Add lock free algorithm for load balancing.

stalkerg · stalkerg · commit 3491b43404e5 · 2016-09-02T20:38:39.000+03:00
diff --git a/backup.c b/backup.c
@@ -315,6 +315,8 @@ do_backup_database(parray *backup_list, pgBackupOption bkupopt)
 		{
 			total_files_num++;
 		}
+
+		__sync_lock_release(&file->lock);
 	}
 
 	if (num_threads < 1)
@@ -329,20 +331,12 @@ do_backup_database(parray *backup_list, pgBackupOption bkupopt)
 		backup_files_args *arg = pg_malloc(sizeof(backup_files_args));
 		arg->from_root = pgdata;
 		arg->to_root = path;
-		arg->files = parray_new();
+		arg->files = backup_files_list;
 		arg->prev_files = prev_files;
 		arg->lsn = lsn;
 		backup_threads_args[i] = arg;
 	}
 
-	/* balance load between threads */
-	for (i = 0; i < parray_num(backup_files_list); i++)
-	{
-		int cur_thread = i % num_threads;
-		parray_append(backup_threads_args[cur_thread]->files,
-					  parray_get(backup_files_list, i));
-	}
-
 	total_copy_files_increment = 0;
 
 	/* Run threads */
@@ -935,6 +929,8 @@ backup_files(void *arg)
 		struct stat	buf;
 
 		pgFile *file = (pgFile *) parray_get(arguments->files, i);
+		if (__sync_lock_test_and_set(&file->lock, 1) != 0)
+			continue;
 
 		/* If current time is rewinded, abort this backup. */
 		if (tv.tv_sec < file->mtime)
diff --git a/pg_arman.h b/pg_arman.h
@@ -56,11 +56,12 @@ typedef struct pgFile
 							   that the file existed but was not backed up
 							   because not modified since last backup. */
 	pg_crc32 crc;			/* CRC value of the file, regular file only */
-	char   *linked;			/* path of the linked file */
+	char	*linked;			/* path of the linked file */
 	bool	is_datafile;	/* true if the file is PostgreSQL data file */
 	char	*path;			/* path of the file */
 	char	*ptrack_path;
 	int		segno;			/* Segment number for ptrack */
+	volatile uint32 lock;
 	datapagemap_t pagemap;
 } pgFile;
 
