Use new receiver instances to allow multiple of same receiver type

receivers/README.md

@@ -7,14 +7,11 @@ This folder contains the ReceiveManager and receiver implementations for the cc-
 The configuration file for the receivers is a list of configurations. The `type` field in each specifies which receiver to initialize.
 
 ```json
-[
 {
-    "type": "nats",
-    "address": "nats://my-url",
-    "port" : "4222",
-    "database": "testcluster"
+  "myreceivername" : {
+    <receiver-specific configuration>
+  }
 }
-]
 ```
 
 
@@ -25,20 +22,21 @@ The configuration file for the receivers is a list of configurations. The `type`
   "type": "nats",
   "address": "<nats-URI or hostname>",
   "port" : "<portnumber>",
-  "database": "<subscribe topic>"
+  "subject": "<subscribe topic>"
 }
 ```
 
 The `nats` receiver subscribes to the topic `database` and listens on `address` and `port` for metrics in the InfluxDB line protocol.
 
 # Contributing own receivers
-A receiver contains three functions and is derived from the type `Receiver` (in `metricReceiver.go`):
-* `Init(config ReceiverConfig) error`
+A receiver contains a few functions and is derived from the type `Receiver` (in `metricReceiver.go`):
+* `Init(name string, config json.RawMessage) error`
 * `Start() error`
 * `Close()`
 * `Name() string`
-* `SetSink(sink chan ccMetric.CCMetric)`
+* `SetSink(sink chan lp.CCMetric)`
+* `New<Typename>(name string, config json.RawMessage)`
 
 The data structures should be set up in `Init()` like opening a file or server connection. The `Start()` function should either start a go routine or issue some other asynchronous mechanism for receiving metrics. The `Close()` function should tear down anything created in `Init()`.
 
-Finally, the receiver needs to be registered in the `receiveManager.go`. There is a list of receivers called `AvailableReceivers` which is a map (`receiver_type_string` -> `pointer to Receiver interface`). Add a new entry with a descriptive name and the new receiver.
+Finally, the receiver needs to be registered in the `receiveManager.go`. There is a list of receivers called `AvailableReceivers` which is a map (`receiver_type_string` -> `pointer to NewReceiver function`). Add a new entry with a descriptive name and the new receiver.

receivers/metricReceiver.go

@@ -20,7 +20,6 @@ type ReceiverConfig struct {
 }
 
 type receiver struct {
-	typename string
 	name string
 	sink chan lp.CCMetric
 }

receivers/natsReceiver.go

@@ -33,8 +33,7 @@ var DefaultTime = func() time.Time {
 }
 
 func (r *NatsReceiver) Init(name string, config json.RawMessage) error {
-	r.typename = "NatsReceiver"
-	r.name = name
+	r.name = fmt.Sprintf("NatsReceiver(%s)", name)
 	r.config.Addr = nats.DefaultURL
 	r.config.Port = "4222"
 	if len(config) > 0 {
@@ -91,3 +90,9 @@ func (r *NatsReceiver) Close() {
 		r.nc.Close()
 	}
 }
+
+func NewNatsReceiver(name string, config json.RawMessage) (Receiver, error) {
+	r := new(NatsReceiver)
+	err := r.Init(name, config)
+	return r, err
+}

receivers/receiveManager.go

@@ -9,8 +9,8 @@ import (
 	lp "github.com/ClusterCockpit/cc-metric-collector/internal/ccMetric"
 )
 
-var AvailableReceivers = map[string]Receiver{
-	"nats": &NatsReceiver{},
+var AvailableReceivers = map[string]func(name string, config json.RawMessage) (Receiver, error){
+	"nats": NewNatsReceiver,
 }
 
 type receiveManager struct {
@@ -75,8 +75,7 @@ func (rm *receiveManager) AddInput(name string, rawConfig json.RawMessage) error
 		cclog.ComponentError("ReceiveManager", "SKIP", config.Type, "unknown receiver:", err.Error())
 		return err
 	}
-	r := AvailableReceivers[config.Type]
-	err = r.Init(name, rawConfig)
+	r, err := AvailableReceivers[config.Type](name, rawConfig)
 	if err != nil {
 		cclog.ComponentError("ReceiveManager", "SKIP", r.Name(), "initialization failed:", err.Error())
 		return err