Author: ivan
Date: Fri Jun 12 11:09:45 2015
New Revision: 1685063
URL: http://svn.apache.org/r1685063
Log:
Optimize svndiff parser a bit: do not parse delta window header on every
chunk written to svndiff parser write handler.
While this change may look like micro-optimization, in reality parsing delta
window header consume significant time of 'svnbench null-export' execution
over http: data received from network/base64 parser in small chunks. This
makes parsing one delta window header 1000 times until all delta window
received.
* subversion/libsvn_delta/svndiff.c
(decode_baton): Add fields to hold length and five integer fields of
parsed delta window header.
(write_handler): Reduce scope of local variables. Store parsed delta window
header fields and length in DECODE_BATON and used on later invocations.
Reset WINDOW_HEADER_LEN to zero once delta window is processed.
(svn_txdelta_parse_svndiff): Initialize WINDOW_HEADER_LEN to zero.
Modified:
subversion/trunk/subversion/libsvn_delta/svndiff.c
Modified: subversion/trunk/subversion/libsvn_delta/svndiff.c
URL:
http://svn.apache.org/viewvc/subversion/trunk/subversion/libsvn_delta/svndiff.c?rev=1685063&r1=1685062&r2=1685063&view=diff
==============================================================================
--- subversion/trunk/subversion/libsvn_delta/svndiff.c (original)
+++ subversion/trunk/subversion/libsvn_delta/svndiff.c Fri Jun 12 11:09:45 2015
@@ -342,6 +342,17 @@ struct decode_baton
/* svndiff version in use by delta. */
unsigned char version;
+
+ /* Length of parsed delta window header. 0 if window is not parsed yet. */
+ apr_size_t window_header_len;
+
+ /* Five integer fields of parsed delta window header. Valid only if
+ WINDOW_HEADER_LEN > 0 */
+ svn_filesize_t sview_offset;
+ apr_size_t sview_len;
+ apr_size_t tview_len;
+ apr_size_t inslen;
+ apr_size_t newlen;
};
@@ -572,8 +583,6 @@ write_handler(void *baton,
{
struct decode_baton *db = (struct decode_baton *) baton;
const unsigned char *p, *end;
- svn_filesize_t sview_offset;
- apr_size_t sview_len, tview_len, inslen, newlen;
apr_size_t buflen = *len;
/* Chew up four bytes at the beginning for the header. */
@@ -617,69 +626,94 @@ write_handler(void *baton,
p = (const unsigned char *) db->buffer->data;
end = (const unsigned char *) db->buffer->data + db->buffer->len;
- p = decode_file_offset(&sview_offset, p, end);
- if (p == NULL)
- break;
-
- p = decode_size(&sview_len, p, end);
- if (p == NULL)
- break;
-
- p = decode_size(&tview_len, p, end);
- if (p == NULL)
- break;
-
- p = decode_size(&inslen, p, end);
- if (p == NULL)
- break;
-
- p = decode_size(&newlen, p, end);
- if (p == NULL)
- break;
-
- if (tview_len > SVN_DELTA_WINDOW_SIZE ||
- sview_len > SVN_DELTA_WINDOW_SIZE ||
- /* for svndiff1, newlen includes the original length */
- newlen > SVN_DELTA_WINDOW_SIZE + SVN__MAX_ENCODED_UINT_LEN ||
- inslen > MAX_INSTRUCTION_SECTION_LEN)
- return svn_error_create(SVN_ERR_SVNDIFF_CORRUPT_WINDOW, NULL,
- _("Svndiff contains a too-large window"));
-
- /* Check for integer overflow. */
- if (sview_offset < 0 || inslen + newlen < inslen
- || sview_len + tview_len < sview_len
- || (apr_size_t)sview_offset + sview_len < (apr_size_t)sview_offset)
- return svn_error_create(SVN_ERR_SVNDIFF_CORRUPT_WINDOW, NULL,
- _("Svndiff contains corrupt window header"));
-
