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Fix BLE companion transport reliability

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This commit is contained in:
Alex
2026-08-01 00:46:59 +02:00
parent 7bbf7aa4cc
commit 13c9f5d983
4 changed files with 136 additions and 57 deletions
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android/app/src/main/java/cloud/molberg/picar/BleClient.kt
+90 -17
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@@ -7,6 +7,7 @@ import android.bluetooth.le.ScanFilter
import android.bluetooth.le.ScanResult
import android.bluetooth.le.ScanSettings
import android.content.Context
import android.os.Build
import android.os.ParcelUuid
import android.os.Handler
import android.os.Looper
@@ -33,6 +34,7 @@ class BleClient(private val context: Context) {
private val incoming = StringBuilder()
private val pending = ConcurrentHashMap<String, CompletableDeferred<JSONObject>>()
private val writes = ArrayDeque<ByteArray>()
private var writeInProgress = false
private val handler = Handler(Looper.getMainLooper())
private var stopped = true
@@ -49,6 +51,7 @@ class BleClient(private val context: Context) {
handler.removeCallbacksAndMessages(null)
bluetoothManager.adapter?.bluetoothLeScanner?.stopScan(scanCallback)
gatt?.close(); gatt = null; rx = null
resetWrites()
state.value = ConnectionState.STOPPED
}
@@ -77,25 +80,71 @@ class BleClient(private val context: Context) {
private val gattCallback = object : BluetoothGattCallback() {
override fun onConnectionStateChange(gatt: BluetoothGatt, status: Int, newState: Int) {
if (newState == BluetoothProfile.STATE_CONNECTED) { this@BleClient.gatt = gatt; gatt.requestMtu(247); gatt.discoverServices() }
if (status == BluetoothGatt.GATT_SUCCESS && newState == BluetoothProfile.STATE_CONNECTED) {
this@BleClient.gatt = gatt
// Android GATT operations are serialized. Starting service
// discovery while the MTU request is still pending can leave
// the client in CONNECTING forever on some phones.
if (!gatt.requestMtu(247)) gatt.discoverServices()
}
else {
rx = null; gatt.close(); state.value = ConnectionState.DISCONNECTED
rx = null; gatt.close(); resetWrites(); state.value = ConnectionState.DISCONNECTED
if (!stopped) handler.postDelayed({ connect() }, 3_000)
}
}
override fun onMtuChanged(gatt: BluetoothGatt, mtu: Int, status: Int) {
gatt.discoverServices()
}
override fun onServicesDiscovered(gatt: BluetoothGatt, status: Int) {
val service = gatt.getService(SERVICE_UUID) ?: return
rx = service.getCharacteristic(RX_UUID)
val tx = service.getCharacteristic(TX_UUID) ?: return
gatt.setCharacteristicNotification(tx, true)
tx.getDescriptor(CCC_UUID)?.let { descriptor ->
descriptor.value = BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE
val service = gatt.getService(SERVICE_UUID)
val nextRx = service?.getCharacteristic(RX_UUID)
val tx = service?.getCharacteristic(TX_UUID)
val descriptor = tx?.getDescriptor(CCC_UUID)
if (status != BluetoothGatt.GATT_SUCCESS || nextRx == null || tx == null || descriptor == null) {
gatt.disconnect()
return
}
rx = nextRx
if (!gatt.setCharacteristicNotification(tx, true)) {
gatt.disconnect()
return
}
val descriptorStarted = if (Build.VERSION.SDK_INT >= 33) {
gatt.writeDescriptor(descriptor, BluetoothGattDescriptor.ENABLE_INDICATION_VALUE) == BluetoothStatusCodes.SUCCESS
} else {
descriptor.value = BluetoothGattDescriptor.ENABLE_INDICATION_VALUE
gatt.writeDescriptor(descriptor)
}
state.value = ConnectionState.CONNECTED
if (!descriptorStarted) gatt.disconnect()
}
override fun onDescriptorWrite(gatt: BluetoothGatt, descriptor: BluetoothGattDescriptor, status: Int) {
