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# Wraps a Worker object in a process-wide commanline handler. Once the `start` method is
# called, signal handlers will be installed for the following signals:
#
# * `TERM`, `USR1` - will soft-terminate the worker (let all the threads complete and die)
# * `KILL` - will hard-kill all the threads
# * `INFO` - will print backtraces and variables of all the Worker threads to STDOUT
module Sqewer::CLI
# Start the commandline handler, and set up a centralized signal handler that reacts
# to USR1 and TERM to do a soft-terminate on the worker.
#
# @param worker[Sqewer::Worker] the worker to start. Must respond to `#start` and `#stop`
# @return [void]
def start(worker = Sqewer::Worker.default)
# Use a self-pipe to accumulate signals in a central location
self_read, self_write = IO.pipe
%w(INT TERM USR1 USR2 INFO TTIN).each do |sig|
begin
trap(sig) { self_write.puts(sig) }
rescue ArgumentError
# Signal not supported
end
end
begin
worker.start
# The worker is non-blocking, so in the main CLI process we select() on the signal
# pipe and handle the signal in a centralized fashion
while (readable_io = IO.select([self_read]))
signal = readable_io.first[0].gets.strip
handle_signal(worker, signal)
end
rescue Interrupt
worker.stop
exit 1
end
end
def handle_signal(worker, sig)
case sig
when 'USR1', 'TERM'
worker.stop
exit 0
when 'INFO' # a good place to print the worker status
worker.debug_thread_information!
else
raise Interrupt
end
end
extend self
end
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25 entries across 25 versions & 1 rubygems