def __getitem__(self, pvname):
try:
return self.pvdb[pvname]
except KeyError as ex:
try:
(rec_field, rec, field, mods) = ca.parse_record_field(pvname)
except ValueError:
raise ex
if not field and not mods:
# No field or modifiers, so there's nothing left to check
raise
# Without the modifiers, try 'record[.field]'
try:
inst = self.pvdb[rec_field]
except KeyError:
# Finally, access 'record', see if it has 'field'
try:
inst = self.pvdb[rec]
except KeyError:
raise CaprotoKeyError(f'Neither record nor field exists: '
f'{rec_field}')
try:
inst = inst.get_field(field)
except (AttributeError, KeyError):
raise CaprotoKeyError(f'Neither record nor field exists: '
f'{rec_field}')
# Cache record.FIELD for later usage
self.pvdb[rec_field] = inst
return inst
def test_parse_record(pvname, expected_tuple):
parsed = ca.parse_record_field(pvname)
print('parsed: ', tuple(parsed))
print('expected:', expected_tuple)
assert tuple(parsed) == expected_tuple
if parsed.modifiers:
modifiers, filter_text = parsed.modifiers
if filter_text:
# smoke test these
ca.parse_channel_filter(filter_text)
def test_parse_record_bad_filters(pvname, expected_tuple):
parsed = ca.parse_record_field(pvname)
print('parsed: ', tuple(parsed))
print('expected:', expected_tuple)
assert tuple(parsed) == expected_tuple
modifiers, filter_text = parsed.modifiers
try:
filter_ = ca.parse_channel_filter(filter_text)
except ValueError:
# expected failure
...
else:
raise ValueError(f'Expected failure, instead returned {filter_}')
def __getitem__(self, pvname):
try:
return self.pvdb[pvname]
except KeyError as ex:
try:
(rec_field, rec, field, mods) = ca.parse_record_field(pvname)
except ValueError:
raise ex from None
if not field and not mods:
# No field or modifiers, but a trailing '.' is valid
return self.pvdb[rec]
# Without the modifiers, try 'record[.field]'
try:
inst = self.pvdb[rec_field]
except KeyError:
# Finally, access 'record', see if it has 'field'
try:
inst = self.pvdb[rec]
except KeyError:
raise CaprotoKeyError(f'Neither record nor field exists: '
f'{rec_field}')
try:
inst = inst.get_field(field)
except (AttributeError, KeyError):
raise CaprotoKeyError(f'Neither record nor field exists: '
f'{rec_field}')
# Verify the modifiers are usable BEFORE caching rec_field in the pvdb:
if ca.RecordModifiers.long_string in (mods or {}):
if inst.data_type not in (ChannelType.STRING,
ChannelType.CHAR):
raise CaprotoKeyError(
f'Long-string modifier not supported with types '
f'other than string or char ({inst.data_type})'
)
# Cache record.FIELD for later usage
self.pvdb[rec_field] = inst
return inst
async def _process_command(self, command):
'''Process a command from a client, and return the server response'''
tags = self._tags
if command is ca.DISCONNECTED:
raise DisconnectedCircuit()
elif isinstance(command, ca.VersionRequest):
to_send = [ca.VersionResponse(ca.DEFAULT_PROTOCOL_VERSION)]
elif isinstance(command, ca.SearchRequest):
pv_name = command.name
try:
self.context[pv_name]
except KeyError:
if command.reply == ca.DO_REPLY:
to_send = [
ca.NotFoundResponse(
version=ca.DEFAULT_PROTOCOL_VERSION,
cid=command.cid)
]
else:
to_send = []
else:
to_send = [
ca.SearchResponse(self.context.port, None, command.cid,
ca.DEFAULT_PROTOCOL_VERSION)
]
elif isinstance(command, ca.CreateChanRequest):
pvname = command.name
try:
db_entry = self.context[pvname]
except KeyError:
self.log.debug('Client requested invalid channel name: %s',
pvname)
to_send = [ca.CreateChFailResponse(cid=command.cid)]
else:
access = db_entry.check_access(self.client_hostname,
self.client_username)
modifiers = ca.parse_record_field(pvname).modifiers
data_type = db_entry.data_type
data_count = db_entry.max_length
if ca.RecordModifiers.long_string in (modifiers or {}):
if data_type in (ChannelType.STRING, ):
data_type = ChannelType.CHAR
data_count = db_entry.long_string_max_length
to_send = [
ca.AccessRightsResponse(cid=command.cid,
access_rights=access),
ca.CreateChanResponse(data_type=data_type,
data_count=data_count,
cid=command.cid,
sid=self.circuit.new_channel_id()),
]
elif isinstance(command, ca.HostNameRequest):
self.client_hostname = command.name
to_send = []
elif isinstance(command, ca.ClientNameRequest):
self.client_username = command.name
to_send = []
elif isinstance(command, (ca.ReadNotifyRequest, ca.ReadRequest)):
chan, db_entry = self._get_db_entry_from_command(command)
try:
data_type = command.data_type
except ValueError:
raise ca.RemoteProtocolError('Invalid data type')
# If we are in the middle of processing a Write[Notify]Request,
# allow a bit of time for that to (maybe) finish. Some requests
# may take a long time, so give up rather quickly to avoid
# introducing too much latency.
await self.write_event.wait(timeout=WRITE_LOCK_TIMEOUT)
read_data_type = data_type
if chan.name.endswith('$'):
try:
read_data_type = _LongStringChannelType(read_data_type)
except ValueError:
# Not requesting a LONG_STRING type
...
