Test-Refcount-0.10000755001750001750 013504644514 12663 5ustar00leoleo000000000000Test-Refcount-0.10/Build.PL000444001750001750 117213504644514 14315 0ustar00leoleo000000000000use strict; use warnings; use Module::Build; my $build = Module::Build->new( module_name => 'Test::Refcount', requires => { 'B' => 0, 'Scalar::Util' => 0, 'Test::Builder' => 0, }, recommends => { 'Devel::MAT' => '0.04', }, configure_requires => { 'Module::Build' => '0.4004', # test_requires }, test_requires => { 'Test::Builder::Tester' => 0, 'Test::More' => '0.88', # done_testing }, license => 'perl', create_license => 1, create_readme => 1, extra_manify_args => { utf8 => 1, # We have UTF-8 manpages }, ); $build->create_build_script; Test-Refcount-0.10/Changes000444001750001750 330413504644514 14313 0ustar00leoleo000000000000Revision history for Test-Refcount 0.10 2019-06-26 11:28:13 [BUGFIXES] * Fix unit tests to handle when both Devel::MAT and Devel::FindRef are available (RT129908) (No module code changes, purely tests) 0.09 2019-06-25 21:06:57 [CHANGES] * Add a `refcount()` function that callers can use to build refcount-preserving tests * Adjust docs to explain more about the Devel::MAT use-case * General build file style updates 0.08 2014/03/27 16:10:38 [CHANGES] * Optional integration with Devel::MAT if available, to heapdump the running unit test for later analysis 0.07 CHANGES: * Use pureperl core B module rather than Devel::Refcount, for avoiding XS in the deptree of a Test module 0.06 CHANGES: * Optionally use Devel::FindRef but don't depend on it being installed. Removes the need to install it on smoke testers and have it fail. 0.05 CHANGES: * Added 'use warnings' * Various small updates to keep CPANTS happy 0.04 BUGFIXES: * Skip regexp count tests on perl 5.11 because of ongoing issue with refcounts there. 0.03 BUGFIXES: * Updated regexps in test code to account for change in Devel::FindRef's output format at version 1.4 (fixes http://rt.cpan.org/Public/Bug/Display.html?id=41487) 0.02 CHANGES: * Use Devel::FindRef to print a trace of references if the assert fails. * Much extended documentation, showing a likely use case and example of broken code. 0.01 First version, released on an unsuspecting world. Test-Refcount-0.10/LICENSE000444001750001750 4376213504644514 14061 0ustar00leoleo000000000000This software is copyright (c) 2019 by Paul Evans . This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself. Terms of the Perl programming language system itself a) the GNU General Public License as published by the Free Software Foundation; either version 1, or (at your option) any later version, or b) the "Artistic License" --- The GNU General Public License, Version 1, February 1989 --- This software is Copyright (c) 2019 by Paul Evans . This is free software, licensed under: The GNU General Public License, Version 1, February 1989 GNU GENERAL PUBLIC LICENSE Version 1, February 1989 Copyright (C) 1989 Free Software Foundation, Inc. 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. Preamble The license agreements of most software companies try to keep users at the mercy of those companies. By contrast, our General Public License is intended to guarantee your freedom to share and change free software--to make sure the software is free for all its users. The General Public License applies to the Free Software Foundation's software and to any other program whose authors commit to using it. You can use it for your programs, too. When we speak of free software, we are referring to freedom, not price. Specifically, the General Public License is designed to make sure that you have the freedom to give away or sell copies of free software, that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs; and that you know you can do these things. To protect your rights, we need to make restrictions that forbid anyone to deny you these rights or to ask you to surrender the rights. These restrictions translate to certain responsibilities for you if you distribute copies of the software, or if you modify it. For example, if you distribute copies of a such a program, whether gratis or for a fee, you must give the recipients all the rights that you have. You must make sure that they, too, receive or can get the source code. And you must tell them their rights. We protect your rights with two steps: (1) copyright the software, and (2) offer you this license which gives you legal permission to copy, distribute and/or modify the software. Also, for each author's protection and ours, we want to make certain that everyone understands that there is no warranty for this free software. If the software is modified by someone else and passed on, we want its recipients to know that what they have is not the original, so that any problems introduced by others will not reflect on the original authors' reputations. The precise terms and conditions for copying, distribution and modification follow. GNU GENERAL PUBLIC LICENSE TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION 0. This License Agreement applies to any program or other work which contains a notice placed by the copyright holder saying it may be distributed under the terms of this General Public License. The "Program", below, refers to any such program or work, and a "work based on the Program" means either the Program or any work containing the Program or a portion of it, either verbatim or with modifications. Each licensee is addressed as "you". 