Support fast communication recovery during printing when printer sends "wait" line

Common setting in Repetier, Marlin might support this sooner or later as well.

docs/configuration/config_yaml.rst

@@ -319,9 +319,11 @@ The following settings are only relevant to you if you want to do OctoPrint deve
        # Forced pause for retrieving from the outgoing buffer
        throttle: 0.01
 
-       # Whether to send "wait" responses while waiting for long moves to finish
-       # or not
-       waitOnLongMoves: false
+       # Whether to send "wait" responses every "waitInterval" seconds when serial rx buffer is empty
+       sendWait: false
+
+       # Interval in which to send "wait" lines when rx buffer is empty
+       waitInterval: 1
 
        # Size of the simulated RX buffer in bytes, when it's full a send from OctoPrint's
        # side will block

src/octoprint/plugins/virtual_printer/virtual.py

@@ -63,6 +63,9 @@ class VirtualPrinter():
 
 		self._okBeforeCommandOutput = settings().getBoolean(["devel", "virtualPrinter", "okBeforeCommandOutput"])
 
+		self._sendWait = settings().getBoolean(["devel", "virtualPrinter", "sendWait"])
+		self._waitInterval = settings().getFloat(["devel", "virtualPrinter", "waitInterval"])
+
 		self.currentLine = 0
 		self.lastN = 0
 
@@ -99,14 +102,20 @@ class VirtualPrinter():
 			pass
 
 	def _processIncoming(self):
+		next_wait_timeout = time.time() + self._waitInterval
 		while self.incoming is not None:
 			self._simulateTemps()
 
 			try:
 				data = self.incoming.get(timeout=0.01)
 			except Queue.Empty:
+				if self._sendWait and time.time() > next_wait_timeout:
+					self.outgoing.put("wait")
+					next_wait_timeout = time.time() + self._waitInterval
 				continue
 
+			next_wait_timeout = time.time() + self._waitInterval
+
 			if data is None:
 				continue
 
@@ -137,7 +146,7 @@ class VirtualPrinter():
 				if linenumber != expected:
 					self._triggerResend(actual=linenumber)
 					continue
-				elif self.currentLine == 100:
+				elif self.currentLine == 101:
 					# simulate a resend at line 100
 					self._triggerResend(expected=100)
 					continue

src/octoprint/settings.py

@@ -139,6 +139,7 @@ default_settings = {
 		"swallowOkAfterResend": True,
 		"repetierTargetTemp": False,
 		"externalHeatupDetection": True,
+		"supportWait": True,
 		"keyboardControl": True
 	},
 	"folder": {
@@ -266,7 +267,9 @@ default_settings = {
 			"waitOnLongMoves": False,
 			"rxBuffer": 64,
 			"txBuffer": 40,
-			"commandBuffer": 4
+			"commandBuffer": 4,
+			"sendWait": True,
+			"waitInterval": 1.0
 		}
 	}
 }

src/octoprint/util/comm.py

@@ -797,6 +797,7 @@ class MachineCom(object):
 
 		startSeen = False
 		supportRepetierTargetTemp = settings().getBoolean(["feature", "repetierTargetTemp"])
+		supportWait = settings().getBoolean(["feature", "supportWait"])
 
 		connection_timeout = settings().getFloat(["serial", "timeout", "connection"])
 		detection_timeout = settings().getFloat(["serial", "timeout", "detection"])
@@ -868,7 +869,7 @@ class MachineCom(object):
 						continue
 
 				##~~ process oks
-				if line.strip().startswith("ok"):
+				if line.strip().startswith("ok") or (supportWait and line.strip().startswith("wait")):
 					self._clear_to_send.set()
 					self._blocking_command = False
 
@@ -1082,7 +1083,9 @@ class MachineCom(object):
 						else:
 							self._logger.debug("Ran into a communication timeout, but a blocking command is currently active")
 
-					if "ok" in line:
+					if "ok" in line or (supportWait and "wait" in line):
+						# a wait while printing means our printer's buffer ran out, probably due to some ok getting
+						# swallowed, so we treat it the same as an ok here teo take up communication again
 						if self._resendSwallowNextOk:
 							self._resendSwallowNextOk = False
 
@@ -1530,7 +1533,7 @@ class MachineCom(object):
 					else:
 						self._doSendWithoutChecksum(command)
 
-				use_up_clear = not self._unknownCommandsNeedAck
+				use_up_clear = self._unknownCommandsNeedAck
 				if is_gcode:
 					# trigger "sent" phase and use up one "ok"
 					self._process_command_phase("sent", command, gcode=gcode_match.group(1))