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86 | package JSON::XS; |
86 | package JSON::XS; |
87 | |
87 | |
88 | use strict; |
88 | use strict; |
89 | |
89 | |
90 | BEGIN { |
90 | BEGIN { |
91 | our $VERSION = '0.8'; |
91 | our $VERSION = '1.23'; |
92 | our @ISA = qw(Exporter); |
92 | our @ISA = qw(Exporter); |
93 | |
93 | |
94 | our @EXPORT = qw(to_json from_json objToJson jsonToObj); |
94 | our @EXPORT = qw(to_json from_json objToJson jsonToObj); |
95 | require Exporter; |
95 | require Exporter; |
96 | |
96 | |
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128 | $perl_scalar = JSON::XS->new->utf8->decode ($json_text) |
128 | $perl_scalar = JSON::XS->new->utf8->decode ($json_text) |
129 | |
129 | |
130 | except being faster. |
130 | except being faster. |
131 | |
131 | |
132 | =back |
132 | =back |
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133 | |
133 | |
134 | |
134 | =head1 OBJECT-ORIENTED INTERFACE |
135 | =head1 OBJECT-ORIENTED INTERFACE |
135 | |
136 | |
136 | The object oriented interface lets you configure your own encoding or |
137 | The object oriented interface lets you configure your own encoding or |
137 | decoding style, within the limits of supported formats. |
138 | decoding style, within the limits of supported formats. |
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153 | |
154 | |
154 | If C<$enable> is true (or missing), then the C<encode> method will not |
155 | If C<$enable> is true (or missing), then the C<encode> method will not |
155 | generate characters outside the code range C<0..127> (which is ASCII). Any |
156 | generate characters outside the code range C<0..127> (which is ASCII). Any |
156 | unicode characters outside that range will be escaped using either a |
157 | unicode characters outside that range will be escaped using either a |
157 | single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence, |
158 | single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence, |
158 | as per RFC4627. |
159 | as per RFC4627. The resulting encoded JSON text can be treated as a native |
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160 | unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string, |
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161 | or any other superset of ASCII. |
159 | |
162 | |
160 | If C<$enable> is false, then the C<encode> method will not escape Unicode |
163 | If C<$enable> is false, then the C<encode> method will not escape Unicode |
161 | characters unless required by the JSON syntax. This results in a faster |
164 | characters unless required by the JSON syntax or other flags. This results |
162 | and more compact format. |
165 | in a faster and more compact format. |
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166 | |
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167 | The main use for this flag is to produce JSON texts that can be |
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168 | transmitted over a 7-bit channel, as the encoded JSON texts will not |
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169 | contain any 8 bit characters. |
163 | |
170 | |
164 | JSON::XS->new->ascii (1)->encode ([chr 0x10401]) |
171 | JSON::XS->new->ascii (1)->encode ([chr 0x10401]) |
165 | => ["\ud801\udc01"] |
172 | => ["\ud801\udc01"] |
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173 | |
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174 | =item $json = $json->latin1 ([$enable]) |
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175 | |
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176 | If C<$enable> is true (or missing), then the C<encode> method will encode |
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177 | the resulting JSON text as latin1 (or iso-8859-1), escaping any characters |
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178 | outside the code range C<0..255>. The resulting string can be treated as a |
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179 | latin1-encoded JSON text or a native unicode string. The C<decode> method |
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180 | will not be affected in any way by this flag, as C<decode> by default |
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181 | expects unicode, which is a strict superset of latin1. |
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182 | |
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183 | If C<$enable> is false, then the C<encode> method will not escape Unicode |
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184 | characters unless required by the JSON syntax or other flags. |
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185 | |
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186 | The main use for this flag is efficiently encoding binary data as JSON |
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187 | text, as most octets will not be escaped, resulting in a smaller encoded |
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188 | size. The disadvantage is that the resulting JSON text is encoded |
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189 | in latin1 (and must correctly be treated as such when storing and |
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190 | transfering), a rare encoding for JSON. It is therefore most useful when |
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191 | you want to store data structures known to contain binary data efficiently |
