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 1.44 by root, Mon Jun 25 04:08:17 2007 UTC vs.
Revision 1.49 by root, Sun Jul 1 14:08:03 2007 UTC

… …
9 # exported functions, they croak on error 9 # exported functions, they croak on error
10 # and expect/generate UTF-8 10 # and expect/generate UTF-8
11 11
12 $utf8_encoded_json_text = to_json $perl_hash_or_arrayref; 12 $utf8_encoded_json_text = to_json $perl_hash_or_arrayref;
13 $perl_hash_or_arrayref = from_json $utf8_encoded_json_text; 13 $perl_hash_or_arrayref = from_json $utf8_encoded_json_text;
14
15 # objToJson and jsonToObj aliases to to_json and from_json
16 # are exported for compatibility to the JSON module,
17 # but should not be used in new code.
18 14
19 # OO-interface 15 # OO-interface
20 16
21 $coder = JSON::XS->new->ascii->pretty->allow_nonref; 17 $coder = JSON::XS->new->ascii->pretty->allow_nonref;
22 $pretty_printed_unencoded = $coder->encode ($perl_scalar); 18 $pretty_printed_unencoded = $coder->encode ($perl_scalar);
… …
88use strict; 84use strict;
89 85
90our $VERSION = '1.4'; 86our $VERSION = '1.4';
91our @ISA = qw(Exporter); 87our @ISA = qw(Exporter);
92 88
93our @EXPORT = qw(to_json from_json objToJson jsonToObj); 89our @EXPORT = qw(to_json from_json);
94 90
95use Exporter; 91use Exporter;
96use XSLoader; 92use XSLoader;
97 93
98=head1 FUNCTIONAL INTERFACE 94=head1 FUNCTIONAL INTERFACE
… …
341 337
342The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON> 338The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON>
343returns other blessed objects, those will be handled in the same 339returns other blessed objects, those will be handled in the same
344way. C<TO_JSON> must take care of not causing an endless recursion cycle 340way. C<TO_JSON> must take care of not causing an endless recursion cycle
345(== crash) in this case. The name of C<TO_JSON> was chosen because other 341(== crash) in this case. The name of C<TO_JSON> was chosen because other
346methods called by the Perl core (== not the user of the object) are 342methods called by the Perl core (== not by the user of the object) are
347usually in upper case letters and to avoid collisions with the C<to_json> 343usually in upper case letters and to avoid collisions with the C<to_json>
348function. 344function.
345
346This setting does not yet influence C<decode> in any way, but in the
347future, global hooks might get installed that influence C<decode> and are
348enabled by this setting.
349 349
350If C<$enable> is false, then the C<allow_blessed> setting will decide what 350If C<$enable> is false, then the C<allow_blessed> setting will decide what
351to do when a blessed object is found. 351to do when a blessed object is found.
352 352
353=item $json = $json->shrink ([$enable]) 353=item $json = $json->shrink ([$enable])
… …
389given character in a string. 389given character in a string.
390 390
391Setting the maximum depth to one disallows any nesting, so that ensures 391Setting the maximum depth to one disallows any nesting, so that ensures
392that the object is only a single hash/object or array. 392that the object is only a single hash/object or array.
393 393
394The argument to C<max_depth> will be rounded up to the next nearest power 394The argument to C<max_depth> will be rounded up to the next highest power
395of two. 395of two. If no argument is given, the highest possible setting will be
396used, which is rarely useful.
397
398See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
399
400=item $json = $json->max_size ([$maximum_string_size])
401
402Set the maximum length a JSON text may have (in bytes) where decoding is
403being attempted. The default is C<0>, meaning no limit. When C<decode>
404is called on a string longer then this number of characters it will not
405attempt to decode the string but throw an exception. This setting has no
406effect on C<encode> (yet).
407
408The argument to C<max_size> will be rounded up to the next B<highest>
409power of two (so may be more than requested). If no argument is given, the
410limit check will be deactivated (same as when C<0> is specified).
396 411
397See SECURITY CONSIDERATIONS, below, for more info on why this is useful. 412See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
398 413
399=item $json_text = $json->encode ($perl_scalar) 414=item $json_text = $json->encode ($perl_scalar)
400 415
… …
692It shows the number of encodes/decodes per second (JSON::XS uses 707It shows the number of encodes/decodes per second (JSON::XS uses
693the functional interface, while JSON::XS/2 uses the OO interface 708the functional interface, while JSON::XS/2 uses the OO interface
