57 lines
2.7 KiB
Markdown
57 lines
2.7 KiB
Markdown
# BaseT
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BaseT is a proof of concept stream handler I wrote on a whim. I was wondering if
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you can reload code in PHP without using runkit or separate processes and so this
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design was born. The aim was to write a quick IRC bot but the base code is so
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generic it can probably handle any line based streams. A few example plugins are
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included.
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The reloading works by putting all code in anonymous functions (this
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forbids the use of classes, constants and similar structures in plugins) and
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just re-including all the plugin files upon a reload. There are a few builtin
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hooks to attach code to and you can add your own, because you can also reload
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core code in the utils.php file. Note that there is no error handling so any
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fatal error – like a parse error during reload – will crash the whole thing.
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## Memory performance
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I am not familiar with PHP internals regarding the loading of code for closures,
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namely will PHP actually delete code attached to a closure when the last reference
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to its variable is gone, so I cannot say there are no memory leaks. My empirical
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testing suggests that the memory use jumps up and down after reloads, but eventually
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grows slightly after many reloads. You can try to follow memory use with the plugin
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9997_memoryusage.php.
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## Requirements
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BaseT should work on PHP 5.3+. It uses signals to force a reload so you'll need
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the pcntl extension, unless you delete the functions at the end of utils.php (and
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the declare at the top of main.php).
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## Usage
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The main loop of the program will exit if there are no streams to handle, so you
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need to write a plugin to open a stream when the program is started. You can check
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$_started to see if the program is starting up for the first time. The plugin
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0020_autojoin.php will have an example of this.
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To reload code, send the program a SIGUSR1. The currently executing code will be
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interrupted, the reload will be scheduled to happen on the next iteration of the
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main loop and your code execution will be resumed. Note that an incoming signal
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can interrupt vital functions in your code and break things, so you may want to
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block signal handling at some points.
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When writing plugins, you need to watch out for name clashes with variables, it's
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probably best to prefix your variables with a plugin identifier to avoid that.
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Plugins are included in ascending filename sort order so you can use numbers to
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order them the way you want.
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## This is a terrible way to write a program
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I know, this was mostly a proof of concept on reloading code and a fun little
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thing to write. This is not what PHP was made for so don't expect great performance
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or stability (though it looks relatively stable with a small amount of plugins).
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## License
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MIT, look at the LICENSE file.
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