1. You may copy and distribute verbatim copies of the Program's source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice and disclaimer of warranty; keep intact all the notices that refer to this General Public License and to the absence of any warranty; and give any other recipients of the Program a copy of this General Public License along with the Program. You may charge a fee for the physical act of transferring a copy. 2. You may modify your copy or copies of the Program or any portion of it, and copy and distribute such modifications under the terms of Paragraph 1 above, provided that you also do the following: a) cause the modified files to carry prominent notices stating that you changed the files and the date of any change; and b) cause the whole of any work that you distribute or publish, that in whole or in part contains the Program or any part thereof, either with or without modifications, to be licensed at no charge to all third parties under the terms of this General Public License (except that you may choose to grant warranty protection to some or all third parties, at your option). c) If the modified program normally reads commands interactively when run, you must cause it, when started running for such interactive use in the simplest and most usual way, to print or display an announcement including an appropriate copyright notice and a notice that there is no warranty (or else, saying that you provide a warranty) and that users may redistribute the program under these conditions, and telling the user how to view a copy of this General Public License. d) You may charge a fee for the physical act of transferring a copy, and you may at your option offer warranty protection in exchange for a fee. Mere aggregation of another independent work with the Program (or its derivative) on a volume of a storage or distribution medium does not bring the other work under the scope of these terms. 3. You may copy and distribute the Program (or a portion or derivative of it, under Paragraph 2) in object code or executable form under the terms of Paragraphs 1 and 2 above provided that you also do one of the following: a) accompany it with the complete corresponding machine-readable source code, which must be distributed under the terms of Paragraphs 1 and 2 above; or, b) accompany it with a written offer, valid for at least three years, to give any third party free (except for a nominal charge for the cost of distribution) a complete machine-readable copy of the corresponding source code, to be distributed under the terms of Paragraphs 1 and 2 above; or, c) accompany it with the information you received as to where the corresponding source code may be obtained. (This alternative is allowed only for noncommercial distribution and only if you received the program in object code or executable form alone.) Source code for a work means the preferred form of the work for making modifications to it. For an executable file, complete source code means all the source code for all modules it contains; but, as a special exception, it need not include source code for modules which are standard libraries that accompany the operating system on which the executable file runs, or for standard header files or definitions files that accompany that operating system. 4. You may not copy, modify, sublicense, distribute or transfer the Program except as expressly provided under this General Public License. Any attempt otherwise to copy, modify, sublicense, distribute or transfer the Program is void, and will automatically terminate your rights to use the Program under this License. However, parties who have received copies, or rights to use copies, from you under this General Public License will not have their licenses terminated so long as such parties remain in full compliance. 5. By copying, distributing or modifying the Program (or any work based on the Program) you indicate your acceptance of this license to do so, and all its terms and conditions. 6. Each time you redistribute the Program (or any work based on the Program), the recipient automatically receives a license from the original licensor to copy, distribute or modify the Program subject to these terms and conditions. You may not impose any further restrictions on the recipients' exercise of the rights granted herein. 7. The Free Software Foundation may publish revised and/or new versions of the General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. Each version is given a distinguishing version number. If the Program specifies a version number of the license which applies to it and "any later version", you have the option of following the terms and conditions either of that version or of any later version published by the Free Software Foundation. If the Program does not specify a version number of the license, you may choose any version ever published by the Free Software Foundation. 