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Posted to commits@subversion.apache.org by st...@apache.org on 2013/03/30 13:25:57 UTC
svn commit: r1462737 - in /subversion/branches/fsfs-format7/subversion:
include/svn_error_codes.h libsvn_fs_fs/changes.c libsvn_fs_fs/changes.h
Author: stefan2
Date: Sat Mar 30 12:25:56 2013
New Revision: 1462737
URL: http://svn.apache.org/r1462737
Log:
On the fsfs-format7 branch: Implement our first container object.
We use it to significantly reduce the size of change lists in memory
and on disk.
It's not being used right now - that will follow in later commits.
* subversion/include/svn_error_codes.h
(SVN_ERR_FS_CONTAINER_INDEX): declare a new error code
* subversion/libsvn_fs_fs/changes.h
(svn_fs_fs__changes_t): declare container type
(svn_fs_fs__changes_create,
svn_fs_fs__changes_start_list,
svn_fs_fs__changes_append_change,
svn_fs_fs__changes_append_list,
svn_fs_fs__changes_estimate_size,
svn_fs_fs__changes_finalize): declare the construction / write API
(svn_fs_fs__changes_get_list): declare the getter API
(svn_fs_fs__write_changes_container,
svn_fs_fs__read_changes_container): declare the I/O API
* subversion/libsvn_fs_fs/changes.c
(CHANGE_TEXT_MOD,
CHANGE_PROP_MOD,
CHANGE_TXN_NODE,
CHANGE_NODE_SHIFT,
CHANGE_NODE_MASK,
CHANGE_NODE_NONE,
CHANGE_NODE_FILE,
CHANGE_NODE_DIR,
CHANGE_NODE_UNKNOWN,
CHANGE_KIND_SHIFT,
CHANGE_KIND_MASK,
CHANGE_KIND_MODIFY,
CHANGE_KIND_ADD,
CHANGE_KIND_DELETE,
CHANGE_KIND_REPLACE,
CHANGE_KIND_RESET): define flags & masks
(binary_change_t,
svn_fs_fs__changes_t): define data types
(changes_create_body,
append_change_body): implementation bodies
(svn_fs_fs__changes_create,
svn_fs_fs__changes_start_list,
svn_fs_fs__changes_append_change,
svn_fs_fs__changes_append_list,
svn_fs_fs__changes_estimate_size,
svn_fs_fs__changes_finalize,
svn_fs_fs__changes_get_list,
svn_fs_fs__write_changes_container,
svn_fs_fs__read_changes_container): implement APIs
Added:
subversion/branches/fsfs-format7/subversion/libsvn_fs_fs/changes.c
subversion/branches/fsfs-format7/subversion/libsvn_fs_fs/changes.h
Modified:
subversion/branches/fsfs-format7/subversion/include/svn_error_codes.h
Modified: subversion/branches/fsfs-format7/subversion/include/svn_error_codes.h
URL: http://svn.apache.org/viewvc/subversion/branches/fsfs-format7/subversion/include/svn_error_codes.h?rev=1462737&r1=1462736&r2=1462737&view=diff
==============================================================================
--- subversion/branches/fsfs-format7/subversion/include/svn_error_codes.h (original)
+++ subversion/branches/fsfs-format7/subversion/include/svn_error_codes.h Sat Mar 30 12:25:56 2013
@@ -817,6 +817,11 @@ SVN_ERROR_START
SVN_ERR_FS_CATEGORY_START + 56,
"Malformed transaction ID string.")
+ /** @since New in 1.9. */
+ SVN_ERRDEF(SVN_ERR_FS_CONTAINER_INDEX,
+ SVN_ERR_FS_CATEGORY_START + 57,
+ "Container index out of range.")
+
/* repos errors */
SVN_ERRDEF(SVN_ERR_REPOS_LOCKED,
Added: subversion/branches/fsfs-format7/subversion/libsvn_fs_fs/changes.c
URL: http://svn.apache.org/viewvc/subversion/branches/fsfs-format7/subversion/libsvn_fs_fs/changes.c?rev=1462737&view=auto
==============================================================================
--- subversion/branches/fsfs-format7/subversion/libsvn_fs_fs/changes.c (added)
+++ subversion/branches/fsfs-format7/subversion/libsvn_fs_fs/changes.c Sat Mar 30 12:25:56 2013
@@ -0,0 +1,453 @@
+/* changes.h --- FSFS changes lists container
+ *
+ * ====================================================================
+ * 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.
