Class: ZK::Server::SubProcess
Overview
This encapsulates the logic of running the zookeeper server, as a sub-process. It is intended that it will be stopped and started with the process that starts it. We are not going to do daemonized process management.
By default, we will create a directory in the current working directory called 'zk-server' to store our data under (configurable).
Instance Attribute Summary collapse
-
#child_startup_timeout ⇒ Object
how long should we wait for the child to start responding to 'ruok'?.
-
#status ⇒ Object
readonly
Returns the value of attribute status.
Attributes inherited from Base
Instance Method Summary collapse
- #alive? ⇒ Boolean
- #fork_and_exec! ⇒ Object protected
-
#initialize(opts = {}) ⇒ SubProcess
constructor
A new instance of SubProcess.
-
#join ⇒ Object
wait for sub-process to exit.
- #kill(signal) ⇒ Object
-
#pid ⇒ Object
the pid of our child process.
-
#run ⇒ false, true
start the child, using the Base#config.
-
#running? ⇒ Boolean
true if the process was started and is still running.
-
#shutdown ⇒ Object
shutdown the child, wait for it to exit, ensure it is dead.
- #spawn! ⇒ Object protected
- #spawn_exit_watching_thread ⇒ Object protected
-
#spawned? ⇒ Boolean
have we started the child process?.
-
#wait_for_pid(timeout = 2) ⇒ Object
protected
wait for up to timeout seconds to pass, polling for completion returns nil if the process didn't exit.
Methods inherited from Base
#clobber!, #create_files!, #ping?, #wait_until_ping, #write_log4j_properties!, #write_myid!, #write_zoo_cfg!
Methods included from Logging
Constructor Details
#initialize(opts = {}) ⇒ SubProcess
Returns a new instance of SubProcess.
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# File 'lib/zk-server/sub_process.rb', line 16 def initialize(opts={}) @exit_watching_thread = nil @pid = nil @status = nil super end |
Instance Attribute Details
#child_startup_timeout ⇒ Object
how long should we wait for the child to start responding to 'ruok'?
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# File 'lib/zk-server/sub_process.rb', line 14 def child_startup_timeout @child_startup_timeout end |
#status ⇒ Object (readonly)
Returns the value of attribute status.
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# File 'lib/zk-server/sub_process.rb', line 11 def status @status end |
Instance Method Details
#alive? ⇒ Boolean
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# File 'lib/zk-server/sub_process.rb', line 39 def alive? return false unless spawned? false|kill(0) rescue Errno::ESRCH false end |
#fork_and_exec! ⇒ Object (protected)
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# File 'lib/zk-server/sub_process.rb', line 158 def fork_and_exec! @pid ||= fork do # gah, use fork because 1.8.7 sucks 3.upto(255) do |fd| begin if io = IO.new(fd) io.close end rescue end end $stderr.puts "stdio_redirect_path: #{stdio_redirect_path.inspect}" $stdout.reopen($stderr) $stderr.reopen(stdio_redirect_path, 'a') exec(*command_args) end end |
#join ⇒ Object
wait for sub-process to exit
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# File 'lib/zk-server/sub_process.rb', line 26 def join @mutex.synchronize do logger.debug { "spawned process #{@pid}" } @exit_cond.wait_until { @status } end @status.success? end |
#kill(signal) ⇒ Object
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# File 'lib/zk-server/sub_process.rb', line 88 def kill(signal) raise "No pid yet!" unless @pid Process.kill(signal, @pid) end |
#pid ⇒ Object
the pid of our child process
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# File 'lib/zk-server/sub_process.rb', line 84 def pid @pid end |
#run ⇒ false, true
start the child, using the Base#config. we create the files necessary, fork the child, and wait 5s for the child to start responding to pings
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# File 'lib/zk-server/sub_process.rb', line 99 def run return false if @run_called @run_called = true create_files! if ZK::Server.mri_187? fork_and_exec! elsif ZK::Server.jruby? and not ZK::Server.ruby_19? raise "You must run Jruby in 1.9 compatibility mode! I'm very sorry, i need Kernel.spawn" else spawn! end spawn_exit_watching_thread unless wait_until_ping(@child_startup_timeout) raise "Oh noes! something went wrong!" unless running? end at_exit { self.shutdown } true end |
#running? ⇒ Boolean
true if the process was started and is still running
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# File 'lib/zk-server/sub_process.rb', line 35 def running? spawned? and !@status and alive? end |
#shutdown ⇒ Object
shutdown the child, wait for it to exit, ensure it is dead
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# File 'lib/zk-server/sub_process.rb', line 52 def shutdown if @pid return if @status @mutex.synchronize do %w[HUP TERM KILL].each do |signal| logger.debug { "sending #{signal} to #{@pid}" } return unless running? # jruby doesn't seem to get @status ? begin kill(signal) rescue Errno::ESRCH return true end @exit_cond.wait(5) # check running? on next pass end end unless @exit_watching_thread.join(3) == @exit_watching_thread logger.warn { "exit watching thread didn't exit after 3 sec" } end @pid = @exit_watching_thread = nil logger.debug { "@status: #{@status}" } end true end |
#spawn! ⇒ Object (protected)
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# File 'lib/zk-server/sub_process.rb', line 148 def spawn! @pid ||= ( args = command_args() args << { :err => [:child, :out], :out => [stdio_redirect_path, 'w'] } ::Kernel.spawn({}, *command_args).tap do |pid| logger.debug { "Spawned process #{pid}" } end ) end |
#spawn_exit_watching_thread ⇒ Object (protected)
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# File 'lib/zk-server/sub_process.rb', line 125 def spawn_exit_watching_thread @exit_watching_thread ||= Thread.new do _, @status = Process.wait2(@pid) @mutex.synchronize do @exit_cond.broadcast end end end |
#spawned? ⇒ Boolean
have we started the child process?
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# File 'lib/zk-server/sub_process.rb', line 47 def spawned? !!@pid end |
#wait_for_pid(timeout = 2) ⇒ Object (protected)
wait for up to timeout seconds to pass, polling for completion returns nil if the process didn't exit
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# File 'lib/zk-server/sub_process.rb', line 136 def wait_for_pid(timeout=2) times_up = timeout ? Time.now + timeout : 0 while Time.now < times_up pid, stat = ::Process.wait2(@pid, ::Process::WNOHANG) return stat if stat sleep(0.01) end nil end |