embutils.serial.stream module

Stream implementation.

date: 2021
author: Christian Wiche
contact: cwichel@gmail.com
license: The MIT License (MIT)

class embutils.serial.stream.AbstractSerializedStreamCodec[source]

Bases: embutils.utils.serialized.AbstractSerializedCodec

AbstractSerializedCodec variant for stream usage. This class includes the logic required to decode a serialized object from a byte stream.

_abc_impl = <_abc_data object>

abstract decode_stream(device: embutils.serial.device.Device) → Optional[embutils.utils.serialized.AbstractSerialized][source]

Decodes a serialized object from a byte stream.

Parameters: device (Device) – Stream source.
Returns: Deserialized object if able, None otherwise.
Return type: Optional[AbstractSerialized]
Raises: ConnectionError – Device raised exception while reading.

class embutils.serial.stream.Stream(device: embutils.serial.device.Device, codec: embutils.serial.stream.AbstractSerializedStreamCodec, **kwargs)[source]

Bases: embutils.utils.service.AbstractService

This class is used to send and receive serialized objects through a serial device in asynchronous way. When a new item is received this class will notify the system using events.

Available events:

on_receive: This event is emitted when an object is received and deserialized from the serial device. Subscribe using callbacks with syntax:
```
def <callback>(item: AbstractSerialized)
```
on_connect: This event is emitted when the system is able to connect to the device. Subscribe using callbacks with syntax:
```
def <callback>()
```
on_reconnect: This event is emitted when the system is able to reconnect to the device. Subscribe using callbacks with syntax:
```
def <callback>()
```
on_disconnect: This event is emitted when the system gets disconnected from the device. Subscribe using callbacks with syntax:
```
def <callback>()
```

Class initialization.

Parameters

device (Device) – Serial device handler.
codec (AbstractSerializedStreamCodec) – Serialized objects codec handler.

RECONNECT_PERIOD_S = 0.5: Stream reconnect period

_abc_impl = <_abc_data object>

_device_connect() → bool[source]

Perform connection attempts on the serial device while the service is running.

Returns: True if connection succeeded, false otherwise.
Return type: bool

_device_init(start: bool = True) → None[source]

Initializes the serial device.

Parameters: start (bool) – True if used on start handler. False otherwise.

_on_end() → None[source]: Closes device when service gets terminated.

_on_pause() → None[source]: Closes device when paused.

_on_resume() → None[source]: Ensures device connected on service resume.

_on_start() → None[source]: Ensures device connected on service start.

_task() → None[source]

Stream process:

Tries to decode items.
If an item is available, emits an event.
Handle disconnection status.

static _transfer_debug(item: embutils.utils.serialized.AbstractSerialized, received: bool) → None[source]

Print the sent/received items on the logger:

Parameters

item (AbstractSerialized) – Item that is being sent/received.
received (bool) – Flag to indicate if we are sending/receiving the item.

property codec: embutils.serial.stream.AbstractSerializedStreamCodec: Serialized objects codec handler.

property device: embutils.serial.device.Device: Serial device handler.

send(item: embutils.utils.serialized.AbstractSerialized) → None[source]

Send a serializable item through the serial device.

Parameters: item (AbstractSerialized) – Item to send.