8. If you wish to incorporate parts of the Program into other free programs whose distribution conditions are different, write to the author to ask for permission. For software which is copyrighted by the Free Software Foundation, write to the Free Software Foundation; we sometimes make exceptions for this. Our decision will be guided by the two goals of preserving the free status of all derivatives of our free software and of promoting the sharing and reuse of software generally. NO WARRANTY 9. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION. 10. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. END OF TERMS AND CONDITIONS Appendix: How to Apply These Terms to Your New Programs If you develop a new program, and you want it to be of the greatest possible use to humanity, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms. To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively convey the exclusion of warranty; and each file should have at least the "copyright" line and a pointer to where the full notice is found. Copyright (C) 19yy This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 1, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA Also add information on how to contact you by electronic and paper mail. If the program is interactive, make it output a short notice like this when it starts in an interactive mode: Gnomovision version 69, Copyright (C) 19xx name of author Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'. This is free software, and you are welcome to redistribute it under certain conditions; type `show c' for details. The hypothetical commands `show w' and `show c' should show the appropriate parts of the General Public License. Of course, the commands you use may be called something other than `show w' and `show c'; they could even be mouse-clicks or menu items--whatever suits your program. You should also get your employer (if you work as a programmer) or your school, if any, to sign a "copyright disclaimer" for the program, if necessary. Here a sample; alter the names: Yoyodyne, Inc., hereby disclaims all copyright interest in the program `Gnomovision' (a program to direct compilers to make passes at assemblers) written by James Hacker. , 1 April 1989 Ty Coon, President of Vice That's all there is to it! --- The Artistic License 1.0 --- This software is Copyright (c) 2019 by Paul Evans . This is free software, licensed under: The Artistic License 1.0 The Artistic License Preamble The intent of this document is to state the conditions under which a Package may be copied, such that the Copyright Holder maintains some semblance of artistic control over the development of the package, while giving the users of the package the right to use and distribute the Package in a more-or-less customary fashion, plus the right to make reasonable modifications. Definitions: - "Package" refers to the collection of files distributed by the Copyright Holder, and derivatives of that collection of files created through textual modification. - "Standard Version" refers to such a Package if it has not been modified, or has been modified in accordance with the wishes of the Copyright Holder. - "Copyright Holder" is whoever is named in the copyright or copyrights for the package. - "You" is you, if you're thinking about copying or distributing this Package. - "Reasonable copying fee" is whatever you can justify on the basis of media cost, duplication charges, time of people involved, and so on. (You will not be required to justify it to the Copyright Holder, but only to the computing community at large as a market that must bear the fee.) - "Freely Available" means that no fee is charged for the item itself, though there may be fees involved in handling the item. It also means that recipients of the item may redistribute it under the same conditions they received it. 1. You may make and give away verbatim copies of the source form of the Standard Version of this Package without restriction, provided that you duplicate all of the original copyright notices and associated disclaimers. 2. You may apply bug fixes, portability fixes and other modifications derived from the Public Domain or from the Copyright Holder. A Package modified in such a way shall still be considered the Standard Version. 3. You may otherwise modify your copy of this Package in any way, provided that you insert a prominent notice in each changed file stating how and when you changed that file, and provided that you do at least ONE of the following: a) place your modifications in the Public Domain or otherwise make them Freely Available, such as by posting said modifications to Usenet or an equivalent medium, or placing the modifications on a major archive site such as ftp.uu.net, or by allowing the Copyright Holder to include your modifications in the Standard Version of the Package. b) use the modified Package only within your corporation or organization. c) rename any non-standard executables so the names do not conflict with standard executables, which must also be provided, and provide a separate manual page for each non-standard executable that clearly documents how it differs from the Standard Version. d) make other distribution arrangements with the Copyright Holder. 