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BLESession: Guard getCharacteristics() and getServiceByUUID() with lock

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It turned out that bluepy Peripheral's getCharacteristics() and
getServiceByUUID() accesses shared resource with other bluepy APIs. Then
it needs guard with lock in same manner as other bluepy API calls. Guard
them with the lock of the session.

Introduce _get_characteristic() and _get_service() helper functions to
wrap the API calls with lock guard, and replace API calls with them.

Also remove unnecessary getCharacteristics() calls.

Signed-off-by: Shin'ichiro Kawasaki <kawasaki@juno.dti.ne.jp>
This commit is contained in:
Shin'ichiro Kawasaki
2020-06-13 19:51:19 +09:00
parent 751a96eec2
commit 128786b06b
1 changed files with 19 additions and 12 deletions
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31
scratch_link.py
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@@ -448,6 +448,17 @@ class BLESession(Session):
# ref: https://github.com/LLK/scratch-link/blob/develop/Documentation/BluetoothLE.md
return False
def _get_service(self, service_id):
with self.lock:
service = self.perip.getServiceByUUID(UUID(service_id))
def _get_characteristic(self, chara_id):
if not self.perip:
return None
with self.lock:
charas = self.perip.getCharacteristics(uuid=chara_id)
return charas[0]
def handle_request(self, method, params):
"""Handle requests from Scratch"""
if self.delegate:
@@ -514,9 +525,8 @@ class BLESession(Session):
logger.debug("handle read request")
service_id = params['serviceId']
chara_id = params['characteristicId']
charas = self.perip.getCharacteristics(uuid=chara_id)
c = charas[0]
if c.uuid != UUID(chara_id):
c = self._get_characteristic(chara_id)
if not c or c.uuid != UUID(chara_id):
logger.error("Failed to get characteristic {chara_id}")
self.status = self.DONE
else:
@@ -531,23 +541,20 @@ class BLESession(Session):
logger.debug("handle startNotifications request")
service_id = params['serviceId']
chara_id = params['characteristicId']
charas = self.perip.getCharacteristics(uuid=chara_id)
self.startNotifications(service_id, chara_id)
elif self.status == self.CONNECTED and method == 'stopNotifications':
logger.debug("handle stopNotifications request")
service_id = params['serviceId']
chara_id = params['characteristicId']
charas = self.perip.getCharacteristics(uuid=chara_id)
self.stopNotifications(service_id, chara_id)
elif self.status == self.CONNECTED and method == 'write':
logger.debug("handle write request")
service_id = params['serviceId']
chara_id = params['characteristicId']
charas = self.perip.getCharacteristics(uuid=chara_id)
c = charas[0]
if c.uuid != UUID(chara_id):
c = self._get_characteristic(chara_id)
if not c or c.uuid != UUID(chara_id):
logger.error("Failed to get characteristic {chara_id}")
self.status = self.DONE
else:
@@ -566,14 +573,14 @@ class BLESession(Session):
return res
def setNotifications(self, service_id, chara_id, value):
service = self.perip.getServiceByUUID(UUID(service_id))
chas = service.getCharacteristics(forUUID=chara_id)
handle = chas[0].getHandle()
service = self._get_service(service_id)
c = self._get_characteristic(chara_id)
handle = c.getHandle()
# prepare notification handler
self.delegate.add_handle(service_id, chara_id, handle)
# request notification to the BLE device
with self.lock:
self.perip.writeCharacteristic(chas[0].getHandle() + 1, value, True)
self.perip.writeCharacteristic(handle + 1, value, True)
def startNotifications(self, service_id, chara_id):
logger.debug(f"start notification for {chara_id}")