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Contents
module Toaster
#
# Simple implementation of a map with thread-safe blocking operations:
# - put(key, value): put a value to the map
# - get(key): get a value from the map, do not remove value
# - take(key): get a value from the map, remove value afterwards
#
# Author: Waldemar Hummer (hummer@dsg.tuwien.ac.at)
#
class BlockingMap
def initialize()
@hash = {}
@semaphore = Mutex.new
@signal = ConditionVariable.new
end
#
# Put a value to the map, notifying waiting threads of new value
#
def put(key, value)
@semaphore.synchronize do
@hash[key] = value
@signal.signal
end
end
#
# Get a value from the map. Blocks until a value with the given key becomes available.
#
def get(key)
return do_get(key, false)
end
#
# Get a value from the map. Blocks until a value with the given key becomes available.
# This operation emoves the value from the map.
#
def take(key)
return do_get(key, true)
end
private
def do_get(key, delete = false)
error_count = 0
while true
begin
@semaphore.synchronize do
# try to get immediately
if @hash.include?(key)
value = @hash[key]
@hash.delete(key) if delete
return value
end
# wait until new value has been added
@signal.wait(@semaphore)
# try to get again
if @hash.include?(key)
value = @hash[key]
@hash.delete(key) if delete
return value
end
end
rescue Exception => ex
puts "WARN: #{ex}\n#{ex.backtrace.join("\n")}"
error_count += 1
if error_count >= 5
raise "Tried 5 times to get value from Toaster::BlockingMap, giving up..."
end
sleep(1)
end
end
end
end
end
Version data entries
5 entries across 5 versions & 1 rubygems