4. You may distribute the programs of this Package in object code or executable form, provided that you do at least ONE of the following: a) distribute a Standard Version of the executables and library files, together with instructions (in the manual page or equivalent) on where to get the Standard Version. b) accompany the distribution with the machine-readable source of the Package with your modifications. c) accompany any non-standard executables with their corresponding Standard Version executables, giving the non-standard executables non-standard names, and clearly documenting the differences in manual pages (or equivalent), together with instructions on where to get the Standard Version. d) make other distribution arrangements with the Copyright Holder. 5. You may charge a reasonable copying fee for any distribution of this Package. You may charge any fee you choose for support of this Package. You may not charge a fee for this Package itself. However, you may distribute this Package in aggregate with other (possibly commercial) programs as part of a larger (possibly commercial) software distribution provided that you do not advertise this Package as a product of your own. 6. The scripts and library files supplied as input to or produced as output from the programs of this Package do not automatically fall under the copyright of this Package, but belong to whomever generated them, and may be sold commercially, and may be aggregated with this Package. 7. C or perl subroutines supplied by you and linked into this Package shall not be considered part of this Package. 8. The name of the Copyright Holder may not be used to endorse or promote products derived from this software without specific prior written permission. 9. THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. The End Test-Refcount-0.10/MANIFEST000444001750001750 25213504644514 14130 0ustar00leoleo000000000000Build.PL Changes lib/Test/Refcount.pm LICENSE MANIFEST This list of files META.json META.yml README t/00use.t t/01count.t t/02one.t t/03weak.t t/04reftypes.t t/99pod.t Test-Refcount-0.10/META.json000444001750001750 226313504644514 14444 0ustar00leoleo000000000000{ "abstract" : "assert reference counts on objects", "author" : [ "Paul Evans " ], "dynamic_config" : 1, "generated_by" : "Module::Build version 0.4224", "license" : [ "perl_5" ], "meta-spec" : { "url" : "http://search.cpan.org/perldoc?CPAN::Meta::Spec", "version" : 2 }, "name" : "Test-Refcount", "prereqs" : { "configure" : { "requires" : { "Module::Build" : "0.4004" } }, "runtime" : { "recommends" : { "Devel::MAT" : "0.04" }, "requires" : { "B" : "0", "Scalar::Util" : "0", "Test::Builder" : "0" } }, "test" : { "requires" : { "Test::Builder::Tester" : "0", "Test::More" : "0.88" } } }, "provides" : { "Test::Refcount" : { "file" : "lib/Test/Refcount.pm", "version" : "0.10" } }, "release_status" : "stable", "resources" : { "license" : [ "http://dev.perl.org/licenses/" ] }, "version" : "0.10", "x_serialization_backend" : "JSON::PP version 4.00" } Test-Refcount-0.10/META.yml000444001750001750 134313504644514 14272 0ustar00leoleo000000000000--- abstract: 'assert reference counts on objects' author: - 'Paul Evans ' build_requires: Test::Builder::Tester: '0' Test::More: '0.88' configure_requires: Module::Build: '0.4004' dynamic_config: 1 generated_by: 'Module::Build version 0.4224, CPAN::Meta::Converter version 2.150010' license: perl meta-spec: url: http://module-build.sourceforge.net/META-spec-v1.4.html version: '1.4' name: Test-Refcount provides: Test::Refcount: file: lib/Test/Refcount.pm version: '0.10' recommends: Devel::MAT: '0.04' requires: B: '0' Scalar::Util: '0' Test::Builder: '0' resources: license: http://dev.perl.org/licenses/ version: '0.10' x_serialization_backend: 'CPAN::Meta::YAML version 0.018' Test-Refcount-0.10/README000444001750001750 2013313504644514 13717 0ustar00leoleo000000000000NAME Test::Refcount - assert reference counts on objects SYNOPSIS use Test::More tests => 2; use Test::Refcount; use Some::Class; my $object = Some::Class->new(); is_oneref( $object, '$object has a refcount of 1' ); my $otherref = $object; is_refcount( $object, 2, '$object now has 2 references' ); DESCRIPTION The Perl garbage collector uses simple reference counting during the normal execution of a program. This means that cycles or unweakened references in other parts of code can keep an object around for longer than intended. To help avoid this problem, the reference count of a new object from its class constructor ought to be 1. This way, the caller can know the object will be properly DESTROYed when it drops all of its references to it. This module provides two test functions to help ensure this property holds for an object class, so as to be polite to its callers. If the assertion fails; that is, if the actual reference count is different to what was expected, either of the following two modules may be used to assist the developer in finding where the references are. * If Devel::MAT is installed, this test module will use it to dump the state of the memory after a failure. It will create a .pmat file named