[Combines r1698359 and r170078 into a single commit for better review.] Introduce a stream wrapper object that adds buffering support to any…
[Combines r1698359 and r170078 into a single commit for better review.]Introduce a stream wrapper object that adds buffering support to anyreadable stream. Use it on the stdin streams in our CL tools. As it turns out, parsing data from a stdin byte-by-byte incurs amassive overhead of 100% internal and 300% system load over a bufferedstream. 'svnadmin load-revprops' sees a 5 times speedup if all datais in OS disc caches. This is a realistic assumption in a "final syncand switch over to new repository" scenario.The other 2 uses of stdin either have less data to process (svnfsfsload-index) or parse only a small fraction of the stream (svnadmin load).* subversion/include/svn_io.h (svn_stream_wrap_buffered_read): Declare the new stream constructor API.* subversion/libsvn_subr/stream.c (read_handler_buffering_wrapper, data_available_handler_buffering_wrapper, is_buffered_handler_buffering_wrapper): Internal logic of the new stream object. (svn_stream_wrap_buffered_read): New constructor implementation.* subversion/svnadmin/svnadmin.c (subcommand_load_revprops): Wrap the stdin stream.* subversion/svnfsfs/load-index-cmd.c (subcommand__load_index): Same.* subversion/tests/libsvn_subr/stream-test.c (struct stream_baton_t, read_handler, data_available_handler, create_test_read_stream): New configurable test read stream. (expect_line_content, test_stream_buffered_wrapper): New test for the new wrapper stream. (test_funcs): Register the new test.