+ * ====================================================================
+ */
+
+#include "svn_private_config.h"
+
+#include "private/svn_packed_data.h"
+
+#include "changes.h"
+#include "string_table.h"
+
+/* These flags will be used with the FLAGS field in binary_change_t.
+ */
+
+/* the change contains a text modification */
+#define CHANGE_TEXT_MOD 0x00001
+
+/* the change contains a property modification */
+#define CHANGE_PROP_MOD 0x00002
+
+/* the last part (rev_id) of node revision ID is a transaction ID */
+#define CHANGE_TXN_NODE 0x00004
+
+/* (flags & CHANGE_NODE_MASK) >> CHANGE_NODE_SHIFT extracts the node type */
+#define CHANGE_NODE_SHIFT 0x00003
+#define CHANGE_NODE_MASK 0x00018
+
+/* node types according to svn_node_kind_t */
+#define CHANGE_NODE_NONE 0x00000
+#define CHANGE_NODE_FILE 0x00008
+#define CHANGE_NODE_DIR 0x00010
+#define CHANGE_NODE_UNKNOWN 0x00018
+
+/* (flags & CHANGE_KIND_MASK) >> CHANGE_KIND_SHIFT extracts the change type */
+#define CHANGE_KIND_SHIFT 0x00005
+#define CHANGE_KIND_MASK 0x000E0
+
+/* node types according to svn_fs_path_change_kind_t */
+#define CHANGE_KIND_MODIFY 0x00000
+#define CHANGE_KIND_ADD 0x00020
+#define CHANGE_KIND_DELETE 0x00040
+#define CHANGE_KIND_REPLACE 0x00060
+#define CHANGE_KIND_RESET 0x00080
+
+/* Our internal representation of a change */
+typedef struct binary_change_t
+{
+ /* define the kind of change and what specific information is present */
+ int flags;
+
+ /* Path of the change. */
+ apr_size_t path;
+
+ /* copy-from information.
+ * Not present if COPYFROM_REV is SVN_INVALID_REVNUM. */
+ svn_revnum_t copyfrom_rev;
+ apr_size_t copyfrom_path;
+
+ /* Relevant parts of the node revision ID of the change.
+ * Empty, if REV_ID is not "used". */
+ svn_fs_fs__id_part_t node_id;
+ svn_fs_fs__id_part_t copy_id;
+ svn_fs_fs__id_part_t rev_id; /* txn ID if CHANGE_TXN_NODE set in FLAGS */
+
+} binary_change_t;
+
+/* The actual container object. Change lists are concatenated into CHANGES
+ * and and their begins and ends are stored in OFFSETS.
+ */
+struct svn_fs_fs__changes_t
+{
+ /* The paths - either in 'builder' mode or finalized mode.
+ * The respective other pointer will be NULL. */
+ string_table_builder_t *builder;
+ string_table_t *paths;
+
+ /* All changes of all change lists concatenated.
+ * Array elements are binary_change_t.structs (not pointer!) */
+ apr_array_header_t *changes;
+
+ /* [Offsets[index] .. Offsets[index+1]) is the range in CHANGES that
+ * forms the contents of change list INDEX. */
+ apr_array_header_t *offsets;
+};
+
+/* Create and return a new container object, allocated in POOL and with
+ * and initial capacity of INITIAL_COUNT changes. The PATH and BUILDER
+ * members must be initialized by the caller afterwards.
+ */
+static svn_fs_fs__changes_t *
+changes_create_body(apr_size_t initial_count,
+ apr_pool_t *pool)
+{
+ svn_fs_fs__changes_t *changes = apr_pcalloc(pool, sizeof(*changes));
+
+ changes->changes = apr_array_make(pool, (int)initial_count,
+ sizeof(binary_change_t));
+ changes->offsets = apr_array_make(pool, 16, sizeof(int));
+ APR_ARRAY_PUSH(changes->offsets, int) = 0;
+
+ return changes;
+}
+
+svn_fs_fs__changes_t *
+svn_fs_fs__changes_create(apr_size_t initial_count,
+ apr_pool_t *pool)
+{
+ svn_fs_fs__changes_t *changes = changes_create_body(initial_count, pool);
+ changes->builder = svn_fs_fs__string_table_builder_create(pool);
+
+ return changes;
+}
+
+apr_size_t
+svn_fs_fs__changes_start_list(svn_fs_fs__changes_t *changes)
+{
+ APR_ARRAY_PUSH(changes->offsets, int) = changes->changes->nelts;
+ return (apr_size_t)(changes->offsets->nelts - 2);
+}
+
+/* Add CHANGE to the latest change list in CHANGES.
