */

ibool
buf_page_peek(
/*==========*/
			/* out: TRUE if found from page hash table,
			NOTE that the page is not necessarily yet read
			from disk! */
	ulint	space,	/* in: space id */
	ulint	offset)	/* in: page number */
{
	if (buf_page_peek_block(space, offset)) {

		return(TRUE);
	}

	return(FALSE);
}

/************************************************************************
Sets file_page_was_freed TRUE if the page is found in the buffer pool.
This function should be called when we free a file page and want the
debug version to check that it is not accessed any more unless
reallocated. */

buf_block_t*
buf_page_set_file_page_was_freed(
/*=============================*/
			/* out: control block if found from page hash table,
			otherwise NULL */
	ulint	space,	/* in: space id */
	ulint	offset)	/* in: page number */
{
	buf_block_t*	block;

	mutex_enter_fast(&(buf_pool->mutex));

	block = buf_page_hash_get(space, offset);

	if (block) {
		block->file_page_was_freed = TRUE;
	}

	mutex_exit(&(buf_pool->mutex));

	return(block);
}

/************************************************************************
Sets file_page_was_freed FALSE if the page is found in the buffer pool.
This function should be called when we free a file page and want the
debug version to check that it is not accessed any more unless
reallocated. */

buf_block_t*
buf_page_reset_file_page_was_freed(
/*===============================*/
			/* out: control block if found from page hash table,
			otherwise NULL */
	ulint	space,	/* in: space id */
	ulint	offset)	/* in: page number */
{
	buf_block_t*	block;

	mutex_enter_fast(&(buf_pool->mutex));

	block = buf_page_hash_get(space, offset);

	if (block) {
		block->file_page_was_freed = FALSE;
	}

	mutex_exit(&(buf_pool->mutex));

	return(block);
}

/************************************************************************
This is the general function used to get access to a database page. */

buf_frame_t*
buf_page_get_gen(
/*=============*/
				/* out: pointer to the frame or NULL */
	ulint		space,	/* in: space id */
	ulint		offset,	/* in: page number */
	ulint		rw_latch,/* in: RW_S_LATCH, RW_X_LATCH, RW_NO_LATCH */
	buf_frame_t*	guess,	/* in: guessed frame or NULL */
	ulint		mode,	/* in: BUF_GET, BUF_GET_IF_IN_POOL,
				BUF_GET_NO_LATCH, BUF_GET_NOWAIT */
	const char*	file,	/* in: file name */
	ulint		line,	/* in: line where called */
	mtr_t*		mtr)	/* in: mini-transaction */
{
	buf_block_t*	block;
	ibool		accessed;
	ulint		fix_type;
	ibool		success;
	ibool		must_read;
	
	ut_ad(mtr);
	ut_ad((rw_latch == RW_S_LATCH)
	      || (rw_latch == RW_X_LATCH)
	      || (rw_latch == RW_NO_LATCH));
	ut_ad((mode != BUF_GET_NO_LATCH) || (rw_latch == RW_NO_LATCH));
	ut_ad((mode == BUF_GET) || (mode == BUF_GET_IF_IN_POOL)
	      || (mode == BUF_GET_NO_LATCH) || (mode == BUF_GET_NOWAIT));
#ifndef UNIV_LOG_DEBUG
	ut_ad(!ibuf_inside() || ibuf_page(space, offset));
#endif
	buf_pool->n_page_gets++;
loop:
	mutex_enter_fast(&(buf_pool->mutex));

	block = NULL;
	
	if (guess) {
		block = buf_block_align(guess);

		if ((offset != block->offset) || (space != block->space)
				|| (block->state != BUF_BLOCK_FILE_PAGE)) {

			block = NULL;
		}
	}

	if (block == NULL) {
		block = buf_page_hash_get(space, offset);
	}

	if (block == NULL) {
		/* Page not in buf_pool: needs to be read from file */

		mutex_exit(&(buf_pool->mutex));

		if (mode == BUF_GET_IF_IN_POOL) {

			return(NULL);
		}

		buf_read_page(space, offset);

#ifdef UNIV_DEBUG
		buf_dbg_counter++;

		if (buf_dbg_counter % 37 == 0) {
			ut_ad(buf_validate());
		}
#endif
		goto loop;
	}

	ut_a(block->state == BUF_BLOCK_FILE_PAGE);

	must_read = FALSE;
	
	if (block->io_fix == BUF_IO_READ) {

		must_read = TRUE;

		if (mode == BUF_GET_IF_IN_POOL) {

			/* The page is only being read to buffer */
			mutex_exit(&(buf_pool->mutex));

			return(NULL);
		}
	}		

	/* If AWE is enabled and the page is not mapped to a frame, then
	map it */

	if (block->frame == NULL) {
		ut_a(srv_use_awe);

