fix(redis): re-cache script if redis has restarted (#51)

keiko-redis/src/main/kotlin/com/netflix/spinnaker/q/redis/RedisQueue.kt

@@ -50,6 +50,7 @@ import redis.clients.jedis.Jedis
 import redis.clients.jedis.JedisCommands
 import redis.clients.jedis.ScriptingCommands
 import redis.clients.jedis.Transaction
+import redis.clients.jedis.exceptions.JedisDataException
 import redis.clients.jedis.params.sortedset.ZAddParams.zAddParams
 import redis.clients.util.Pool
 import java.io.IOException
@@ -93,10 +94,14 @@ class RedisQueue(
   private lateinit var readMessageWithLockScriptSha: String
 
   init {
+    cacheScript()
+    log.info("Configured queue: $queueName")
+  }
+
+  fun cacheScript() {
     pool.resource.use { redis ->
       readMessageWithLockScriptSha = redis.scriptLoad(READ_MESSAGE_WITH_LOCK_SRC)
     }
-    log.info("Configured queue: $queueName")
   }
 
   override fun poll(callback: (Message, () -> Unit) -> Unit) {
@@ -321,29 +326,38 @@ class RedisQueue(
   }
 
   private fun ScriptingCommands.readMessageWithLock(): Triple<String, Instant, String?>? {
-    val response = evalsha(readMessageWithLockScriptSha, listOf(
-      queueKey,
-      unackedKey,
-      locksKey,
-      messagesKey
-    ), listOf(
-      score().toString(),
-      10.toString(), // TODO rz - make this configurable.
-      lockTtlSeconds.toString(),
-      format(Locale.US, "%f", score(ackTimeout)),
-      format(Locale.US, "%f", score())
-    ))
-    if (response is List<*>) {
-      return Triple(
-        response[0].toString(), // fingerprint
-        Instant.ofEpochMilli(response[1].toString().toLong()), // fingerprintScore
-        response[2]?.toString() // message
-      )
-    }
-    if (response == "ReadLockFailed") {
-      // This isn't a "bad" thing, but means there's more work than keiko can process in a cycle
-      // in this case, but may be a signal to tune `peekFingerprintCount`
-      fire(LockFailed)
+    try {
+      val response = evalsha(readMessageWithLockScriptSha, listOf(
+        queueKey,
+        unackedKey,
+        locksKey,
+        messagesKey
+      ), listOf(
+        score().toString(),
+        10.toString(), // TODO rz - make this configurable.
+        lockTtlSeconds.toString(),
+        format(Locale.US, "%f", score(ackTimeout)),
+        format(Locale.US, "%f", score())
+      ))
+      if (response is List<*>) {
+        return Triple(
+          response[0].toString(), // fingerprint
+          Instant.ofEpochMilli(response[1].toString().toLong()), // fingerprintScore
+          response[2]?.toString() // message
+        )
+      }
+      if (response == "ReadLockFailed") {
+        // This isn't a "bad" thing, but means there's more work than keiko can process in a cycle
+        // in this case, but may be a signal to tune `peekFingerprintCount`
+        fire(LockFailed)
+      }
+    } catch (e: JedisDataException) {
+      if ((e.message ?: "").startsWith("NOSCRIPT")) {
+        cacheScript()
+        return readMessageWithLock()
+      } else {
+        throw e
+      }
     }
     return null
   }