Merge playrtp readahead reduction

[disorder] / README.developers

Dependencies:

   * You'll need, in addition to the packages mentioned in README:
     Automake         1.10           1.7 is no good; 1.8/9 might work
     Autoconf         2.61           Slightly older might work too
     Libtool          1.5.22         1.4 is no good
     Bazaar (bzr)                    You might be able to manage without
     Python           2.4

   * On Debian and derivatives this should work:

     apt-get install gcc libc-dev automake autoconf libtool libgtk2.0-dev \
		     libgc-dev libgcrypt-dev libpcre3-dev libvorbis-dev \
		     libao-dev libmad0-dev libasound2-dev libdb4.3-dev \
		     libflac-dev vorbis-tools wget

     (Use the bzr from backports, the one in etch is obsolete.)

     On lenny use libdb4.5-deb.  libdb4.6 does not work (and configure will
     refuse to use it).

   * On FreeBSD you'll need at least these packages:
	 autotools
	 bash
	 flac
	 mad
         boehm-gc
         db43
         gmake
         gsed
         libao
         libgcrypt
         wget
         vorbis-tools

   * Please report unstated dependencies (here, README or debian/control).

Building:

   * Compiled versions of configure and the makefiles are not included in bzr,
     so if you didn't use a source tarball, you must start as follows:

        bash ./prepare
        ./configure -C
        make

   * On FreeBSD you must use gmake.

Testing:

   * There is an extensive test suite in lib/test.c and tests/*.py.  You can
     run the tests with 'make check'.  If possible please add tests for new
     code to at least one of these.  At the very least the existing tests
     should continue to pass.

   * The tests will not currently pass in an ASCII locale.  This is essentially
     unavoidable given the need to test Unicode support.  ISO 8859-1 or UTF-8
     locales should be OK for the time being.

APIs And Formats:

   * To support a new sound API:
     1) Teach configure.ac how to detect any libraries required.
     2) Define a new BACKEND_ value and update configuration.[ch] for it.
     3) Create a suitable server/speaker-*.c along the pattern of the existing
        ones.
     4) If possible create a suitable lib/mixer-*.c.  This doesn't make sense
        for all APIs (e.g. network), but even for those it does, playback
        support without volume control support is likely to be acceptable (even
        if inferior to full support).
     5) Update doc/disorder_config.5.in.
     6) If relevant, create a suitable clients/playrtp-*.c and update
        doc/disorder-playrtp.1.in.

   * To support a new file format:
     1) Teach configure.ac how to detect any libraries required.
     2) Add a new section to server/decode.c.  NB this file may be split into
        several bits one day.
     3) Add a new section to plugins/tracklength.c.  Again this file may be
        split up in a future version.
     4) Update default_players[] in lib/configuration.c.
     5) Update doc/disorder_config.5.in.

The Server:

   * The server's command implementations must not block.  Waiting for a little
     disk IO is OK but blocking for extended periods on long-lasting
     transactions or external resources is not acceptable; it will wedge the
     server for all other users.

     Long-running subprocesses should use subprograms (rather than forking but
     not execing) if reasonably possible; see c_stats() for an example.
     c_reminder() is probably in the grey area.

   * The server process does not use threads and I would like to keep it that
     way.

   * The server uses the Boehm garbage collector.  This eliminates the need to
     call free() and similar functions in many cases, though teardown calls to
     that do more than free GC-allocated memory (such as fclose()) are still
     required.

   * DisOrder's *printf calls, such as byte_xasprintf(), are mostly preferred
     within the server to the ones built into libc.  An important distinction
     is that they will always accept UTF-8 strings whereas the built-in ones
     may reject them in non-UTF-8 locales (for instance Glibc does this) with
     EILSEQ.  Only where the data is guaranteed to be ASCII may the libc
     functions be used.

   * To add a new configuration directive:
     1) Add a new entry to the struct in lib/configuration.h
     2) Add a new table entry to conf[] in lib/configuration.c
     3) If the directive is entirely unlike existing ones add a new type_
        to lib/configuration.c
     4) Set the default if non-0 in config_default().  In some cases
        config_postdefaults() may be more appropriate.
     5) Document the new directive in doc/disorder_config.5.in

   * To add a new command:
     1) Add a new c_ function and table entry in server/server.c
     2) Document the new command in doc/disorder_protocol.5.in
     3) Add a new function to lib/client.c
     4) Add a new function to lib/eclient.c
     5) Add a new function to python/disorder.py.in
     6) Add a new command to clients/disorder.c and update doc/disorder.1.in
     7) Add a new test somewhere in tests/*.py
     Depending on the purpose of the command it may be acceptable to leave out
     some of the client side work - for instance commands only ever used by the
     web interface are not implemented in lib/eclient.c.

   * See disorder_protocol(5) for details of how the status code is
     constructed, and the existing commands for examples.

   * If the command needs a new right to be defined then update lib/rights.[ch]
     and doc/disorder_config.5.in.  New rights should definitely be mentioned
     in README.upgrades as existing users will not automatically get new rights
     even if they are in default_rights.  If the new right should not be in
     default_rights by default then you must update config_postdefaults().

Web Interface:

   * The web interface does not use Javascript or Flash and I would like to
     keep it that way.  Clever use of CSS is OK provided it works well on the
     mainstream browsers.

   * Update templates/help.tmpl for any changes you make.

Disobedience:

   * Disobedience does not currently use threads and I'd prefer to keep it that
     way.

   * Disobedience uses the Boehm garbage collector but not for GTK+/GLIB's
     memory allocation, as they are incompatible with it.  So you still have to
     do somewhat manual memory management for GTK+ objects.  Fortunately it has
     its own refcounting system which does most of the work for you.

   * Lengthy operations must not block.  In practice this seems to be a less of
     a problem for Disobedience than the server.  Use the GLIB event loop to
     deal with long-running operations if you do need any.

   * Update doc/disobedience.1.in for any changes you make.

New Platforms:

   * It is not mandatory to have an entry in configure's 'case $host' section,
     but may well be convenient.

   * Complete support for a new platform implies updating scripts/setup.in and
     scripts/teardown.in as well as getting the software to build and work (but
     this doesn't mean that patches that don't achieve this will be rejected).

Code And Patches:

   * Please follow the existing layout conventions.

   * Please try to write doc comments for new functions, types, etc using the
     same syntax as the existing ones.  Doxygen can be used to turn this into
     reference documentation (see http://www.stack.nl/~dimitri/doxygen/) but
     really the point is to have good inline code documentation, not the
     Doxygen output as such.

   * More importantly, new configuration directives, protocol commands,
     interface features etc should be documented in the relevant places.

   * If you add new dependencies please update README, README.developers and
     debian/control.

   * New dependencies that are not in Debian stable are likely to be rejected.
     (But if your new feature only makes sense on a given platform then
     obviously its new dependencies don't need to be available elsewhere.)

   * GCCisms such as typeof and C99isms such as mixed declarations and named
     structure initializers are used; the configure script asks for -std=gnu99
     by default.  Some supported platforms are still on GCC 4.0.

   * Please submit patches either using 'diff -u', or by publishing a bzr
     branch somewhere I can get at it.

   * Please make it clear that your changes can be distributed under DisOrder's
     licence (which is "GPL v3 or later").

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