		/* We set second parameter TRUE because the block is in the
		LRU list and we must put it to awe_LRU_free_mapped list once
		mapped to a frame */
		
		buf_awe_map_page_to_frame(block, TRUE);
	}
	
#ifdef UNIV_SYNC_DEBUG
	buf_block_buf_fix_inc_debug(block, file, line);
#else
	buf_block_buf_fix_inc(block);
#endif
	buf_block_make_young(block);

	/* Check if this is the first access to the page */

	accessed = block->accessed;

	block->accessed = TRUE;

#ifdef UNIV_DEBUG_FILE_ACCESSES
	ut_a(block->file_page_was_freed == FALSE);
#endif	
	mutex_exit(&(buf_pool->mutex));

#ifdef UNIV_DEBUG
	buf_dbg_counter++;

	if (buf_dbg_counter % 5771 == 0) {
		ut_ad(buf_validate());
	}
#endif
	ut_ad(block->buf_fix_count > 0);
	ut_ad(block->state == BUF_BLOCK_FILE_PAGE);

	if (mode == BUF_GET_NOWAIT) {
		if (rw_latch == RW_S_LATCH) {
			success = rw_lock_s_lock_func_nowait(&(block->lock),
								file, line);
			fix_type = MTR_MEMO_PAGE_S_FIX;
		} else {
			ut_ad(rw_latch == RW_X_LATCH);
			success = rw_lock_x_lock_func_nowait(&(block->lock),
					file, line);
			fix_type = MTR_MEMO_PAGE_X_FIX;
		}

		if (!success) {
			mutex_enter(&(buf_pool->mutex));

			block->buf_fix_count--;
#ifdef UNIV_SYNC_DEBUG
			rw_lock_s_unlock(&(block->debug_latch));
#endif			
			mutex_exit(&(buf_pool->mutex));

			return(NULL);
		}
	} else if (rw_latch == RW_NO_LATCH) {

		if (must_read) {
		        /* Let us wait until the read operation
			completes */

		        for (;;) {
			        mutex_enter(&(buf_pool->mutex));

		                if (block->io_fix == BUF_IO_READ) {

				        mutex_exit(&(buf_pool->mutex));
				  
				        /* Sleep 20 milliseconds */

				        os_thread_sleep(20000);
				} else {
				  
				       mutex_exit(&(buf_pool->mutex));

				       break;
				}
			}
		}

		fix_type = MTR_MEMO_BUF_FIX;
	} else if (rw_latch == RW_S_LATCH) {

		rw_lock_s_lock_func(&(block->lock), 0, file, line);

		fix_type = MTR_MEMO_PAGE_S_FIX;
	} else {
		rw_lock_x_lock_func(&(block->lock), 0, file, line);

		fix_type = MTR_MEMO_PAGE_X_FIX;
	}

	mtr_memo_push(mtr, block, fix_type);

	if (!accessed) {
		/* In the case of a first access, try to apply linear
		read-ahead */

		buf_read_ahead_linear(space, offset);
	}

#ifdef UNIV_IBUF_DEBUG
	ut_a(ibuf_count_get(block->space, block->offset) == 0);
#endif
	return(block->frame);		
}

/************************************************************************
This is the general function used to get optimistic access to a database
page. */

ibool
buf_page_optimistic_get_func(
/*=========================*/
				/* out: TRUE if success */
	ulint		rw_latch,/* in: RW_S_LATCH, RW_X_LATCH */
	buf_block_t*	block,	/* in: guessed buffer block */
	buf_frame_t*	guess,	/* in: guessed frame; note that AWE may move
				frames */
	dulint		modify_clock,/* in: modify clock value if mode is
				..._GUESS_ON_CLOCK */
	const char*	file,	/* in: file name */
	ulint		line,	/* in: line where called */
	mtr_t*		mtr)	/* in: mini-transaction */
{
	ibool		accessed;
	ibool		success;
	ulint		fix_type;

	ut_ad(mtr && block);
	ut_ad((rw_latch == RW_S_LATCH) || (rw_latch == RW_X_LATCH));
	
	mutex_enter(&(buf_pool->mutex));

