Merge pull request #29 from seamusabshere/recover-function

recover from SCRIPT FLUSH

lib/redlock/client.rb

@@ -102,11 +102,15 @@ def initialize(connection)
       end
 
       def lock(resource, val, ttl)
-        @redis.evalsha(@lock_script_sha, keys: [resource], argv: [val, ttl])
+        recover_from_script_flush do
+          @redis.evalsha @lock_script_sha, keys: [resource], argv: [val, ttl]
+        end
       end
 
       def unlock(resource, val)
-        @redis.evalsha(@unlock_script_sha, keys: [resource], argv: [val])
+        recover_from_script_flush do
+          @redis.evalsha @unlock_script_sha, keys: [resource], argv: [val]
+        end
       rescue
         # Nothing to do, unlocking is just a best-effort attempt.
       end
@@ -117,6 +121,19 @@ def load_scripts
         @unlock_script_sha = @redis.script(:load, UNLOCK_SCRIPT)
         @lock_script_sha = @redis.script(:load, LOCK_SCRIPT)
       end
+
+      def recover_from_script_flush
+        tries = 0
+        yield
+      rescue Redis::CommandError
+        if $!.message.include?('NOSCRIPT') and tries == 0
+          load_scripts
+          tries += 1
+          retry
+        else
+          raise $!
+        end
+      end
     end
 
     def try_lock_instances(resource, ttl, extend)

spec/client_spec.rb

@@ -175,4 +175,25 @@
       end
     end
   end
+
+  describe 'after SCRIPT FLUSH' do
+    let(:server) { Redis.new }
+    it 'recovers lock function' do
+      lock_info = lock_manager.lock('a', ttl)
+      expect(lock_info).to be_lock_info_for('a')
+      server.script :flush
+      lock_info = lock_manager.lock('b', ttl)
+      expect(lock_info).to be_lock_info_for('b')
+    end
+
+    it 'recovers unlock function' do
+      lock_info = lock_manager.lock(resource_key, ttl)
+      lock_manager.unlock(lock_info)
+      expect(resource_key).to be_lockable(lock_manager, ttl)
+      server.script :flush
+      lock_info = lock_manager.lock(resource_key, ttl)
+      lock_manager.unlock(lock_info)
+      expect(resource_key).to be_lockable(lock_manager, ttl)
+    end
+  end
 end