Daniel Näslund <daniel_at_longitudo.com
<mailto:daniel_at_longitudo.com?Subject=Re:%20svn%20commit:%20r985514%20-%20in%20/subversion/branches/performance/subversion:%20include/svn_io.h%20libsvn_subr/stream.c%20libsvn_subr/subst.c>>
wrote:
On Sat, Aug 14, 2010 at 03:46:13PM -0000, stefan2_at_apache.org wrote:
/> Author: stefan2 /
/> Date: Sat Aug 14 15:46:13 2010 /
/> New Revision: 985514 /
/> /
/> URL: http://svn.apache.org/viewvc?rev=985514&view=rev
<http://svn.apache.org/viewvc?rev=985514&view=rev> /
/> Log: /
/> Extend the stream API by three functions: /
/> svn_stream_move_mark() to move an existing mark by some delta /
/> svn_stream_supports_mark() tells whether getting, setting and
moving marks is supported by this stream /
/> /
/> * subversion/include/svn_io.h /
/> (svn_io_move_mark_fn_t, svn_io_buffered_fn_t): /
/> declare new vtable function pointers /
/> (svn_stream_set_move_mark, svn_stream_set_buffered): /
/> declare functions to set these vtable pointers /
/> (svn_stream_supports_mark, svn_stream_move_mark,
svn_stream_buffered): /
/> declare new stream API functions /
/> /
/> * subversion/libsvn_subr/stream.c /
/> (svn_stream_t): extend the vtable part by the new functions /
/> (svn_stream_create): add initialization code for the new vtable
entries /
/> (svn_stream_set_move_mark, svn_stream_set_buffered): /
/> implement new vtable modifiers /
/> (svn_stream_supports_mark, svn_stream_buffered, svn_stream_buffered): /
/> implement new stream generic API functions /
/> (move_mark_handler_empty, buffered_handler_empty, svn_stream_empty): /
/> implement support for the new stream API in empty streams /
/> (move_mark_handler_disown, buffered_handler_disown,
svn_stream_disown): /
/> implement support for the new stream API in disowned streams /
/> (move_mark_handler_apr, buffered_handler_apr, stream_from_aprfile, /
/> svn_stream_from_aprfile_range_readonly): /
/> implement support for the new stream API in APR file based streams /
/> (move_mark_handler_stringbuf, buffered_handler_stringbuf, /
/> svn_stream_from_stringbuf): /
/> implement support for the new stream API in stringbuf streams /
/> /
/> * subversion/libsvn_subr/subst.c /
/> (translated_stream_move_mark, translated_stream_buffered, /
/> svn_subst_stream_translated): /
/> implement support for the new stream API in translated streams /
Out of curiosity, why are you touching the svn_stream_mark() code on
the performance branch? AFAIK, svn_stream_mark() is only used in the
patch code. What performance benefits are you hoping to achieve?
See r985601. If the parser is to read larger chunks of data speculatively,
it needs to re-position the stream read pointer afterwards. Not all streams
can support that feature efficiently or at all.
-- Stefan^2.