694with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables 709with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
695shrink). Higher is better: 710shrink). Higher is better:
696 711
712 Storable | 15779.925 | 14169.946 |
713 -----------+------------+------------+
697 module | encode | decode | 714 module | encode | decode |
698 -----------|------------|------------| 715 -----------|------------|------------|
699 JSON | 7645.468 | 4208.613 | 716 JSON | 4990.842 | 4088.813 |
700 JSON::DWIW | 40721.398 | 77101.176 | 717 JSON::DWIW | 51653.990 | 71575.154 |
701 JSON::PC | 65948.176 | 78251.940 | 718 JSON::PC | 65948.176 | 74631.744 |
702 JSON::Syck | 22844.793 | 26479.192 | 719 JSON::PP | 8931.652 | 3817.168 |
720 JSON::Syck | 24877.248 | 27776.848 |
703 JSON::XS | 388361.481 | 199728.762 | 721 JSON::XS | 388361.481 | 227951.304 |
704 JSON::XS/2 | 218453.333 | 192399.266 | 722 JSON::XS/2 | 227951.304 | 218453.333 |
705 JSON::XS/3 | 338250.323 | 192399.266 | 723 JSON::XS/3 | 338250.323 | 218453.333 |
706 Storable | 15779.925 | 14169.946 | 724 Storable | 16500.016 | 135300.129 |
707 -----------+------------+------------+ 725 -----------+------------+------------+
708 726
709That is, JSON::XS is about five times faster than JSON::DWIW on encoding, 727That is, JSON::XS is about five times faster than JSON::DWIW on encoding,
710about three times faster on decoding, and over fourty times faster 728about three times faster on decoding, and over fourty times faster
711than JSON, even with pretty-printing and key sorting. It also compares 729than JSON, even with pretty-printing and key sorting. It also compares
… …
714Using a longer test string (roughly 18KB, generated from Yahoo! Locals 732Using a longer test string (roughly 18KB, generated from Yahoo! Locals
715search API (http://nanoref.com/yahooapis/mgPdGg): 733search API (http://nanoref.com/yahooapis/mgPdGg):
716 734
717 module | encode | decode | 735 module | encode | decode |
718 -----------|------------|------------| 736 -----------|------------|------------|
719 JSON | 254.685 | 37.665 | 737 JSON | 55.260 | 34.971 |
720 JSON::DWIW | 843.343 | 1049.731 | 738 JSON::DWIW | 825.228 | 1082.513 |
721 JSON::PC | 3602.116 | 2307.352 | 739 JSON::PC | 3571.444 | 2394.829 |
740 JSON::PP | 210.987 | 32.574 |
722 JSON::Syck | 505.107 | 787.899 | 741 JSON::Syck | 552.551 | 787.544 |
723 JSON::XS | 5747.196 | 3690.220 | 742 JSON::XS | 5780.463 | 4854.519 |
724 JSON::XS/2 | 3968.121 | 3676.634 | 743 JSON::XS/2 | 3869.998 | 4798.975 |
725 JSON::XS/3 | 6105.246 | 3662.508 | 744 JSON::XS/3 | 5862.880 | 4798.975 |
726 Storable | 4417.337 | 5285.161 | 745 Storable | 4445.002 | 5235.027 |
727 -----------+------------+------------+ 746 -----------+------------+------------+
728 747
729Again, JSON::XS leads by far (except for Storable which non-surprisingly 748Again, JSON::XS leads by far (except for Storable which non-surprisingly
730decodes faster). 749decodes faster).
731 750
… …
748Second, you need to avoid resource-starving attacks. That means you should 767Second, you need to avoid resource-starving attacks. That means you should
749limit the size of JSON texts you accept, or make sure then when your 768limit the size of JSON texts you accept, or make sure then when your
750resources run out, thats just fine (e.g. by using a separate process that 769resources run out, thats just fine (e.g. by using a separate process that
751can crash safely). The size of a JSON text in octets or characters is 770can crash safely). The size of a JSON text in octets or characters is
752usually a good indication of the size of the resources required to decode 771usually a good indication of the size of the resources required to decode
753it into a Perl structure. 772it into a Perl structure. While JSON::XS can check the size of the JSON
773text, it might be too late when you already have it in memory, so you
774might want to check the size before you accept the string.
754 775
755Third, JSON::XS recurses using the C stack when decoding objects and 776Third, JSON::XS recurses using the C stack when decoding objects and
756arrays. The C stack is a limited resource: for instance, on my amd64 777arrays. The C stack is a limited resource: for instance, on my amd64
757machine with 8MB of stack size I can decode around 180k nested arrays but 778machine with 8MB of stack size I can decode around 180k nested arrays but
758only 14k nested JSON objects (due to perl itself recursing deeply on croak 779only 14k nested JSON objects (due to perl itself recursing deeply on croak

Diff Legend

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