ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/JSON-XS/XS.pm
(Generate patch)

Comparing JSON-XS/XS.pm (file contents):
Revision 1.46 by root, Mon Jun 25 04:21:14 2007 UTC vs.
Revision 1.48 by root, Mon Jun 25 22:11:39 2007 UTC

… …
393given character in a string. 393given character in a string.
394 394
395Setting the maximum depth to one disallows any nesting, so that ensures 395Setting the maximum depth to one disallows any nesting, so that ensures
396that the object is only a single hash/object or array. 396that the object is only a single hash/object or array.
397 397
398The argument to C<max_depth> will be rounded up to the next nearest power 398The argument to C<max_depth> will be rounded up to the next highest power
399of two. 399of two. If no argument is given, the highest possible setting will be
400used, which is rarely useful.
401
402See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
403
404=item $json = $json->max_size ([$maximum_string_size])
405
406Set the maximum length a JSON text may have (in bytes) where decoding is
407being attempted. The default is C<0>, meaning no limit. When C<decode>
408is called on a string longer then this number of characters it will not
409attempt to decode the string but throw an exception. This setting has no
410effect on C<encode> (yet).
411
412The argument to C<max_size> will be rounded up to the next B<highest>
413power of two (so may be more than requested). If no argument is given, the
414limit check will be deactivated (same as when C<0> is specified).
400 415
401See SECURITY CONSIDERATIONS, below, for more info on why this is useful. 416See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
402 417
403=item $json_text = $json->encode ($perl_scalar) 418=item $json_text = $json->encode ($perl_scalar)
404 419
… …
696It shows the number of encodes/decodes per second (JSON::XS uses 711It shows the number of encodes/decodes per second (JSON::XS uses
697the functional interface, while JSON::XS/2 uses the OO interface 712the functional interface, while JSON::XS/2 uses the OO interface
698with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables 713with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
699shrink). Higher is better: 714shrink). Higher is better:
700 715
716 Storable | 15779.925 | 14169.946 |
717 -----------+------------+------------+
701 module | encode | decode | 718 module | encode | decode |
702 -----------|------------|------------| 719 -----------|------------|------------|
703 JSON | 7645.468 | 4208.613 | 720 JSON | 4990.842 | 4088.813 |
704 JSON::DWIW | 40721.398 | 77101.176 | 721 JSON::DWIW | 51653.990 | 71575.154 |
705 JSON::PC | 65948.176 | 78251.940 | 722 JSON::PC | 65948.176 | 74631.744 |
706 JSON::Syck | 22844.793 | 26479.192 | 723 JSON::PP | 8931.652 | 3817.168 |
724 JSON::Syck | 24877.248 | 27776.848 |
707 JSON::XS | 388361.481 | 199728.762 | 725 JSON::XS | 388361.481 | 227951.304 |
708 JSON::XS/2 | 218453.333 | 192399.266 | 726 JSON::XS/2 | 227951.304 | 218453.333 |
709 JSON::XS/3 | 338250.323 | 192399.266 | 727 JSON::XS/3 | 338250.323 | 218453.333 |
710 Storable | 15779.925 | 14169.946 | 728 Storable | 16500.016 | 135300.129 |
711 -----------+------------+------------+ 729 -----------+------------+------------+
712 730
713That is, JSON::XS is about five times faster than JSON::DWIW on encoding, 731That is, JSON::XS is about five times faster than JSON::DWIW on encoding,
714about three times faster on decoding, and over fourty times faster 732about three times faster on decoding, and over fourty times faster
715than JSON, even with pretty-printing and key sorting. It also compares 733than JSON, even with pretty-printing and key sorting. It also compares
… …
718Using a longer test string (roughly 18KB, generated from Yahoo! Locals 736Using a longer test string (roughly 18KB, generated from Yahoo! Locals
719search API (http://nanoref.com/yahooapis/mgPdGg): 737search API (http://nanoref.com/yahooapis/mgPdGg):
720 738
721 module | encode | decode | 739 module | encode | decode |
722 -----------|------------|------------| 740 -----------|------------|------------|
723 JSON | 254.685 | 37.665 | 741 JSON | 55.260 | 34.971 |
724 JSON::DWIW | 843.343 | 1049.731 | 742 JSON::DWIW | 825.228 | 1082.513 |
725 JSON::PC | 3602.116 | 2307.352 | 743 JSON::PC | 3571.444 | 2394.829 |
744 JSON::PP | 210.987 | 32.574 |
726 JSON::Syck | 505.107 | 787.899 | 745 JSON::Syck | 552.551 | 787.544 |
727 JSON::XS | 5747.196 | 3690.220 | 746 JSON::XS | 5780.463 | 4854.519 |
728 JSON::XS/2 | 3968.121 | 3676.634 | 747 JSON::XS/2 | 3869.998 | 4798.975 |
729 JSON::XS/3 | 6105.246 | 3662.508 | 748 JSON::XS/3 | 5862.880 | 4798.975 |
730 Storable | 4417.337 | 5285.161 | 749 Storable | 4445.002 | 5235.027 |
731 -----------+------------+------------+ 750 -----------+------------+------------+
732 751
733Again, JSON::XS leads by far (except for Storable which non-surprisingly 752Again, JSON::XS leads by far (except for Storable which non-surprisingly
734decodes faster). 753decodes faster).
735 754
… …
752Second, you need to avoid resource-starving attacks. That means you should 771Second, you need to avoid resource-starving attacks. That means you should
753limit the size of JSON texts you accept, or make sure then when your 772limit the size of JSON texts you accept, or make sure then when your
754resources run out, thats just fine (e.g. by using a separate process that 773resources run out, thats just fine (e.g. by using a separate process that
755can crash safely). The size of a JSON text in octets or characters is 774can crash safely). The size of a JSON text in octets or characters is
756usually a good indication of the size of the resources required to decode 775usually a good indication of the size of the resources required to decode
757it into a Perl structure. 776it into a Perl structure. While JSON::XS can check the size of the JSON
777text, it might be too late when you already have it in memory, so you
778might want to check the size before you accept the string.
758 779
759Third, JSON::XS recurses using the C stack when decoding objects and 780Third, JSON::XS recurses using the C stack when decoding objects and
760arrays. The C stack is a limited resource: for instance, on my amd64 781arrays. The C stack is a limited resource: for instance, on my amd64
761machine with 8MB of stack size I can decode around 180k nested arrays but 782machine with 8MB of stack size I can decode around 180k nested arrays but
762only 14k nested JSON objects (due to perl itself recursing deeply on croak 783only 14k nested JSON objects (due to perl itself recursing deeply on croak

Diff Legend

– Removed lines
+ Added lines
< Changed lines
> Changed lines