the same as the unit test, but with the trailing .t suffix replaced with -TEST.pmat where TEST is the number of the test that failed (in case there was more than one). * If Devel::FindRef module is installed, a reverse-references trace is printed to the test output. See the examples below for more information. FUNCTIONS is_refcount is_refcount( $object, $count, $name ) Test that $object has $count references to it. is_oneref is_oneref( $object, $name ) Assert that the $object has only 1 reference to it. refcount $count = refcount( $object ) Since version 0.09. Returns the reference count of the given object as used by the test functions. This is useful for making tests that don't care what the count is before they start, but simply assert that the count hasn't changed by the end. use Test::Refcount import => [qw( is_refcount refcount )]; { my $count = refcount( $object ); do_something( $object ); is_refcount( $object, $count, 'do_something() preserves refcount' ); } EXAMPLE Suppose, having written a new class MyBall, you now want to check that its constructor and methods are well-behaved, and don't leak references. Consider the following test script: use Test::More tests => 2; use Test::Refcount; use MyBall; my $ball = MyBall->new(); is_oneref( $ball, 'One reference after construct' ); $ball->bounce; # Any other code here that might be part of the test script is_oneref( $ball, 'One reference just before EOF' ); The first assertion is just after the constructor, to check that the reference returned by it is the only reference to that object. This fact is important if we ever want DESTROY to behave properly. The second call is right at the end of the file, just before the main scope closes. At this stage we expect the reference count also to be one, so that the object is properly cleaned up. Suppose, when run, this produces the following output (presuming Devel::MAT::Dumper is available): 1..2 ok 1 - One reference after construct not ok 2 - One reference just before EOF # Failed test 'One reference just before EOF' # at ex.pl line 26. # expected 1 references, found 2 # SV address is 0x55e14c310278 # Writing heap dump to ex-2.pmat # Looks like you failed 1 test of 2. This has written a ex-2.pmat file we can load using the pmat shell and use the identify command on the given address to find where it went: $ pmat ex-2.pmat Perl memory dumpfile from perl 5.28.1 threaded Heap contains 25233 objects pmat> identify 0x55e14c310278 HASH(0)=MyBall at 0x55e14c310278 is: ├─(via RV) the lexical $ball at depth 1 of CODE() at 0x55e14c3104a0=main_cv, which is: │ └─the main code └─(via RV) value {self} of HASH(2) at 0x55e14cacb860, which is (*A): └─(via RV) value {cycle} of HASH(2) at 0x55e14cacb860, which is: itself (This document isn't intended to be a full tutorial on Devel::MAT and the pmat shell; for that see Devel::MAT::UserGuide). Alternatively, this produces the following output when using Devel::FindRef instead: 1..2 ok 1 - One reference after construct not ok 2 - One reference just before EOF # Failed test 'One reference just before EOF' # at demo.pl line 16. # expected 1 references, found 2 # MyBall=ARRAY(0x817f880) is # +- referenced by REF(0x82c1fd8), which is # | in the member 'self' of HASH(0x82c1f68), which is # | referenced by REF(0x81989d0), which is # | in the member 'cycle' of HASH(0x82c1f68), which was seen before. # +- referenced by REF(0x82811d0), which is # in the lexical '$ball' in CODE(0x817fa00), which is # the main body of the program. # Looks like you failed 1 test of 2. From this output, we can see that the constructor was well-behaved, but that a reference was leaked by the end of the script - the reference count was 2, when we expected just 1. Reading the trace output, we can see that there were 2 references that could be found - one stored in the $ball lexical in the main program, and one stored in a HASH. Since we expected to find the $ball lexical variable, we know we are now looking for a leak in a hash somewhere in the code. From reading the test script, we can guess this leak is likely to be in the bounce() method. Furthermore, we know that the reference to the object will be stored in a HASH in a member called self. By reading the code which implements the bounce() method, we can see this is indeed the case: sub bounce { my $self = shift; my $cycle = { self => $self }; $cycle->{cycle} = $cycle; } From reading the tracing output, we find that the HASH this object is referenced in also contains a reference to itself, in a member called cycle. This comes from the last line in this function, a line that purposely created a cycle, to demonstrate the point. While a real program probably wouldn't do anything quite this obvious, the trace would still be useful in finding the likely cause of the leak. If neither Devel::MAT::Dumper nor Devel::FindRef are available, then these detailed traces will not be produced. The basic reference count testing will still take place, but a smaller message will be produced: 1..2 ok 1 - One reference after construct not ok 2 - One reference just before EOF # Failed test 'One reference just before EOF' # at demo.pl line 16. # expected 1 references, found 2 # Looks