Allow users to cancel requests

ocpp1.6/charge_point.go

@@ -1,6 +1,7 @@
 package ocpp16
 
 import (
+ "context"
  "fmt"
 
  "github.com/lorenzodonini/ocpp-go/internal/callbackqueue"
@@ -238,7 +239,7 @@ func (cp *chargePoint) SendRequest(request ocpp.Request) (ocpp.Response, error)
  }
 }
 
-func (cp *chargePoint) SendRequestAsync(request ocpp.Request, callback func(confirmation ocpp.Response, err error)) error {
+func (cp *chargePoint) SendRequestAsync(ctx context.Context, request ocpp.Request, callback func(confirmation ocpp.Response, err error)) error {
  featureName := request.GetFeatureName()
  if _, found := cp.client.GetProfileForFeature(featureName); !found {
  return fmt.Errorf("feature %v is unsupported on charge point (missing profile), cannot send request", featureName)
@@ -252,7 +253,7 @@ func (cp *chargePoint) SendRequestAsync(request ocpp.Request, callback func(conf
  }
  // Response will be retrieved asynchronously via asyncHandler
  send := func() error {
- return cp.client.SendRequest(request)
+ return cp.client.SendRequestCtx(ctx, request)
  }
  err := cp.callbacks.TryQueue("main", send, callback)
  return err

ocpp1.6/v16.go

@@ -2,6 +2,7 @@
 package ocpp16
 
 import (
+ "context"
  "crypto/tls"
 
  "github.com/gorilla/websocket"
@@ -86,7 +87,7 @@ type ChargePoint interface {
  // The central system will respond with a confirmation messages, or with an error if the request was invalid or could not be processed.
  // This result is propagated via a callback, called asynchronously.
  // In case of network issues (i.e. the remote host couldn't be reached), the function returns an error directly. In this case, the callback is never called.
- SendRequestAsync(request ocpp.Request, callback func(confirmation ocpp.Response, protoError error)) error
+ SendRequestAsync(ctx context.Context, request ocpp.Request, callback func(confirmation ocpp.Response, protoError error)) error
  // Connects to the central system and starts the charge point routine.
  // The function doesn't block and returns right away, after having attempted to open a connection to the central system.
  // If the connection couldn't be opened, an error is returned.

ocppj/client.go

@@ -1,6 +1,7 @@
 package ocppj
 
 import (
+ "context"
  "fmt"
 
  "github.com/lorenzodonini/ocpp-go/ocpp"
@@ -108,7 +109,7 @@ func (c *Client) Stop() {
 // - the endpoint doesn't support the feature
 //
 // - the output queue is full
-func (c *Client) SendRequest(request ocpp.Request) error {
+func (c *Client) SendRequestCtx(ctx context.Context, request ocpp.Request) error {
  if !c.dispatcher.IsRunning() {
  return fmt.Errorf("ocppj client is not started, couldn't send request")
  }
@@ -125,14 +126,18 @@ func (c *Client) SendRequest(request ocpp.Request) error {
  return err
  }
  // Message will be processed by dispatcher. A dedicated mechanism allows to delegate the message queue handling.
- if err := c.dispatcher.SendRequest(RequestBundle{Call: call, Data: jsonMessage}); err != nil {
+ if err := c.dispatcher.SendRequest(RequestBundle{Call: call, Data: jsonMessage, Ctx: ctx}); err != nil {
  log.Errorf("request %v - %v: %v", call.UniqueId, call.Action, err)
  return err
  }
  log.Debugf("enqueued request %v - %v", call.UniqueId, call.Action)
  return nil
 }
 
+func (c *Client) SendRequest(request ocpp.Request) error {
+ return c.SendRequestCtx(context.Background(), request)
+}
+
 // Sends an OCPP Response to the server.
 // The requestID parameter is required and identifies the previously received request.
 //

ocppj/dispatcher.go

@@ -1,6 +1,7 @@
 package ocppj
 
 import (
+ "context"
  "fmt"
  "sync"
  "time"
@@ -168,6 +169,20 @@ func (d *DefaultClientDispatcher) SendRequest(req RequestBundle) error {
 