+ */
+static svn_error_t *
+append_change_body(svn_fs_fs__changes_t *changes,
+ change_t *change)
+{
+ binary_change_t binary_change = { 0 };
+ svn_boolean_t is_txn_id;
+
+ /* CHANGE must be sufficiently complete */
+ SVN_ERR_ASSERT(change);
+ SVN_ERR_ASSERT(change->path);
+
+ /* define the kind of change and what specific information is present */
+ is_txn_id = change->noderev_id && svn_fs_fs__id_is_txn(change->noderev_id);
+ binary_change.flags = (change->text_mod ? CHANGE_TEXT_MOD : 0)
+ | (change->prop_mod ? CHANGE_PROP_MOD : 0)
+ | (is_txn_id ? CHANGE_TXN_NODE : 0)
+ | ((int)change->kind < CHANGE_KIND_SHIFT)
+ | ((int)change->node_kind < CHANGE_NODE_SHIFT);
+
+ /* Path of the change. */
+ binary_change.path
+ = svn_fs_fs__string_table_builder_add(changes->builder, change->path, 0);
+
+ /* copy-from information, if presence is indicated by FLAGS */
+ if (SVN_IS_VALID_REVNUM(change->copyfrom_rev))
+ {
+ binary_change.copyfrom_rev = change->copyfrom_rev;
+ binary_change.copyfrom_path
+ = svn_fs_fs__string_table_builder_add(changes->builder,
+ change->copyfrom_path,
+ 0);
+ }
+ else
+ {
+ binary_change.copyfrom_rev = SVN_INVALID_REVNUM;
+ binary_change.copyfrom_path = 0;
+ }
+
+ /* Relevant parts of the revision ID of the change. */
+ if (change->noderev_id)
+ {
+ binary_change.node_id = *svn_fs_fs__id_node_id(change->noderev_id);
+ binary_change.copy_id = *svn_fs_fs__id_copy_id(change->noderev_id);
+ binary_change.rev_id = is_txn_id
+ ? *svn_fs_fs__id_txn_id(change->noderev_id)
+ : *svn_fs_fs__id_rev_item(change->noderev_id);
+ }
+ else
+ {
+ svn_fs_fs__id_txn_reset(&binary_change.rev_id);
+ }
+
+ APR_ARRAY_PUSH(changes->changes, binary_change_t) = binary_change;
+
+ return SVN_NO_ERROR;
+}
+
+svn_error_t *
+svn_fs_fs__changes_append_change(svn_fs_fs__changes_t *changes,
+ change_t *change)
+{
+ /* CHANGES must be in 'builder' mode */
+ SVN_ERR_ASSERT(changes->builder);
+ SVN_ERR_ASSERT(changes->paths == NULL);
+
+ return append_change_body(changes, change);
+}
+
+svn_error_t *
+svn_fs_fs__changes_append_list(apr_size_t *list_index,
+ svn_fs_fs__changes_t *changes,
+ apr_array_header_t *list)
+{
+ int i;
+
+ /* CHANGES must be in 'builder' mode */
+ SVN_ERR_ASSERT(changes->builder);
+ SVN_ERR_ASSERT(changes->paths == NULL);
+
+ /* simply append the list and all changes */
+ *list_index = svn_fs_fs__changes_start_list(changes);
+ for (i = 0; i < list->nelts; ++i)
+ append_change_body(changes, APR_ARRAY_IDX(list, i, change_t *));
+
+ return SVN_NO_ERROR;
+}
+
+apr_size_t
+svn_fs_fs__changes_estimate_size(const svn_fs_fs__changes_t *changes)
+{
+ /* CHANGES must be in 'builder' mode */
+ if (changes->builder == NULL)
+ return 0;
+
+ /* string table code makes its own prediction,
+ * changes should be < 20 bytes each,
+ * some static overhead should be assumed */
+ return svn_fs_fs__string_table_builder_estimate_size(changes->builder)
+ + changes->changes->nelts * 20
+ + 100;
+}
+
+svn_error_t *
+svn_fs_fs__changes_finalize(svn_fs_fs__changes_t *changes)
+{
+ /* CHANGES must be in 'builder' mode */
+ SVN_ERR_ASSERT(changes->builder);
+ SVN_ERR_ASSERT(changes->paths == NULL);
+
+ /* finalize paths string table */
+ changes->paths = svn_fs_fs__string_table_create(changes->builder,
+ changes->offsets->pool);
+
+ /* we are no longer in 'builder' mode */
+ changes->builder = NULL;
+
+ return SVN_NO_ERROR;
+}
+
+svn_error_t *
+svn_fs_fs__changes_get_list(apr_array_header_t **list,
+ const svn_fs_fs__changes_t *changes,
+ apr_size_t idx,
+ apr_pool_t *pool)
+{
+ int first;
+ int last;
+ int i;
+
+ /* CHANGES must be in 'finalized' mode */
+ SVN_ERR_ASSERT(changes->builder == NULL);
+ SVN_ERR_ASSERT(changes->paths);
