From 53152a824f5186452504f0b68306d10ebebee416 Mon Sep 17 00:00:00 2001
From: Sebastian Thiel <byronimo@gmail.com>
Date: Tue, 8 Jun 2010 14:23:58 +0200
Subject: queue: adjusted queue to be closable ( without own testing yet,
 except for the pool which runs it ) - its not yet stable, but should be
 solvable.

---
 lib/git/async/util.py | 68 ++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 48 insertions(+), 20 deletions(-)

(limited to 'lib/git/async/util.py')

diff --git a/lib/git/async/util.py b/lib/git/async/util.py
index 01073f6d..51219cc4 100644
--- a/lib/git/async/util.py
+++ b/lib/git/async/util.py
@@ -166,15 +166,21 @@ class _AsyncQueue(Queue):
 		self.not_full = HSCondition(self.mutex)
 		self.all_tasks_done = HSCondition(self.mutex)
 
-	
+
+class ReadOnly(Exception):
+	"""Thrown when trying to write to a read-only queue"""
+
 class AsyncQueue(Queue):
-	"""A queue using different condition objects to gain multithreading performance"""
-	__slots__ = ('mutex', 'not_empty', 'queue')
+	"""A queue using different condition objects to gain multithreading performance.
+	Additionally it has a threadsafe writable flag, which will alert all readers
+	that there is nothing more to get here."""
+	__slots__ = ('mutex', 'not_empty', 'queue', '_writable')
 	
 	def __init__(self, maxsize=0):
 		self.queue = deque()
 		self.mutex = Lock()
 		self.not_empty = HSCondition(self.mutex)
+		self._writable = True
 		
 	def qsize(self):
 		self.mutex.acquire()
@@ -183,6 +189,29 @@ class AsyncQueue(Queue):
 		finally:
 			self.mutex.release()
 
+	def writable(self):
+		self.mutex.acquire()
+		try:
+			return self._writable
+		finally:
+			self.mutex.release()
+
+	def set_writable(self, state):
+		"""Set the writable flag of this queue to True or False
+		:return: The previous state"""
+		self.mutex.acquire()
+		try:
+			old = self._writable
+			self._writable = state
+			return old
+		finally:
+			# if we won't receive anymore items, inform the getters
+			if not state:
+				self.not_empty.notify_all()
+			# END tell everyone
+			self.mutex.release()
+		# END handle locking
+
 	def empty(self):
 		self.mutex.acquire()
 		try:
@@ -192,6 +221,9 @@ class AsyncQueue(Queue):
 
 	def put(self, item, block=True, timeout=None):
 		self.mutex.acquire()
+		if not self._writable:
+			raise ReadOnly
+		# END handle read-only
 		self.queue.append(item)
 		self.mutex.release()
 		self.not_empty.notify()
@@ -200,24 +232,20 @@ class AsyncQueue(Queue):
 		self.not_empty.acquire()	# == self.mutex.acquire in that case
 		q = self.queue
 		try:
-			if not block:
-				if not len(q):
-					raise Empty
-			elif timeout is None:
-				while not len(q):
-					self.not_empty.wait()
-			else:
-				print "with timeout", timeout
-				import traceback
-				traceback.print_stack()
-				endtime = _time() + timeout
-				while not len(q):
-					remaining = endtime - _time()
-					if remaining <= 0.0:
-						raise Empty
-					self.not_empty.wait(remaining)
+			if block:
+				if timeout is None:
+					while not len(q) and self._writable:
+						self.not_empty.wait()
+				else:
+					endtime = _time() + timeout
+					while not len(q) and self._writable:
+						remaining = endtime - _time()
+						if remaining <= 0.0:
+							raise Empty
+						self.not_empty.wait(remaining)
+				# END handle timeout mode
 			# END handle block
-			# can happen if someone else woke us up
+			# can happen if we woke up because we are not writable anymore
 			try:
 				return q.popleft()
 			except IndexError:
-- 
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