[core] stop graph execution mechanism

meshroom/core/graph.py

@@ -219,6 +219,7 @@ class Node(BaseObject):
             self.attribute(k)._value = v
         self.status = StatusData(self.name, self.nodeType())
         self.statistics = stats.Statistics()
+        self._subprocess = None
 
     def __getattr__(self, k):
         try:
@@ -407,6 +408,10 @@ class Node(BaseObject):
     def beginSequence(self):
         self.upgradeStatusTo(Status.SUBMITTED_LOCAL)
 
+    def stopProcess(self):
+        if self._subprocess:
+            self._subprocess.terminate()
+
     def process(self):
         self.upgradeStatusTo(Status.RUNNING)
         statThread = stats.StatisticsThread(self)
@@ -416,20 +421,20 @@ class Node(BaseObject):
                 cmd = self.commandLine()
                 print('\n =====> commandLine:\n', cmd, '\n')
                 print(' - logFile: ', self.logFile())
-                self.proc = psutil.Popen(cmd, stdout=logF, stderr=logF, shell=True)
+                self._subprocess = psutil.Popen(cmd, stdout=logF, stderr=logF, shell=True)
 
                 # store process static info into the status file
                 self.status.commandLine = cmd
                 # self.status.env = self.proc.environ()
                 # self.status.createTime = self.proc.create_time()
 
-                statThread.proc = self.proc
-                stdout, stderr = self.proc.communicate()
-                self.proc.wait()
+                statThread.proc = self._subprocess
+                stdout, stderr = self._subprocess.communicate()
+                self._subprocess.wait()
                 
-                self.status.returnCode = self.proc.returncode
+                self.status.returnCode = self._subprocess.returncode
 
-            if self.proc.returncode != 0:
+            if self._subprocess.returncode != 0:
                 logContent = ''
                 with open(self.logFile(), 'r') as logF:
                     logContent = ''.join(logF.readlines())
@@ -438,9 +443,11 @@ class Node(BaseObject):
         except:
             self.upgradeStatusTo(Status.ERROR)
             raise
-        statThread.running = False
-        # Don't need to join, the thread will finish a bit later.
-        # statThread.join()
+        finally:
+            statThread.running = False
+            # Don't need to join, the thread will finish a bit later.
+            # statThread.join()
+            self._subprocess = None
 
         self.upgradeStatusTo(Status.SUCCESS)
 
@@ -548,6 +555,7 @@ class Graph(BaseObject):
             node._name = self._createUniqueNodeName(node.nodeType())
         node.graph = self
         self._nodes.add(node)
+        self.stopExecutionRequested.connect(node.stopProcess)
 
         # Trigger internal update when an attribute is modified
         for attr in node.attributes:  # type: Attribute
@@ -732,6 +740,10 @@ class Graph(BaseObject):
         self.updateInternals()
         self.updateStatusFromCache()
 
+    def stopExecution(self):
+        """ Request graph execution to be stopped """
+        self.stopExecutionRequested.emit()
+
     @property
     def nodes(self):
         return self._nodes
@@ -743,6 +755,7 @@ class Graph(BaseObject):
     nodes = Property(BaseObject, nodes.fget, constant=True)
     edges = Property(BaseObject, edges.fget, constant=True)
 
+    stopExecutionRequested = Signal()
 
 def loadGraph(filepath):
     """