Reset OpenCL when settings change

- previously, changing the OpenCL vendor (or turning it on/off) required
  a restart and this wasn't clear

src/bitmessageqt/__init__.py

@@ -2444,6 +2444,7 @@ class MyForm(settingsmixin.SMainWindow):
 
             if self.settingsDialogInstance.ui.comboBoxOpenCL.currentText().toUtf8() != BMConfigParser().safeGet("bitmessagesettings", "opencl"):
                 BMConfigParser().set('bitmessagesettings', 'opencl', str(self.settingsDialogInstance.ui.comboBoxOpenCL.currentText()))
+                queues.workerQueue.put(('resetPoW', ''))
 
             acceptableDifficultyChanged = False
             

src/class_singleWorker.py

@@ -120,6 +120,11 @@ class singleWorker(threading.Thread, StoppableThread):
                     self.sendOutOrStoreMyV4Pubkey(data)
                 except:
                     pass
+            elif command == 'resetPoW':
+                try:
+                    proofofwork.resetPoW()
+                except:
+                    pass
             elif command == 'stopThread':
                 self.busy = 0
                 return

src/openclpow.py

@@ -26,7 +26,12 @@ except:
     libAvailable = False
 
 def initCL():
-    global ctx, queue, program, enabledGpus, hash_dt
+    global ctx, queue, program, enabledGpus, hash_dt, vendors
+    gpus = []
+    ctx = False
+    enabledGpus = []
+    vendors = []
+    hash_dt = None
     try:
         hash_dt = numpy.dtype([('target', numpy.uint64), ('v', numpy.str_, 73)])
         try:

src/proofofwork.py

@@ -231,6 +231,9 @@ def run(target, initialHash):
     except:
         pass #fallback
 
+def resetPoW():
+    openclpow.initCL()
+
 # init
 def init():
     global bitmsglib, bso, bmpow