if (descriptor.uuid == CCC_UUID && status == BluetoothGatt.GATT_SUCCESS) {
state.value = ConnectionState.CONNECTED
} else {
gatt.disconnect()
}
}
@Deprecated("Used on Android 12 and earlier")
override fun onCharacteristicChanged(gatt: BluetoothGatt, characteristic: BluetoothGattCharacteristic) {
incoming.append(characteristic.value.toString(Charsets.UTF_8))
handleIncoming(characteristic.value)
}
override fun onCharacteristicChanged(gatt: BluetoothGatt, characteristic: BluetoothGattCharacteristic, value: ByteArray) {
handleIncoming(value)
}
override fun onCharacteristicWrite(gatt: BluetoothGatt, characteristic: BluetoothGattCharacteristic, status: Int) {
if (status == BluetoothGatt.GATT_SUCCESS) writeNext() else {
synchronized(this@BleClient) { writeInProgress = false }
gatt.disconnect()
}
}
}
private fun handleIncoming(value: ByteArray) {
incoming.append(value.toString(Charsets.UTF_8))
while (incoming.contains("\n")) {
val index = incoming.indexOf("\n")
val line = incoming.substring(0, index); incoming.delete(0, index + 1)
@@ -107,19 +156,43 @@ class BleClient(private val context: Context) {
}
}
}
override fun onCharacteristicWrite(gatt: BluetoothGatt, characteristic: BluetoothGattCharacteristic, status: Int) { writeNext() }
}
@Synchronized private fun enqueue(bytes: ByteArray) {
bytes.asList().chunked(180).forEach { chunk -> writes.add(chunk.toByteArray()) }
if (writes.size == bytes.asList().chunked(180).size) writeNext()
val chunks = bytes.asList().chunked(180)
chunks.forEach { chunk -> writes.add(chunk.toByteArray()) }
if (!writeInProgress) {
writeInProgress = true
writeNext()
}
}
@Synchronized private fun writeNext() {
val characteristic = rx ?: return
val next = writes.removeFirstOrNull() ?: return
val characteristic = rx
val currentGatt = gatt
if (characteristic == null || currentGatt == null) {
writeInProgress = false
return
}
val next = writes.removeFirstOrNull()
if (next == null) {
writeInProgress = false
return
}
val started = if (Build.VERSION.SDK_INT >= 33) {
currentGatt.writeCharacteristic(characteristic, next, BluetoothGattCharacteristic.WRITE_TYPE_DEFAULT) == BluetoothStatusCodes.SUCCESS
} else {
characteristic.writeType = BluetoothGattCharacteristic.WRITE_TYPE_DEFAULT
characteristic.value = next
gatt?.writeCharacteristic(characteristic)
currentGatt.writeCharacteristic(characteristic)
}
if (!started) {
writeInProgress = false
currentGatt.disconnect()
}
}
@Synchronized private fun resetWrites() {
writes.clear()
writeInProgress = false
}
}
apks/pi-car-companion-debug.apk
BIN
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scripts/pi-car-companion-bluetooth
+35 -30
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@@ -21,8 +21,6 @@ DBUS_PROPERTIES = "org.freedesktop.DBus.Properties"
GATT_MANAGER = "org.bluez.GattManager1"
GATT_SERVICE = "org.bluez.GattService1"
GATT_CHARACTERISTIC = "org.bluez.GattCharacteristic1"
AD_MANAGER = "org.bluez.LEAdvertisingManager1"
ADVERTISEMENT = "org.bluez.LEAdvertisement1"
SERVICE_UUID = "6c7a0001-7c6d-4f74-9bb0-c5a4e5efc001"
RX_UUID = "6c7a0002-7c6d-4f74-9bb0-c5a4e5efc001"
@@ -103,19 +101,30 @@ class Characteristic(dbus.service.Object):
class TxCharacteristic(Characteristic):
def __init__(self, bus, service):
super().__init__(bus, 1, TX_UUID, ["notify"], service)
super().__init__(bus, 1, TX_UUID, ["indicate"], service)
self.notifying = False
self.queue = deque()
self.sending = False
@dbus.service.method(GATT_CHARACTERISTIC, in_signature="a{sv}")
def StartNotify(self, _options):
@dbus.service.method(GATT_CHARACTERISTIC)
def StartNotify(self):
self.notifying = True
if self.queue and not self.sending:
