module Strelka::SignalHandling
A module containing signal-handling logic for the 'start' command line.
Public Instance Methods
Set all signal handlers to ignore.
# File lib/strelka/signal_handling.rb, line 90 def ignore_signals( *signals ) self.log.debug "Ignoring signals." signals.each do |sig| next if sig == :CHLD Signal.trap( sig, :IGNORE ) end end
Set the signal handlers back to their defaults.
# File lib/strelka/signal_handling.rb, line 100 def reset_signal_traps( *signals ) self.log.debug "Restoring default signal handlers." signals.each do |sig| Signal.trap( sig, :DEFAULT ) end end
Set up signal handlers for common signals that will shut down, restart, etc.
# File lib/strelka/signal_handling.rb, line 78 def set_signal_traps( *signals ) self.log.debug "Setting up deferred signal handlers." signals.each do |sig| Signal.trap( sig ) do Thread.main[:signal_queue] << sig self.wake_up end end end
Set up data structures for signal handling.
# File lib/strelka/signal_handling.rb, line 25 def set_up_signal_handling # Self-pipe for deferred signal-handling (ala djb: # http://cr.yp.to/docs/selfpipe.html) reader, writer = IO.pipe reader.close_on_exec = true writer.close_on_exec = true @selfpipe = { reader: reader, writer: writer } # Set up a global signal queue Thread.main[:signal_queue] = [] end
Simulate the receipt of the specified signal
(probably only useful in testing).
# File lib/strelka/signal_handling.rb, line 110 def simulate_signal( signal ) Thread.main[:signal_queue] << signal.to_sym self.wake_up end
The body of the signal handler. Wait for at least one signal to arrive and handle it, or timeout and return if a timeout
integer is provided. This should be called inside a loop, either in its own thread or in another loop that doesn't block anywhere else. Returns true if a signal was handled, or false if a timeout occurred.
# File lib/strelka/signal_handling.rb, line 43 def wait_for_signals( timeout=nil ) # Wait on the selfpipe for signals # self.log.debug " waiting for the selfpipe" fds = IO.select( [@selfpipe[:reader]], [], [], timeout ) begin rval = @selfpipe[:reader].read_nonblock( 11 ) self.log.debug " read from the selfpipe: %p" % [ rval ] rescue Errno::EAGAIN, Errno::EINTR => err # ignore end # Look for any signals that arrived and handle them while sig = Thread.main[:signal_queue].shift self.log.debug " got a queued signal: %p" % [ sig ] self.handle_signal( sig ) end return fds ? true : false end
Wake the main thread up through the self-pipe. Note: since this is a signal-handler method, it needs to be re-entrant.
# File lib/strelka/signal_handling.rb, line 67 def wake_up @selfpipe[:writer].write_nonblock('.') rescue Errno::EAGAIN # Ignore. rescue Errno::EINTR # Repeated signal. :TODO: Does this need a counter? retry end
Wrap a block in signal-handling.
# File lib/strelka/signal_handling.rb, line 11 def with_signal_handler( *signals ) self.set_up_signal_handling self.set_signal_traps( *signals ) self.start_signal_handler return yield ensure self.stop_signal_handler self.reset_signal_traps( *signals ) end