From 0317a894e5dc755338401d3ddc8356e19b46ee1d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johan=20Andr=C3=A9n?= <johan@markatta.com>
Date: Wed, 18 Oct 2023 14:07:26 +0200
Subject: [PATCH] docs: Start from snapshot for drone push projection

---
 .../src/main/resources/persistence-h2.conf             |  4 ++++
 .../src/main/resources/persistence-postgres.conf       |  2 ++
 .../src/main/scala/local/drones/Drone.scala            |  5 +++++
 .../src/main/scala/local/drones/DroneEvents.scala      | 10 +++++++++-
 4 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/samples/grpc/local-drone-control-scala/src/main/resources/persistence-h2.conf b/samples/grpc/local-drone-control-scala/src/main/resources/persistence-h2.conf
index 4d27f6e45..ea806a02c 100644
--- a/samples/grpc/local-drone-control-scala/src/main/resources/persistence-h2.conf
+++ b/samples/grpc/local-drone-control-scala/src/main/resources/persistence-h2.conf
@@ -27,3 +27,7 @@ akka {
     }
   }
 }
+
+// #startFromSnapshot
+akka.persistence.r2dbc.query.start-from-snapshot.enabled = true
+// #startFromSnapshot
diff --git a/samples/grpc/local-drone-control-scala/src/main/resources/persistence-postgres.conf b/samples/grpc/local-drone-control-scala/src/main/resources/persistence-postgres.conf
index 694f3ee02..4ad66bb14 100644
--- a/samples/grpc/local-drone-control-scala/src/main/resources/persistence-postgres.conf
+++ b/samples/grpc/local-drone-control-scala/src/main/resources/persistence-postgres.conf
@@ -31,3 +31,5 @@ akka {
     }
   }
 }
+
+akka.persistence.r2dbc.query.start-from-snapshot.enabled = true
diff --git a/samples/grpc/local-drone-control-scala/src/main/scala/local/drones/Drone.scala b/samples/grpc/local-drone-control-scala/src/main/scala/local/drones/Drone.scala
index a21f89022..f34c82e51 100644
--- a/samples/grpc/local-drone-control-scala/src/main/scala/local/drones/Drone.scala
+++ b/samples/grpc/local-drone-control-scala/src/main/scala/local/drones/Drone.scala
@@ -96,6 +96,11 @@ object Drone {
         .receiveSignal { case (_, PostStop) =>
           telemetry.droneEntityPassivated()
         }
+        // #startFromSnapshot
+        .snapshotWhen { (_, event, _) =>
+          event.isInstanceOf[CoarseGrainedLocationChanged]
+        }
+    // #startFromSnapshot
     }
 
   // #commandHandler
diff --git a/samples/grpc/local-drone-control-scala/src/main/scala/local/drones/DroneEvents.scala b/samples/grpc/local-drone-control-scala/src/main/scala/local/drones/DroneEvents.scala
index 4a89af47c..79f178525 100644
--- a/samples/grpc/local-drone-control-scala/src/main/scala/local/drones/DroneEvents.scala
+++ b/samples/grpc/local-drone-control-scala/src/main/scala/local/drones/DroneEvents.scala
@@ -101,7 +101,15 @@ object DroneEvents {
         EventProducerSettings(system),
         // only push coarse grained coordinate changes
         producerFilter = envelope =>
-          envelope.event.isInstanceOf[Drone.CoarseGrainedLocationChanged]),
+          envelope.event.isInstanceOf[Drone.CoarseGrainedLocationChanged])
+        // #startFromSnapshot
+        // start from latest drone snapshot and don't replay history
+        .withStartingFromSnapshots[
+          Drone.State,
+          Drone.CoarseGrainedLocationChanged](state =>
+          Drone.CoarseGrainedLocationChanged(
+            state.coarseGrainedCoordinates.get)),
+      // #startFromSnapshot
       GrpcClientSettings.fromConfig("central-drone-control"))
 
     def projectionForPartition(