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In January 2013 Zeev Suraski raised the RFC, Integrating Zend Optimizer+ into the PHP distribution, which proposed that Zend Technologies Inc open-source OPcache (previously known as Zend Optimizer+) for incorporation into the PHP core distribution. At that point, I decided to suspend work on my earlier APC-based LPC extension, and to create this fork of Zend OPcache. My aim was to develop variant of OPcache using file-cache technology to demonstrate the feasibility of extending OPcache's benefits into the CLI and GCI SAPI environments.
Since then, I have developed MLC-OPcache and achieved these objectives. My aim is now to work with the Zend OPcache development team to incorporate some or all of this technology into the core OPcache code base.
These wiki pages to provide some documentation for OPcache and my Multi-Level Cache (MLC) derivative. The following pages give further detailed description of the topics:
- The Zend Engine and opcode caching. A general overview of how the Zend engine executes a PHP script and how opcode caching interacts with this.
- MLC OPcache details. MLC-specific issues and changes.
- Implementation principles. An overview of my coding and design practices. Readers who are only interested in the MLC functionality can skip this.
- The Instrumentation stage An early minimum-change demonstrator of the MLC concept. Now archived.
Terry Ellison