[Issue #228]: bufferization of writes to page header map

Author: gsmolk

src/catalog.c

@@ -475,11 +475,12 @@ catalog_get_backup_list(const char *instance_name, time_t requested_backup_id)
 		join_path_components(backup->database_dir, backup->root_dir, DATABASE_DIR);
 
 		/* block header map, TODO: move to separate function */
+		backup->hdr_map.fp = NULL;
+		backup->hdr_map.buf = NULL;
 		backup->hdr_map.path = pgut_malloc(MAXPGPATH);
-		join_path_components(backup->hdr_map.path, backup->database_dir, HEADER_MAP);
+		join_path_components(backup->hdr_map.path, backup->root_dir, HEADER_MAP);
 		backup->hdr_map.path_tmp = pgut_malloc(MAXPGPATH);
-		join_path_components(backup->hdr_map.path_tmp, backup->database_dir, HEADER_MAP_TMP);
-		backup->hdr_map.fp = NULL;
+		join_path_components(backup->hdr_map.path_tmp, backup->root_dir, HEADER_MAP_TMP);
 
 		/* TODO: save encoded backup id */
 		backup->backup_id = backup->start_time;
@@ -855,11 +856,12 @@ pgBackupCreateDir(pgBackup *backup)
 	join_path_components(backup->database_dir, backup->root_dir, DATABASE_DIR);
 
 	/* block header map */
+	backup->hdr_map.fp = NULL;
+	backup->hdr_map.buf = NULL;
 	backup->hdr_map.path = pgut_malloc(MAXPGPATH);
-	join_path_components(backup->hdr_map.path, backup->database_dir, HEADER_MAP);
+	join_path_components(backup->hdr_map.path, backup->root_dir, HEADER_MAP);
 	backup->hdr_map.path_tmp = pgut_malloc(MAXPGPATH);
-	join_path_components(backup->hdr_map.path_tmp, backup->database_dir, HEADER_MAP_TMP);
-	backup->hdr_map.fp = NULL;
+	join_path_components(backup->hdr_map.path_tmp, backup->root_dir, HEADER_MAP_TMP);
 
 	/* create directories for actual backup files */
 	for (i = 0; i < parray_num(subdirs); i++)

src/data.c

@@ -2198,8 +2198,9 @@ write_page_headers(BackupPageHeader2 *headers, pgFile *file, HeaderMap *hdr_map,
 			elog(ERROR, "Cannot open header file \"%s\": %s",
 				 map_path, strerror(errno));
 
-		/* disable buffering for header file */
-		setvbuf(hdr_map->fp, NULL, _IONBF, BUFSIZ);
+		/* enable buffering for header file */
+		hdr_map->buf = pgut_malloc(STDIO_BUFSIZE);
+		setvbuf(hdr_map->fp, hdr_map->buf, _IOFBF, STDIO_BUFSIZE);
 
 		/* update file permission */
 		if (chmod(map_path, FILE_PERMISSION) == -1)

src/merge.c

@@ -720,6 +720,10 @@ merge_chain(parray *parent_chain, pgBackup *full_backup, pgBackup *dest_backup)
 		if (rename(full_backup->hdr_map.path_tmp, full_backup->hdr_map.path) == -1)
 			elog(ERROR, "Could not rename file \"%s\" to \"%s\": %s",
 				 full_backup->hdr_map.path_tmp, full_backup->hdr_map.path, strerror(errno));
+
+		full_backup->hdr_map.fp = NULL;
+		pg_free(full_backup->hdr_map.buf);
+		full_backup->hdr_map.buf = NULL;
 	}
 
 	/*
@@ -866,8 +870,8 @@ merge_chain(parray *parent_chain, pgBackup *full_backup, pgBackup *dest_backup)
 
 	/* Reinit some path variables */
 	join_path_components(full_backup->database_dir, full_backup->root_dir, DATABASE_DIR);
-	join_path_components(full_backup->hdr_map.path, full_backup->database_dir, HEADER_MAP);
-	join_path_components(full_backup->hdr_map.path_tmp, full_backup->database_dir, HEADER_MAP_TMP);
+	join_path_components(full_backup->hdr_map.path, full_backup->root_dir, HEADER_MAP);
+	join_path_components(full_backup->hdr_map.path_tmp, full_backup->root_dir, HEADER_MAP_TMP);
 	full_backup->hdr_map.fp = NULL;
 
 	/* If we crash here, it will produce full backup in MERGED

src/pg_probackup.h

@@ -365,6 +365,7 @@ typedef struct HeaderMap
 {
 	char  *path;
 	char  *path_tmp;	/* used only in merge */
+	char  *buf;	        /* buffer */
 	FILE  *fp;
 	off_t  offset;
 	pthread_mutex_t mutex;
@@ -449,7 +450,7 @@ struct pgBackup
 
 	pg_crc32         content_crc;
 
-	/* mutex used for write access to block header map */
+	/* map used for access to page headers */
 	HeaderMap       hdr_map;
 };