Fix/abort listener execution

examples/abort.js

@@ -1,46 +1,72 @@
 const workerpool = require("..");
 
-var workerCount = 0;
-
 // create a worker pool
 const pool = workerpool.pool(__dirname + "/workers/cleanupAbort.js", {
   // maximum time to wait for worker to cleanup it's resources
   // on termination before forcefully stopping the worker
   workerTerminateTimeout: 1000,
-  onCreateWorker: (args) => {
+  onCreateWorker: function (args) {
     console.log("New worker created");
-    workerCount += 1;
-  }
+  },
+  onTerminateWorker: function () {
+    console.log("worker terminated");
+  },
+  maxWorkers: 1,
 });
 
-function add (a, b) {
-    return a + b;
-}
-
 const main = async () => {
-    const cleanedUpTask = pool.exec('asyncTimeout', []).timeout(1_000).catch((err) => {
-        console.log("task timeout");
-        console.log("timeout occured: ", err.message);
-        console.log("worker count ", workerCount);
-        return pool.exec(add, [1, 2]).then((sum) => {
-            console.log('add result', sum);
-            console.log("worker count: ", workerCount);
-        });
+  let abortResolverSuccess;
+  await pool
+    .exec("asyncTimeout", [], {
+        onAbortResolution: function (args) {
+          console.log("abort operation concluded for task:", args.id);
+          console.log("is worker terminating", args.isTerminating);
+        },
+        onAbortStart: async function (args) {
+          console.log(
+            "abort operation started from task timeout, in onAbortStart",
+          );
+          abortResolverSuccess = args.abortPromise;
+      },
+    })
+    .timeout(100)
+    .catch((err) => {
+      console.log("timeout handled: ", err.message);
     });
-    await cleanedUpTask;
-
-    const canceledTask = pool.exec('asyncAbortHandlerNeverResolves').cancel().catch((err) => {
-        console.log("task canceled");
-        console.log("cancel occured: ", err.message);
-        console.log("worker count ", workerCount);
-        return pool.exec(add, [1, 2]).then((sum) => {
-            console.log('add result', sum);
-            console.log("worker count: ", workerCount);
-        }); 
+
+  await abortResolverSuccess.catch((err) => {
+    console.log("abort operation concluded ", err);
+  });
+
+  console.log("pool status after abort operation:", pool.stats());
+
+  let abortResolverFailure;
+  await pool
+    .exec("asyncAbortHandlerNeverResolves", [], {
+      onAbortStart: function (args) {
+        console.log(
+          "abort operation started from task cancel, in onAbortStart",
+        );
+        abortResolverFailure = args.abortPromise;
+      },
+      onAbortResolution: function (args) {
+        console.log("abort operation concluded for task:", args.id);
+        console.log("is worker terminating", args.isTerminating);
+        console.log("no min workers are set, no new worker should be created");
+      }
+    })
+    .cancel()
+    .catch((err) => {
+      console.log("task canceled");
+      console.log("cancel occured: ", err.message);
     });
 
-    await canceledTask;
-}
+  await abortResolverFailure.catch((e) => {
+    console.log("cancelation handled: ", e.message);
+  });
 
+  console.log("final pool stats", pool.stats());
+  // we dont need to terminate the pool, since all workers should be terminated by this point even though there is a handler.
+};
 
 main();

src/Pool.js

@@ -229,18 +229,18 @@ Pool.prototype._next = function () {
       // get the first task from the queue
       var me = this;
       var task = this.tasks.shift();
-
+      var terminationHandler = function() {
+        // if the worker crashed and terminated, remove it from the pool
+        if (worker.terminated) {
+          return me._removeWorker(worker);
+        }
+      }
       // check if the task is still pending (and not cancelled -> promise rejected)
       if (task.resolver.promise.pending) {
         // send the request to the worker
-        var promise = worker.exec(task.method, task.params, task.resolver, task.options)
+        var promise = worker.exec(task.method, task.params, task.resolver, task.options, terminationHandler)
           .then(me._boundNext)
-          .catch(function () {
-            // if the worker crashed and terminated, remove it from the pool
-            if (worker.terminated) {
-              return me._removeWorker(worker);
-            }
-          }).then(function() {
+          .then(function() {
             me._next(); // trigger next task in the queue
           });
 
