feature: Postgres support

Makefile

@@ -48,6 +48,10 @@ run:
 run_mongodb:
 	docker-compose up -d mongodb
 
+.PHONY: run_postgres
+run_postgres:
+	docker-compose up -d postgres
+
 .PHONY: run_gpubsub
 run_gpubsub:
 	docker-compose up -d gpubsub

docker-compose.yml

@@ -43,6 +43,16 @@ services:
     volumes:
       - mongodb:/data/db
 
+  postgres:
+    image: postgres:14
+    ports:
+      - "5432:5432"
+    environment:
+      POSTGRES_PASSWORD: "password"
+    # PGDATA: "/data/postgres"
+    # volumes:
+    #   - postgres:/data/postgres
+
   gpubsub:
     image: gcr.io/google.com/cloudsdktool/cloud-sdk:355.0.0-emulators
     ports:

eventstore/postgres/eventmaintenance.go.off

@@ -0,0 +1,133 @@
+// Copyright (c) 2021 - The Event Horizon authors
+//
+// 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 postgres
+
+import (
+	"context"
+	"fmt"
+
+	"go.mongodb.org/mongo-driver/bson"
+	"go.mongodb.org/mongo-driver/mongo"
+
+	// Register uuid.UUID as BSON type.
+	_ "github.com/looplab/eventhorizon/codec/bson"
+
+	eh "github.com/looplab/eventhorizon"
+)
+
+// Replace implements the Replace method of the eventhorizon.EventStore interface.
+func (s *EventStore) Replace(ctx context.Context, event eh.Event) error {
+	sess, err := s.client.StartSession(nil)
+	if err != nil {
+		return eh.EventStoreError{
+			Err:     eh.ErrCouldNotSaveEvents,
+			BaseErr: err,
+		}
+	}
+	defer sess.EndSession(ctx)
+
+	if _, err := sess.WithTransaction(ctx, func(txCtx mongo.SessionContext) (interface{}, error) {
+		// First check if the aggregate exists, the not found error in the update
+		// query can mean both that the aggregate or the event is not found.
+		if n, err := s.events.CountDocuments(ctx,
+			bson.M{"aggregate_id": event.AggregateID()}); n == 0 {
+			return nil, eh.ErrAggregateNotFound
+		} else if err != nil {
+			return nil, err
+		}
+
+		// Create the event record for the Database.
+		e, err := newEvt(ctx, event)
+		if err != nil {
+			return nil, err
+		}
+
+		// Copy the event position from the old event (and set in metadata).
+		res := s.events.FindOne(ctx, bson.M{
+			"aggregate_id": event.AggregateID(),
+			"version":      event.Version(),
+		})
+		if res.Err() != nil {
+			if res.Err() == mongo.ErrNoDocuments {
+				return nil, eh.ErrInvalidEvent
+			}
+			return nil, fmt.Errorf("could not find event to replace: %w", res.Err())
+		}
+		var eventToReplace evt
+		if err := res.Decode(&eventToReplace); err != nil {
+			return nil, fmt.Errorf("could not decode event to replace: %w", err)
+		}
+		e.Position = eventToReplace.Position
+		e.Metadata["position"] = eventToReplace.Position
+
+		// Find and replace the event.
+		if r, err := s.events.ReplaceOne(ctx, bson.M{
+			"aggregate_id": event.AggregateID(),
+			"version":      event.Version(),
+		}, e); err != nil {
+			return nil, err
+		} else if r.MatchedCount == 0 {
+			return nil, eh.ErrInvalidEvent
+		}
+		return nil, nil
+	}); err != nil {
+		// Return some errors intact.
+		if err == eh.ErrAggregateNotFound || err == eh.ErrInvalidEvent {
+			return err
+		}
+		return eh.EventStoreError{
+			Err:     eh.ErrCouldNotSaveEvents,
+			BaseErr: err,
+		}
+	}
+
+	return nil
+}
+
+// RenameEvent implements the RenameEvent method of the eventhorizon.EventStore interface.
+func (s *EventStore) RenameEvent(ctx context.Context, from, to eh.EventType) error {
+	// Find and rename all events.
+	// TODO: Maybe use change info.
+	if _, err := s.events.UpdateMany(ctx,
+		bson.M{
+			"event_type": from.String(),
+		},
+		bson.M{
+			"$set": bson.M{"event_type": to.String()},
+		},
+	); err != nil {
+		return eh.EventStoreError{
+			Err:     eh.ErrCouldNotSaveEvents,
+			BaseErr: err,
+		}
+	}
+
+	return nil
+}
+
+// Clear clears the event storage.
+func (s *EventStore) Clear(ctx context.Context) error {
+	if err := s.events.Drop(ctx); err != nil {
+		return eh.EventStoreError{
+			Err: fmt.Errorf("could not clear events collection: %w", err),
+		}
+	}
+	if err := s.streams.Drop(ctx); err != nil {
+		return eh.EventStoreError{
+			Err: fmt.Errorf("could not clear streams collection: %w", err),
+		}
+	}
+	return nil
+}

eventstore/postgres/eventmaintenance_test.go.off

@@ -0,0 +1,57 @@
+// Copyright (c) 2021 - The Event Horizon authors
+//
+// 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 postgres
+
+import (
+	"context"
+	"crypto/rand"
+	"encoding/hex"
+	"os"
+	"testing"
+
+	"github.com/looplab/eventhorizon/eventstore"
+)
+
+func TestEventStoreMaintenanceIntegration(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping integration test")
+	}
+
+	// Use MongoDB in Docker with fallback to localhost.
+	addr := os.Getenv("MONGODB_ADDR")
+	if addr == "" {
+		addr = "localhost:27017"
+	}
+	url := "mongodb://" + addr
+
+	// Get a random DB name.
+	b := make([]byte, 4)
+	if _, err := rand.Read(b); err != nil {
+		t.Fatal(err)
+	}
+	db := "test-" + hex.EncodeToString(b)
+	t.Log("using DB:", db)
+
+	store, err := NewEventStore(url, db)
+	if err != nil {
+		t.Fatal("there should be no error:", err)
+	}
+	if store == nil {
+		t.Fatal("there should be a store")
+	}
+	defer store.Close(context.Background())
+
+	eventstore.MaintenanceAcceptanceTest(t, store, store, context.Background())
+}