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192 | in files or databases, not when talking to other JSON encoders/decoders. |
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193 | |
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194 | JSON::XS->new->latin1->encode (["\x{89}\x{abc}"] |
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195 | => ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not) |
166 | |
196 | |
167 | =item $json = $json->utf8 ([$enable]) |
197 | =item $json = $json->utf8 ([$enable]) |
168 | |
198 | |
169 | If C<$enable> is true (or missing), then the C<encode> method will encode |
199 | If C<$enable> is true (or missing), then the C<encode> method will encode |
170 | the JSON result into UTF-8, as required by many protocols, while the |
200 | the JSON result into UTF-8, as required by many protocols, while the |
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283 | => "Hello, World!" |
313 | => "Hello, World!" |
284 | |
314 | |
285 | =item $json = $json->shrink ([$enable]) |
315 | =item $json = $json->shrink ([$enable]) |
286 | |
316 | |
287 | Perl usually over-allocates memory a bit when allocating space for |
317 | Perl usually over-allocates memory a bit when allocating space for |
288 | strings. This flag optionally resizes strings generated by either |
318 | strings. This flag optionally resizes strings generated by either |
289 | C<encode> or C<decode> to their minimum size possible. This can save |
319 | C<encode> or C<decode> to their minimum size possible. This can save |
290 | memory when your JSON texts are either very very long or you have many |
320 | memory when your JSON texts are either very very long or you have many |
291 | short strings. It will also try to downgrade any strings to octet-form |
321 | short strings. It will also try to downgrade any strings to octet-form |
292 | if possible: perl stores strings internally either in an encoding called |
322 | if possible: perl stores strings internally either in an encoding called |
293 | UTF-X or in octet-form. The latter cannot store everything but uses less |
323 | UTF-X or in octet-form. The latter cannot store everything but uses less |
294 | space in general. |
324 | space in general (and some buggy Perl or C code might even rely on that |
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325 | internal representation being used). |
295 | |
326 | |
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327 | The actual definition of what shrink does might change in future versions, |
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328 | but it will always try to save space at the expense of time. |
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329 | |
296 | If C<$enable> is true (or missing), the string returned by C<encode> will be shrunk-to-fit, |
330 | If C<$enable> is true (or missing), the string returned by C<encode> will |
297 | while all strings generated by C<decode> will also be shrunk-to-fit. |
331 | be shrunk-to-fit, while all strings generated by C<decode> will also be |
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332 | shrunk-to-fit. |
298 | |
333 | |
299 | If C<$enable> is false, then the normal perl allocation algorithms are used. |
334 | If C<$enable> is false, then the normal perl allocation algorithms are used. |
300 | If you work with your data, then this is likely to be faster. |
335 | If you work with your data, then this is likely to be faster. |
301 | |
336 | |
302 | In the future, this setting might control other things, such as converting |
337 | In the future, this setting might control other things, such as converting |
303 | strings that look like integers or floats into integers or floats |
338 | strings that look like integers or floats into integers or floats |
304 | internally (there is no difference on the Perl level), saving space. |
339 | internally (there is no difference on the Perl level), saving space. |
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340 | |
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341 | =item $json = $json->max_depth ([$maximum_nesting_depth]) |
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342 | |
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343 | Sets the maximum nesting level (default C<512>) accepted while encoding |
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344 | or decoding. If the JSON text or Perl data structure has an equal or |
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345 | higher nesting level then this limit, then the encoder and decoder will |
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346 | stop and croak at that point. |
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347 | |
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348 | Nesting level is defined by number of hash- or arrayrefs that the encoder |
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349 | needs to traverse to reach a given point or the number of C<{> or C<[> |
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350 | characters without their matching closing parenthesis crossed to reach a |
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351 | given character in a string. |
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352 | |
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353 | Setting the maximum depth to one disallows any nesting, so that ensures |
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354 | that the object is only a single hash/object or array. |
