branches/zip: recv_no_log_write: New debug flag for tracking down

Mantis Issue #347.  No modifications should be made to the database
while recv_apply_hashed_log_recs() is about to complete.

include/log0recv.h

@@ -433,6 +433,11 @@ are allowed yet: the variable name is misleading. */
 extern ibool		recv_no_ibuf_operations;
 /** TRUE when recv_init_crash_recovery() has been called. */
 extern ibool		recv_needed_recovery;
+#ifdef UNIV_DEBUG
+/** TRUE if writing to the redo log (mtr_commit) is forbidden.
+Protected by log_sys->mutex. */
+extern ibool		recv_no_log_write;
+#endif /* UNIV_DEBUG */
 
 /** TRUE if buf_page_is_corrupted() should check if the log sequence
 number (FIL_PAGE_LSN) is in the future.  Initially FALSE, and set by

log/log0log.c

@@ -241,6 +241,7 @@ log_reserve_and_open(
 	ut_a(len < log->buf_size / 2);
 loop:
 	mutex_enter(&(log->mutex));
+	ut_ad(!recv_no_log_write);
 
 	/* Calculate an upper limit for the space the string may take in the
 	log buffer */
@@ -309,6 +310,7 @@ log_write_low(
 
 	ut_ad(mutex_own(&(log->mutex)));
 part_loop:
+	ut_ad(!recv_no_log_write);
 	/* Calculate a part length */
 
 	data_len = (log->buf_free % OS_FILE_LOG_BLOCK_SIZE) + str_len;
@@ -377,6 +379,7 @@ log_close(void)
 	ib_uint64_t	checkpoint_age;
 
 	ut_ad(mutex_own(&(log->mutex)));
+	ut_ad(!recv_no_log_write);
 
 	lsn = log->lsn;
 
@@ -668,8 +671,6 @@ log_calc_max_ages(void)
 	ulint		archive_margin;
 	ulint		smallest_archive_margin;
 
-	ut_ad(!mutex_own(&(log_sys->mutex)));
-
 	mutex_enter(&(log_sys->mutex));
 
 	group = UT_LIST_GET_FIRST(log_sys->log_groups);
@@ -1117,6 +1118,7 @@ log_io_complete(
 	}
 
 	mutex_enter(&(log_sys->mutex));
+	ut_ad(!recv_no_log_write);
 
 	ut_a(group->n_pending_writes > 0);
 	ut_a(log_sys->n_pending_writes > 0);
@@ -1148,6 +1150,7 @@ log_group_file_header_flush(
 	ulint	dest_offset;
 
 	ut_ad(mutex_own(&(log_sys->mutex)));
+	ut_ad(!recv_no_log_write);
 	ut_a(nth_file < group->n_files);
 
 	buf = *(group->file_header_bufs + nth_file);
@@ -1219,6 +1222,7 @@ log_group_write_buf(
 	ulint	i;
 
 	ut_ad(mutex_own(&(log_sys->mutex)));
+	ut_ad(!recv_no_log_write);
 	ut_a(len % OS_FILE_LOG_BLOCK_SIZE == 0);
 	ut_a(((ulint) start_lsn) % OS_FILE_LOG_BLOCK_SIZE == 0);
 
@@ -1361,6 +1365,7 @@ log_write_up_to(
 #endif
 
 	mutex_enter(&(log_sys->mutex));
+	ut_ad(!recv_no_log_write);
 
 	if (flush_to_disk
 	    && log_sys->flushed_to_disk_lsn >= lsn) {
@@ -1974,6 +1979,7 @@ log_checkpoint(
 
 	mutex_enter(&(log_sys->mutex));
 
+	ut_ad(!recv_no_log_write);
 	oldest_lsn = log_buf_pool_get_oldest_modification();
 
 	mutex_exit(&(log_sys->mutex));
@@ -2086,6 +2092,7 @@ log_checkpoint_margin(void)
 	do_checkpoint = FALSE;
 
 	mutex_enter(&(log->mutex));
+	ut_ad(!recv_no_log_write);
 
 	if (log->check_flush_or_checkpoint == FALSE) {
 		mutex_exit(&(log->mutex));
@@ -3035,6 +3042,7 @@ log_check_margins(void)
 #endif /* UNIV_LOG_ARCHIVE */
 
 	mutex_enter(&(log_sys->mutex));
+	ut_ad(!recv_no_log_write);
 
 	if (log_sys->check_flush_or_checkpoint) {
 

log/log0recv.c

@@ -78,6 +78,11 @@ UNIV_INTERN ibool	recv_recovery_from_backup_on = FALSE;
 #ifndef UNIV_HOTBACKUP
 /** TRUE when recv_init_crash_recovery() has been called. */
 UNIV_INTERN ibool	recv_needed_recovery = FALSE;
+# ifdef UNIV_DEBUG
+/** TRUE if writing to the redo log (mtr_commit) is forbidden.
+Protected by log_sys->mutex. */
+UNIV_INTERN ibool	recv_no_log_write = FALSE;
+# endif /* UNIV_DEBUG */
 
 /** TRUE if buf_page_is_corrupted() should check if the log sequence
 number (FIL_PAGE_LSN) is in the future.  Initially FALSE, and set by
@@ -1705,6 +1710,7 @@ recv_apply_hashed_log_recs(
 		/* Flush all the file pages to disk and invalidate them in
 		the buffer pool */
 
+		ut_d(recv_no_log_write = TRUE);
 		mutex_exit(&(recv_sys->mutex));
 		mutex_exit(&(log_sys->mutex));
 
@@ -1718,6 +1724,7 @@ recv_apply_hashed_log_recs(
 
 		mutex_enter(&(log_sys->mutex));
 		mutex_enter(&(recv_sys->mutex));
+		ut_d(recv_no_log_write = FALSE);
 
 		recv_no_ibuf_operations = FALSE;
 	}

mtr/mtr0mtr.c

@@ -35,6 +35,7 @@ Created 11/26/1995 Heikki Tuuri
 #include "log0log.h"
 
 #ifndef UNIV_HOTBACKUP
+# include "log0recv.h"
 /*****************************************************************//**
 Releases the item in the slot given. */
 UNIV_INLINE
@@ -181,6 +182,8 @@ mtr_commit(
 	ut_d(mtr->state = MTR_COMMITTING);
 
 #ifndef UNIV_HOTBACKUP
+	/* This is a dirty read, for debugging. */
+	ut_ad(!recv_no_log_write);
 	write_log = mtr->modifications && mtr->n_log_recs;
 
 	if (write_log) {