	/* If AWE is used, block may have a different frame now, e.g., NULL */
	
	if (UNIV_UNLIKELY(block->state != BUF_BLOCK_FILE_PAGE)
			|| UNIV_UNLIKELY(block->frame != guess)) {
	exit_func:
		mutex_exit(&(buf_pool->mutex));

		return(FALSE);
	}

#ifdef UNIV_SYNC_DEBUG
	buf_block_buf_fix_inc_debug(block, file, line);
#else
	buf_block_buf_fix_inc(block);
#endif
	buf_block_make_young(block);

	/* Check if this is the first access to the page */

	accessed = block->accessed;

	block->accessed = TRUE;

	mutex_exit(&(buf_pool->mutex));

	ut_ad(!ibuf_inside() || ibuf_page(block->space, block->offset));

	if (rw_latch == RW_S_LATCH) {
		success = rw_lock_s_lock_func_nowait(&(block->lock),
								file, line);
		fix_type = MTR_MEMO_PAGE_S_FIX;
	} else {
		success = rw_lock_x_lock_func_nowait(&(block->lock),
								file, line);
		fix_type = MTR_MEMO_PAGE_X_FIX;
	}

	if (UNIV_UNLIKELY(!success)) {
		mutex_enter(&(buf_pool->mutex));
		
		block->buf_fix_count--;
#ifdef UNIV_SYNC_DEBUG
		rw_lock_s_unlock(&(block->debug_latch));
#endif
		goto exit_func;
	}

	if (UNIV_UNLIKELY(!UT_DULINT_EQ(modify_clock, block->modify_clock))) {
#ifdef UNIV_SYNC_DEBUG
		buf_page_dbg_add_level(block->frame, SYNC_NO_ORDER_CHECK);
#endif /* UNIV_SYNC_DEBUG */
		if (rw_latch == RW_S_LATCH) {
			rw_lock_s_unlock(&(block->lock));
		} else {
			rw_lock_x_unlock(&(block->lock));
		}

		mutex_enter(&(buf_pool->mutex));
		
		block->buf_fix_count--;
#ifdef UNIV_SYNC_DEBUG
		rw_lock_s_unlock(&(block->debug_latch));
#endif
		goto exit_func;
	}

	mtr_memo_push(mtr, block, fix_type);

#ifdef UNIV_DEBUG
	buf_dbg_counter++;

	if (buf_dbg_counter % 5771 == 0) {
		ut_ad(buf_validate());
	}
#endif
	ut_ad(block->buf_fix_count > 0);
	ut_ad(block->state == BUF_BLOCK_FILE_PAGE);

#ifdef UNIV_DEBUG_FILE_ACCESSES
	ut_a(block->file_page_was_freed == FALSE);
#endif
	if (UNIV_UNLIKELY(!accessed)) {
		/* In the case of a first access, try to apply linear
		read-ahead */

		buf_read_ahead_linear(buf_frame_get_space_id(guess),
					buf_frame_get_page_no(guess));
	}

#ifdef UNIV_IBUF_DEBUG
	ut_a(ibuf_count_get(block->space, block->offset) == 0);
#endif
	buf_pool->n_page_gets++;

	return(TRUE);
}

/************************************************************************
This is used to get access to a known database page, when no waiting can be
done. For example, if a search in an adaptive hash index leads us to this
frame. */

ibool
buf_page_get_known_nowait(
/*======================*/
				/* out: TRUE if success */
	ulint		rw_latch,/* in: RW_S_LATCH, RW_X_LATCH */
	buf_frame_t*	guess,	/* in: the known page frame */
	ulint		mode,	/* in: BUF_MAKE_YOUNG or BUF_KEEP_OLD */
	const char*	file,	/* in: file name */
	ulint		line,	/* in: line where called */
	mtr_t*		mtr)	/* in: mini-transaction */
{
	buf_block_t*	block;
	ibool		success;
	ulint		fix_type;

	ut_ad(mtr);
	ut_ad((rw_latch == RW_S_LATCH) || (rw_latch == RW_X_LATCH));
	
	mutex_enter(&(buf_pool->mutex));

	block = buf_block_align(guess);

	if (block->state == BUF_BLOCK_REMOVE_HASH) {
	        /* Another thread is just freeing the block from the LRU list
	        of the buffer pool: do not try to access this page; this
		attempt to access the page can only come through the hash
		index because when the buffer block state is ..._REMOVE_HASH,
		we have already removed it from the page address hash table
		of the buffer pool. */

	        mutex_exit(&(buf_pool->mutex));