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355 | |
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356 | The argument to C<max_depth> will be rounded up to the next nearest power |
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357 | of two. |
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358 | |
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359 | See SECURITY CONSIDERATIONS, below, for more info on why this is useful. |
305 | |
360 | |
306 | =item $json_text = $json->encode ($perl_scalar) |
361 | =item $json_text = $json->encode ($perl_scalar) |
307 | |
362 | |
308 | Converts the given Perl data structure (a simple scalar or a reference |
363 | Converts the given Perl data structure (a simple scalar or a reference |
309 | to a hash or array) to its JSON representation. Simple scalars will be |
364 | to a hash or array) to its JSON representation. Simple scalars will be |
… | |
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319 | |
374 | |
320 | JSON numbers and strings become simple Perl scalars. JSON arrays become |
375 | JSON numbers and strings become simple Perl scalars. JSON arrays become |
321 | Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes |
376 | Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes |
322 | C<1>, C<false> becomes C<0> and C<null> becomes C<undef>. |
377 | C<1>, C<false> becomes C<0> and C<null> becomes C<undef>. |
323 | |
378 | |
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379 | =item ($perl_scalar, $characters) = $json->decode_prefix ($json_text) |
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380 | |
|
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381 | This works like the C<decode> method, but instead of raising an exception |
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382 | when there is trailing garbage after the first JSON object, it will |
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383 | silently stop parsing there and return the number of characters consumed |
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384 | so far. |
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385 | |
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386 | This is useful if your JSON texts are not delimited by an outer protocol |
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387 | (which is not the brightest thing to do in the first place) and you need |
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388 | to know where the JSON text ends. |
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389 | |
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390 | JSON::XS->new->decode_prefix ("[1] the tail") |
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391 | => ([], 3) |
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392 | |
324 | =back |
393 | =back |
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394 | |
325 | |
395 | |
326 | =head1 MAPPING |
396 | =head1 MAPPING |
327 | |
397 | |
328 | This section describes how JSON::XS maps Perl values to JSON values and |
398 | This section describes how JSON::XS maps Perl values to JSON values and |
329 | vice versa. These mappings are designed to "do the right thing" in most |
399 | vice versa. These mappings are designed to "do the right thing" in most |
… | |
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383 | =over 4 |
453 | =over 4 |
384 | |
454 | |
385 | =item hash references |
455 | =item hash references |
386 | |
456 | |
387 | Perl hash references become JSON objects. As there is no inherent ordering |
457 | Perl hash references become JSON objects. As there is no inherent ordering |
388 | in hash keys, they will usually be encoded in a pseudo-random order that |
458 | in hash keys (or JSON objects), they will usually be encoded in a |
389 | can change between runs of the same program but stays generally the same |
459 | pseudo-random order that can change between runs of the same program but |
390 | within a single run of a program. JSON::XS can optionally sort the hash |
460 | stays generally the same within a single run of a program. JSON::XS can |
391 | keys (determined by the I<canonical> flag), so the same datastructure |
461 | optionally sort the hash keys (determined by the I<canonical> flag), so |
392 | will serialise to the same JSON text (given same settings and version of |
462 | the same datastructure will serialise to the same JSON text (given same |
393 | JSON::XS), but this incurs a runtime overhead. |
463 | settings and version of JSON::XS), but this incurs a runtime overhead |
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464 | and is only rarely useful, e.g. when you want to compare some JSON text |
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465 | against another for equality. |
394 | |
466 | |
395 | =item array references |
467 | =item array references |
396 | |
468 | |
397 | Perl array references become JSON arrays. |
469 | Perl array references become JSON arrays. |
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470 | |
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471 | =item other references |
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472 | |
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473 | Other unblessed references are generally not allowed and will cause an |
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474 | exception to be thrown, except for references to the integers C<0> and |
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475 | C<1>, which get turned into C<false> and C<true> atoms in JSON. You can |
