From d6b84b3b79b4afbec3d6b1394cc95edc0b348436 Mon Sep 17 00:00:00 2001
From: Patrick J Cherry <patrick@bytemark.co.uk>
Date: Tue, 17 Feb 2015 21:04:52 +0000
Subject: fix the redis queue not to melt the cpu when polling redis for a job

---
 lib/custodian/queue.rb | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

(limited to 'lib')

diff --git a/lib/custodian/queue.rb b/lib/custodian/queue.rb
index 67c5346..9a7d90f 100644
--- a/lib/custodian/queue.rb
+++ b/lib/custodian/queue.rb
@@ -85,13 +85,28 @@ end
 
 
     #
-    #  Fetch a job from the queue - the timeout parameter is ignored.
+    #  Fetch a job from the queue.
+    #
+    #  The timeout is used to specify the period we wait for a new job.
     #
     def fetch(timeout)
-      job = false
-      while( ! job )
+      job = nil
+      timeout ||= 0
+
+      # 
+      # Don't melt the CPU.
+      #
+      sleep_interval = 0.5
+
+      loop do
         job = @redis.lpop( "queue" )
+        break if job or timeout < 0
+
+        sleep( sleep_interval )
+
+        timeout -= sleep_interval
       end
+
       return( job )
     end
 
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