driver: introduce txchunk argument for console drivers

The txdelay argument only applies to single bytes.
Sending those packets over the Internet causes additional per packet
overhead, as each packet only contains a single byte payload.

Introduce an argument to group bytes into chunks, such that the txdelay
applies to the chunk. This will reduce the overhead of packets send over
the internet and better utilizes hardware FIFO's on the receiver side.

The default chunk size is 1 byte.

Signed-off-by: Fabian Pfitzner <f.pfitzner@pengutronix.de>

Author: N3xp7im3

CHANGES.rst

@@ -12,6 +12,8 @@ New Features in 25.1
   ``add_port_forward()`` and ``remove_port_forward()``  in case there is more
   than one network interface defined.
 - Guermok HDMI to USB 3.0 capture dongle supported
+- The `consoleexpectmixin` now supports chunking of multiple bytes
+  with the ``txchunk`` attribute.
 
 Breaking changes in 25.1
 ~~~~~~~~~~~~~~~~~~~~~~~~

doc/configuration.rst

@@ -1961,13 +1961,15 @@ Binds to:
 
    SerialDriver:
      txdelay: 0.05
+     txchunk: 1
 
 Implements:
   - :any:`ConsoleProtocol`
   - :any:`ResetProtocol`
 
 Arguments:
-  - txdelay (float, default=0.0): time in seconds to wait before sending each byte
+  - txdelay (float, default=0.0): time in seconds to wait before sending a chunk
+  - txchunk (int, default=1): number of bytes the `txdelay` should apply to
   - timeout (float, default=3.0): time in seconds to wait for a network serial port before
     an error occurs
 
@@ -2221,10 +2223,12 @@ Implements:
    ExternalConsoleDriver:
      cmd: 'microcom /dev/ttyUSB2'
      txdelay: 0.05
+     txchunk: 1
 
 Arguments:
   - cmd (str): command to execute and then bind to.
-  - txdelay (float, default=0.0): time in seconds to wait before sending each byte
+  - txdelay (float, default=0.0): time in seconds to wait before sending a chunk
+  - txchunk (int, default=1): number of bytes the `txdelay` should apply to
 
 AndroidFastbootDriver
 ~~~~~~~~~~~~~~~~~~~~~

doc/overview.rst

@@ -147,7 +147,7 @@ specific driver set a binding mapping before creating the driver:
   >>> t.set_binding_map({"port": "Second"})
   >>> sd = SerialDriver(t, "Driver")
   >>> sd
-  SerialDriver(target=Target(name='Test', env=None), name='Driver', state=<BindingState.bound: 1>, txdelay=0.0, timeout=3.0)
+  SerialDriver(target=Target(name='Test', env=None), name='Driver', state=<BindingState.bound: 1>, txdelay=0.0, txchunk=1, timeout=3.0)
   >>> sd.port
   SerialPort(target=Target(name='Test', env=None), name='Second', state=<BindingState.bound: 1>, avail=True, port=None, speed=115200)
 

doc/usage.rst

@@ -283,9 +283,9 @@ Active drivers can be accessed by class (any :any:`Driver <labgrid.driver>` or
   >>> console = FakeConsoleDriver(target, 'console')
   >>> target.activate(console)
   >>> target[FakeConsoleDriver]
-  FakeConsoleDriver(target=Target(name='main', env=None), name='console', state=<BindingState.active: 2>, txdelay=0.0)
+  FakeConsoleDriver(target=Target(name='main', env=None), name='console', state=<BindingState.active: 2>, txdelay=0.0, txchunk=1)
   >>> target[FakeConsoleDriver, 'console']
-  FakeConsoleDriver(target=Target(name='main', env=None), name='console', state=<BindingState.active: 2>, txdelay=0.0)
+  FakeConsoleDriver(target=Target(name='main', env=None), name='console', state=<BindingState.active: 2>, txdelay=0.0, txchunk=1)
 
 Driver Deactivation
 ^^^^^^^^^^^^^^^^^^^
@@ -302,7 +302,7 @@ Driver deactivation works in a similar manner:
 .. doctest:: driver-deactivation
 
