view release on metacpan or  search on metacpan

src/subversion/subversion/libsvn_fs_fs/dag.h  view on Meta::CPAN

/* dag.h : DAG-like interface filesystem, private to libsvn_fs
 *
 * ====================================================================
 *    Licensed to the Apache Software Foundation (ASF) under one
 *    or more contributor license agreements.  See the NOTICE file
 *    distributed with this work for additional information
 *    regarding copyright ownership.  The ASF licenses this file
 *    to you under the Apache License, Version 2.0 (the
 *    "License"); you may not use this file except in compliance
 *    with the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing,
 *    software distributed under the License is distributed on an
 *    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *    KIND, either express or implied.  See the License for the
 *    specific language governing permissions and limitations
 *    under the License.
 * ====================================================================
 */

#ifndef SVN_LIBSVN_FS_DAG_H
#define SVN_LIBSVN_FS_DAG_H

#include "svn_fs.h"
#include "svn_delta.h"
#include "private/svn_cache.h"

#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */


/* The interface in this file provides all the essential filesystem
   operations, but exposes the filesystem's DAG structure.  This makes
   it simpler to implement than the public interface, since a client
   of this interface has to understand and cope with shared structure
   directly as it appears in the database.  However, it's still a
   self-consistent set of invariants to maintain, making it
   (hopefully) a useful interface boundary.

   In other words:

   - The dag_node_t interface exposes the internal DAG structure of
     the filesystem, while the svn_fs.h interface does any cloning
     necessary to make the filesystem look like a tree.

   - The dag_node_t interface exposes the existence of copy nodes,
     whereas the svn_fs.h handles them transparently.

   - dag_node_t's must be explicitly cloned, whereas the svn_fs.h
     operations make clones implicitly.

   - Callers of the dag_node_t interface use Berkeley DB transactions
     to ensure consistency between operations, while callers of the
     svn_fs.h interface use Subversion transactions.  */


/* Generic DAG node stuff.  */

typedef struct dag_node_t dag_node_t;

/* Fill *NODE with a dag_node_t representing node revision ID in FS,
   allocating in POOL.  */
svn_error_t *
svn_fs_fs__dag_get_node(dag_node_t **node,
                        svn_fs_t *fs,
                        const svn_fs_id_t *id,
                        apr_pool_t *pool);


/* Return a new dag_node_t object referring to the same node as NODE,
   allocated in POOL.  If you're trying to build a structure in a
   pool that wants to refer to dag nodes that may have been allocated
   elsewhere, you can call this function and avoid inter-pool pointers. */
dag_node_t *
svn_fs_fs__dag_dup(const dag_node_t *node,
                   apr_pool_t *pool);

/* Serialize a DAG node, except don't try to preserve the 'fs' member.
   Implements svn_cache__serialize_func_t */
svn_error_t *
svn_fs_fs__dag_serialize(void **data,
                         apr_size_t *data_len,
                         void *in,
                         apr_pool_t *pool);

/* Deserialize a DAG node, leaving the 'fs' member as NULL.
   Implements svn_cache__deserialize_func_t */
svn_error_t *
svn_fs_fs__dag_deserialize(void **out,
                           void *data,
                           apr_size_t data_len,
                           apr_pool_t *pool);

/* Return the filesystem containing NODE.  */
svn_fs_t *svn_fs_fs__dag_get_fs(dag_node_t *node);

/* Changes the filesystem containing NODE to FS.  (Used when pulling
   nodes out of a shared cache, say.) */
void svn_fs_fs__dag_set_fs(dag_node_t *node, svn_fs_t *fs);


/* Set *REV to NODE's revision number, allocating in POOL.  If NODE
   has never been committed as part of a revision, set *REV to
   SVN_INVALID_REVNUM.  */
svn_error_t *svn_fs_fs__dag_get_revision(svn_revnum_t *rev,
                                         dag_node_t *node,
                                         apr_pool_t *pool);