Cleanup: Remove recv_sys.buf_size

Also, correctly document what recv_sys.mutex is protecting.

storage/innobase/include/log0recv.h

@@ -149,7 +149,7 @@ struct recv_dblwr_t {
 /** the recovery state and buffered records for a page */
 struct page_recv_t
 {
-  /** Recovery state */
+  /** Recovery state; protected by recv_sys.mutex */
   enum
   {
     /** not yet processed */
@@ -216,10 +216,14 @@ struct page_recv_t
 };
 
 /** Recovery system data structure */
-struct recv_sys_t{
-	ib_mutex_t		mutex;	/*!< mutex protecting the fields apply_log_recs,
-				n_addrs, and the state field in each recv_addr
-				struct */
+struct recv_sys_t
+{
+  /** mutex protecting apply_log_recs and page_recv_t::state */
+  ib_mutex_t mutex;
+  /** whether recv_recover_page(), invoked from buf_page_io_complete(),
+  should apply log records*/
+  bool apply_log_recs;
+
 	ib_mutex_t		writer_mutex;/*!< mutex coordinating
 				flushing between recv_writer_thread and
 				the recovery thread. */
@@ -230,13 +234,9 @@ struct recv_sys_t{
 	buf_flush_t		flush_type;/*!< type of the flush request.
 				BUF_FLUSH_LRU: flush end of LRU, keeping free blocks.
 				BUF_FLUSH_LIST: flush all of blocks. */
-	/** whether recv_recover_page(), invoked from buf_page_io_complete(),
-	should apply log records*/
-	bool		apply_log_recs;
 	/** whether recv_apply_hashed_log_recs() is running */
 	bool		apply_batch_on;
 	byte*		buf;	/*!< buffer for parsing log records */
-	size_t		buf_size;	/*!< size of buf */
 	ulint		len;	/*!< amount of data in buf */
 	lsn_t		parse_start_lsn;
 				/*!< this is the lsn from which we were able to
@@ -294,7 +294,7 @@ struct recv_sys_t{
   recv_dblwr_t dblwr;
 
   /** Last added LSN to pages. */
-  lsn_t last_stored_lsn;
+  lsn_t last_stored_lsn= 0;
 
   /** After successful upgrade from multiple redo log files we'd like
   to remove extra ones */
@@ -339,7 +339,7 @@ struct recv_sys_t{
   /** Clean up after create() */
   void close();
 
-  bool is_initialised() const { return buf_size != 0; }
+  bool is_initialised() const { return last_stored_lsn != 0; }
 
   /** Register a redo log snippet for a page.
   @param page_id  page identifier

storage/innobase/log/log0recv.cc

@@ -902,11 +902,11 @@ void recv_sys_t::close()
 		}
 
 		if (buf) {
-			ut_free_dodump(buf, buf_size);
+			ut_free_dodump(buf, RECV_PARSING_BUF_SIZE);
 			buf = NULL;
 		}
 
-		buf_size = 0;
+		last_stored_lsn = 0;
 		mutex_free(&writer_mutex);
 		mutex_free(&mutex);
 	}
@@ -1009,7 +1009,6 @@ void recv_sys_t::create()
 
 	max_log_blocks = buf_pool_get_n_pages() / 3;
 	buf = static_cast<byte*>(ut_malloc_dontdump(RECV_PARSING_BUF_SIZE));
-	buf_size = RECV_PARSING_BUF_SIZE;
 	len = 0;
 	parse_start_lsn = 0;
 	scanned_lsn = 0;
@@ -1024,7 +1023,7 @@ void recv_sys_t::create()
 	recv_max_page_lsn = 0;
 
 	memset(truncated_undo_spaces, 0, sizeof truncated_undo_spaces);
-	last_stored_lsn = 0;
+	last_stored_lsn = 1;
 	UT_LIST_INIT(blocks, &buf_block_t::unzip_LRU);
 }
 
@@ -1055,7 +1054,7 @@ void recv_sys_t::debug_free()
 	mutex_enter(&mutex);
 
 	pages.clear();
-	ut_free_dodump(buf, buf_size);
+	ut_free_dodump(buf, RECV_PARSING_BUF_SIZE);
 
 	buf = NULL;