metadata, data = await db_entry.auth_read(
self.client_hostname,
self.client_username,
read_data_type,
user_address=self.circuit.address,
)
old_version = self.circuit.protocol_version < 13
if command.data_count > 0 or old_version:
data = data[:command.data_count]
# This is a pass-through if arr is None.
data = apply_arr_filter(chan.channel_filter.arr, data)
# If the timestamp feature is active swap the timestamp.
# Information must copied because not all clients will have the
# timestamp filter
if chan.channel_filter.ts and command.data_type in ca.time_types:
time_type = type(metadata)
now = ca.TimeStamp.from_unix_timestamp(time.time())
metadata = time_type(
**ChainMap({'stamp': now},
dict((field, getattr(metadata, field))
for field, _ in time_type._fields_)))
notify = isinstance(command, ca.ReadNotifyRequest)
data_count = db_entry.calculate_length(data)
to_send = [
chan.read(data=data,
data_type=command.data_type,
data_count=data_count,
status=1,
ioid=command.ioid,
metadata=metadata,
notify=notify)
]
elif isinstance(command, (ca.WriteRequest, ca.WriteNotifyRequest)):
chan, db_entry = self._get_db_entry_from_command(command)
client_waiting = isinstance(command, ca.WriteNotifyRequest)
async def handle_write():
'''Wait for an asynchronous caput to finish'''
try:
write_status = await db_entry.auth_write(
self.client_hostname,
self.client_username,
command.data,
command.data_type,
command.metadata,
user_address=self.circuit.address)
except Exception as ex:
self.log.exception('Invalid write request by %s (%s): %r',
self.client_username,
self.client_hostname, command)
cid = self.circuit.channels_sid[command.sid].cid
response_command = ca.ErrorResponse(
command,
cid,
status=ca.CAStatus.ECA_PUTFAIL,
error_message=('Python exception: {} {}'
''.format(type(ex).__name__, ex)))
await self.send(response_command)
else:
if client_waiting:
if write_status is None:
# errors can be passed back by exceptions, and
# returning none for write_status can just be
# considered laziness
write_status = True
response_command = chan.write(
ioid=command.ioid,
status=write_status,
data_count=db_entry.length)
await self.send(response_command)
finally:
maybe_awaitable = self.write_event.set()
# The curio backend makes this an awaitable thing.
if maybe_awaitable is not None:
await maybe_awaitable
self.write_event.clear()
await self._start_write_task(handle_write)
to_send = []
elif isinstance(command, ca.EventAddRequest):
chan, db_entry = self._get_db_entry_from_command(command)
# TODO no support for deprecated low/high/to
read_data_type = command.data_type
if chan.name.endswith('$'):
try:
read_data_type = _LongStringChannelType(read_data_type)
except ValueError:
# Not requesting a LONG_STRING type
...
sub = Subscription(mask=command.mask,
channel_filter=chan.channel_filter,
channel=chan,
circuit=self,
data_type=read_data_type,
data_count=command.data_count,
subscriptionid=command.subscriptionid,
db_entry=db_entry)
sub_spec = SubscriptionSpec(db_entry=db_entry,
data_type_name=read_data_type.name,
mask=command.mask,
channel_filter=chan.channel_filter)
self.subscriptions[sub_spec].append(sub)
self.context.subscriptions[sub_spec].append(sub)
# If we are in the middle of processing a Write[Notify]Request,
# allow a bit of time for that to (maybe) finish. Some requests
# may take a long time, so give up rather quickly to avoid
# introducing too much latency.
if not self.write_event.is_set():
await self.write_event.wait(timeout=WRITE_LOCK_TIMEOUT)
await db_entry.subscribe(self.context.subscription_queue, sub_spec,
sub)
to_send = []
elif isinstance(command, ca.EventCancelRequest):
chan, db_entry = self._get_db_entry_from_command(command)
removed = await self._cull_subscriptions(
db_entry,
lambda sub: sub.subscriptionid == command.subscriptionid)
if removed:
_, removed_sub = removed[0]
data_count = removed_sub.data_count
else:
data_count = db_entry.length
to_send = [
chan.unsubscribe(command.subscriptionid,
data_type=command.data_type,
data_count=data_count)
]
elif isinstance(command, ca.EventsOnRequest):
# Immediately send most recent updates for all subscriptions.
most_recent_updates = list(self.most_recent_updates.values())
self.most_recent_updates.clear()
if most_recent_updates:
await self.send(*most_recent_updates)
maybe_awaitable = self.events_on.set()
# The curio backend makes this an awaitable thing.
if maybe_awaitable is not None:
await maybe_awaitable
self.circuit.log.info("Client at %s:%d has turned events on.",
*self.circuit.address)
to_send = []
elif isinstance(command, ca.EventsOffRequest):
# The client has signaled that it does not think it will be able to
# catch up to the backlog. Clear all updates queued to be sent...
self.unexpired_updates.clear()
# ...and tell the Context that any future updates from ChannelData
# should not be added to this circuit's queue until further notice.
self.events_on.clear()
self.circuit.log.info("Client at %s:%d has turned events off.",
*self.circuit.address)
to_send = []
elif isinstance(command, ca.ClearChannelRequest):
chan, db_entry = self._get_db_entry_from_command(command)
await self._cull_subscriptions(
db_entry, lambda sub: sub.channel == command.sid)
to_send = [chan.clear()]
elif isinstance(command, ca.EchoRequest):
to_send = [ca.EchoResponse()]
if isinstance(command, ca.Message):
tags['bytesize'] = len(command)
self.log.debug("%r", command, extra=tags)
return to_send
