research-article

Copy-on-write in the PHP language

Authors:

Akihiko Tozawa,

Michiaki Tatsubori,

Tamiya Onodera,

Yasuhiko MinamideAuthors Info & Claims

ACM SIGPLAN Notices, Volume 44, Issue 1

Pages 200 - 212

https://doi.org/10.1145/1594834.1480908

Published: 21 January 2009 Publication History

Abstract

PHP is a popular language for server-side applications. In PHP, assignment to variables copies the assigned values, according to its so-called copy-on-assignment semantics. In contrast, a typical PHP implementation uses a copy-on-write scheme to reduce the copy overhead by delaying copies as much as possible. This leads us to ask if the semantics and implementation of PHP coincide, and actually this is not the case in the presence of sharings within values. In this paper, we describe the copy-on-assignment semantics with three possible strategies to copy values containing sharings. The current PHP implementation has inconsistencies with these semantics, caused by its naïve use of copy-on-write. We fix this problem by the novel mostly copy-on-write scheme, making the copy-on-write implementations faithful to the semantics. We prove that our copy-on-write implementations are correct, using bisimulation with the copy-on-assignment semantics.

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Cited By

Husák RMíšek JZavoral FKofroň J(2022)PeachPie: Mature PHP to CLI compilerJournal of Computer Languages10.1016/j.cola.2022.10115273(101152)Online publication date: Dec-2022
https://doi.org/10.1016/j.cola.2022.101152
Racordon DBuchs DPearce DMayerhofer TSteimann F(2018)A practical type system for safe aliasingProceedings of the 11th ACM SIGPLAN International Conference on Software Language Engineering10.1145/3276604.3276612(133-146)Online publication date: 24-Oct-2018
https://dl.acm.org/doi/10.1145/3276604.3276612
Popov NCosenza BJuurlink BStogov DWu PHack S(2017)Static optimization in PHP 7Proceedings of the 26th International Conference on Compiler Construction10.1145/3033019.3033026(65-75)Online publication date: 5-Feb-2017
https://dl.acm.org/doi/10.1145/3033019.3033026
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Index Terms

Copy-on-write in the PHP language
1. Software and its engineering
  1. Software notations and tools
    1. General programming languages
      1. Language features

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Published In

cover image ACM SIGPLAN Notices

ACM SIGPLAN Notices Volume 44, Issue 1

POPL '09

January 2009

453 pages

ISSN:0362-1340

EISSN:1558-1160

DOI:10.1145/1594834

Issue’s Table of Contents

POPL '09: Proceedings of the 36th annual ACM SIGPLAN-SIGACT symposium on Principles of programming languages
January 2009
464 pages
ISBN:9781605583792
DOI:10.1145/1480881
General Chair:
Zhong Shao
Yale University, USA
,
Program Chair:
Benjamin C. Pierce
University of Pennsylvania, USA

Copyright © 2009 ACM.

Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. Copyrights for components of this work owned by others than ACM must be honored. Abstracting with credit is permitted. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. Request permissions from [email protected]

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Association for Computing Machinery

New York, NY, United States

Publication History

Published: 21 January 2009

Published in SIGPLAN Volume 44, Issue 1

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Cited By

Husák RMíšek JZavoral FKofroň J(2022)PeachPie: Mature PHP to CLI compilerJournal of Computer Languages10.1016/j.cola.2022.10115273(101152)Online publication date: Dec-2022
https://doi.org/10.1016/j.cola.2022.101152
Racordon DBuchs DPearce DMayerhofer TSteimann F(2018)A practical type system for safe aliasingProceedings of the 11th ACM SIGPLAN International Conference on Software Language Engineering10.1145/3276604.3276612(133-146)Online publication date: 24-Oct-2018
https://dl.acm.org/doi/10.1145/3276604.3276612
Popov NCosenza BJuurlink BStogov DWu PHack S(2017)Static optimization in PHP 7Proceedings of the 26th International Conference on Compiler Construction10.1145/3033019.3033026(65-75)Online publication date: 5-Feb-2017
https://dl.acm.org/doi/10.1145/3033019.3033026
Korb IKotthaus HMarwedel POssowski S(2016)mmapcopyProceedings of the 31st Annual ACM Symposium on Applied Computing10.1145/2851613.2851736(1832-1837)Online publication date: 4-Apr-2016
https://dl.acm.org/doi/10.1145/2851613.2851736
Adams KEvans JMaher BOttoni GParoski ASimmers BSmith EYamauchi O(2014)The hiphop virtual machineACM SIGPLAN Notices10.1145/2714064.266019949:10(777-790)Online publication date: 15-Oct-2014
https://dl.acm.org/doi/10.1145/2714064.2660199
Filaretti DMaffeis S(2014)An Executable Formal Semantics of PHPProceedings of the 28th European Conference on ECOOP 2014 --- Object-Oriented Programming - Volume 858610.1007/978-3-662-44202-9_23(567-592)Online publication date: 1-Aug-2014
https://dl.acm.org/doi/10.1007/978-3-662-44202-9_23
Racordon DBuchs DPearce DMayerhofer TSteimann F(2018)A practical type system for safe aliasingProceedings of the 11th ACM SIGPLAN International Conference on Software Language Engineering10.1145/3276604.3276612(133-146)Online publication date: 24-Oct-2018
https://dl.acm.org/doi/10.1145/3276604.3276612
Popov NCosenza BJuurlink BStogov DWu PHack S(2017)Static optimization in PHP 7Proceedings of the 26th International Conference on Compiler Construction10.1145/3033019.3033026(65-75)Online publication date: 5-Feb-2017
https://dl.acm.org/doi/10.1145/3033019.3033026
Korb IKotthaus HMarwedel POssowski S(2016)mmapcopyProceedings of the 31st Annual ACM Symposium on Applied Computing10.1145/2851613.2851736(1832-1837)Online publication date: 4-Apr-2016
https://dl.acm.org/doi/10.1145/2851613.2851736
Adams KEvans JMaher BOttoni GParoski ASimmers BSmith EYamauchi O(2014)The hiphop virtual machineACM SIGPLAN Notices10.1145/2714064.266019949:10(777-790)Online publication date: 15-Oct-2014
https://dl.acm.org/doi/10.1145/2714064.2660199
Show More Cited By

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