Mariabackup: Copy all of the redo log correctly

xtrabackup_copy_log(), xtrabackup_copy_logfile():
Change the Boolean parameter to an enum, with the values
COPY_FIRST, COPY_ONLINE, COPY_LAST.

xtrabackup_copy_log(): Return the latest scanned LSN,
which may be less than the last copied LSN. Remove some
dead code that was duplicating some logic that in 10.2
has been moved to log_group_read_log_seg().

log_copying_thread(): Correct the termination condition.

stop_backup_threads(): Shut down the threads that were
created during backup.

extra/mariabackup/xtrabackup.cc

@@ -2188,59 +2188,33 @@ xtrabackup_copy_datafile(fil_node_t* node, uint thread_n)
 	return(FALSE);
 }
 
+/** How to copy a redo log segment in backup */
+enum copy_logfile {
+	/** Initial copying: copy at least one block */
+	COPY_FIRST,
+	/** Tracking while copying data files */
+	COPY_ONLINE,
+	/** Final copying: copy until the end of the log */
+	COPY_LAST
+};
+
 /** Copy redo log blocks to the data sink.
-@param[in]	is_last		whether this is the last log segment to copy
+@param[in]	copy		how to copy the log
 @param[in]	start_lsn	buffer start LSN
 @param[in]	end_lsn		buffer end LSN
-@return	last copied LSN
+@return	last scanned LSN (equals to last copied LSN if copy=COPY_LAST)
 @retval	0	on failure */
 static
 lsn_t
-xtrabackup_copy_log(bool is_last, lsn_t start_lsn, lsn_t end_lsn)
+xtrabackup_copy_log(copy_logfile copy, lsn_t start_lsn, lsn_t end_lsn)
 {
 	lsn_t	scanned_lsn	= start_lsn;
 
-	const ulint blocks_in_group = log_block_convert_lsn_to_no(
-		log_sys->log.capacity()) - 1;
 	const byte* log_block = log_sys->buf;
 
 	for (ulint scanned_checkpoint = 0;
 	     scanned_lsn < end_lsn;
 	     log_block += OS_FILE_LOG_BLOCK_SIZE) {
-		ulint	no = log_block_get_hdr_no(log_block);
-		ulint	scanned_no = log_block_convert_lsn_to_no(scanned_lsn);
-
-		if (no != scanned_no) {
-			if ((no < scanned_no &&
-			    ((scanned_no - no) % blocks_in_group) == 0) ||
-			    no == 0 ||
-			    /* Log block numbers wrap around at 0x3FFFFFFF */
-			    ((scanned_no | 0x40000000UL) - no) %
-			    blocks_in_group == 0) {
-
-				/* old log block, do nothing */
-				break;
-			}
-
-			msg("xtrabackup: error:"
-			    " log block numbers mismatch:\n"
-			    "xtrabackup: error: expected log block no. "
-			    ULINTPF ", but got no. " ULINTPF
-			    " from the log file.\n",
-			    scanned_no, no);
-
-			if ((no - scanned_no) % blocks_in_group == 0) {
-				msg("xtrabackup: error:"
-				    " it looks like InnoDB log has wrapped"
-				    " around before xtrabackup could"
-				    " process all records due to either"
-				    " log copying being too slow, or "
-				    " log files being too small.\n");
-			}
-
-			return(0);
-		}
-
 		ulint checkpoint = log_block_get_checkpoint_no(log_block);
 
 		if (scanned_checkpoint > checkpoint
@@ -2255,20 +2229,18 @@ xtrabackup_copy_log(bool is_last, lsn_t start_lsn, lsn_t end_lsn)
 		scanned_lsn += data_len;
 
 		if (data_len != OS_FILE_LOG_BLOCK_SIZE) {
+			/* The current end of the log was reached. */
 			break;
 		}
 	}
 
-	if (!is_last && scanned_lsn & (OS_FILE_LOG_BLOCK_SIZE - 1)) {
-		/* Omit the partial last block. */
-		scanned_lsn &= ~(OS_FILE_LOG_BLOCK_SIZE - 1);
-	}
-
 	log_sys->log.scanned_lsn = scanned_lsn;
 
