Fixed acquireForMe() bug in the redis module

* Previously, blocked callers (due to no slots being open) would just timeout
  instead of getting unblocked when the slot holder released the slot.

Change-Id: I67e328ca8bc1ccfb77d1ba0a753c37de3c459021

diff --git a/includes/poolcounter/PoolCounterRedis.php b/includes/poolcounter/PoolCounterRedis.php
index 093fe49..2b37b0b 100644 (file)
--- a/includes/poolcounter/PoolCounterRedis.php
+++ b/includes/poolcounter/PoolCounterRedis.php
@@ -154,8 +154,12 @@ class PoolCounterRedis extends PoolCounter {
                if rSlot ~= 'w' and redis.call('exists',kSlotsNextRelease) == 1 then
                        if 1*redis.call('zScore',kSlotsNextRelease,rSlot) ~= (rSlotTime + rExpiry) then
                                -- Slot lock expired and was released already
-                       elseif redis.call('lLen',kSlots) >= (1*rMaxWorkers - 1) then
-                               -- Clear list to save space; it will re-init as needed
+                       elseif redis.call('lLen',kSlots) >= 1*rMaxWorkers then
+                               -- Slots somehow got out of sync; reset the list for sanity
+                               redis.call('del',kSlots,kSlotsNextRelease)
+                       elseif redis.call('lLen',kSlots) == (1*rMaxWorkers - 1) and redis.call('zCard',kWaiting) == 0 then
+                               -- Slot list will be made full; clear it to save space (it re-inits as needed)
+                               -- since nothing is waiting on being unblocked by a push to the list
                                redis.call('del',kSlots,kSlotsNextRelease)
                        else
                                -- Add slot back to pool and update the "next release" time