 func (d *DefaultClientDispatcher) messagePump() {
  rdy := true // Ready to transmit at the beginning
+ cancelled := func() {
+ if d.pendingRequestState.HasPendingRequest() {
+ // Current request timed out. Removing request and triggering cancel callback
+ el := d.requestQueue.Peek()
+ bundle, _ := el.(RequestBundle)
+ d.CompleteRequest(bundle.Call.UniqueId)
+ if d.onRequestCancel != nil {
+ d.onRequestCancel(bundle.Call.UniqueId, bundle.Call.Action, bundle.Call.Payload)
+ }
+ }
+ // No request is currently pending -> set timer to high number
+ d.timer.Reset(defaultTimeoutTick)
+ }
+ var reqContextDone <-chan struct{}
  for {
  select {
  case _, ok := <-d.requestChannel:
@@ -177,22 +192,15 @@ func (d *DefaultClientDispatcher) messagePump() {
  d.requestChannel = nil
  return
  }
+ case <-reqContextDone:
+ // user cancelled request
+ cancelled()
  case _, ok := <-d.timer.C:
  // Timeout elapsed
  if !ok {
  continue
  }
- if d.pendingRequestState.HasPendingRequest() {
- // Current request timed out. Removing request and triggering cancel callback
- el := d.requestQueue.Peek()
- bundle, _ := el.(RequestBundle)
- d.CompleteRequest(bundle.Call.UniqueId)
- if d.onRequestCancel != nil {
- d.onRequestCancel(bundle.Call.UniqueId, bundle.Call.Action, bundle.Call.Payload)
- }
- }
- // No request is currently pending -> set timer to high number
- d.timer.Reset(defaultTimeoutTick)
+ cancelled()
  case rdy = <-d.readyForDispatch:
  // Ready flag set, keep going
  }
@@ -206,22 +214,36 @@ func (d *DefaultClientDispatcher) messagePump() {
  }
  // Only dispatch request if able to send and request queue isn't empty
  if rdy && !d.requestQueue.IsEmpty() {
- d.dispatchNextRequest()
- rdy = false
- // Set timer
- if !d.timer.Stop() {
- <-d.timer.C
+ if done, ok := d.dispatchNextRequest(); ok {
+ rdy = false
+ // Set timer
+ if !d.timer.Stop() {
+ <-d.timer.C
+ }
+ d.timer.Reset(d.timeout)
+ reqContextDone = done
  }
- d.timer.Reset(d.timeout)
  }
  }
 }
 
-func (d *DefaultClientDispatcher) dispatchNextRequest() {
+func (d *DefaultClientDispatcher) dispatchNextRequest() (<-chan struct{}, bool) {
  // Get first element in queue
  el := d.requestQueue.Peek()
  bundle, _ := el.(RequestBundle)
  jsonMessage := bundle.Data
+ ctx := bundle.Ctx
+ if ctx == nil {
+ ctx = context.Background()
+ }
+ select {
+ case <-ctx.Done():
+ if d.onRequestCancel != nil {
+ d.onRequestCancel(bundle.Call.UniqueId, bundle.Call.Action, bundle.Call.Payload)
+ }
+ return nil, false
+ default:
+ }
  d.pendingRequestState.AddPendingRequest(bundle.Call.UniqueId, bundle.Call.Payload)
  // Attempt to send over network
  err := d.network.Write(jsonMessage)
@@ -232,6 +254,7 @@ func (d *DefaultClientDispatcher) dispatchNextRequest() {
  d.onRequestCancel(bundle.Call.UniqueId, bundle.Call.Action, bundle.Call.Payload)
  }
  }
+ return ctx.Done(), true
 }
 
 func (d *DefaultClientDispatcher) Pause() {

ocppj/queue.go

@@ -1,6 +1,7 @@
 package ocppj
 
 import (
+ "context"
  "fmt"
  "sync"
 )
@@ -10,6 +11,7 @@ import (
 type RequestBundle struct {
  Call *Call
  Data []byte
+ Ctx context.Context
 }
 
 // RequestQueue can be arbitrarily implemented, as long as it conforms to the Queue interface.

ocppj/server.go

@@ -1,6 +1,7 @@
 package ocppj
 
 import (
+ "context"
  "fmt"
 
  "github.com/lorenzodonini/ocpp-go/ocpp"
@@ -137,7 +138,7 @@ func (s *Server) SendRequest(clientID string, request ocpp.Request) error {
  return err
  }
  // Will not send right away. Queuing message and let it be processed by dedicated requestPump routine
- if err := s.dispatcher.SendRequest(clientID, RequestBundle{call, jsonMessage}); err != nil {
+ if err := s.dispatcher.SendRequest(clientID, RequestBundle{call, jsonMessage, context.Background()}); err != nil {
  log.Errorf("request %v - %v for client %v: %v", call.UniqueId, call.Action, clientID, err)
  return err
  }