Use stream wrapper to extract files on demand.

[kherge]

Problem

After creating some rough benchmarks for runtime performance comparison between PHAR and Sqon, I realized that the first run for a PHAR kicked Sqon's butt. I believe that this has something to do with the phar extension's support for stream wrapping. An attempt should be made to offer something similar with Sqon.

Resolution

I am hoping to see faster run times when a Sqon is first run and for each subsequent run. This improvement should take advantage of PHP's optimizations (i.e. opcode caching).

References

1. https://github.com/php/php-src/blob/master/ext/phar/stream.c
2. https://secure.php.net/manual/en/class.streamwrapper.php
3. https://secure.php.net/manual/en/book.opcache.php

[kherge]

I am currently trying to figure out if there is a net benefit using a stream wrapper.

Research

These are questions that need answering.

• Does opcode caching work for stream wrappers?
• How long does it take to extract the embedded database?
• How long does it take to include a file (extracted and stream wrapped)?

Opcode Caching

Opcode caching is not supported for streams. @flaupretre is working on adding support^{1, 2, 3}, but I'm not sure if it's going to make it to the 7.1 release. Since Sqon will only be supporting current LTS releases, this functionality is considered non-existent at the moment.

The conclusion is that opcode caching does not support streams at the moment. As a consequence, using stream wrapping will not be as performant as extracting the Sqon to the filesystem. The only benefit is reducing the startup time for a command line application. I should probably consider providing this as an alternative PHP bootstrap script.

1. https://wiki.php.net/rfc/streams-is-cacheable
2. Add is_cacheable() stream wrapper operation php/php-src#976
3. New 'cache_key' streams operation php/php-src#1711

Extract vs Streaming Times

Using rough benchmarks, I received the following times for executing a Symfony 3 (symfony/framework-standard-edition) application console:

• Stream: 0.713 seconds
• Extract: 2.807 seconds
• Post Extract: 0.187 seconds

The 0.713 seconds is a very noticeable pause and is enough for me to determine that support streaming is not a viable option at this time. When an LTS version of PHP with stream caching support is available, this potential enhancement must be revisited.

[kherge]

I'm reopening this issue to investigate the possible use of opcache_compile_file.