+
+ /* validate index */
+ if (idx + 1 >= (apr_size_t)changes->offsets->nelts)
+ return svn_error_createf(SVN_ERR_FS_CONTAINER_INDEX, NULL,
+ _("Changes list index %" APR_SSIZE_T_FMT
+ " exceeds container size %d"),
+ idx, changes->offsets->nelts - 1);
+
+ /* range of changes to return */
+ first = APR_ARRAY_IDX(changes->offsets, (int)idx, int);
+ last = APR_ARRAY_IDX(changes->offsets, (int)idx + 1, int);
+
+ /* construct result */
+ *list = apr_array_make(pool, last - first, sizeof(change_t*));
+ for (i = first; i < last; ++i)
+ {
+ const binary_change_t *binary_change
+ = &APR_ARRAY_IDX(changes->changes, i, binary_change_t);
+
+ /* convert BINARY_CHANGE into a standard FSFS change_t */
+ change_t *change = apr_pcalloc(pool, sizeof(*change));
+ change->path = svn_fs_fs__string_table_get(changes->paths,
+ binary_change->path,
+ pool);
+
+ if (svn_fs_fs__id_txn_used(&binary_change->rev_id))
+ change->noderev_id
+ = (binary_change->flags & CHANGE_TXN_NODE)
+ ? svn_fs_fs__id_txn_create(&binary_change->node_id,
+ &binary_change->copy_id,
+ &binary_change->rev_id,
+ pool)
+ : svn_fs_fs__id_rev_create(&binary_change->node_id,
+ &binary_change->copy_id,
+ &binary_change->rev_id,
+ pool);
+
+ change->kind = (svn_fs_path_change_kind_t)
+ ((binary_change->flags & CHANGE_KIND_MASK) >> CHANGE_KIND_SHIFT);
+ change->text_mod = (binary_change->flags & CHANGE_TEXT_MOD) != 0;
+ change->prop_mod = (binary_change->flags & CHANGE_PROP_MOD) != 0;
+ change->node_kind = (svn_node_kind_t)
+ ((binary_change->flags & CHANGE_NODE_MASK) >> CHANGE_NODE_SHIFT);
+
+ change->copyfrom_rev = binary_change->copyfrom_rev;
+ if (SVN_IS_VALID_REVNUM(binary_change->copyfrom_rev))
+ change->copyfrom_path
+ = svn_fs_fs__string_table_get(changes->paths,
+ binary_change->copyfrom_rev,
+ pool);
+
+ /* add it to the result */
+ APR_ARRAY_PUSH(*list, change_t*) = change;
+ }
+
+ return SVN_NO_ERROR;
+}
+
+svn_error_t *
+svn_fs_fs__write_changes_container(svn_stream_t *stream,
+ const svn_fs_fs__changes_t *changes,
+ apr_pool_t *pool)
+{
+ int i;
+
+ svn__packed_data_root_t *root = svn__packed_data_create_root(pool);
+
+ /* one top-level stream for each array */
+ svn__packed_int_stream_t *offsets_stream
+ = svn__packed_create_int_stream(root, TRUE, FALSE);
+ svn__packed_int_stream_t *changes_stream
+ = svn__packed_create_int_stream(root, FALSE, FALSE);
+
+ /* structure the CHANGES_STREAM such we can extract much of the redundancy
+ * from the binary_change_t structs */
+ svn__packed_create_int_substream(changes_stream, TRUE, FALSE);
+ svn__packed_create_int_substream(changes_stream, TRUE, FALSE);
+ svn__packed_create_int_substream(changes_stream, TRUE, TRUE);
+ svn__packed_create_int_substream(changes_stream, TRUE, FALSE);
+ svn__packed_create_int_substream(changes_stream, TRUE, TRUE);
+ svn__packed_create_int_substream(changes_stream, TRUE, FALSE);
+ svn__packed_create_int_substream(changes_stream, TRUE, TRUE);
+ svn__packed_create_int_substream(changes_stream, TRUE, FALSE);
+ svn__packed_create_int_substream(changes_stream, TRUE, TRUE);
+ svn__packed_create_int_substream(changes_stream, TRUE, FALSE);
+
+ /* CHANGES must be in 'finalized' mode */
+ SVN_ERR_ASSERT(changes->builder == NULL);
+ SVN_ERR_ASSERT(changes->paths);
+
+ /* serialize offsets array */
+ for (i = 0; i < changes->offsets->nelts; ++i)
+ svn__packed_add_uint(offsets_stream,
+ APR_ARRAY_IDX(changes->offsets, i, int));
+
+ /* serialize changes array */
+ for (i = 0; i < changes->changes->nelts; ++i)
+ {
+ const binary_change_t *change
+ = &APR_ARRAY_IDX(changes->changes, i, binary_change_t);
+
+ svn__packed_add_uint(changes_stream, change->flags);