like you failed 1 test of 2. BUGS * Temporaries created on the stack Code which creates temporaries on the stack, to be released again when the called function returns does not work correctly on perl 5.8 (and probably before). Examples such as is_oneref( [] ); may fail and claim a reference count of 2 instead. Passing a variable such as my $array = []; is_oneref( $array ); works fine. Because of the intention of this test module; that is, to assert reference counts on some object stored in a variable during the lifetime of the test script, this is unlikely to cause any problems. ACKNOWLEDGEMENTS Peter Rabbitson - for suggesting using core's B instead of Devel::Refcount to obtain refcounts AUTHOR Paul Evans Test-Refcount-0.10/lib000755001750001750 013504644514 13431 5ustar00leoleo000000000000Test-Refcount-0.10/lib/Test000755001750001750 013504644514 14350 5ustar00leoleo000000000000Test-Refcount-0.10/lib/Test/Refcount.pm000444001750001750 2266313504644514 16661 0ustar00leoleo000000000000# You may distribute under the terms of either the GNU General Public License # or the Artistic License (the same terms as Perl itself) # # (C) Paul Evans, 2008-2019 -- leonerd@leonerd.org.uk package Test::Refcount; use strict; use warnings; use base qw( Test::Builder::Module ); use Scalar::Util qw( weaken refaddr ); use B qw( svref_2object ); our $VERSION = '0.10'; our @EXPORT = qw( is_refcount is_oneref ); our @EXPORT_OK = qw( refcount ); use constant HAVE_DEVEL_FINDREF => defined eval { require Devel::FindRef }; use constant HAVE_DEVEL_MAT_DUMPER => defined eval { require Devel::MAT::Dumper }; =encoding UTF-8 =head1 NAME C - assert reference counts on objects =head1 SYNOPSIS use Test::More tests => 2; use Test::Refcount; use Some::Class; my $object = Some::Class->new(); is_oneref( $object, '$object has a refcount of 1' ); my $otherref = $object; is_refcount( $object, 2, '$object now has 2 references' ); =head1 DESCRIPTION The Perl garbage collector uses simple reference counting during the normal execution of a program. This means that cycles or unweakened references in other parts of code can keep an object around for longer than intended. To help avoid this problem, the reference count of a new object from its class constructor ought to be 1. This way, the caller can know the object will be properly DESTROYed when it drops all of its references to it. This module provides two test functions to help ensure this property holds for an object class, so as to be polite to its callers. If the assertion fails; that is, if the actual reference count is different to what was expected, either of the following two modules may be used to assist the developer in finding where the references are. =over 4 =item * If L is installed, this test module will use it to dump the state of the memory after a failure. It will create a F<.pmat> file named the same as the unit test, but with the trailing F<.t> suffix replaced with F<-TEST.pmat> where C is the number of the test that failed (in case there was more than one). =item * If L module is installed, a reverse-references trace is printed to the test output. =back See the examples below for more information. =cut =head1 FUNCTIONS =cut =head2 is_refcount is_refcount( $object, $count, $name ) Test that $object has $count references to it. =cut sub is_refcount($$;$) { my ( $object, $count, $name ) = @_; @_ = (); my $tb = __PACKAGE__->builder; if( !ref $object ) { my $ok = $tb->ok( 0, $name ); $tb->diag( " expected a reference, was not given one" ); return $ok; } weaken $object; # So this reference itself doesn't show up my $REFCNT = refcount( $object ); my $ok = $tb->ok( $REFCNT == $count, $name ); unless( $ok ) { $tb->diag( " expected $count references, found $REFCNT" ); if( HAVE_DEVEL_MAT_DUMPER ) { my $file = $0; my $num = $tb->current_test; # Trim the .t off first then append -$num.pmat, in case $0 wasn't a .t file $file =~ s/\.(?:t|pm|pl)$//; $file .= "-$num\.pmat"; $tb->diag( sprintf "SV address is 0x%x", refaddr $object ); $tb->diag( "Writing heap dump to $file" ); Devel::MAT::Dumper::dump( $file ); } if( HAVE_DEVEL_FINDREF ) { $tb->diag( Devel::FindRef::track( $object ) ); } } return $ok; } =head2 is_oneref is_oneref( $object, $name ) Assert that the $object has only 1 reference to it. =cut sub is_oneref($;$) { splice( @_, 1, 0, ( 1 ) ); goto &is_refcount; } =head2 refcount $count = refcount( $object ) I Returns the reference count of the given object as used by the test functions. This is useful for making tests that don't care what the count is before they start, but simply assert that the count hasn't changed by the end. use Test::Refcount import => [qw( is_refcount refcount )]; { my $count = refcount( $object ); do_something( $object ); is_refcount( $object, $count, 'do_something() preserves refcount' ); } =cut sub refcount { return svref_2object( $_[0] )->REFCNT; } =head1 EXAMPLE Suppose, having written a new class C, you now want to check that its constructor and methods are well-behaved, and don't leak references. Consider the following test script: use Test::More tests => 2; use Test::Refcount; use MyBall; my $ball = MyBall->new(); is_oneref( $ball, 'One reference after