README

= DRAKE -- Distributed Rake

A branch of Rake supporting parallel task execution.

== Synopsis

Run up to three tasks in parallel:

  % drake -j3

or equivalently,

  % drake --threads 3

== Installation

  % gem install drake

== Notes

=== Compatibility

Drake is 100% compatible with Rake.  The code path for
<tt>--threads=1</tt> is effectively identical to that of Rake's.
Drake passes all of Rake's unit tests, with any number of threads from
1 to 1000 (the most tested).

=== Dependencies

In a given Rakefile, it is possible (even likely) that the
dependency tree has not been properly defined.  Consider

   task :a => [:x, :y, :z]

With single-threaded Rake, _x_,_y_,_z_ will be invoked <em>in that
order</em> before _a_ is invoked (assuming there are no other rules
involving these tasks).  However with <code>drake -jN</code> (for +N+
> 1), one should not expect any particular order of execution.  Since
there is no dependency specified between _x_,_y_,_z_ above, Drake is
free to run them in any order.

If you wish _x_,_y_,_z_ to be invoked sequentially, then write

   task :a => seq[:x, :y, :z]

This is shorthand for

   task :a => :z
   task :z => :y
   task :y => :x

Upon invoking _a_, the above rules say: "Can't do _a_ until _z_ is
complete; can't do _z_ until _y_ is complete; can't do _y_ until _x_
is complete; therefore do _x_."  In this fashion the sequence
_x_,_y_,_z_ is enforced.

The problem of insufficient dependencies plagues Makefiles as well,
and is sometimes called "not j-safe".

=== MultiTask

When more than one thread is given, +multitask+ behaves just like
+task+.  Those tasks which may properly be run in parallel will be run
in parallel; those which cannot, will not.  It is not the user's job
to decide.  In other words, for <tt>-jN</tt> (+N+ > 1), +multitask+ is
an alias of +task+.

For <tt>-j1</tt> (default), +multitask+ behaves as the original.

=== Task#invoke inside Task#invoke

Parallelizing code means surrendering control over the
micro-management of its execution.  Manually invoking tasks inside
other tasks is rather contrary to this notion, throwing a monkey
wrench into the system.  An exception will be raised when this is
attempted in multi-threaded mode.

=== Migrating to -j

First of all, do you want to bother with <tt>-j</tt>?  If you are
satisfied with your build time, then there is really no reason to use
it.

If on the other hand your build takes twenty minutes to complete, you
may be interested in investing some time getting the full dependency
tree correct in order to take advantage of multiple CPUs or cores.

Though Drake cannot fathom what <em>you</em> mean by a correct
dependency, there is a tool available which may help you get closer to
saying what you mean:

  % drake --rand[=SEED]

This will randomize the order of sibling prerequisites for each task.
When given the optional SEED string, it will call
<tt>srand(SEED.hash)</tt> to produce the same permutation each time.
The randomize option also disables +multitask+, making it a regular
+task+.  (In multi-threaded mode, +multitask+ is already a regular
+task+.)

Though this option may produce an error due to unspecified
dependencies, with SEED at least it will be an error which is exactly
the same on each run.  In addition you'll have the major debugging
advantage of using a single thread.

== Links

* Download: http://rubyforge.org/frs/?group_id=6530
* Documentation: http://drake.rubyforge.org
* Rubyforge home: http://rubyforge.org/projects/drake
* Repository: http://github.com/quix/rake

== Author

* James M. Lawrence <quixoticsycophant@gmail.com>

== License

Copyright (c) 2003, 2004 Jim Weirich

Copyright (c) 2008 James M. Lawrence

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

= RAKE -- Ruby Make -- <em>master branch</em>

Supporting Rake version: 0.8.4

This package contains Rake, a simple ruby build program with
capabilities similar to make.

Rake has the following features:

* Rakefiles (rake's version of Makefiles) are completely defined in
  standard Ruby syntax.  No XML files to edit.  No quirky Makefile
  syntax to worry about (is that a tab or a space?)

* Users can specify tasks with prerequisites.

* Rake supports rule patterns to synthesize implicit tasks.

* Flexible FileLists that act like arrays but know about manipulating
  file names and paths.

* A library of prepackaged tasks to make building rakefiles easier. For example,
  tasks for building tarballs, gems and RDoc output are provided.

* Supports parallel execution of tasks.


== Installation

=== Gem Installation

Download and install  rake with the following.

   gem install rake

=== Normal Installation

You can download the source tarball of the latest version of Rake from

* http://rubyforge.org/project/showfiles.php?group_id=50

Extract the tarball and run

  % ruby install.rb

from its distribution directory.

