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README.md
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@ -2,30 +2,34 @@
**I**nternet **R**elay **C**hat **d**aemon: *Charybdis*
Charybdis is designed to be fast and highly scalable. It is also designed to be community-
developed by volunteer contributors over the internet. This makes Charybdis easy to understand,
modify, audit, and extend.
IRCd is a free and open source server which facilitates real-time communication over the
internet. It was started in 1988 by Jarkko Oikarinen in the University of Oulu and eventually
made its way to William Pitcock et al, whom after 2005 developed the project under the alias
made its way to William Pitcock et al, whom after 2005 developed the project under the brand
*Charybdis*.
In 2014 a protocol was proposed to reinvigorate real-time communication in lieu of growing
commercial competition and a lack of innovation from open source alternatives to
compete. This protcol is known as the **Matrix protocol**.
compete. This protocol is known as the **Matrix protocol**.
##### IRCd now implements the Matrix protocol.
**IRCd now implements the Matrix protocol.**
# Charybdis/5
Charybdis Five is the first high performance implementation of **Matrix** written in C++. It remains
true to its roots for being highly scalable, modular and having minimal requirements. Most of the
old code has been rewritten but with the same architecture and spirit of the original.
Charybdis is designed to be fast and highly scalable, and to be community
developed by volunteer contributors over the internet. This mission strives to
make the software easy to understand, modify, audit, and extend.
Charybdis Five is the first implementation of *Matrix* written in C++. It remains
true to its roots for being highly scalable, modular and having minimal requirements.
Most of the old code has been rewritten but with the same architecture and spirit of
the original.
### Dependencies
## Installation
#### Dependencies
**Boost** (1.61 or later) - We have replaced libratbox with the well known and actively
developed Boost libraries. These are included as a submodule in this repository.
@ -39,9 +43,6 @@ and have furthered the mission of eliminating the need for external "IRC service
*Other dependencies:* **OpenSSL**, **zlib**, **snappy** (for rocksdb)
### Installation
#### Downloading Charybdis
`git clone https://github.com/charybdis-ircd/charybdis`
@ -50,7 +51,7 @@ and have furthered the mission of eliminating the need for external "IRC service
- Verify you have the latest source tree and **are on the Matrix branch**.
#### Building from git (production)
### Building from git (production)
`./autogen.sh`
`./configure`
@ -60,11 +61,14 @@ and have furthered the mission of eliminating the need for external "IRC service
#### Building from git (DEVELOPER PREVIEW INSTRUCTIONS)
*This is only intended to allow development with dependencies that have not made
their way to mainstream systems yet.* **Not for release.**
The developer preview will install charybdis in a specific directory isolated from the
system. It will not install and avoid using system libraries. Instead it will download
and build the dependencies from the submodules we have pinned here and build them the
way we have configured. Charybdis should be executed using those builds. You may need
to set the `LD_LIBRARY_PATH` to the built libraries. This is not required for release.
system. It will avoid using system libraries by downloading and building the dependencies
from the submodules we have pinned here and build them the way we have configured. You may
need to set the `LD_LIBRARY_PATH` to the built libraries and/or maintain an intact build
directory.
`./autogen.sh`
`mkdir build`

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doc/CPP_HOWTO.md
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@ -240,5 +240,3 @@ other words, if you have a prototype like `foo(const std::string &message)` you
`message` because std::string is common and *what* the string is for is otherwise opaque.
OTOH, if you have `foo(const options &, const std::string &message)` one should skip the name
for `options &` as it just adds redundant text to the prototype.

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include/ircd/README.md
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# IRCd Library
This library can be embedded by developers creating their own server or those
who simply want to use the library of routines it provides. See the section for
`Using libircd`.
The purpose of `libircd` is to facilitate the execution of a server which
handles requests from end-users. The library hosts a set of pluggable modules
which introduce the actual application features (or the "business logic") of
the server. These additional modules are found in the `modules/` directory;
see the section for `Developing a module` for more information. This library
can be embedded by developers creating their own server or those who simply
want to use the routines it provides; see the section for `Using libircd`.
which may introduce the actual application features (or the "business logic")
of the server. These additional modules are found in the `modules/` directory;
### Using libircd
`libircd` can be embedded in your application. This allows you to customize and
extend the functionality of the server and have control over its execution, or,
simply use library routines provided by the library without any daemonization.