@@ -430,6 +430,7 @@ Pool.prototype._createWorkerHandler = function () {
     workerType: this.workerType,
     workerTerminateTimeout: this.workerTerminateTimeout,
     emitStdStreams: this.emitStdStreams,
+    onAbortResolution: this.onAbortResolution
   });
 }
 

src/WorkerHandler.js

@@ -222,9 +222,9 @@ function handleEmittedStdPayload(handler, payload) {
   // TODO: refactor if parallel task execution gets added
   Object.values(handler.processing)
     .forEach(task => task?.options?.on(payload));
-  
+
   Object.values(handler.tracking)
-    .forEach(task => task?.options?.on(payload)); 
+    .forEach(task => task?.options?.on(payload));
 }
 
 /**
@@ -289,7 +289,7 @@ function WorkerHandler(script, _options) {
             me.terminate();
           }
 
-          // resolve the task's promise
+          // resolve the task's promis
           if (response.error) {
             task.resolver.reject(objectToError(response.error));
           }
@@ -306,21 +306,27 @@ function WorkerHandler(script, _options) {
               task.options.on(response.payload);
             }
           }
-        } 
+        }
       }
 
       if (response.method === CLEANUP_METHOD_ID) {
         var trackedTask = me.tracking[response.id];
         if (trackedTask !== undefined) {
+          delete me.tracking[id];
           if (response.error) {
             clearTimeout(trackedTask.timeoutId);
-            trackedTask.resolver.reject(objectToError(response.error))
+            trackedTask.resolver.reject(objectToError(response.error));
           } else {
             me.tracking && clearTimeout(trackedTask.timeoutId);
-            trackedTask.resolver.resolve(trackedTask.result);            
+            trackedTask.resolver.resolve(trackedTask.result);
+            if (trackedTask.options) {
+              trackedTask.options.onAbortResolution && trackedTask.options.onAbortResolution({
+                id,
+                isTerminating: false,
+              })
+            }
           }
         }
-        delete me.tracking[id];
       }
     }
   });
@@ -334,7 +340,7 @@ function WorkerHandler(script, _options) {
         me.processing[id].resolver.reject(error);
       }
     }
-    
+
     me.processing = Object.create(null);
   }
 
@@ -390,7 +396,7 @@ WorkerHandler.prototype.methods = function () {
  * @param {import('./types.js').ExecOptions}  [options]
  * @return {Promise.<*, Error>} result
  */
-WorkerHandler.prototype.exec = function(method, params, resolver, options) {
+WorkerHandler.prototype.exec = function(method, params, resolver, options, terminationHandler) {
   if (!resolver) {
     resolver = Promise.defer();
   }
@@ -428,12 +434,17 @@ WorkerHandler.prototype.exec = function(method, params, resolver, options) {
   var me = this;
   return resolver.promise.catch(function (error) {
     if (error instanceof Promise.CancellationError || error instanceof Promise.TimeoutError) {
+
+      const abortResolver = options && options.abortResolver
+        ? options.abortResolver
+        : Promise.defer();
+
       me.tracking[id] = {
         id,
-        resolver: Promise.defer(),
+        resolver: abortResolver,
         options: options,
       };
-      
+
       // remove this task from the queue. It is already rejected (hence this
       // catch event), and else it will be rejected again when terminating
       delete me.processing[id];
@@ -442,39 +453,71 @@ WorkerHandler.prototype.exec = function(method, params, resolver, options) {
         delete me.tracking[id];
 
         var promise = me.terminateAndNotify(true)
-          .then(function() { 
-            throw err;
+          .then(function() {
+            if (options) {
+              options.onAbortResolution && options.onAbortResolution({
+                error: err,
+                id,
+                isTerminating: true
+              });
+            }
+            if (terminationHandler) {
+              return terminationHandler();
+            } else {
+              throw err;
+            }
           }, function(err) {
-            throw err;
+            if (options) {
+              options.onAbortResolution && options.onAbortResolution({
+                error: err,
+                id,
+                isTerminating: true
+              });
+            }
+            if (terminationHandler) {
+              return terminationHandler();
+            } else {
+              throw err;
+            }
           });
 
