batch_fsync.h revision 362181 
1/* batch_fsync.h --- efficiently fsync multiple targets
2 *
3 * ====================================================================
4 *    Licensed to the Apache Software Foundation (ASF) under one
5 *    or more contributor license agreements.  See the NOTICE file
6 *    distributed with this work for additional information
7 *    regarding copyright ownership.  The ASF licenses this file
8 *    to you under the Apache License, Version 2.0 (the
9 *    "License"); you may not use this file except in compliance
10 *    with the License.  You may obtain a copy of the License at
11 *
12 *      http://www.apache.org/licenses/LICENSE-2.0
13 *
14 *    Unless required by applicable law or agreed to in writing,
15 *    software distributed under the License is distributed on an
16 *    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 *    KIND, either express or implied.  See the License for the
18 *    specific language governing permissions and limitations
19 *    under the License.
20 * ====================================================================
21 */
22
23#ifndef SVN_LIBSVN_FS_X__BATCH_FSYNC_H
24#define SVN_LIBSVN_FS_X__BATCH_FSYNC_H
25
26#include "svn_error.h"
27
28/* Infrastructure for efficiently calling fsync on files and directories.
29 *
30 * The idea is to have a container of open file handles (including
31 * directory handles on POSIX), at most one per file.  During the course
32 * of an FS operation that needs to be fsync'ed, all touched files and
33 * folders accumulate in the container.
34 *
35 * At the end of the FS operation, all file changes will be written the
36 * physical disk, once per file and folder.  Afterwards, all handles will
37 * be closed and the container is ready for reuse.
38 *
39 * To minimize the delay caused by the batch flush, run all fsync calls
40 * concurrently - if the OS supports multi-threading.
41 */
42
43/* Opaque container type.
44 */
45typedef struct svn_fs_x__batch_fsync_t svn_fs_x__batch_fsync_t;
46
47/* Initialize the concurrent fsync infrastructure.  Clean it up when
48 * OWNING_POOL gets cleared.
49 *
50 * This function must be called before using any of the other functions in
51 * in this module.  It should only be called once.
52 */
53svn_error_t *
54svn_fs_x__batch_fsync_init(apr_pool_t *owning_pool);
55
56/* Set *RESULT_P to a new batch fsync structure, allocated in RESULT_POOL.
57 * If FLUSH_TO_DISK is not set, the resulting struct will not actually use
58 * fsync. */
59svn_error_t *
60svn_fs_x__batch_fsync_create(svn_fs_x__batch_fsync_t **result_p,
61                             svn_boolean_t flush_to_disk,
62                             apr_pool_t *result_pool);
63
64/* Open the file at FILENAME for read and write access.  Return it in *FILE
65 * and schedule it for fsync in BATCH.  If BATCH already contains an open
66 * file for FILENAME, return that instead creating a new instance.
67 *
68 * Use SCRATCH_POOL for temporaries. */
69svn_error_t *
70svn_fs_x__batch_fsync_open_file(apr_file_t **file,
71                                svn_fs_x__batch_fsync_t *batch,
72                                const char *filename,
73                                apr_pool_t *scratch_pool);
74
75/* Inform the BATCH that a file or directory has been created at PATH.
76 * "Created" means either newly created to renamed to PATH - even if another
77 * item with the same name existed before.  Depending on the OS, the correct
78 * path will scheduled for fsync.
79 *
80 * Use SCRATCH_POOL for temporaries. */
81svn_error_t *
82svn_fs_x__batch_fsync_new_path(svn_fs_x__batch_fsync_t *batch,
83                               const char *path,
84                               apr_pool_t *scratch_pool);
85
86/* For all files and directories in BATCH, flush all changes to disk and
87 * close the file handles.  Use SCRATCH_POOL for temporaries. */
88svn_error_t *
89svn_fs_x__batch_fsync_run(svn_fs_x__batch_fsync_t *batch,
90                          apr_pool_t *scratch_pool);
91
92#endif
93