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.

References

[1]

A. Aasa, S. Holmström, and C. Nilsson. An efficiency comparison of some representations of purely functional arrays. BIT, 28(3):490--503, 1988.

Digital Library

[2]

H. G. Baker. Shallow binding in LISP 1.5. Communications of the ACM, 21(7):565--569, 1978.

Digital Library

[3]

H. P. Barendregt, M. C. J. D. Eekelen, J. R. W. Glauert, J. R. Kennaway, M. J. Plasmeijer, and M. R. Sleep. Term graph reduction. In Volume II: Parallel Languages on PARLE: Parallel Architectures and Languages Europe, pages 141--158, 1987.

[4]

E. Barendsen and S. Smetsers. Graph rewriting and copying. Technical Report 92-20, University of Nijmegen, 1992.

[5]

A. Bloss. Update analysis and the efficient implementation of functional aggregates. In FPCA '89: Proceedings of the fourth international conference on Functional programming languages and computer architecture, pages 26--38, New York, NY, USA, 1989. ACM.

Digital Library

[6]

S. Conchon and J.-C. Filliâtre. A persistent union-find data structure. In ML '07: Proceedings of the 2007 workshop on Workshop on ML, pages 37--46, New York, NY, USA, 2007. ACM.

Digital Library

[7]

R. Cytron, J. Ferrante, B. K. Rosen, M. N. Wegman, and F. K. Zadeck. Efficiently computing static single assignment form and the control dependence graph. ACM Transactions on Programming Languages and Systems, 13(4):451--490, October 1991.

Digital Library

[8]

M. Hofmann. A type system for bounded space and functional in-place update. Nordic J. of Computing, 7(4):258--289, 2000.

Digital Library

[9]

P. Hudak and A. Bloss. The aggregate update problem in functional programming systems. In POPL, pages 300--314, 1985.

Digital Library

[10]

Y. Minamide. Static approximation of dynamically generated Web pages. In Proceedings of the 14th International World Wide Web Conference, pages 432--441. ACM Press, 2005.

Digital Library

[11]

M. Odersky. How to make destructive updates less destructive. In POPL '91: Proceedings of the 18th ACM SIGPLAN-SIGACT symposium on Principles of programming languages, pages 25--36, 1991.

Digital Library

[12]

M. E. O'Neill and F. W. Burton. A new method for functional arrays. Journal of Functional Programming, 7(5):487--514, Sept. 1997.

Digital Library

[13]

A. D. Robison. The Illinois functional programming interpreter. In SIGPLAN '87: Papers of the Symposium on Interpreters and interpretive techniques, pages 64--73, 1987.

Digital Library

[14]

J. T. Schwartz. Optimization of very high level languages, parts I, II. Comput. Lang., 1(2-3):161--218, 1975.

Digital Library

[15]

N. Shankar. Static analysis for safe destructive updates in a functional language. In Proc. of LOPSTER 2001, 11th International Workshop on Logic Based Program Synthesis and Transformation, Paphos, Cyprus, November 28-30, 2001, LNCS 2372, pages 1--24, 2001.

Digital Library

[16]

D. N. Turner, P. Wadler, and C. Mossin. Once upon a type. In Functional Programming Languages and Computer Architecture, San Diego, California, 1995.

Digital Library

[17]

P. Wadler. Linear types can change the world! In IFIP TC 2 Working Conference on Programming Concepts and Methods, pages 347--359, 1990.

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
Show More Cited By

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

Recommendations

Copy-on-write in the PHP language
POPL '09: Proceedings of the 36th annual ACM SIGPLAN-SIGACT symposium on Principles of programming languages

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 ...
AJAX and PHP: Building Modern Web Applications 2nd Edition
PHP Ajax Cookbook

Comments

Information & Contributors

Information

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]

Publisher

Association for Computing Machinery

New York, NY, United States

Publication History

Published: 21 January 2009

Published in SIGPLAN Volume 44, Issue 1

Check for updates

Author Tags

Qualifiers

Research-article

Contributors

Other Metrics

View Article Metrics

Bibliometrics & Citations

Bibliometrics

Article Metrics

16
Total Citations
View Citations
1,143
Total Downloads

Downloads (Last 12 months)8
Downloads (Last 6 weeks)0

Reflects downloads up to 27 Jul 2024

Other Metrics

View Author Metrics

Citations

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

View Options

Get Access

Login options

Check if you have access through your login credentials or your institution to get full access on this article.

Full Access

Get this Publication

View options

PDF

View or Download as a PDF file.

eReader

View online with eReader.

Media

Figures

Other

Tables

View Issue’s Table of Contents