Use MAX_LOCK_TTL in RedisLockManager to avoid premature lock expiration

App servers should not lower the redis structure TTL of locks set
from CLI scripts, which is what would typically happen before if
they touched the same keys. Instead, keep a high lock record TTL
and rely on the logical TTLs for expiry semantics.

Change-Id: I2948369845c47d2682a85dd0564673f3b813be83

diff --git a/includes/libs/lockmanager/RedisLockManager.php b/includes/libs/lockmanager/RedisLockManager.php
index 6001705..ea9dde7 100644 (file)
--- a/includes/libs/lockmanager/RedisLockManager.php
+++ b/includes/libs/lockmanager/RedisLockManager.php
@@ -102,7 +102,7 @@ class RedisLockManager extends QuorumLockManager {
 <<<LUA
                        local failed = {}
                        -- Load input params (e.g. session, ttl, time of request)
-                       local rSession, rTTL, rTime = unpack(ARGV)
+                       local rSession, rTTL, rMaxTTL, rTime = unpack(ARGV)
                        -- Check that all the locks can be acquired
                        for i,requestKey in ipairs(KEYS) do
                                local _, _, rType, resourceKey = string.find(requestKey,"(%w+):(%w+)$")
@@ -133,7 +133,7 @@ class RedisLockManager extends QuorumLockManager {
                                        local _, _, rType, resourceKey = string.find(requestKey,"(%w+):(%w+)$")
                                        redis.call('hSet',resourceKey,rType .. ':' .. rSession,rTime + rTTL)
                                        -- In addition to invalidation logic, be sure to garbage collect
-                                       redis.call('expire',resourceKey,rTTL)
+                                       redis.call('expire',resourceKey,rMaxTTL)
                                end
                        end
                        return failed
@@ -144,7 +144,8 @@ LUA;
                                        [
                                                $this->session, // ARGV[1]
                                                $this->lockTTL, // ARGV[2]
-                                               time() // ARGV[3]
+                                               self::MAX_LOCK_TTL, // ARGV[3]
+                                               time() // ARGV[4]
                                        ]
                                ),
                                count( $pathsByKey ) # number of first argument(s) that are keys