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476 | also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability. |
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477 | |
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478 | to_json [\0,JSON::XS::true] # yields [false,true] |
398 | |
479 | |
399 | =item blessed objects |
480 | =item blessed objects |
400 | |
481 | |
401 | Blessed objects are not allowed. JSON::XS currently tries to encode their |
482 | Blessed objects are not allowed. JSON::XS currently tries to encode their |
402 | underlying representation (hash- or arrayref), but this behaviour might |
483 | underlying representation (hash- or arrayref), but this behaviour might |
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435 | $x *= 1; # same thing, the choise is yours. |
516 | $x *= 1; # same thing, the choise is yours. |
436 | |
517 | |
437 | You can not currently output JSON booleans or force the type in other, |
518 | You can not currently output JSON booleans or force the type in other, |
438 | less obscure, ways. Tell me if you need this capability. |
519 | less obscure, ways. Tell me if you need this capability. |
439 | |
520 | |
440 | =item circular data structures |
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441 | |
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442 | Those will be encoded until memory or stackspace runs out. |
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443 | |
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444 | =back |
521 | =back |
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522 | |
445 | |
523 | |
446 | =head1 COMPARISON |
524 | =head1 COMPARISON |
447 | |
525 | |
448 | As already mentioned, this module was created because none of the existing |
526 | As already mentioned, this module was created because none of the existing |
449 | JSON modules could be made to work correctly. First I will describe the |
527 | JSON modules could be made to work correctly. First I will describe the |
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534 | It seems that JSON::XS is surprisingly fast, as shown in the following |
612 | It seems that JSON::XS is surprisingly fast, as shown in the following |
535 | tables. They have been generated with the help of the C<eg/bench> program |
613 | tables. They have been generated with the help of the C<eg/bench> program |
536 | in the JSON::XS distribution, to make it easy to compare on your own |
614 | in the JSON::XS distribution, to make it easy to compare on your own |
537 | system. |
615 | system. |
538 | |
616 | |
539 | First comes a comparison between various modules using a very short JSON |
617 | First comes a comparison between various modules using a very short |
540 | string: |
618 | single-line JSON string: |
541 | |
619 | |
542 | {"method": "handleMessage", "params": ["user1", "we were just talking"], "id": null} |
620 | {"method": "handleMessage", "params": ["user1", "we were just talking"], \ |
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|
621 | "id": null, "array":[1,11,234,-5,1e5,1e7, true, false]} |
543 | |
622 | |
544 | It shows the number of encodes/decodes per second (JSON::XS uses the |
623 | It shows the number of encodes/decodes per second (JSON::XS uses the |
545 | functional interface, while JSON::XS/2 uses the OO interface with |
624 | functional interface, while JSON::XS/2 uses the OO interface with |
546 | pretty-printing and hashkey sorting enabled). Higher is better: |
625 | pretty-printing and hashkey sorting enabled). Higher is better: |
547 | |
626 | |
548 | module | encode | decode | |
627 | module | encode | decode | |
549 | -----------|------------|------------| |
628 | -----------|------------|------------| |
550 | JSON | 11488.516 | 7823.035 | |
629 | JSON | 7645.468 | 4208.613 | |
551 | JSON::DWIW | 94708.054 | 129094.260 | |
630 | JSON::DWIW | 68534.379 | 79437.576 | |
552 | JSON::PC | 63884.157 | 128528.212 | |
631 | JSON::PC | 65948.176 | 78251.940 | |
553 | JSON::Syck | 34898.677 | 42096.911 | |
632 | JSON::Syck | 23379.621 | 28416.694 | |
554 | JSON::XS | 654027.064 | 396423.669 | |
633 | JSON::XS | 388361.481 | 199728.762 | |
555 | JSON::XS/2 | 371564.190 | 371725.613 | |
634 | JSON::XS/2 | 218453.333 | 192399.266 | |
|
|
635 | JSON::XS/3 | 338250.323 | 192399.266 | |
|
|
636 | Storable | 15732.573 | 28571.553 | |
556 | -----------+------------+------------+ |
637 | -----------+------------+------------+ |
557 | |
638 | |
558 | That is, JSON::XS is more than six times faster than JSON::DWIW on |
639 | That is, JSON::XS is about five times faster than JSON::DWIW on encoding, |
559 | encoding, more than three times faster on decoding, and about thirty times |
640 | about three times faster on decoding, and over fourty times faster |
560 | faster than JSON, even with pretty-printing and key sorting. |
641 | than JSON, even with pretty-printing and key sorting. It also compares |
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642 | favourably to Storable for small amounts of data. |
561 | |
643 | |
562 | Using a longer test string (roughly 18KB, generated from Yahoo! Locals |
644 | Using a longer test string (roughly 18KB, generated from Yahoo! Locals |
563 | search API (http://nanoref.com/yahooapis/mgPdGg): |
645 | search API (http://nanoref.com/yahooapis/mgPdGg): |
564 | |
646 | |
565 | module | encode | decode | |
647 | module | encode | decode | |
566 | -----------|------------|------------| |