         return promise;
       });
- 
+
       me.worker.send({
         id,
-        method: CLEANUP_METHOD_ID 
+        method: CLEANUP_METHOD_ID
       });
-
-
+
+      if (options) {
+        options.onAbortStart && options.onAbortStart({
+          id,
+          abortPromise: me.tracking[id].resolver.promise,
+        });
+      }
       /**
         * Sets a timeout to reject the cleanup operation if the message sent to the worker
         * does not receive a response. see worker.tryCleanup for worker cleanup operations.
         * Here we use the workerTerminateTimeout as the worker will be terminated if the timeout does invoke.
-        * 
+        *
         * We need this timeout in either case of a Timeout or Cancellation Error as if
         * the worker does not send a message we still need to give a window of time for a response.
-        * 
+        *
         * The workerTermniateTimeout is used here if this promise is rejected the worker cleanup
         * operations will occure.
       */
       me.tracking[id].timeoutId = setTimeout(function() {
-          me.tracking[id].resolver.reject(error);
+        me.tracking[id].resolver.reject(error);
+        delete me.tracking[id];
       }, me.workerTerminateTimeout);
 
       return me.tracking[id].resolver.promise;
     } else {
-      throw error;
+      if (terminationHandler) {
+        return terminationHandler();
+      } else {
+        throw error;
+      }
     }
   })
 };
@@ -484,7 +527,7 @@ WorkerHandler.prototype.exec = function(method, params, resolver, options) {
  * @return {boolean} Returns true if the worker is busy
  */
 WorkerHandler.prototype.busy = function () {
-  return this.cleaning || Object.keys(this.processing).length > 0;
+  return this.cleaning || Object.keys(this.processing).length > 0 || Object.keys(this.tracking).length > 0;
 };
 
 /**

src/types.js

@@ -27,10 +27,28 @@
  * @property { (arg: WorkerArg) => void } [onTerminateWorker] A callback that is called whenever a worker is being terminated. It can be used to release resources that might have been allocated for this specific worker. The callback is passed as argument an object as described for `onCreateWorker`, with each property sets with the value for the worker being terminated.
  */
 
+
+/**
+  * @typedef {Object} AbortStartArgs
+  * @property {number} [id] identifier of the task which is starting its abort operation.
+  * @property {PromiseLike<void>} [abortPromise] PromiseLike Object which resolves or rejects when the abort operation concludes.
+  *
+  */
+
+/**
+  * @typedef {Object} AbortResolutionArgs
+  * @property {Error | undefined} [error] An error which occured during the abort operation. If an error did not occure the value will be `undefined`.
+  * @property {number} [id] identifier of the task.
+  * @property {boolean} [isTerminating] A flag which indicates the termination status of the worker which ececuted the task.
+  */
+
 /**
  * @typedef {Object} ExecOptions
  * @property {(payload: any) => unknown} [on] An event listener, to handle events sent by the worker for this execution.
  * @property {Object[]} [transfer] A list of transferable objects to send to the worker. Not supported by `process` worker type. See ./examples/transferableObjects.js for usage.
+ * @property {(payload: any) => AbortResolutionArgs} [onAbortResolution] An event listener triggered when whenever an abort operation concludes.
+ * @property {(payload: AbortStartArgs) => void} [onAbortStart] An event listener triggered when a task throws a Timeout or Canceltion exception and cleanup is starting.
+ * @property {{ promise: import('./Promise.js').Promise<any, Error>; resolve: Function; reject: Function; }} [abortResolver] Defered Promise which resolves or rejects when the abort operation for the task concludes.
  */
 
 /**

src/worker.js

@@ -197,7 +197,7 @@ worker.cleanup = function(requestId) {
       error: convertError(new Error('Worker terminating')),
     });
 
-    // If there are no handlers registered, reject the promise with an error as we want the handler to be notified
+    // If there are no handlers registered, as we want the handler to be notified
     // that cleanup should begin and the handler should be GCed.
     return new Promise(function(resolve) { resolve(); });
   }
@@ -236,10 +236,10 @@ worker.cleanup = function(requestId) {
   // - Reject if one or more handlers reject
   // Upon one of the above cases a message will be sent to the handler with the result of the handler execution
   // which will either kill the worker if the result contains an error, or 
-  return Promise.all([
-    settlePromise,
-    timeoutPromise
-  ]).then(function() {
+  return new Promise(function (resolve, reject) {
+    settlePromise.then(resolve, reject);
+    timeoutPromise.then(resolve, reject);
+  }).then(function() {
     worker.send({
       id: requestId,
       method: CLEANUP_METHOD_ID,