From 0f06e84f4079150658e0808451cea2b36665c91c Mon Sep 17 00:00:00 2001
From: Silvan <silvan.reusser@gmail.com>
Date: Wed, 6 Sep 2023 16:34:07 +0200
Subject: [PATCH] fix(eventstore): cache instances (#6501)

* fix(eventstore): cache instances

* fix: consider succeeded once during instance ids query

* fix(eventstore): return correct instances
---
 internal/eventstore/eventstore.go             | 36 +++++++++++++++++--
 .../eventstore/handler/handler_projection.go  |  2 +-
 2 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/internal/eventstore/eventstore.go b/internal/eventstore/eventstore.go
index 67ab235910..f602a53f12 100644
--- a/internal/eventstore/eventstore.go
+++ b/internal/eventstore/eventstore.go
@@ -23,6 +23,10 @@ type Eventstore struct {
 	eventTypes        []string
 	aggregateTypes    []string
 	PushTimeout       time.Duration
+
+	instancesMu        sync.Mutex
+	instances          []string
+	lastInstancesQuery time.Time
 }
 
 type eventTypeInterceptors struct {
@@ -73,7 +77,16 @@ func (es *Eventstore) Push(ctx context.Context, cmds ...Command) ([]Event, error
 }
 
 func (es *Eventstore) NewInstance(ctx context.Context, instanceID string) error {
-	return es.repo.CreateInstance(ctx, instanceID)
+	err := es.repo.CreateInstance(ctx, instanceID)
+	if err != nil {
+		return err
+	}
+
+	es.instancesMu.Lock()
+	es.instances = append(es.instances, instanceID)
+	es.instancesMu.Unlock()
+
+	return nil
 }
 
 func (es *Eventstore) EventTypes() []string {
@@ -208,12 +221,29 @@ func (es *Eventstore) LatestSequence(ctx context.Context, queryFactory *SearchQu
 }
 
 // InstanceIDs returns the instance ids found by the search query
-func (es *Eventstore) InstanceIDs(ctx context.Context, queryFactory *SearchQueryBuilder) ([]string, error) {
+// forceDBCall forces to query the database, the instance ids are not cached
+func (es *Eventstore) InstanceIDs(ctx context.Context, maxAge time.Duration, forceDBCall bool, queryFactory *SearchQueryBuilder) ([]string, error) {
+	es.instancesMu.Lock()
+	defer es.instancesMu.Unlock()
+
+	if !forceDBCall && time.Since(es.lastInstancesQuery) <= maxAge {
+		return es.instances, nil
+	}
+
 	query, err := queryFactory.build(authz.GetInstance(ctx).InstanceID())
 	if err != nil {
 		return nil, err
 	}
-	return es.repo.InstanceIDs(ctx, query)
+	instances, err := es.repo.InstanceIDs(ctx, query)
+	if err != nil {
+		return nil, err
+	}
+	if !forceDBCall {
+		es.instances = instances
+		es.lastInstancesQuery = time.Now()
+	}
+
+	return instances, nil
 }
 
 type QueryReducer interface {
diff --git a/internal/eventstore/handler/handler_projection.go b/internal/eventstore/handler/handler_projection.go
index dcd24b3d7b..2dbcfc9aa0 100644
--- a/internal/eventstore/handler/handler_projection.go
+++ b/internal/eventstore/handler/handler_projection.go
@@ -279,7 +279,7 @@ func (h *ProjectionHandler) schedule(ctx context.Context) {
 			// This ensures that only instances with recent events on the handler are projected
 			query = query.CreationDateAfter(h.nowFunc().Add(-1 * h.handleActiveInstances))
 		}
-		ids, err := h.Eventstore.InstanceIDs(ctx, query.Builder())
+		ids, err := h.Eventstore.InstanceIDs(ctx, h.requeueAfter, !succeededOnce, query.Builder())
 		if err != nil {
 			logging.WithFields("projection", h.ProjectionName).WithError(err).Error("instance ids")
 			h.triggerProjection.Reset(h.requeueAfter)