648 | -----------|------------|------------| |
567 | JSON | 273.023 | 44.674 | |
649 | JSON | 254.685 | 37.665 | |
568 | JSON::DWIW | 1089.383 | 1145.704 | |
650 | JSON::DWIW | 1014.244 | 1087.678 | |
569 | JSON::PC | 3097.419 | 2393.921 | |
651 | JSON::PC | 3602.116 | 2307.352 | |
570 | JSON::Syck | 514.060 | 843.053 | |
652 | JSON::Syck | 558.035 | 776.263 | |
571 | JSON::XS | 6479.668 | 3636.364 | |
653 | JSON::XS | 5747.196 | 3543.684 | |
572 | JSON::XS/2 | 3774.221 | 3599.124 | |
654 | JSON::XS/2 | 3968.121 | 3589.170 | |
|
|
655 | JSON::XS/3 | 6105.246 | 3561.134 | |
|
|
656 | Storable | 4456.337 | 5320.020 | |
573 | -----------+------------+------------+ |
657 | -----------+------------+------------+ |
574 | |
658 | |
575 | Again, JSON::XS leads by far. |
659 | Again, JSON::XS leads by far. |
576 | |
660 | |
577 | On large strings containing lots of high unicode characters, some modules |
661 | On large strings containing lots of high unicode characters, some modules |
578 | (such as JSON::PC) seem to decode faster than JSON::XS, but the result |
662 | (such as JSON::PC) seem to decode faster than JSON::XS, but the result |
579 | will be broken due to missing (or wrong) unicode handling. Others refuse |
663 | will be broken due to missing (or wrong) unicode handling. Others refuse |
580 | to decode or encode properly, so it was impossible to prepare a fair |
664 | to decode or encode properly, so it was impossible to prepare a fair |
581 | comparison table for that case. |
665 | comparison table for that case. |
582 | |
666 | |
583 | =head1 RESOURCE LIMITS |
|
|
584 | |
667 | |
585 | JSON::XS does not impose any limits on the size of JSON texts or Perl |
668 | =head1 SECURITY CONSIDERATIONS |
586 | values they represent - if your machine can handle it, JSON::XS will |
669 | |
587 | encode or decode it. Future versions might optionally impose structure |
670 | When you are using JSON in a protocol, talking to untrusted potentially |
588 | depth and memory use resource limits. |
671 | hostile creatures requires relatively few measures. |
|
|
672 | |
|
|
673 | First of all, your JSON decoder should be secure, that is, should not have |
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674 | any buffer overflows. Obviously, this module should ensure that and I am |
|
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675 | trying hard on making that true, but you never know. |
|
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676 | |
|
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677 | Second, you need to avoid resource-starving attacks. That means you should |
|
|
678 | limit the size of JSON texts you accept, or make sure then when your |
|
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679 | resources run out, thats just fine (e.g. by using a separate process that |
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680 | can crash safely). The size of a JSON text in octets or characters is |
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681 | usually a good indication of the size of the resources required to decode |
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|
682 | it into a Perl structure. |
|
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683 | |
|
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684 | Third, JSON::XS recurses using the C stack when decoding objects and |
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685 | arrays. The C stack is a limited resource: for instance, on my amd64 |
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686 | machine with 8MB of stack size I can decode around 180k nested arrays but |
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687 | only 14k nested JSON objects (due to perl itself recursing deeply on croak |
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688 | to free the temporary). If that is exceeded, the program crashes. to be |
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689 | conservative, the default nesting limit is set to 512. If your process |
|
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690 | has a smaller stack, you should adjust this setting accordingly with the |
|
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691 | C<max_depth> method. |
|
|
692 | |
|
|
693 | And last but least, something else could bomb you that I forgot to think |
|
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694 | of. In that case, you get to keep the pieces. I am always open for hints, |
|
|
695 | though... |
|
|
696 | |
589 | |
697 | |
590 | =head1 BUGS |
698 | =head1 BUGS |
591 | |
699 | |
592 | While the goal of this module is to be correct, that unfortunately does |
700 | While the goal of this module is to be correct, that unfortunately does |
593 | not mean its bug-free, only that I think its design is bug-free. It is |
701 | not mean its bug-free, only that I think its design is bug-free. It is |
594 | still very young and not well-tested. If you keep reporting bugs they will |
702 | still relatively early in its development. If you keep reporting bugs they |
595 | be fixed swiftly, though. |
703 | will be fixed swiftly, though. |
596 | |
704 | |
597 | =cut |
705 | =cut |
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|
706 | |
|
|
707 | sub true() { \1 } |
|
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708 | sub false() { \0 } |
598 | |
709 | |
599 | 1; |
710 | 1; |
600 | |
711 | |
601 | =head1 AUTHOR |
712 | =head1 AUTHOR |
602 | |
713 | |