Merge pull request #43 from ClusterCockpit/new_receiver_instances

New receiver instances

receivers/README.md

@@ -7,17 +7,13 @@ 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
-[
+{
-  {
+  "myreceivername" : {
-    "type": "nats",
+    <receiver-specific configuration>
-    "address": "nats://my-url",
-    "port" : "4222",
-    "database": "testcluster"
   }
-]
+}
 ```
 
-
 ## Type `nats`
 
 ```json
@@ -25,20 +21,20 @@ 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`):
+A receiver contains a few functions and is derived from the type `Receiver` (in `metricReceiver.go`):
-* `Init(config ReceiverConfig) 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

@@ -1,9 +1,6 @@
 package receivers
 
 import (
-	//	"time"
-	"encoding/json"
-
 	lp "github.com/ClusterCockpit/cc-metric-collector/internal/ccMetric"
 )
 
@@ -20,13 +17,11 @@ type ReceiverConfig struct {
 }
 
 type receiver struct {
-	typename string
 	name string
 	sink chan lp.CCMetric
 }
 
 type Receiver interface {
-	Init(name string, config json.RawMessage) error
 	Start()
 	Close()
 	Name() string

receivers/natsReceiver.go

@@ -32,39 +32,6 @@ var DefaultTime = func() time.Time {
 	return time.Unix(42, 0)
 }
 
-func (r *NatsReceiver) Init(name string, config json.RawMessage) error {
-	r.typename = "NatsReceiver"
-	r.name = name
-	r.config.Addr = nats.DefaultURL
-	r.config.Port = "4222"
-	if len(config) > 0 {
-		err := json.Unmarshal(config, &r.config)
-		if err != nil {
-			cclog.ComponentError(r.name, "Error reading config:", err.Error())
-			return err
-		}
-	}
-	if len(r.config.Addr) == 0 ||
-		len(r.config.Port) == 0 ||
-		len(r.config.Subject) == 0 {
-		return errors.New("not all configuration variables set required by NatsReceiver")
-	}
-	r.meta = map[string]string{"source": r.name}
-	uri := fmt.Sprintf("%s:%s", r.config.Addr, r.config.Port)
-	cclog.ComponentDebug(r.name, "INIT", uri, "Subject", r.config.Subject)
-	nc, err := nats.Connect(uri)
-	if err == nil {
-		r.nc = nc
-	} else {
-		r.nc = nil
-		return err
-	}
-	r.handler = influx.NewMetricHandler()
-	r.parser = influx.NewParser(r.handler)
-	r.parser.SetTimeFunc(DefaultTime)
-	return err
-}
-
 func (r *NatsReceiver) Start() {
 	cclog.ComponentDebug(r.name, "START")
 	r.nc.Subscribe(r.config.Subject, r._NatsReceive)
@@ -91,3 +58,35 @@ func (r *NatsReceiver) Close() {
 		r.nc.Close()
 	}
 }
+
+func NewNatsReceiver(name string, config json.RawMessage) (Receiver, error) {
+	r := new(NatsReceiver)
+	r.name = fmt.Sprintf("NatsReceiver(%s)", name)
+	r.config.Addr = nats.DefaultURL
+	r.config.Port = "4222"
+	if len(config) > 0 {
+		err := json.Unmarshal(config, &r.config)
+		if err != nil {
+			cclog.ComponentError(r.name, "Error reading config:", err.Error())
+			return nil, err
+		}
+	}
+	if len(r.config.Addr) == 0 ||
+		len(r.config.Port) == 0 ||
+		len(r.config.Subject) == 0 {
+		return nil, errors.New("not all configuration variables set required by NatsReceiver")
+	}
+	r.meta = map[string]string{"source": r.name}
+	uri := fmt.Sprintf("%s:%s", r.config.Addr, r.config.Port)
+	cclog.ComponentDebug(r.name, "NewNatsReceiver", uri, "Subject", r.config.Subject)
+	if nc, err := nats.Connect(uri); err == nil {
+		r.nc = nc
+	} else {
+		r.nc = nil
+		return nil, err
+	}
+	r.handler = influx.NewMetricHandler()
+	r.parser = influx.NewParser(r.handler)
+	r.parser.SetTimeFunc(DefaultTime)
+	return r, nil
+}

receivers/receiveManager.go

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