-	if (ulint write_size = ulint(ut_uint64_align_up(scanned_lsn,
-							OS_FILE_LOG_BLOCK_SIZE)
-				     - start_lsn)) {
+	end_lsn = copy == COPY_LAST
+		? ut_uint64_align_up(scanned_lsn, OS_FILE_LOG_BLOCK_SIZE)
+		: scanned_lsn & ~(OS_FILE_LOG_BLOCK_SIZE - 1);
+
+	if (ulint write_size = ulint(end_lsn - start_lsn)) {
 		if (srv_encrypt_log) {
 			log_crypt(log_sys->buf, write_size);
 		}
@@ -2284,10 +2256,10 @@ xtrabackup_copy_log(bool is_last, lsn_t start_lsn, lsn_t end_lsn)
 }
 
 /** Copy redo log until the current end of the log is reached
-@param is_last	whether this is the last run at the end of backup
+@param copy	how to copy the log
 @return	whether the operation failed */
 static bool
-xtrabackup_copy_logfile(bool is_last)
+xtrabackup_copy_logfile(copy_logfile copy)
 {
 	ut_a(dst_log_file != NULL);
 	ut_ad(recv_sys != NULL);
@@ -2298,9 +2270,10 @@ xtrabackup_copy_logfile(bool is_last)
 	start_lsn = ut_uint64_align_down(log_copy_scanned_lsn,
 					 OS_FILE_LOG_BLOCK_SIZE);
 
-	/* When copying the last part of the log, retry a few times to
-	ensure that all log up to the last checkpoint will be read. */
-	for (unsigned retries = is_last ? 3 : 0;;) {
+	/* When copying the first or last part of the log, retry a few
+	times to ensure that all log up to the last checkpoint will be
+	read. */
+	do {
 		end_lsn = start_lsn + RECV_SCAN_SIZE;
 
 		xtrabackup_io_throttling();
@@ -2310,7 +2283,7 @@ xtrabackup_copy_logfile(bool is_last)
 		lsn_t lsn = log_group_read_log_seg(log_sys->buf, &log_sys->log,
 						   start_lsn, end_lsn);
 
-		start_lsn = xtrabackup_copy_log(is_last, start_lsn, lsn);
+		start_lsn = xtrabackup_copy_log(copy, start_lsn, lsn);
 
 		log_mutex_exit();
 
@@ -2321,22 +2294,7 @@ xtrabackup_copy_logfile(bool is_last)
 			    " failed.\n");
 			return(true);
 		}
-
-		if (start_lsn == end_lsn) {
-			/* All RECV_SCAN_SIZE bytes that were read
-			were valid redo log. Proceed to read more. */
-		} else if (start_lsn & (OS_FILE_LOG_BLOCK_SIZE - 1)) {
-			/* The end of the log was encountered. */
-			ut_ad(is_last);
-			break;
-		} else if (retries--) {
-			/* Retry copying the last log segment. */
-			ut_ad(is_last);
-			os_thread_sleep(xtrabackup_log_copy_interval * 1000);
-		} else {
-			break;
-		}
-	}
+	} while (start_lsn == end_lsn);
 
 	ut_ad(start_lsn == log_sys->log.scanned_lsn);
 
@@ -2349,13 +2307,7 @@ xtrabackup_copy_logfile(bool is_last)
 	return(false);
 }
 
-static
-#ifndef __WIN__
-void*
-#else
-ulint
-#endif
-log_copying_thread(void*)
+static os_thread_ret_t log_copying_thread(void*)
 {
 	/*
 	  Initialize mysys thread-specific memory so we can
@@ -2363,15 +2315,12 @@ log_copying_thread(void*)
 	*/
 	my_thread_init();
 