self.sending = True
GLib.idle_add(self._send_next)
@dbus.service.method(GATT_CHARACTERISTIC, in_signature="a{sv}")
def StopNotify(self, _options):
@dbus.service.method(GATT_CHARACTERISTIC)
def StopNotify(self):
self.notifying = False
self.queue.clear()
self.sending = False
@dbus.service.method(GATT_CHARACTERISTIC)
def Confirm(self):
if self.queue:
GLib.idle_add(self._send_next)
else:
self.sending = False
def send(self, message):
encoded = (json.dumps(message, separators=(",", ":")) + "\n").encode("utf-8")
@@ -123,7 +132,7 @@ class TxCharacteristic(Characteristic):
self.queue.append(encoded[offset:offset + NOTIFY_CHUNK_BYTES])
if not self.sending:
self.sending = True
GLib.timeout_add(20, self._send_next)
GLib.idle_add(self._send_next)
def _send_next(self):
if not self.notifying or not self.queue:
@@ -132,7 +141,7 @@ class TxCharacteristic(Characteristic):
chunk = self.queue.popleft()
value = dbus.Array([dbus.Byte(byte) for byte in chunk], signature="y")
self.PropertiesChanged(GATT_CHARACTERISTIC, {"Value": value}, [])
return bool(self.queue)
return False
class RxCharacteristic(Characteristic):
@@ -216,26 +225,10 @@ def call_api(method, path, body, token):
raise ProtocolError("PI_SERVICE_UNAVAILABLE", "The Pi companion service is unavailable") from error
class Advertisement(dbus.service.Object):
def __init__(self, bus):
self.path = "/org/pi_car_companion/advertisement0"
super().__init__(bus, self.path)
@dbus.service.method(DBUS_PROPERTIES, in_signature="s", out_signature="a{sv}")
def GetAll(self, interface):
if interface != ADVERTISEMENT:
raise InvalidArgs()
return {"Type": "peripheral", "ServiceUUIDs": dbus.Array([SERVICE_UUID], signature="s"), "LocalName": "Pi Car"}
@dbus.service.method(ADVERTISEMENT)
def Release(self):
pass
def find_adapter(bus):
objects = dbus.Interface(bus.get_object(BLUEZ, "/"), DBUS_OM).GetManagedObjects()
for path, interfaces in objects.items():
if GATT_MANAGER in interfaces and AD_MANAGER in interfaces:
if GATT_MANAGER in interfaces:
return path
raise RuntimeError("No Bluetooth LE adapter with GATT server support was found")
@@ -253,10 +246,22 @@ def main():
service.add_characteristic(rx)
service.add_characteristic(tx)
application.add_service(service)
advertisement = Advertisement(bus)
dbus.Interface(adapter, GATT_MANAGER).RegisterApplication(application.path, {}, reply_handler=lambda: None, error_handler=lambda error: (_ for _ in ()).throw(error))
dbus.Interface(adapter, AD_MANAGER).RegisterAdvertisement(advertisement.path, {}, reply_handler=lambda: None, error_handler=lambda error: (_ for _ in ()).throw(error))
GLib.MainLoop().run()
loop = GLib.MainLoop()
registration_errors = []
def registration_failed(error):
registration_errors.append(error)
loop.quit()
dbus.Interface(adapter, GATT_MANAGER).RegisterApplication(
application.path,
{},
reply_handler=lambda: None,
error_handler=registration_failed,
)
loop.run()
if registration_errors:
raise registration_errors[0]
if __name__ == "__main__":
systemd/pi-car-companion-bluetooth.service
+2 -1
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@@ -7,6 +7,7 @@ Wants=pi-car-companion.service
[Service]
Type=simple
ExecStart=/usr/local/libexec/pi-car-companion-bluetooth
ExecStartPost=-/usr/bin/timeout 10 /usr/bin/btmgmt add-adv -c -u 6c7a0001-7c6d-4f74-9bb0-c5a4e5efc001 1
Restart=on-failure
RestartSec=5s
NoNewPrivileges=true
@@ -18,7 +19,7 @@ ProtectKernelModules=true
ProtectControlGroups=true
RestrictRealtime=true
LockPersonality=true
RestrictAddressFamilies=AF_UNIX AF_INET AF_INET6
RestrictAddressFamilies=AF_UNIX AF_INET AF_INET6 AF_BLUETOOTH
[Install]
WantedBy=multi-user.target