Author: stefan2
Date: Fri Sep 7 08:56:50 2012
New Revision: 1381938
URL: http://svn.apache.org/viewvc?rev=1381938&view=rev
Log:
Partly implements issue #3372: When building the rep state read
sequence along the skip-delta chain, re-use file instances that
pertain to the same pack file.
* subversion/libsvn_fs_fs/fs_fs.c
(create_rep_state_body): re-use the last file instance, if possible
(create_rep_state): extended docstring to cover new parameters
(build_rep_list): provide hints
(read_window): seek before read as the file object may be shared
(svn_fs_fs__get_file_delta_stream,
verify_walker): adapt callers not using hints
Modified:
subversion/trunk/subversion/libsvn_fs_fs/fs_fs.c
Modified: subversion/trunk/subversion/libsvn_fs_fs/fs_fs.c
URL:
http://svn.apache.org/viewvc/subversion/trunk/subversion/libsvn_fs_fs/fs_fs.c?rev=1381938&r1=1381937&r2=1381938&view=diff
==============================================================================
--- subversion/trunk/subversion/libsvn_fs_fs/fs_fs.c (original)
+++ subversion/trunk/subversion/libsvn_fs_fs/fs_fs.c Fri Sep 7 08:56:50 2012
@@ -4203,6 +4203,8 @@ struct rep_state
static svn_error_t *
create_rep_state_body(struct rep_state **rep_state,
struct rep_args **rep_args,
+ apr_file_t **file_hint,
+ svn_revnum_t *rev_hint,
representation_t *rep,
svn_fs_t *fs,
apr_pool_t *pool)
@@ -4212,7 +4214,43 @@ create_rep_state_body(struct rep_state *
struct rep_args *ra;
unsigned char buf[4];
- SVN_ERR(open_and_seek_representation(&rs->file, fs, rep, pool));
+ /* If the hint is
+ * - given,
+ * - refers to a packed revision,
+ * - as does the rep we want to read, and
+ * - refers to the same pack file as the rep
+ * ...
+ */
+ if ( file_hint && rev_hint && *file_hint
+ && *rev_hint < ffd->min_unpacked_rev
+ && rep->revision < ffd->min_unpacked_rev
+ && ( (*rev_hint / ffd->max_files_per_dir)
+ == (rep->revision / ffd->max_files_per_dir)))
+ {
+ /* ... we can re-use the same, already open file object
+ */
+ apr_off_t offset;
+ SVN_ERR(get_packed_offset(&offset, fs, rep->revision, pool));
+
+ offset += rep->offset;
+ SVN_ERR(svn_io_file_seek(*file_hint, APR_SET, &offset, pool));
+
+ rs->file = *file_hint;
+ }
+ else
+ {
+ /* otherwise, create a new file object
+ */
+ SVN_ERR(open_and_seek_representation(&rs->file, fs, rep, pool));
+ }
+
+ /* remember the current file, if suggested by the caller */
+ if (file_hint)
+ *file_hint = rs->file;
+ if (rev_hint)
+ *rev_hint = rep->revision;
+
+ /* continue constructing RS and RA */
rs->window_cache = ffd->txdelta_window_cache;
rs->combined_cache = ffd->combined_window_cache;
@@ -4244,15 +4282,25 @@ create_rep_state_body(struct rep_state *
/* Read the rep args for REP in filesystem FS and create a rep_state
for reading the representation. Return the rep_state in *REP_STATE
- and the rep args in *REP_ARGS, both allocated in POOL. */
+ and the rep args in *REP_ARGS, both allocated in POOL.
+
+ When reading multiple reps, i.e. a skip delta chain, you may provide
+ non-NULL FILE_HINT and REV_HINT. The function will use these variables
+ to store the previous call results and tries to re-use them. This may
+ result in significant savings in I/O for packed files.
+ */
static svn_error_t *
create_rep_state(struct rep_state **rep_state,
struct rep_args **rep_args,
+ apr_file_t **file_hint,
+ svn_revnum_t *rev_hint,
representation_t *rep,
svn_fs_t *fs,
apr_pool_t *pool)
{
- svn_error_t *err = create_rep_state_body(rep_state, rep_args, rep, fs, pool);
+ svn_error_t *err = create_rep_state_body(rep_state, rep_args,
+ file_hint, rev_hint,
+ rep, fs, pool);
if (err && err->apr_err == SVN_ERR_FS_CORRUPT)
{
fs_fs_data_t *ffd = fs->fsap_data;
@@ -4519,13 +4567,16 @@ build_rep_list(apr_array_header_t **list
struct rep_state *rs;
struct rep_args *rep_args;
svn_boolean_t is_cached = FALSE;
+ apr_file_t *last_file = NULL;
+ svn_revnum_t last_revision;
*list = apr_array_make(pool, 1, sizeof(struct rep_state *));
rep = *first_rep;
while (1)
{
- SVN_ERR(create_rep_state(&rs, &rep_args, &rep, fs, pool));
+ SVN_ERR(create_rep_state(&rs, &rep_args, &last_file,
+ &last_revision, &rep, fs, pool));
SVN_ERR(get_cached_combined_window(window_p, rs, &is_cached, pool));
if (is_cached)
{
@@ -4617,6 +4668,10 @@ read_window(svn_txdelta_window_t **nwin,
SVN_ERR_ASSERT(rs->chunk_index <= this_chunk);
+ /* RS->FILE may be shared between RS instances -> make sure we point
+ * to the right data. */
+ SVN_ERR(svn_io_file_seek(rs->file, APR_SET, &rs->off, pool));
+
/* Skip windows to reach the current chunk if we aren't there yet. */
while (rs->chunk_index < this_chunk)
{
@@ -5003,8 +5058,8 @@ svn_fs_fs__get_file_delta_stream(svn_txd
struct rep_args *rep_args;
/* Read target's base rep if any. */
- SVN_ERR(create_rep_state(&rep_state, &rep_args, target->data_rep,
- fs, pool));
+ SVN_ERR(create_rep_state(&rep_state, &rep_args, NULL, NULL,
+ target->data_rep, fs, pool));
/* If that matches source, then use this delta as is. */
if (rep_args->is_delta
&& (rep_args->is_delta_vs_empty
@@ -9789,7 +9844,7 @@ verify_walker(representation_t *rep,
struct rep_args *rep_args;
/* ### Should this be using read_rep_line() directly? */
- SVN_ERR(create_rep_state(&rs, &rep_args, rep, fs, scratch_pool));
+ SVN_ERR(create_rep_state(&rs, &rep_args, NULL, NULL, rep, fs, scratch_pool));
return SVN_NO_ERROR;
}