- /* Check for source windows which slide backwards. */
- if (sview_len > 0
- && (sview_offset < db->last_sview_offset
+ if (db->window_header_len == 0)
+ {
+ svn_filesize_t sview_offset;
+ apr_size_t sview_len, tview_len, inslen, newlen;
+ const unsigned char *hdr_start = p;
+
+ p = decode_file_offset(&sview_offset, p, end);
+ if (p == NULL)
+ break;
+
+ p = decode_size(&sview_len, p, end);
+ if (p == NULL)
+ break;
+
+ p = decode_size(&tview_len, p, end);
+ if (p == NULL)
+ break;
+
+ p = decode_size(&inslen, p, end);
+ if (p == NULL)
+ break;
+
+ p = decode_size(&newlen, p, end);
+ if (p == NULL)
+ break;
+
+ if (tview_len > SVN_DELTA_WINDOW_SIZE ||
+ sview_len > SVN_DELTA_WINDOW_SIZE ||
+ /* for svndiff1, newlen includes the original length */
+ newlen > SVN_DELTA_WINDOW_SIZE + SVN__MAX_ENCODED_UINT_LEN ||
+ inslen > MAX_INSTRUCTION_SECTION_LEN)
+ return svn_error_create(
+ SVN_ERR_SVNDIFF_CORRUPT_WINDOW, NULL,
+ _("Svndiff contains a too-large window"));
+
+ /* Check for integer overflow. */
+ if (sview_offset < 0 || inslen + newlen < inslen
+ || sview_len + tview_len < sview_len
+ || (apr_size_t)sview_offset + sview_len <
(apr_size_t)sview_offset)
+ return svn_error_create(
+ SVN_ERR_SVNDIFF_CORRUPT_WINDOW, NULL,
+ _("Svndiff contains corrupt window header"));
+
+ /* Check for source windows which slide backwards. */
+ if (sview_len > 0
+ && (sview_offset < db->last_sview_offset
|| (sview_offset + sview_len
< db->last_sview_offset + db->last_sview_len)))
- return svn_error_create
- (SVN_ERR_SVNDIFF_BACKWARD_VIEW, NULL,
- _("Svndiff has backwards-sliding source views"));
+ return svn_error_create(
+ SVN_ERR_SVNDIFF_BACKWARD_VIEW, NULL,
+ _("Svndiff has backwards-sliding source views"));
+
+ /* Remember parsed window header. */
+ db->window_header_len = p - hdr_start;
+ db->sview_offset = sview_offset;
+ db->sview_len = sview_len;
+ db->tview_len = tview_len;
+ db->inslen = inslen;
+ db->newlen = newlen;
+ }
+ else
+ {
+ /* Skip already parsed window header. */
+ p += db->window_header_len;
+ }
/* Wait for more data if we don't have enough bytes for the
whole window. */
- if ((apr_size_t) (end - p) < inslen + newlen)
+ if ((apr_size_t) (end - p) < db->inslen + db->newlen)
return SVN_NO_ERROR;
/* Decode the window and send it off. */
- SVN_ERR(decode_window(&window, sview_offset, sview_len, tview_len,
- inslen, newlen, p, db->subpool,
- db->version));
+ SVN_ERR(decode_window(&window, db->sview_offset, db->sview_len,
+ db->tview_len, db->inslen, db->newlen, p,
+ db->subpool, db->version));
SVN_ERR(db->consumer_func(&window, db->consumer_baton));
- p += inslen + newlen;
+ p += db->inslen + db->newlen;
/* Remove processed data from the buffer. */
svn_stringbuf_remove(db->buffer, 0, db->buffer->len - (end - p));
+ /* Reset window header length. */
+ db->window_header_len = 0;
+
/* Remember the offset and length of the source view for next time. */
- db->last_sview_offset = sview_offset;
- db->last_sview_len = sview_len;
+ db->last_sview_offset = db->sview_offset;
+ db->last_sview_len = db->sview_len;
/* Clear subpool. */
svn_pool_clear(db->subpool);
@@ -747,6 +781,7 @@ svn_txdelta_parse_svndiff(svn_txdelta_wi
db->last_sview_len = 0;
db->header_bytes = 0;
db->error_on_early_close = error_on_early_close;
+ db->window_header_len = 0;
stream = svn_stream_create(db, pool);
svn_stream_set_write(stream, write_handler);
