MDEV-21572 buf_page_get_gen() should apply buffered page initialized

		redo log during recovery

- InnoDB unnecessarily reads the page even though it has fully initialized
buffered redo log records. Allow the page initialization redo log to
apply for the page in buf_page_get_gen() during recovery.
- Renamed buf_page_get_gen() to buf_page_get_low()
- Newly added buf_page_get_gen() will check for buffered redo log for
the particular page id during recovery
- Added new function buf_page_mtr_lock() which basically latches the page
for the given latch type.
- recv_recovery_create_page() is inline function which creates a page
if it has page initialization redo log records.

2 files changed, 42 insertions, 0 deletions

diff --git a/storage/innobase/include/buf0buf.h b/storage/innobase/include/buf0buf.h
index a04936a19cf..d120dc36091 100644
--- a/storage/innobase/include/buf0buf.h
+++ b/storage/innobase/include/buf0buf.h
@@ -436,6 +436,7 @@ buf_page_get_zip(
 	const page_size_t&	page_size);
 
 /** This is the general function used to get access to a database page.
+It does page initialization and applies the buffered redo logs.
 @param[in]	page_id		page id
 @param[in]	rw_latch	RW_S_LATCH, RW_X_LATCH, RW_NO_LATCH
 @param[in]	guess		guessed block or NULL
@@ -458,6 +459,29 @@ buf_page_get_gen(
 	mtr_t*			mtr,
 	dberr_t*		err);
 
+/** This is the low level function used to get access to a database page.
+@param[in]	page_id		page id
+@param[in]	rw_latch	RW_S_LATCH, RW_X_LATCH, RW_NO_LATCH
+@param[in]	guess		guessed block or NULL
+@param[in]	mode		BUF_GET, BUF_GET_IF_IN_POOL,
+BUF_PEEK_IF_IN_POOL, BUF_GET_NO_LATCH, or BUF_GET_IF_IN_POOL_OR_WATCH
+@param[in]	file		file name
+@param[in]	line		line where called
+@param[in]	mtr		mini-transaction
+@param[out]	err		DB_SUCCESS or error code
+@return pointer to the block or NULL */
+buf_block_t*
+buf_page_get_low(
+	const page_id_t		page_id,
+	const page_size_t&	page_size,
+	ulint			rw_latch,
+	buf_block_t*		guess,
+	ulint			mode,
+	const char*		file,
+	unsigned		line,
+	mtr_t*			mtr,
+	dberr_t*		err);
+
 /** Initializes a page to the buffer buf_pool. The page is usually not read
 from a file even if it cannot be found in the buffer buf_pool. This is one
 of the functions which perform to a block a state transition NOT_USED =>
diff --git a/storage/innobase/include/log0recv.h b/storage/innobase/include/log0recv.h
index 068d7813c20..b91312e81e2 100644
--- a/storage/innobase/include/log0recv.h
+++ b/storage/innobase/include/log0recv.h
@@ -342,4 +342,22 @@ times! */
 roll-forward */
 #define RECV_SCAN_SIZE		(4 * UNIV_PAGE_SIZE)
 
+/** This is a low level function for the recovery system
+to create a page which has buffered intialized redo log records.
+@param[in]	page_id	page to be created using redo logs
+@return whether the page creation successfully */
+buf_block_t* recv_recovery_create_page_low(const page_id_t page_id);
+
+/** Recovery system creates a page which has buffered intialized
+redo log records.
+@param[in]	page_id	page to be created using redo logs
+@return block which contains page was initialized */
+inline buf_block_t* recv_recovery_create_page(const page_id_t page_id)
+{
+  if (UNIV_LIKELY(!recv_recovery_on))
+    return NULL;
+
+  return recv_recovery_create_page_low(page_id);
+}
+
 #endif