== Usage

=== Simple Example

First, you must write a "Rakefile" file which contains the build rules. Here's
a simple example:

  task :default => [:test]
  
  task :test do
    ruby "test/unittest.rb"
  end

This Rakefile has two tasks:

* A task named "test", which - upon invocation - will run a unit test file in
  Ruby.
* A task named "default". This task does nothing by itself, but it has exactly
  one dependency, namely the "test" task. Invoking the "default" task will
  cause Rake to invoke the "test" task as well.

Running the "rake" command without any options will cause it to run the
"default" task in the Rakefile:

  % ls
  Rakefile     test/
  % rake
  (in /home/some_user/Projects/rake)
  ruby test/unittest.rb
  ....unit test output here...

Type "rake --help" for all available options.


=== More Information

* For details on Rake's command-line invocation, read
  doc/command_line_usage.rdoc[http://rake.rubyforge.org/files/doc/command_line_usage_rdoc.html]
* For details on writing Rakefiles, see
  doc/rakefile.rdoc[http://rake.rubyforge.org/files/doc/rakefile_rdoc.html].
* For the original announcement of Rake, see
  doc/rational.rdoc[http://rake.rubyforge.org/files/doc/rational_rdoc.html].
* For a glossary of terms, see
  doc/glossary.rdoc[http://rake.rubyforge.org/files/doc/glossary_rdoc.html].


== Development

=== Source Repository

Rake is currently hosted at github. The github web page is
http://github.com/jimweirich/rake. The public git clone URL is

* git://github.com/jimweirich/rake.git

=== Running the Rake Test Suite

If you wish to run the unit and functional tests that come with Rake:

* Install the 'session' gem in order to run the functional tests.
* CD into the top project directory of rake.
* Type one of the following:

     rake                  # If you have a version of rake installed
     ruby -Ilib bin/rake   # If you do not have a version of rake installed.

=== Issues and Bug Reports

Bugs, features requests and other issues can be logged at

* http://onestepback.org/redmine/projects/show/rake

You will need an account to before you can post issues.  Register at
http://onestepback.org/redmine/account/register.  Or you can send me
an email (at jim dot weirich at gmail dot com)


== Online Resources

=== Rake References

* Rake Documentation Home: http://docs.rubyrake.org
* Rake Project Page: http://rubyforge.org/projects/rake
* Rake API Documents: http://rake.rubyforge.org
* Rake Source Code Repo:  http://github.com/jimweirich/rake
* Rake Git Repo Clone URL: git://github.com/jimweirich/rake.git

=== Presentations and Articles about Rake

* Jim Weirich's 2003 RubyConf presentation: http://onestepback.org/articles/buildingwithrake/
* Martin Fowler's article on Rake: http://martinfowler.com/articles/rake.html

== Other Make Reinvisionings ...

Rake is a late entry in the make replacement field.  Here are links to
other projects with similar (and not so similar) goals.

* http://directory.fsf.org/bras.html -- Bras, one of earliest
  implementations of "make in a scripting language".
* http://www.a-a-p.org -- Make in Python
* http://www.aromatic.com/tools/jam.txt -- JAM, Java Automated Make
* http://ant.apache.org -- The Ant project
* http://ppt.perl.org/commands/make/index.html -- Make from the Perl
  Power Tools implementation.
* http://search.cpan.org/search?query=PerlBuildSystem -- The Perl Build System
* http://make.rubyforge.org -- Rant, another Ruby make tool.

== Credits

[<b>Ryan Dlugosz</b>] For the initial conversation that sparked Rake.

[<b>nobu.nokada@softhome.net</b>] For the initial patch for rule support.

[<b>Tilman Sauerbeck <tilman@code-monkey.de></b>] For the recursive rule patch.

== License

Rake is available under an MIT-style license.

:include: MIT-LICENSE

== Support

The Rake homepage is http://rake.rubyforge.org.  You can find the Rake
RubyForge page at http://rubyforge.org/projects/rake.

Feel free to submit commits or feature requests.  If you send a patch,
remember to update the corresponding unit tests.  If fact, I prefer
new feature to be submitted in the form of new unit tests.

For other information, feel free to ask on the ruby-talk mailing list
(which is mirrored to comp.lang.ruby) or contact
jim dot weirich at gmail.com.

---

= Other stuff

Author::   Jim Weirich <jim.weirich@gmail.com>
Requires:: Ruby 1.8.0 or later
License::  Copyright 2003-2008 by Jim Weirich.
           Released under an MIT-style license.  See the LICENSE file
           included in the distribution.

== Warranty

This software is provided "as is" and without any express or
implied warranties, including, without limitation, the implied
warranties of merchantibility and fitness for a particular
purpose.