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|
#
# Attempt to load the Redis-library.
#
# Without this we cannot connect to our queue.
#
%w( redis ).each do |library|
begin
require library
rescue LoadError
puts("Failed to load the #{library} library - queue access will fail!")
end
end
module Custodian
#
# An abstraction layer for our queue.
#
class QueueType
#
# Retrieve a job from the queue.
#
def fetch(_timeout)
raise 'Subclasses must implement this method!'
end
#
# Add a new job to the queue.
#
def add(_job_string)
raise 'Subclasses must implement this method!'
end
#
# Get the size of the queue
#
def size?
raise 'Subclasses must implement this method!'
end
#
# Empty the queue
#
def flush!
raise 'Subclasses must implement this method!'
end
end
#
# This is a simple queue which uses Redis for storage.
#
class RedisQueueType < QueueType
#
# Connect to the server on localhost, unless QUEUE_ADDRESS is set.
#
def initialize
host = ENV['QUEUE_ADDRESS'] || '127.0.0.1'
@redis = Redis.new(:host => host)
end
#
# Fetch a job from the queue.
#
# The timeout is used to specify the period we wait for a new job, and
# we pause that same period between fetches.
#
def fetch(timeout = 1)
job = nil
loop do
# Get a random job
job = @redis.spop('custodian_queue')
# If that worked return it
if !job.nil?
return job
else
sleep(timeout)
end
end
end
#
# Add a new job to the queue.
#
def add(test)
# Add unless already present
@redis.sadd('custodian_queue', test) unless
( @redis.sismember( 'custodian_queue', test ) )
end
#
# How many jobs in the queue?
#
def size?
@redis.zcard('custodian_queue')
end
#
# Empty the queue, discarding all pending jobs.
#
def flush!
@redis.del('custodian_queue')
end
end
end
|
