From: BlackMinou <romain.chanoir@viacesi.fr>
Date: Mon, 8 May 2017 02:03:39 +0000 (-0400)
Subject: Move `BlockingQueue` and `ReverseBlockingQueue` to `concurrent_collection`
X-Git-Url: http://nitlanguage.org

Move `BlockingQueue` and `ReverseBlockingQueue` to `concurrent_collection`

Signed-off-by: BlackMinou <romain.chanoir@viacesi.fr>
---

diff --git a/lib/pthreads/concurrent_collections.nit b/lib/pthreads/concurrent_collections.nit
index e0c53af..3c5ae98 100644
--- a/lib/pthreads/concurrent_collections.nit
+++ b/lib/pthreads/concurrent_collections.nit
@@ -508,3 +508,76 @@ class ConcurrentList[E]
 		return value
 	end
 end
+
+# A collection which `is_empty` method blocks until it's empty
+class ReverseBlockingQueue[E]
+	super ConcurrentList[E]
+
+	# Used to block or signal on waiting threads
+	private var cond = new PthreadCond
+
+	# Adding the signal to release eventual waiting thread(s)
+	redef fun push(e) do
+		mutex.lock
+		real_collection.push(e)
+		mutex.unlock
+	end
+
+	# When the Queue is empty, signal any possible waiting thread
+	redef fun remove(e) do
+		mutex.lock
+		real_collection.remove(e)
+		if real_collection.is_empty then cond.signal
+		mutex.unlock
+	end
+
+	# Wait until the Queue is empty
+	redef fun is_empty do
+		mutex.lock
+		while not real_collection.is_empty do self.cond.wait(mutex)
+		mutex.unlock
+		return true
+	end
+end
+
+# A Blocking queue implemented from a `ConcurrentList`
+# `shift` is blocking if there isn't any element in `self`
+# `push` or `unshift` releases every blocking threads
+class BlockingQueue[E]
+	super ConcurrentList[E]
+
+	# Used to block or signal on waiting threads
+	private var cond = new PthreadCond
+
+	# Adding the signal to release eventual waiting thread(s)
+	redef fun push(e) do
+		mutex.lock
+		real_collection.push(e)
+		self.cond.signal
+		real_collection.push(e)
+		mutex.unlock
+	end
+
+	redef fun unshift(e) do
+		mutex.lock
+		real_collection.unshift(e)
+		self.cond.signal
+		mutex.unlock
+	end
+
+	# If empty, blocks until an item is inserted with `push` or `unshift`
+	redef fun shift do
+		mutex.lock
+		while real_collection.is_empty do self.cond.wait(mutex)
+		var r = real_collection.shift
+		mutex.unlock
+		return r
+	end
+
+	redef fun is_empty do
+		mutex.lock
+		var r = real_collection.is_empty
+		mutex.unlock
+		return r
+	end
+end