IterableStore

project/Build.scala

@@ -118,7 +118,7 @@ object StorehausBuild extends Build {
 
   val algebirdVersion = "0.3.1"
   val bijectionVersion = "0.6.0"
-  val utilVersion = "6.3.7"
+  val utilVersion = "6.11.0"
   val scaldingVersion = "0.9.0rc4"
 
   lazy val storehaus = Project(

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

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2013 Twitter Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License. You may obtain
+ * a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.twitter.storehaus
+
+import com.twitter.util.{ Future, Promise, Return }
+import com.twitter.concurrent.Spool
+import com.twitter.concurrent.Spool.*::
+
+object IterableStore {
+  /** Factory method to create a IterableStore from a Map. */
+  def fromMap[K, V](m: Map[K, V]): IterableStore[K, V] = new MapStore(m)
+
+  /** Helper method to convert Iterator to Spool. */
+  def iteratorToSpool[K, V](it: Iterator[(K, V)]): Future[Spool[(K, V)]] = Future.value {
+    if (it.hasNext)
+      // *:: for lazy/deferred tail
+      it.next *:: iteratorToSpool(it)
+    else
+      Spool.empty
+  }
+}
+import IterableStore._
+
+/**
+ * Trait for stores that allow iterating over their key-value pairs.
+ */
+trait IterableStore[+K, +V] {
+
+  /** Returns a lazy Spool that wraps the store's keyspace. */
+  def getAll: Future[Spool[(K, V)]] =
+    multiGetAll.flatMap { batchSpool =>
+      batchSpool.flatMap { seq =>
+        iteratorToSpool(seq.iterator)
+      }
+    }
+
+  /** Batched version of getAll. Useful for paging stores. */
+  def multiGetAll: Future[Spool[Seq[(K, V)]]] =
+    getAll.map { spool =>
+      spool.map(Seq(_))
+    }
+}
+

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

@@ -23,6 +23,9 @@ import com.twitter.util.Future
  *  @author Oscar Boykin
  *  @author Sam Ritchie
  */
-class MapStore[K, +V](val backingStore: Map[K, V] = Map[K, V]()) extends ReadableStore[K, V] {
+class MapStore[K, +V](val backingStore: Map[K, V] = Map[K, V]()) extends ReadableStore[K, V]
+    with IterableStore[K, V] {
   override def get(k: K) = Future.value(backingStore.get(k))
+
+  override def getAll = IterableStore.iteratorToSpool(backingStore.iterator)
 }

storehaus-core/src/test/scala/com/twitter/storehaus/IterableStoreProperties.scala

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2013 Twitter Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License. You may obtain
+ * a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.twitter.storehaus
+
+import com.twitter.util.{ Await, Future }
+
+import org.scalacheck.{ Arbitrary, Properties }
+import org.scalacheck.Gen.choose
+import org.scalacheck.Prop._
+
+object IterableStoreProperties extends Properties("IterableStore") {
+
+  def iterableStoreLaw[K: Arbitrary, V: Arbitrary](fn: Map[K, V] => IterableStore[K, V]) =
+    forAll { m: Map[K,V] =>
+      val store = fn(m)
+      Await.result(store.getAll.flatMap { _.toSeq }).toMap == m
+    }
+
+  property("MapStore obeys the IterableStore laws") = {
+    iterableStoreLaw[Int, String](IterableStore.fromMap(_))
+  }
+}
+