+ svn__packed_add_uint(changes_stream, change->path);
+
+ svn__packed_add_uint(changes_stream, change->copyfrom_rev);
+ svn__packed_add_uint(changes_stream, change->copyfrom_path);
+
+ svn__packed_add_uint(changes_stream, change->node_id.revision);
+ svn__packed_add_uint(changes_stream, change->node_id.number);
+ svn__packed_add_uint(changes_stream, change->copy_id.revision);
+ svn__packed_add_uint(changes_stream, change->copy_id.number);
+ svn__packed_add_uint(changes_stream, change->rev_id.revision);
+ svn__packed_add_uint(changes_stream, change->rev_id.number);
+ }
+
+ /* write to disk */
+ SVN_ERR(svn_fs_fs__write_string_table(stream, changes->paths, pool));
+ SVN_ERR(svn__packed_data_write(stream, root, pool));
+
+ return SVN_NO_ERROR;
+}
+
+svn_error_t *
+svn_fs_fs__read_changes_container(svn_fs_fs__changes_t **changes_p,
+ svn_stream_t *stream,
+ apr_pool_t *result_pool,
+ apr_pool_t *scratch_pool)
+{
+ apr_size_t i;
+ apr_size_t count;
+
+ svn_fs_fs__changes_t *changes = apr_pcalloc(result_pool, sizeof(*changes));
+
+ svn__packed_data_root_t *root;
+ svn__packed_int_stream_t *offsets_stream;
+ svn__packed_int_stream_t *changes_stream;
+
+ /* write from disk */
+ SVN_ERR(svn_fs_fs__read_string_table(&changes->paths, stream,
+ result_pool, scratch_pool));
+
+ SVN_ERR(svn__packed_data_read(&root, stream, result_pool, scratch_pool));
+ offsets_stream = svn__packed_first_int_stream(root);
+ changes_stream = svn__packed_next_int_stream(offsets_stream);
+
+ /* read offsets array */
+ count = svn__packed_int_count(offsets_stream);
+ changes->offsets = apr_array_make(result_pool, count, sizeof(int));
+ for (i = 0; i < count; ++i)
+ APR_ARRAY_PUSH(changes->offsets, int)
+ = (int)svn__packed_get_uint(offsets_stream);
+
+ /* read changes array */
+ count
+ = svn__packed_int_count(svn__packed_first_int_substream(changes_stream));
+ changes->changes
+ = apr_array_make(result_pool, count, sizeof(binary_change_t));
+ for (i = 0; i < count; ++i)
+ {
+ binary_change_t change;
+
+ change.flags = svn__packed_get_uint(changes_stream);
+ change.path = svn__packed_get_uint(changes_stream);
+
+ change.copyfrom_rev = svn__packed_get_uint(changes_stream);
+ change.copyfrom_path = svn__packed_get_uint(changes_stream);
+
+ change.node_id.revision = svn__packed_get_uint(changes_stream);
+ change.node_id.number = svn__packed_get_uint(changes_stream);
+ change.copy_id.revision = svn__packed_get_uint(changes_stream);
+ change.copy_id.number = svn__packed_get_uint(changes_stream);
+ change.rev_id.revision = svn__packed_get_uint(changes_stream);
+ change.rev_id.number = svn__packed_get_uint(changes_stream);
+
+ APR_ARRAY_PUSH(changes->changes, binary_change_t) = change;
+ }
+
+ *changes_p = changes;
+
+ return SVN_NO_ERROR;
+}
Added: subversion/branches/fsfs-format7/subversion/libsvn_fs_fs/changes.h
URL: http://svn.apache.org/viewvc/subversion/branches/fsfs-format7/subversion/libsvn_fs_fs/changes.h?rev=1462737&view=auto
==============================================================================
--- subversion/branches/fsfs-format7/subversion/libsvn_fs_fs/changes.h (added)
+++ subversion/branches/fsfs-format7/subversion/libsvn_fs_fs/changes.h Sat Mar 30 12:25:56 2013
@@ -0,0 +1,119 @@
+/* changes.h --- FSFS changes lists container
+ *
+ * ====================================================================
+ * 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__CHANGES_H
+#define SVN_LIBSVN_FS__CHANGES_H
+
+#include "svn_io.h"
+#include "fs.h"
+
+/* Entries in a revision's change list tend to be widely redundant (similar
+ * changes to similar paths). Even more so, change lists from a larger
+ * revision range also tend to overlap.