   >>> target.deactivate(console)
-  [FakeConsoleDriver(target=Target(name='main', env=None), name='console', state=<BindingState.bound: 1>, txdelay=0.0)]
+  [FakeConsoleDriver(target=Target(name='main', env=None), name='console', state=<BindingState.bound: 1>, txdelay=0.0, txchunk=1)]
 
 Drivers need to be deactivated in the following cases:
 
@@ -393,7 +393,7 @@ To access the target's console, the correct driver object can be found by using
 
   >>> cp = t.get_driver('ConsoleProtocol')
   >>> cp
-  SerialDriver(target=Target(name='example', env=Environment(config_file='example-env.yaml')), name=None, state=<BindingState.active: 2>, txdelay=0.0, timeout=3.0)
+  SerialDriver(target=Target(name='example', env=Environment(config_file='example-env.yaml')), name=None, state=<BindingState.active: 2>, txdelay=0.0, txchunk=1, timeout=3.0)
   >>> cp.write(b'test')
   4
 

examples/strategy/local.yaml

@@ -8,6 +8,7 @@ targets:
         name: "example"
       SerialDriver:
         txdelay: 0.01
+        txchunk: 1
       BareboxDriver:
         prompt: 'barebox@[^:]+:[^ ]+ '
         bootstring: 'Modules linked in'

labgrid/driver/consoleexpectmixin.py

@@ -34,12 +34,14 @@ def read(self, size=1, timeout=0.0, max_size=None):
     @step(args=['data'], tag='console')
     def write(self, data):
         if self.txdelay:
-            self.logger.debug("Write %i bytes: %s (with %fs txdelay)",
-                              len(data), data, self.txdelay)
+            self.logger.debug("Write %i bytes: %s (with %fs txdelay per %i bytes)",
+                              len(data), data, self.txdelay, self.txchunk)
+
             count = 0
-            for i in range(len(data)):
+            for i in range(0, len(data), self.txchunk):
                 time.sleep(self.txdelay)
-                count += self._write(data[i:i+1])
+                count += self._write(data[i:i+self.txchunk])
+
             return count
 
         self.logger.debug("Write %i bytes: %s", len(data), data)

labgrid/driver/externalconsoledriver.py

@@ -21,6 +21,7 @@ class ExternalConsoleDriver(ConsoleExpectMixin, Driver, ConsoleProtocol):
     """
     cmd = attr.ib(validator=attr.validators.instance_of(str))
     txdelay = attr.ib(default=0.0, validator=attr.validators.instance_of(float))
+    txchunk = attr.ib(default=1, validator=attr.validators.instance_of(int))
 
     def __attrs_post_init__(self):
         super().__attrs_post_init__()

labgrid/driver/fake.py

@@ -14,6 +14,7 @@
 @attr.s(eq=False)
 class FakeConsoleDriver(ConsoleExpectMixin, Driver, ConsoleProtocol):
     txdelay = attr.ib(default=0.0, validator=attr.validators.instance_of(float))
+    txchunk = attr.ib(default=1, validator=attr.validators.instance_of(int))
 
     def __attrs_post_init__(self):
         super().__attrs_post_init__()

labgrid/driver/qemudriver.py

@@ -99,6 +99,7 @@ def __attrs_post_init__(self):
         super().__attrs_post_init__()
         self.status = 0
         self.txdelay = None
+        self.txchunk = None
         self._child = None
         self._tempdir = None
         self._socket = None

labgrid/driver/serialdriver.py

@@ -20,6 +20,7 @@ class SerialDriver(ConsoleExpectMixin, Driver, ConsoleProtocol):
     bindings = {"port": {"SerialPort", "NetworkSerialPort"}, }
 
     txdelay = attr.ib(default=0.0, validator=attr.validators.instance_of(float))
+    txchunk = attr.ib(default=1, validator=attr.validators.instance_of(int))
     timeout = attr.ib(default=3.0, validator=attr.validators.instance_of(float))
 
     def __attrs_post_init__(self):