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61 lines
3.2 KiB
Markdown
61 lines
3.2 KiB
Markdown
# IRCd Library
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The purpose of `libircd` is to facilitate the execution of a server which
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handles requests from end-users. The library hosts a set of pluggable modules
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which introduce the actual application features (or the "business logic") of
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the server. These additional modules are found in the `modules/` directory;
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see the section for `Developing a module` for more information. This library
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can be embedded by developers creating their own server or those who simply
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want to use the routines it provides; see the section for `Using libircd`.
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### Using libircd
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`libircd` can be embedded in your application. This allows you to customize and
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extend the functionality of the server and have control over its execution, or,
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simply use library routines provided by the library without any daemonization.
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The prototypical embedding of `libircd` is `charybdis` found in the `charybdis/`
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directory.
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Keeping with the spirit of simplicity of the original architecture, `libircd`
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continues to be a "singleton" object which uses globals and keeps actual server
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state. In other words, only one IRC daemon can exist within a process's address
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space at any time. This is actually a profitable design decision for making
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IRCd easier to understand for contributors. The original version of this library
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was created at the dawn of the era of dynamic shared objects and began as an
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abstraction of code from the server executable. This was done so that additional
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feature modules could be created while all sharing the same maps of routines.
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The library is based around the `boost::asio::io_service` event loop. It is
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nominally single threaded and serializes operations on a single asio strand.
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In other words, most code is executed on the thread where you call `ios.run()`;
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this is referred to as the "main thread." If ios.run() is called on multiple
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threads no concurrency will occur. IRCd occasionally uses global and static
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variables; the expectation is that these will not be contended outside of the
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main thread. The library may spawn additional threads, mostly from 3rd party
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libraries and only under daemonization. We don't like this, and try to prevent
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it, but it may happen under certain circumstances. These are all dealt with
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internally and shouldn't affect the users of the library.
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### Developing a module
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libircd facilitates the development of dynamic shared modules which implement
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specific application logic used in the server.
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### Hacking on libircd
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#### Style
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##### Misc
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* When using a `switch` over an `enum` type, put what would be the `default` case after/outside
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of the `switch` unless the situation specifically calls for one. We use -Wswitch so changes to
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the enum will provide a good warning to update any `switch`.
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* Prototypes should name their argument variables to make them easier to understand, except if
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such a name is redundant because the type carries enough information to make it obvious. In
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other words, if you have a prototype like `foo(const std::string &message)` you should name
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`message` because std::string is common and *what* the string is for is otherwise opaque.
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OTOH, if you have `foo(const options &, const std::string &message)` one should skip the name
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for `options &` as it just adds redundant text to the prototype.
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