construct' ); $ball->bounce; # Any other code here that might be part of the test script is_oneref( $ball, 'One reference just before EOF' ); The first assertion is just after the constructor, to check that the reference returned by it is the only reference to that object. This fact is important if we ever want C to behave properly. The second call is right at the end of the file, just before the main scope closes. At this stage we expect the reference count also to be one, so that the object is properly cleaned up. Suppose, when run, this produces the following output (presuming L is available): 1..2 ok 1 - One reference after construct not ok 2 - One reference just before EOF # Failed test 'One reference just before EOF' # at ex.pl line 26. # expected 1 references, found 2 # SV address is 0x55e14c310278 # Writing heap dump to ex-2.pmat # Looks like you failed 1 test of 2. This has written a F file we can load using the C shell and use the C command on the given address to find where it went: $ pmat ex-2.pmat Perl memory dumpfile from perl 5.28.1 threaded Heap contains 25233 objects pmat> identify 0x55e14c310278 HASH(0)=MyBall at 0x55e14c310278 is: ├─(via RV) the lexical $ball at depth 1 of CODE() at 0x55e14c3104a0=main_cv, which is: │ └─the main code └─(via RV) value {self} of HASH(2) at 0x55e14cacb860, which is (*A): └─(via RV) value {cycle} of HASH(2) at 0x55e14cacb860, which is: itself (This document isn't intended to be a full tutorial on L and the C shell; for that see L). Alternatively, this produces the following output when using L instead: 1..2 ok 1 - One reference after construct not ok 2 - One reference just before EOF # Failed test 'One reference just before EOF' # at demo.pl line 16. # expected 1 references, found 2 # MyBall=ARRAY(0x817f880) is # +- referenced by REF(0x82c1fd8), which is # | in the member 'self' of HASH(0x82c1f68), which is # | referenced by REF(0x81989d0), which is # | in the member 'cycle' of HASH(0x82c1f68), which was seen before. # +- referenced by REF(0x82811d0), which is # in the lexical '$ball' in CODE(0x817fa00), which is # the main body of the program. # Looks like you failed 1 test of 2. From this output, we can see that the constructor was well-behaved, but that a reference was leaked by the end of the script - the reference count was 2, when we expected just 1. Reading the trace output, we can see that there were 2 references that could be found - one stored in the $ball lexical in the main program, and one stored in a HASH. Since we expected to find the $ball lexical variable, we know we are now looking for a leak in a hash somewhere in the code. From reading the test script, we can guess this leak is likely to be in the bounce() method. Furthermore, we know that the reference to the object will be stored in a HASH in a member called C. By reading the code which implements the bounce() method, we can see this is indeed the case: sub bounce { my $self = shift; my $cycle = { self => $self }; $cycle->{cycle} = $cycle; } From reading the tracing output, we find that the HASH this object is referenced in also contains a reference to itself, in a member called C. This comes from the last line in this function, a line that purposely created a cycle, to demonstrate the point. While a real program probably wouldn't do anything quite this obvious, the trace would still be useful in finding the likely cause of the leak. If neither C nor C are available, then these detailed traces will not be produced. The basic reference count testing will still take place, but a smaller message will be produced: 1..2 ok 1 - One reference after construct not ok 2 - One reference just before EOF # Failed test 'One reference just before EOF' # at demo.pl line 16. # expected 1 references, found 2 # Looks like you failed 1 test of 2. =head1 BUGS =over 4 =item * Temporaries created on the stack Code which creates temporaries on the stack, to be released again when the called function returns does not work correctly on perl 5.8 (and probably before). Examples such as is_oneref( [] ); may fail and claim a reference count of 2 instead. Passing a variable such as my $array = []; is_oneref( $array ); works fine. Because of the intention of this test module; that is, to assert reference counts on some object stored in a variable during the lifetime of the test script, this is unlikely to cause any problems. =back =head1 ACKNOWLEDGEMENTS Peter Rabbitson - for suggesting using core's C instead of C to obtain refcounts =head1 AUTHOR Paul Evans =cut 0x55AA; Test-Refcount-0.10/t000755001750001750 013504644514 13126 5ustar00leoleo000000000000Test-Refcount-0.10/t/00use.t000444001750001750 15013504644514 14360 0ustar00leoleo000000000000#!/usr/bin/perl use strict; use warnings; use Test::More; use_ok( "Test::Refcount" ); done_testing; Test-Refcount-0.10/t/01count.t000444001750001750 370713504644514 14750 0ustar00leoleo000000000000#!