FIFO Locks

1 files changed, 19 insertions, 0 deletions

diff --git a/realtime/rt/util.py b/realtime/rt/util.py
index 6e07f116..05dcae96 100644
--- a/realtime/rt/util.py
+++ b/realtime/rt/util.py
@@ -1,4 +1,5 @@
 import os
+import Queue
 import subprocess
 import sys
 import threading
@@ -13,6 +14,24 @@ SA_INI_FILES = set((
     'precompute_file',
     ))
 
+class FIFOLock:
+
+    def __init__(self):
+        self.q = Queue.Queue()
+        self.i = 0
+
+    def acquire(self):
+        self.i += 1
+        if self.i > 1:
+            event = threading.Event()
+            self.q.put(event)
+            event.wait()
+
+    def release(self):
+        self.i -= 1
+        if self.i > 0:
+            self.q.get().set()
+
 def cdec_ini_for_config(config):
     # This is a list of (k, v), not a ConfigObj or dict
     for i in range(len(config)):