# A concurrent variant to the standard `Collection`
abstract class ConcurrentCollection[E]
	super Collection[E]

	# Type of the equivalent non thread-safe collection
	type REAL: Collection[E]

	# Collection wrapped by `self`
	var real_collection: REAL is noinit

	# `Mutex` used to synchronize access to `self`
	#
	# It is used by the implementation on each protected methods. It can also
	# be used externally to ensure that no other `Thread` modify this object.
	var mutex = new Mutex

	redef fun count(e)
	do
		mutex.lock
		var r = real_collection.count(e)
		mutex.unlock
		return r
	end

	redef fun first
	do
		mutex.lock
		var r = real_collection.first
		mutex.unlock
		return r
	end

	redef fun has(e)
	do
		mutex.lock
		var r = real_collection.has(e)
		mutex.unlock
		return r
	end

	redef fun has_all(e)
	do
		mutex.lock
		var r = real_collection.has_all(e)
		mutex.unlock
		return r
	end

	redef fun has_only(e)
	do
		mutex.lock
		var r = real_collection.has_only(e)
		mutex.unlock
		return r
	end

	redef fun is_empty
	do
		mutex.lock
		var r = real_collection.is_empty
		mutex.unlock
		return r
	end

	redef fun iterator
	do
		mutex.lock
		var r = real_collection.iterator
		mutex.unlock
		return r
	end

	redef fun length
	do
		mutex.lock
		var r = real_collection.length
		mutex.unlock
		return r
	end

	redef fun to_a
	do
		mutex.lock
		var r = real_collection.to_a
		mutex.unlock
		return r
	end

	redef fun rand
	do
		mutex.lock
		var r = real_collection.rand
		mutex.unlock
		return r
	end

	redef fun join(sep, last_sep)
	do
		mutex.lock
		var r = real_collection.join(sep, last_sep)
		mutex.unlock
		return r
	end

	redef fun to_s
	do
		mutex.lock
		var r = real_collection.to_s
		mutex.unlock
		return r
	end
end