Merge the RetryingRWStore to RetryingStore.

storehaus-core/src/main/scala/com/twitter/storehaus/RetryingStore.scala

@@ -16,6 +16,7 @@
 
 package com.twitter.storehaus
 
+import com.twitter.conversions.time._
 import com.twitter.util.{ Duration, Future, Return, Throw, Timer }
 
 /**
@@ -52,6 +53,35 @@ class RetryingReadableStore[-K, +V](store: ReadableStore[K, V], backoffs: Iterab
 class RetryingStore[-K, V](store: Store[K, V], backoffs: Iterable[Duration])(pred: Option[V] => Boolean)(implicit timer: Timer)
   extends RetryingReadableStore[K, V](store, backoffs)(pred)
   with Store[K, V] {
-  override def put(kv: (K, Option[V])) = store.put(kv)
-  override def multiPut[K1 <: K](kvs: Map[K1, Option[V]]): Map[K1, Future[Unit]] = store.multiPut(kvs)
+
+  private val padded_backoffs = backoffs ++ Seq(0.second)
+
+  private def find[T](futures: Iterator[(Future[T], Duration)])(pred: T => Boolean): Future[T] = {
+    if (!futures.hasNext) {
+      Future.exception(new RuntimeException("RetryingRWStore: empty iterator in function find"))
+    } else {
+      val (next, delay) = futures.next()
+      if (!futures.hasNext) {
+        next
+      } else {
+        next.filter(pred).rescue {
+          case e: Exception =>
+            timer.doLater(delay)(()) flatMap { _ =>
+              find(futures)(pred)
+            }
+        }
+      }
+    }
+  }
+
+  override def multiPut[K1 <: K](kvs: Map[K1, Option[V]]): Map[K1, Future[Unit]] = {
+    store.multiPut(kvs) map { case (k, future) =>
+      val retryStream = (Iterator(future) ++ Iterator.continually { store.put((k, kvs(k)))})
+          .zip(padded_backoffs.iterator)
+      (k, find(retryStream) { t => true })
+    }
+  }
+
+  override def put(kv: (K, Option[V])) = multiPut(Map(kv)).apply(kv._1)
 }
+