From 66cbe8c56d72edeca33bd39bf5063cab54ab9a4a Mon Sep 17 00:00:00 2001
From: Andras Slemmer <andras.slemmer@r3cev.com>
Date: Wed, 21 Feb 2018 15:56:29 +0000
Subject: [PATCH] CORDA-1043

---
 .../main/kotlin/net/corda/core/flows/FlowLogic.kt  |  4 ++--
 .../kotlin/net/corda/core/flows/FlowTestsUtils.kt  |  3 +--
 docs/source/api-flows.rst                          |  7 +++++++
 .../src/main/kotlin/net/corda/docs/FlowCookbook.kt | 14 ++++++++++++++
 4 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/core/src/main/kotlin/net/corda/core/flows/FlowLogic.kt b/core/src/main/kotlin/net/corda/core/flows/FlowLogic.kt
index 6b92c533ab..c0a369a730 100644
--- a/core/src/main/kotlin/net/corda/core/flows/FlowLogic.kt
+++ b/core/src/main/kotlin/net/corda/core/flows/FlowLogic.kt
@@ -232,7 +232,7 @@ abstract class FlowLogic<out T> {
      * @returns a [Map] containing the objects received, wrapped in an [UntrustworthyData], by the [FlowSession]s who sent them.
      */
     @Suspendable
-    open fun receiveAll(sessions: Map<FlowSession, Class<out Any>>): Map<FlowSession, UntrustworthyData<Any>> {
+    open fun receiveAllMap(sessions: Map<FlowSession, Class<out Any>>): Map<FlowSession, UntrustworthyData<Any>> {
         return stateMachine.receiveAll(sessions, this)
     }
 
@@ -250,7 +250,7 @@ abstract class FlowLogic<out T> {
     @Suspendable
     open fun <R : Any> receiveAll(receiveType: Class<R>, sessions: List<FlowSession>): List<UntrustworthyData<R>> {
         enforceNoDuplicates(sessions)
-        return castMapValuesToKnownType(receiveAll(associateSessionsToReceiveType(receiveType, sessions)))
+        return castMapValuesToKnownType(receiveAllMap(associateSessionsToReceiveType(receiveType, sessions)))
     }
 
     /**
diff --git a/core/src/test/kotlin/net/corda/core/flows/FlowTestsUtils.kt b/core/src/test/kotlin/net/corda/core/flows/FlowTestsUtils.kt
index 9ea4d254f1..1c5934aadb 100644
--- a/core/src/test/kotlin/net/corda/core/flows/FlowTestsUtils.kt
+++ b/core/src/test/kotlin/net/corda/core/flows/FlowTestsUtils.kt
@@ -5,7 +5,6 @@ import net.corda.core.utilities.UntrustworthyData
 import net.corda.core.utilities.unwrap
 import net.corda.node.internal.InitiatedFlowFactory
 import net.corda.node.internal.StartedNode
-import net.corda.testing.node.StartedMockNode
 import net.corda.testing.node.internal.InternalMockNetwork
 import kotlin.reflect.KClass
 
@@ -81,7 +80,7 @@ infix fun <T : Any> KClass<T>.from(session: FlowSession): Pair<FlowSession, Clas
 fun FlowLogic<*>.receiveAll(session: Pair<FlowSession, Class<out Any>>, vararg sessions: Pair<FlowSession, Class<out Any>>): Map<FlowSession, UntrustworthyData<Any>> {
     val allSessions = arrayOf(session, *sessions)
     allSessions.enforceNoDuplicates()
-    return receiveAll(mapOf(*allSessions))
+    return receiveAllMap(mapOf(*allSessions))
 }
 
 /**
diff --git a/docs/source/api-flows.rst b/docs/source/api-flows.rst
index f42661aa85..780c2572da 100644
--- a/docs/source/api-flows.rst
+++ b/docs/source/api-flows.rst
@@ -264,6 +264,13 @@ In order to create a communication session between your initiator flow and the r
 * ``sendAndReceive(receiveType: Class<R>, payload: Any): R``
     * Sends the ``payload`` object and receives an object of type ``receiveType`` back
 
+In addition ``FlowLogic`` provides functions that batch receives:
+* ``receiveAllMap(sessions: Map<FlowSession, Class<out Any>>): Map<FlowSession, UntrustworthyData<Any>>``
+    * Receives from all ``FlowSession``s specified in the passed in map. The received types may differ.
+* ``receiveAll(receiveType: Class<R>, sessions: List<FlowSession>): List<UntrustworthyData<R>>``
+    * Receives from all ``FlowSession``s specified in the passed in list. The received types must be the same.
+
+The batched functions are implemented more efficiently by the flow framework.
 
 InitiateFlow
 ~~~~~~~~~~~~
diff --git a/docs/source/example-code/src/main/kotlin/net/corda/docs/FlowCookbook.kt b/docs/source/example-code/src/main/kotlin/net/corda/docs/FlowCookbook.kt
index e0179281da..0528caeaf3 100644
--- a/docs/source/example-code/src/main/kotlin/net/corda/docs/FlowCookbook.kt
+++ b/docs/source/example-code/src/main/kotlin/net/corda/docs/FlowCookbook.kt
@@ -27,6 +27,7 @@ import net.corda.finance.contracts.asset.Cash
 import net.corda.testing.contracts.DummyContract
 import net.corda.testing.contracts.DummyState
 import java.security.PublicKey
+import java.security.Signature
 import java.time.Instant
 
 // ``InitiatorFlow`` is our first flow, and will communicate with
@@ -205,6 +206,19 @@ class InitiatorFlow(val arg1: Boolean, val arg2: Int, private val counterparty:
         val packet3: UntrustworthyData<Any> = regulatorSession.receive<Any>()
         // DOCEND 06
 
+        // We may also batch receives in order to increase performance. This
+        // ensures that only a single checkpoint is created for all received
+        // messages.
+        // Type-safe variant:
+        val signatures: List<UntrustworthyData<Signature>> =
+                receiveAll(Signature::class.java, listOf(counterpartySession, regulatorSession))
+        // Dynamic variant:
+        val messages: Map<FlowSession, UntrustworthyData<*>> =
+                receiveAllMap(mapOf(
+                        counterpartySession to Boolean::class.java,
+                        regulatorSession to String::class.java
+                ))
+
         /**-----------------------------------
          * EXTRACTING STATES FROM THE VAULT *
         -----------------------------------**/