/usr/bin/perl use strict; use warnings; use Test::More; use Test::Builder::Tester; use Test::Refcount; my $anon = []; test_out( "ok 1 - anon ARRAY ref" ); is_refcount( $anon, 1, 'anon ARRAY ref' ); test_test( "anon ARRAY ref succeeds" ); test_out( "not ok 1 - not ref" ); test_fail( +2 ); test_err( "# expected a reference, was not given one" ); is_refcount( "hello", 1, 'not ref' ); test_test( "not ref fails" ); my $object = bless {}, "Some::Class"; test_out( "ok 1 - object" ); is_refcount( $object, 1, 'object' ); test_test( "normal object succeeds" ); my $newref = $object; test_out( "ok 1 - two refs" ); is_refcount( $object, 2, 'two refs' ); test_test( "two refs to object succeeds" ); test_out( "not ok 1 - one ref" ); test_fail( +10 ); test_err( "# expected 1 references, found 2" ); if( Test::Refcount::HAVE_DEVEL_MAT_DUMPER ) { test_err( qr/^# SV address is 0x[0-9a-f]+\n/ ); test_err( qr/^# Writing heap dump to \S+\n/ ); } if( Test::Refcount::HAVE_DEVEL_FINDREF ) { test_err( qr/^# Some::Class=HASH\(0x[0-9a-f]+\) (?:\[refcount 2\] )?is\n/ ); test_err( qr/(?:^#.*\n){1,}/m ); # Don't be sensitive on what Devel::FindRef actually prints } is_refcount( $object, 1, 'one ref' ); test_test( "two refs to object fails to be 1" ); undef $newref; $object->{self} = $object; test_out( "ok 1 - circular" ); is_refcount( $object, 2, 'circular' ); test_test( "circular object succeeds" ); undef $object->{self}; my $otherobject = bless { firstobject => $object }, "Other::Class"; test_out( "ok 1 - other ref to object" ); is_refcount( $object, 2, 'other ref to object' ); test_test( "object with another reference succeeds" ); undef $otherobject; test_out( "ok 1 - undefed other ref to object" ); is_refcount( $object, 1, 'undefed other ref to object' ); test_test( "object with another reference undefed succeeds" ); END { # Clean up Devel::MAT dumpfile my $pmat = $0; $pmat =~ s/\.t$/-1.pmat/; unlink $pmat if -f $pmat; } done_testing; Test-Refcount-0.10/t/02one.t000444001750001750 210413504644514 14370 0ustar00leoleo000000000000#!/usr/bin/perl use strict; use warnings; use Test::More; use Test::Builder::Tester; use Test::Refcount; my $anon = []; test_out( "ok 1 - anon ARRAY ref" ); is_oneref( $anon, 'anon ARRAY ref' ); test_test( "anon ARRAY ref succeeds" ); my $object = bless {}, "Some::Class"; test_out( "ok 1 - object" ); is_oneref( $object, 'object' ); test_test( "normal object succeeds" ); my $newref = $object; test_out( "not ok 1 - one ref" ); test_fail( +10 ); test_err( "# expected 1 references, found 2" ); if( Test::Refcount::HAVE_DEVEL_MAT_DUMPER ) { test_err( qr/^# SV address is 0x[0-9a-f]+\n/ ); test_err( qr/^# Writing heap dump to \S+\n/ ); } if( Test::Refcount::HAVE_DEVEL_FINDREF ) { test_err( qr/^# Some::Class=HASH\(0x[0-9a-f]+\) (?:\[refcount 2\] )?is\n/ ); test_err( qr/(?:^#.*\n){1,}/m ); # Don't be sensitive on what Devel::FindRef actually prints } is_oneref( $object, 'one ref' ); test_test( "two refs to object fails to be 1" ); END { # Clean up Devel::MAT dumpfile my $pmat = $0; $pmat =~ s/\.t$/-1.pmat/; unlink $pmat if -f $pmat; } done_testing; Test-Refcount-0.10/t/03weak.t000444001750001750 202413504644514 14540 0ustar00leoleo000000000000#!/usr/bin/perl use strict; use warnings; use Test::More; use Test::Builder::Tester; use Scalar::Util qw( weaken ); use Test::Refcount; my $object = bless {}, "Some::Class"; my $newref = $object; test_out( "not ok 1 - one ref" ); test_fail( +10 ); test_err( "# expected 1 references, found 2" ); if( Test::Refcount::HAVE_DEVEL_MAT_DUMPER ) { test_err( qr/^# SV address is 0x[0-9a-f]+\n/ ); test_err( qr/^# Writing heap dump to \S+\n/ ); } if( Test::Refcount::HAVE_DEVEL_FINDREF ) { test_err( qr/^# Some::Class=HASH\(0x[0-9a-f]+\) (?:\[refcount 2\] )?is\n/ ); test_err( qr/(?:^#.*\n){1,}/m ); # Don't be sensitive on what Devel::FindRef actually prints } is_oneref( $object, 'one ref' ); test_test( "two refs to object fails to be 1" ); weaken( $newref ); test_out( "ok 1 - object with weakref" ); is_oneref( $object, 'object with weakref' ); test_test( "object with weakref succeeds" ); END { # Clean up Devel::MAT dumpfile my $pmat = $0; $pmat =~ s/\.t$/-1.pmat/; unlink $pmat if -f $pmat; } done_testing; Test-Refcount-0.10/t/04reftypes.t000444001750001750 203113504644514 15451 0ustar00leoleo000000000000#!/usr/bin/perl use strict; use warnings; use Test::More; use Test::Builder::Tester; use Symbol qw( gensym ); use Test::Refcount; my %refs = ( SCALAR => do { my $var; \$var }, ARRAY => [], HASH => +{}, # This magic is to ensure the code ref is new, not shared. To be a new one # it has to contain a unique pad. CODE => do { my $var; sub { $var } }, GLOB => gensym(), Regex => qr/foo/, ); foreach my $type (qw( SCALAR ARRAY HASH CODE GLOB Regex )) { SKIP: { if( $type eq "Regex" and $] >= 5.011 ) { # Perl v5.11 seems to have odd behaviour with Regexp references. They start # off with a refcount of 2. Not sure if this is a bug in Perl, or my # assumption. Until P5P have worked it out, we'll skip this. See also # similar skip logic in Devel-Refcount's tests skip "Bleadperl", 1; } test_out( "ok 1 - anon $type ref" ); is_refcount( $refs{$type}, 1, "anon $type ref" ); test_test( "anon $type ref succeeds" ); } } done_testing; Test-Refcount-0.10/t/99pod.t000444001750001750 25713504644514 14400 0ustar00leoleo000000000000#!/usr/bin/perl use strict; use warnings; use Test::More; eval "use Test::Pod 1.00"; plan skip_all => "Test::Pod 1.00 required for testing POD" if $@; all_pod_files_ok();