# Slave-1.0.0 **URL:** \ **Category:** Ruby\ **Created:** [October 13, 2006, 9:32pm UTC](https://www.ruby-forum.com/t/slave-1-0-0/72047 "2006-10-13T21:32:49Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![unknown](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/u/4bbf92/32.png) [@unknown](https://www.ruby-forum.com/u/unknown)\ **Post date:** [October 13, 2006, 9:32pm UTC](https://www.ruby-forum.com/t/slave-1-0-0/72047/1 "2006-10-13T21:32:49Z")
\*\* PLEASE NOTE THAT THIS IS A DEVELOPMENTAL RELEASE \*\* SYNOPSIS the Slave class forks a process and starts a drb server in the child using any object as the server. the process is detached so it is not required (nor possible) to wait on the child pid. a Heartbeat is set up between the parent and child processes so that the child will exit of the parent exits for any reason - preventing orphaned slaves from running indefinitely. the purpose of Slaves is to be able to easily set up a collection of objects communicating via drb protocols instead of having to use IPC. typical usage: ``` obj = AnyClass::new slave = Slave::new 'object' => obj p slave.object # handle on drb object p slave.uri # uri of the drb object p slave.socket # unix domain socket path for drb ``` object p slave.psname # title shown in ps/top slaves may be configured via the environment, the Slave class, or via the ctor for object itself. attributes which may be configured include ``` * socket_creation_attempts * pulse_rate * psname * debug * dumped ``` URIS [http://rubyforge.org/projects/codeforpeople/](http://rubyforge.org/projects/codeforpeople/) [http://codeforpeople.com/lib/ruby/slave](http://codeforpeople.com/lib/ruby/slave) HISTORY THIS RELEASE IS !! NOT !! BACKWARD COMPATIBLE. NOTE NEW CTOR SYNTAX. 1.0.0: ``` - detach method also sets up at_exit handler. extra protection ``` from zombies. ``` - ezra zygmuntowicz asked for a feature whereby a parent could be ``` notified when a child exited. obviously such a mechanism should be both async and sync. to accomplish this the wait method was extended to support a callback with is either sync or async ``` slave = Server.new{ Server.new } slave.wait and puts 'this is sync!' slave.wait(:non_block=>true){ 'this is async!' } - patch to getval from skaar. the impl dropped ``` opts delgating to the class method from the instance one. SAMPLES \<========\< samples/a.rb \>========\> ~ \> cat samples/a.rb ``` require 'slave' # # simple usage is simply to stand up a server object as a slave. ``` you do not # need to wait for the server, join it, etc. it will die when the parent # process dies - even under ‘kill -9’ conditions # class Server def add\_two n n + 2 end end ``` slave = Slave.new :object => Server.new server = slave.object p server.add_two(40) #=> 42 ``` ~ \> ruby samples/a.rb ``` 42 ``` \<========\< samples/b.rb \>========\> ~ \> cat samples/b.rb ``` require 'slave' # # if certain operations need to take place in the child only a ``` block can be # used # class Server def connect\_to\_db “we only want to do this in the child process!” @connection = :postgresql end attr :connection end ``` slave = Slave.new('object' => Server.new){|s| s.connect_to_db} server = slave.object p server.connection #=> :postgresql # # errors in the child are detected and raised in the parent # slave = Slave.new('object' => Server.new){|s| s.typo} #=> raises ``` an error! ~ \> ruby samples/b.rb ``` :postgresql ./lib/slave.rb:276:in `initialize': undefined method `typo' for ``` #Server:0xb7573350 (NoMethodError) from samples/b.rb:22:in `new’ from samples/b.rb:22 \<========\< samples/c.rb \>========\> ~ \> cat samples/c.rb ``` require 'slave' # # if no slave object is given the block itself is used to contruct ``` it # class Server def initialize “this is run only in the child” @pid = Process.pid end attr ‘pid’ end ``` slave = Slave.new{ Server.new } server = slave.object p Process.pid p server.pid # not going to be the same as parents! # # errors are still detected though # slave = Slave.new{ fubar } # raises error in parent ``` ~ \> ruby samples/c.rb ``` 12244 12245 ./lib/slave.rb:276:in `initialize': undefined local variable or ``` method `fubar' for main:Object (NameError) from samples/c.rb:21:in `new’ from samples/c.rb:21 \<========\< samples/d.rb \>========\> ~ \> cat samples/d.rb ``` require 'slave' # # at_exit hanlders are handled correctly in both child and parent # at_exit{ p 'parent' } slave = Slave.new{ at_exit{ p 'child' }; 'the server is this ``` string’ } # # this will print ‘child’, then ‘parent’ # ~ \> ruby samples/d.rb ``` "child" "parent" ``` \<========\< samples/e.rb \>========\> ~ \> cat samples/e.rb ``` require 'slave' # # slaves never outlive their parent. if the parent exits, even ``` under kill -9, # the child will die. # slave = Slave.new{ at\_exit{ p ‘child’ }; ‘the server is this string’ } ``` Process.kill brutal=9, the_parent_pid=Process.pid # # even though parent dies a nasty death the child will still print ``` ‘child’ # ~ \> ruby samples/e.rb ``` "child" ``` enjoy. -a ---
**Author:** ![unknown](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/u/4bbf92/32.png) [@unknown](https://www.ruby-forum.com/u/unknown)\ **Post date:** [October 13, 2006, 10:21pm UTC](https://www.ruby-forum.com/t/slave-1-0-0/72047/2 "2006-10-13T22:21:10Z")
Hi Ara- On Oct 13, 2006, at 12:30 PM, removed\_email\_address@domain.invalid wrote: > ``` > and sync. to accomplish this the wait method was extended to > > ``` > > support a > callback with is either sync or async > > ``` > slave = Server.new{ Server.new } > > slave.wait and puts 'this is sync!' > > slave.wait(:non_block=>true){ 'this is async!' } > > ``` Awesome thanks Ara! > ``` > # used > > server = slave.object > > p server.connection #=> :postgresql > > ``` ``` This part if killer too. Very nice to be able to run the block in ``` the child! I am getting a ton of use out of Slave. Thanks for the killer library. Cheers- -Ezra ---
**Author:** ![unknown](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/u/4bbf92/32.png) [@unknown](https://www.ruby-forum.com/u/unknown)\ **Post date:** [October 13, 2006, 10:29pm UTC](https://www.ruby-forum.com/t/slave-1-0-0/72047/3 "2006-10-13T22:29:12Z")
On Sat, 14 Oct 2006, Ezra Z. wrote: > Awesome thanks Ara! no prob - it was a good idea > This part if killer too. Very nice to be able to run the block in the > child! I am getting a ton of use out of Slave. Thanks for the killer library. great! test this one out though - i made quite few small changes, and you know how that goes! let me know what you find… have a good weekend. -a