subversion/libsvn_fs_x/changes.h

   1 /* changes.h --- FSX changed paths lists container
   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_CHANGES_H
  24 #define SVN_LIBSVN_FS_X_CHANGES_H
  25
  26 #include "svn_io.h"
  27 #include "fs.h"
  28
  29 /* Entries in a revision's change list tend to be widely redundant (similar
  30  * changes to similar paths).  Even more so, change lists from a larger
  31  * revision range also tend to overlap.
  32  *
  33  * In its serialized form, the svn_fs_x__changes_t container extracts most
  34  * of that redundancy and the run-time representation is also much smaller
  35  * than sum of the respective svn_fs_x__change_t* arrays.
  36  *
  37  * As with other containers, this one has two modes: 'construction', in
  38  * which you may add data to it, and 'getter' in which there is only r/o
  39  * access to the data.
  40  */
  41
  42 /* An opaque collection of change lists (apr_array_header_t * of
  43  * svn_fs_x__change_t *).
  44  */
  45 typedef struct svn_fs_x__changes_t svn_fs_x__changes_t;
  46
  47 /* Create and populate changes containers. */
  48
  49 /* Create and return a new changes container with an initial capacity of
  50  * INITIAL_COUNT svn_fs_x__change_t objects.
  51  * Allocate the result in RESULT_POOL.
  52  */
  53 svn_fs_x__changes_t *
  54 svn_fs_x__changes_create(apr_size_t initial_count,
  55                          apr_pool_t *result_pool);
  56
  57 /* Start a new change list CHANGES (implicitly terminating the previous one)
  58  * and return its index in *LIST_INDEX.  Append all changes from LIST to
  59  * that new change list.
  60  */
  61 svn_error_t *
  62 svn_fs_x__changes_append_list(apr_size_t *list_index,
  63                               svn_fs_x__changes_t *changes,
  64                               apr_array_header_t *list);
  65
  66 /* Return a rough estimate in bytes for the serialized representation
  67  * of CHANGES.
  68  */
  69 apr_size_t
  70 svn_fs_x__changes_estimate_size(const svn_fs_x__changes_t *changes);
  71
  72 /* Read changes containers. */
  73
  74 /* From CHANGES, access the change list with the given IDX and extract the
  75  * next entries according to CONTEXT.  Allocate the result in RESULT_POOL
  76  * and return it in *LIST.
  77  */
  78 svn_error_t *
  79 svn_fs_x__changes_get_list(apr_array_header_t **list,
  80                            const svn_fs_x__changes_t *changes,
  81                            apr_size_t idx,
  82                            svn_fs_x__changes_context_t *context,
  83                            apr_pool_t *result_pool);
  84
  85 /* I/O interface. */
  86
  87 /* Write a serialized representation of CHANGES to STREAM.
  88  * Use SCRATCH_POOL for temporary allocations.
  89  */
  90 svn_error_t *
  91 svn_fs_x__write_changes_container(svn_stream_t *stream,
  92                                   const svn_fs_x__changes_t *changes,
  93                                   apr_pool_t *scratch_pool);
  94
  95 /* Read a changes container from its serialized representation in STREAM.
  96  * Allocate the result in RESULT_POOL and return it in *CHANGES_P.  Use
  97  * SCRATCH_POOL for temporary allocations.
  98  */
  99 svn_error_t *
 100 svn_fs_x__read_changes_container(svn_fs_x__changes_t **changes_p,
 101                                  svn_stream_t *stream,
 102                                  apr_pool_t *result_pool,
 103                                  apr_pool_t *scratch_pool);
 104
 105 /* Implements #svn_cache__serialize_func_t for svn_fs_x__changes_t objects.
 106  */
 107 svn_error_t *
 108 svn_fs_x__serialize_changes_container(void **data,
 109                                       apr_size_t *data_len,
 110                                       void *in,
 111                                       apr_pool_t *pool);
 112
 113 /* Implements #svn_cache__deserialize_func_t for svn_fs_x__changes_t objects.
 114  */
 115 svn_error_t *
 116 svn_fs_x__deserialize_changes_container(void **out,
 117                                         void *data,
 118                                         apr_size_t data_len,
 119                                         apr_pool_t *result_pool);
 120
 121 /* Baton type to be used with svn_fs_x__changes_get_list_func. */
 122 typedef struct svn_fs_x__changes_get_list_baton_t
 123 {
 124   /* Sub-item to query */
 125   apr_uint32_t sub_item;
 126
 127   /* Deliver data starting from this index within the changes list. */
 128   int start;
 129
 130   /* To be set by svn_fs_x__changes_get_list_func:
 131      Did we deliver the last change in that list? */
 132   svn_boolean_t *eol;
 133 } svn_fs_x__changes_get_list_baton_t;
 134
 135 /* Implements svn_cache__partial_getter_func_t for svn_fs_x__changes_t,
 136  * setting *OUT to the change list (apr_array_header_t *) selected by
 137  * the svn_fs_x__changes_get_list_baton_t passed in as *BATON.  This
 138  * function is similar to svn_fs_x__changes_get_list but operates on
 139  * the cache serialized representation of the container.
 140  */
 141 svn_error_t *
 142 svn_fs_x__changes_get_list_func(void **out,
 143                                 const void *data,
 144                                 apr_size_t data_len,
 145                                 void *baton,
 146                                 apr_pool_t *pool);
 147
 148 #endif