01_Main.dox

/*
 * Copyright (C) 1996-2023 The Squid Software Foundation and contributors
 *
 * Squid software is distributed under GPLv2+ license and includes
 * contributions from numerous individuals and organizations.
 * Please see the COPYING and CONTRIBUTORS files for details.
 */

/**
\mainpage Squid Developer Programming Guide

\section Abstract Abstract

\par
     Squid is a WWW Cache application developed by the National Laboratory
     for Applied Network Research and members of the Web Caching community.
     Squid is implemented as a single, non-blocking process based around
     a BSD select() loop.  This document describes the operation of the Squid
     source code and is intended to be used by others who wish to customize
     or improve it.


\section Introduction Introduction

\par
        The Squid source code has evolved more from empirical
        observation and tinkering, rather than a solid design
        process.  It carries a legacy of being "touched" by
        numerous individuals, each with somewhat different techniques
        and terminology.

\par
        Squid is a single-process proxy server.  Every request is
        handled by the main process, with the exception of FTP.
        However, Squid does not use a "threads package" such has
        Pthreads.  While this might be easier to code, it suffers
        from portability and performance problems.  Instead Squid
        maintains data structures and state information for each
        active request.

\par
        The code is often difficult to follow because there are no
        explicit state variables for the active requests.  Instead,
        thread execution progresses as a sequence of "callback
        functions" which get executed when I/O is ready to occur,
        or some other event has happened.  As a callback function
        completes, it is responsible for registering the next
        callback function for subsequent I/O.

\par
        Note there is only a pseudo-consistent naming scheme.  In
        most cases functions are named like \c moduleFooBar() .
        However, there are also some functions named like
        \c module_foo_bar() .

\par
        Note that the Squid source changes rapidly, and while we
        do make some effort to document code as we go some parts
        of the documentation may be left out.  If you find any
        inconsistencies, please feel free to notify
        http://www.squid-cache.org/Support/contact.dyn the Squid Developers.

 */