Merge pull request #83 from Arkatufus/#53_Fix_snapshot_store_sequential_access_is_broken

Fix broken SnapshotStore when sequential-access is turned on

Author: Arkatufus

src/Akka.Persistence.PostgreSql.Tests/PostgreSqlSnapshotStoreSequentialAccessSpec.cs

@@ -0,0 +1,72 @@
+//-----------------------------------------------------------------------
+// <copyright file="PostgreSqlSnapshotStoreSpec.cs" company="Akka.NET Project">
+//     Copyright (C) 2009-2016 Lightbend Inc. <http://www.lightbend.com>
+//     Copyright (C) 2013-2016 Akka.NET project <https://github.com/akkadotnet/akka.net>
+// </copyright>
+//-----------------------------------------------------------------------
+
+using Akka.Configuration;
+using Akka.Persistence.TCK.Snapshot;
+using Akka.TestKit;
+using Xunit;
+using Xunit.Abstractions;
+
+namespace Akka.Persistence.PostgreSql.Tests
+{
+    [Collection("PostgreSqlSpec")]
+    public class PostgreSqlSnapshotStoreSequentialAccessSpec : SnapshotStoreSpec
+    {
+        private static Config Initialize(PostgresFixture fixture)
+        {
+            //need to make sure db is created before the tests start
+            DbUtils.Initialize(fixture);
+
+            var config = @"
+                akka.persistence {
+                    publish-plugin-commands = on
+                    snapshot-store {
+                        plugin = ""akka.persistence.snapshot-store.postgresql""
+                        postgresql {
+                            class = ""Akka.Persistence.PostgreSql.Snapshot.PostgreSqlSnapshotStore, Akka.Persistence.PostgreSql""
+                            plugin-dispatcher = ""akka.actor.default-dispatcher""
+                            table-name = snapshot_store
+                            schema-name = public
+                            auto-initialize = on
+                            connection-string = """ + DbUtils.ConnectionString + @"""
+                            sequential-access = on
+                        }
+                    }
+                }
+                akka.test.single-expect-default = 10s";
+
+            return ConfigurationFactory.ParseString(config);
+        }
+
+        public PostgreSqlSnapshotStoreSequentialAccessSpec(ITestOutputHelper output, PostgresFixture fixture)
+            : base(Initialize(fixture), "PostgreSqlSnapshotStoreSpec", output: output)
+        {
+            Initialize();
+        }
+
+        protected override void Dispose(bool disposing)
+        {
+            base.Dispose(disposing);
+            DbUtils.Clean();
+        }
+
+        [Fact]
+        public void SnapshotStore_should_save_and_overwrite_snapshot_with_same_sequence_number_unskipped()
+        {
+            TestProbe _senderProbe = CreateTestProbe();
+            var md = Metadata[4];
+            SnapshotStore.Tell(new SaveSnapshot(md, "s-5-modified"), _senderProbe.Ref);
+            var md2 = _senderProbe.ExpectMsg<SaveSnapshotSuccess>().Metadata;
+            Assert.Equal(md.SequenceNr, md2.SequenceNr);
+            SnapshotStore.Tell(new LoadSnapshot(Pid, new SnapshotSelectionCriteria(md.SequenceNr), long.MaxValue), _senderProbe.Ref);
+            var result = _senderProbe.ExpectMsg<LoadSnapshotResult>();
+            Assert.Equal("s-5-modified", result.Snapshot.Snapshot.ToString());
+            Assert.Equal(md.SequenceNr, result.Snapshot.Metadata.SequenceNr);
+            // metadata timestamp may have been changed
+        }
+    }
+}

src/Akka.Persistence.PostgreSql/Snapshot/PostgreSqlQueryExecutor.cs

@@ -139,6 +139,7 @@ protected override SelectedSnapshot ReadSnapshot(DbDataReader reader)
             var sequenceNr = reader.GetInt64(1);
             var timestamp = new DateTime(reader.GetInt64(2));
             var manifest = reader.GetString(3);
+            var payloadObject = reader[4];
 
             int? serializerId = null;
             Type type = null;
@@ -151,7 +152,7 @@ protected override SelectedSnapshot ReadSnapshot(DbDataReader reader)
                 serializerId = reader.GetInt32(5);
             }
 
-            var snapshot = _deserialize(type, reader[4], manifest, serializerId);
+            var snapshot = _deserialize(type, payloadObject, manifest, serializerId);
 
             var metadata = new SnapshotMetadata(persistenceId, sequenceNr, timestamp);
             return new SelectedSnapshot(metadata, snapshot);