Add TTL to MongoDB Cache

docs/modules/components/pages/caches/mongodb.adoc

@@ -44,6 +44,8 @@ mongodb:
   collection: "" # No default (required)
   key_field: "" # No default (required)
   value_field: "" # No default (required)
+  ttl_field: "" # No default (optional)
+  default_ttl: "" # No default (optional)
 ```
 
 --
@@ -63,6 +65,8 @@ mongodb:
   collection: "" # No default (required)
   key_field: "" # No default (required)
   value_field: "" # No default (required)
+  ttl_field: "" # No default (optional)
+  default_ttl: "" # No default (optional)
 ```
 
 --
@@ -148,4 +152,20 @@ The field in the document that is used as the value.
 *Type*: `string`
 
 
+=== `ttl_field`
+
+The field in the document that is used as the TTL. A TTL index on that field has to be manually added in MongoDB.
+
+
+*Type*: `string`
+
+
+=== `default_ttl`
+
+The default TTL of each item. After this period an item will be eligible for removal during the next MongoDB cleanup.
+
+
+*Type*: `string`
+
+
 

internal/impl/mongodb/cache.go

@@ -40,6 +40,12 @@ func mongodbCacheConfig() *service.ConfigSpec {
 				Description("The field in the document that is used as the key."),
 			service.NewStringField("value_field").
 				Description("The field in the document that is used as the value."),
+			service.NewStringField("ttl_field").
+				Description("The field in the document that is used as the TTL. A TTL index on that field has to be manually added in MongoDB.").
+				Optional(),
+			service.NewStringField("default_ttl").
+				Description("The default TTL of each item. After this period an item will be eligible for removal during the next MongoDB cleanup.").
+				Optional(),
 		)
 }
 
@@ -72,7 +78,25 @@ func newMongodbCacheFromConfig(parsedConf *service.ParsedConfig) (*mongodbCache,
 		return nil, err
 	}
 
-	return newMongodbCache(collectionName, keyField, valueField, client, database)
+	var ttlField *string
+	if parsedConf.Contains("ttl_field") {
+		ttlf, err := parsedConf.FieldString("ttl_field")
+		if err != nil {
+			return nil, err
+		}
+		ttlField = &ttlf
+	}
+
+	var defaultTTL *time.Duration
+	if parsedConf.Contains("default_ttl") {
+		defTTL, err := parsedConf.FieldDuration("default_ttl")
+		if err != nil {
+			return nil, err
+		}
+		defaultTTL = &defTTL
+	}
+
+	return newMongodbCache(collectionName, keyField, valueField, ttlField, defaultTTL, client, database)
 }
 
 //------------------------------------------------------------------------------
@@ -83,14 +107,18 @@ type mongodbCache struct {
 
 	keyField   string
 	valueField string
+	ttlField   *string
+	defaultTTL *time.Duration
 }
 
-func newMongodbCache(collectionName, keyField, valueField string, client *mongo.Client, database *mongo.Database) (*mongodbCache, error) {
+func newMongodbCache(collectionName, keyField, valueField string, ttlField *string, defaultTTL *time.Duration, client *mongo.Client, database *mongo.Database) (*mongodbCache, error) {
 	return &mongodbCache{
 		client:     client,
 		collection: database.Collection(collectionName),
 		keyField:   keyField,
 		valueField: valueField,
+		ttlField:   ttlField,
+		defaultTTL: defaultTTL,
 	}, nil
 }
 
@@ -110,17 +138,35 @@ func (m *mongodbCache) Get(ctx context.Context, key string) ([]byte, error) {
 	return []byte(valueStr), nil
 }
 
-func (m *mongodbCache) Set(ctx context.Context, key string, value []byte, _ *time.Duration) error {
+func (m *mongodbCache) Set(ctx context.Context, key string, value []byte, ttl *time.Duration) error {
 	opts := options.UpdateOne().SetUpsert(true)
 	filter := bson.M{m.keyField: key}
-	update := bson.M{"$set": bson.M{m.valueField: string(value)}}
+	val := bson.M{m.valueField: string(value)}
 
+	if m.ttlField != nil {
+		if ttl != nil {
+			val[*m.ttlField] = time.Now().Add(*ttl)
+		} else if m.defaultTTL != nil {
+			val[*m.ttlField] = time.Now().Add(*m.defaultTTL)
+		}
+	}
+
+	update := bson.M{"$set": val}
 	_, err := m.collection.UpdateOne(ctx, filter, update, opts)
 	return err
 }
 
-func (m *mongodbCache) Add(ctx context.Context, key string, value []byte, _ *time.Duration) error {
+func (m *mongodbCache) Add(ctx context.Context, key string, value []byte, ttl *time.Duration) error {
 	document := bson.M{m.keyField: key, m.valueField: string(value)}
+
+	if m.ttlField != nil {
+		if ttl != nil {
+			document[*m.ttlField] = time.Now().Add(*ttl)
+		} else if m.defaultTTL != nil {
+			document[*m.ttlField] = time.Now().Add(*m.defaultTTL)
+		}
+	}
+
 	_, err := m.collection.InsertOne(ctx, document)
 	if err != nil {
 		if errCode := getMongoErrorCode(err); errCode == mongoDuplicateKeyErrCode {