+ *
+ * In its serialized form, the svn_fs_fs__changes_t container extracts most
+ * of that redundancy and the run-time representation is also much smaller
+ * than sum of the respective change_t* arrays.
+ *
+ * As with other containers, this one has two modes: 'construction', in
+ * which you may add data to it, and 'getter' in which there is only r/o
+ * access to the data.
+ */
+
+/* An opaque collection of change lists (apr_array_header_t * of change_t*).
+ */
+typedef struct svn_fs_fs__changes_t svn_fs_fs__changes_t;
+
+/* Create and populate changes containers. */
+
+/* Create and return a new changes container with an initial capacity of
+ * INITIAL_COUNT change_t objects. Allocate the result in POOL.
+ */
+svn_fs_fs__changes_t *
+svn_fs_fs__changes_create(apr_size_t initial_count,
+ apr_pool_t *pool);
+
+/* Begin a new change list in CHANGES and return its index.
+ * Implicitly terminates the previous change list (if any).
+ */
+apr_size_t
+svn_fs_fs__changes_start_list(svn_fs_fs__changes_t *changes);
+
+/* Add CHANGE to the latest change list in CHANGES.
+ */
+svn_error_t *
+svn_fs_fs__changes_append_change(svn_fs_fs__changes_t *changes,
+ change_t *change);
+
+/* Start a new change list CHANGES (implicitly terminating the previous one)
+ * and return its index in *LIST_INDEX. Append all changes from LIST to
+ * that new change list.
+ */
+svn_error_t *
+svn_fs_fs__changes_append_list(apr_size_t *list_index,
+ svn_fs_fs__changes_t *changes,
+ apr_array_header_t *list);
+
+/* Return a rough estimate in bytes for the serialized representation
+ * of CHANGES.
+ */
+apr_size_t
+svn_fs_fs__changes_estimate_size(const svn_fs_fs__changes_t *changes);
+
+/* Convert CHANGES from its writable internal representation to its final
+ * memory-friendly r/o representation.
+ */
+svn_error_t *
+svn_fs_fs__changes_finalize(svn_fs_fs__changes_t *changes);
+
+/* Read changes containers. */
+
+/* From CHANGES, extract the change list with the given INDEX. Allocate
+ * the result in POOL and return it in *LIST.
+ */
+svn_error_t *
+svn_fs_fs__changes_get_list(apr_array_header_t **list,
+ const svn_fs_fs__changes_t *changes,
+ apr_size_t index,
+ apr_pool_t *pool);
+
+/* I/O interface. */
+
+/* Write a serialized representation of CHANGES to STREAM. Use POOL for
+ * temporary allocations.
+ */
+svn_error_t *
+svn_fs_fs__write_changes_container(svn_stream_t *stream,
+ const svn_fs_fs__changes_t *changes,
+ apr_pool_t *pool);
+
+/* Read a changes container from its serialized representation in STREAM.
+ * Allocate the result in RESULT_POOL and return it in *CHANGES_P. Use
+ * SCRATCH_POOL for temporary allocations.
+ */
+svn_error_t *
+svn_fs_fs__read_changes_container(svn_fs_fs__changes_t **changes_p,
+ svn_stream_t *stream,
+ apr_pool_t *result_pool,
+ apr_pool_t *scratch_pool);
+
+#endif
\ No newline at end of file