The prototypical embedding of `libircd` is `charybdis` found in the `charybdis/`
directory.
##### libircd can be embedded in your application with very minimal overhead.
This allows you to customize and extend the functionality of the server and have
control over its execution, or, simply use library routines provided by the library
without any daemonization. Including libircd headers will not include any other
headers beyond those in the standard library, with minimal impact on your project's
compile complexity. The prototypical embedding of `libircd` is `charybdis` found in
the `charybdis/` directory.
##### libircd runs only one server at a time.
Keeping with the spirit of simplicity of the original architecture, `libircd`
continues to be a "singleton" object which uses globals and keeps actual server
state. In other words, only one IRC daemon can exist within a process's address
space at any time. This is actually a profitable design decision for making
IRCd easier to understand for contributors. The original version of this library
was created at the dawn of the era of dynamic shared objects and began as an
abstraction of code from the server executable. This was done so that additional
feature modules could be created while all sharing the same maps of routines.
state in the library itself. In other words, **only one IRC daemon can exist
within a process's address space at a time.** This is actually a profitable
design decision for making IRCd easier to understand for contributors.
The library is based around the `boost::asio::io_service` event loop. It is
nominally single threaded and serializes operations on a single asio strand.
In other words, most code is executed on the thread where you call `ios.run()`;
this is referred to as the "main thread." If ios.run() is called on multiple
threads no concurrency will occur. IRCd occasionally uses global and static
variables; the expectation is that these will not be contended outside of the
main thread. The library may spawn additional threads, mostly from 3rd party
libraries and only under daemonization. We don't like this, and try to prevent
it, but it may happen under certain circumstances. These are all dealt with
internally and shouldn't affect the users of the library.
##### libircd is single-threaded✝
The library is based around the `boost::asio::io_service` event loop. It is still
an asynchronous event-based system. We process one event at a time; developers must
not block execution. Events are never processed concurrently on different threads✝.
However, there are some ✝'s here which must be addressed. We have introduced
additional standard threads to libircd with the purpose of "offloading" operations
from some library dependencies that don't cooperate asynchronously. This ensures the
"main thread" running the actual event loop is never blocked in any case. Furthermore,
some 3rd party dependencies like RocksDB (and boost::asio's DNS resolver) may
introduce threads into the address space which they handle privately.
##### libircd introduces userspace threading
IRCd presents an interface introducing stackful coroutines, a.k.a. userspace context
switching, or green threads. The library does not use callbacks as the way to break
up execution when waiting for events. Instead, we harken back to the simple old ways
of synchronous programming, where control flow and data are easy to follow.
##### libircd innovates with formal grammars
We leverage the boost::spirit system of parsing and printing through formal grammars,
rather than writing our own parsers manually. In addition, we build several tools
on top of such formal devices like a type-safe format string library acting as a
drop-in for ::sprintf(), but accepting objects like std::string without .c_str()
and prevention of outputting unprintable/unwanted characters that may have been
injected into the system somewhere prior.
### Developing a module
libircd facilitates the development of dynamic shared modules which implement
specific application logic used in the server.
### Hacking on libircd
#### Style
##### Misc
* When using a `switch` over an `enum` type, put what would be the `default` case after/outside
of the `switch` unless the situation specifically calls for one. We use -Wswitch so changes to
the enum will provide a good warning to update any `switch`.
* Prototypes should name their argument variables to make them easier to understand, except if
such a name is redundant because the type carries enough information to make it obvious. In
other words, if you have a prototype like `foo(const std::string &message)` you should name
`message` because std::string is common and *what* the string is for is otherwise opaque.
OTOH, if you have `foo(const options &, const std::string &message)` one should skip the name
for `options &` as it just adds redundant text to the prototype.