-	while (log_copying) {
+	do {
 		os_event_reset(log_copying_stop);
 		os_event_wait_time_low(log_copying_stop,
 				       xtrabackup_log_copy_interval * 1000ULL,
 				       0);
-		if (log_copying && xtrabackup_copy_logfile(false)) {
-			break;
-		}
-	}
+	} while (log_copying && xtrabackup_copy_logfile(COPY_ONLINE));
 
 	log_copying_running = false;
 	my_thread_end();
@@ -2381,13 +2330,7 @@ log_copying_thread(void*)
 }
 
 /* io throttle watching (rough) */
-static
-#ifndef __WIN__
-void*
-#else
-ulint
-#endif
-io_watching_thread(void*)
+static os_thread_ret_t io_watching_thread(void*)
 {
 	/* currently, for --backup only */
 	ut_a(xtrabackup_backup);
@@ -3356,6 +3299,30 @@ xb_set_max_open_files(
 #endif
 }
 
+static void stop_backup_threads()
+{
+	log_copying = false;
+
+	if (log_copying_stop) {
+		os_event_set(log_copying_stop);
+		msg("xtrabackup: Stopping log copying thread.\n");
+		while (log_copying_running) {
+			msg(".");
+			os_thread_sleep(200000); /*0.2 sec*/
+		}
+		msg("\n");
+		os_event_destroy(log_copying_stop);
+	}
+
+	if (wait_throttle) {
+		/* wait for io_watching_thread completion */
+		while (io_watching_thread_running) {
+			os_thread_sleep(1000000);
+		}
+		os_event_destroy(wait_throttle);
+	}
+}
+
 /** Implement --backup
 @return	whether the operation succeeded */
 static
@@ -3404,6 +3371,7 @@ xtrabackup_backup_func()
 	/* initialize components */
         if(innodb_init_param()) {
 fail:
+		stop_backup_threads();
 		innodb_shutdown();
 		return(false);
 	}
@@ -3679,7 +3647,7 @@ xtrabackup_backup_func()
 
 	/* copy log file by current position */
 	log_copy_scanned_lsn = checkpoint_lsn_start;
-	if (xtrabackup_copy_logfile(false))
+	if (xtrabackup_copy_logfile(COPY_FIRST))
 		goto fail;
 
 	log_copying_stop = os_event_create(0);
@@ -3785,19 +3753,9 @@ xtrabackup_backup_func()
 		log_mutex_exit();
 	}
 
-	/* stop log_copying_thread */
-	log_copying = FALSE;
-	os_event_set(log_copying_stop);
-	msg("xtrabackup: Stopping log copying thread.\n");
-	while (log_copying_running) {
-		msg(".");
-		os_thread_sleep(200000); /*0.2 sec*/
-	}
-	msg("\n");
-
-	os_event_destroy(log_copying_stop);
+	stop_backup_threads();
 
-	if (!dst_log_file || xtrabackup_copy_logfile(true)) {
+	if (!dst_log_file || xtrabackup_copy_logfile(COPY_LAST)) {
 		goto fail;
 	}
 
@@ -3841,14 +3799,6 @@ xtrabackup_backup_func()
 
 	xtrabackup_destroy_datasinks();
 
-	if (wait_throttle) {
-		/* wait for io_watching_thread completion */
-		while (io_watching_thread_running) {
-			os_thread_sleep(1000000);
-		}
-		os_event_destroy(wait_throttle);
-	}
-
 	msg("xtrabackup: Redo log (from LSN " LSN_PF " to " LSN_PF
 	    ") was copied.\n", checkpoint_lsn_start, log_copy_scanned_lsn);
 	xb_filters_free();
@@ -3857,9 +3807,9 @@ xtrabackup_backup_func()
 
 	/* Make sure that the latest checkpoint was included */
 	if (latest_cp > log_copy_scanned_lsn) {
-		msg("xtrabackup: error: last checkpoint LSN (" LSN_PF
-		    ") is larger than last copied LSN (" LSN_PF ").\n",
-		    latest_cp, log_copy_scanned_lsn);
+		msg("xtrabackup: error: failed to copy enough redo log ("
+		    "LSN=" LSN_PF "; checkpoint LSN=" LSN_PF ").\n",
+		    log_copy_scanned_lsn, latest_cp);
 		goto fail;
 	}