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bytewax_connectors.py
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168 lines (156 loc) · 6.43 KB
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import time
import queue
import threading
import weakref
import pyarrow as pa
from bytewax.inputs import DynamicInput, StatelessSource
import btrdb
_empty_values = pa.Table.from_arrays(
[pa.array([]), pa.array([])],
schema=pa.schema(
[
pa.field("time", pa.timestamp("ns", tz="UTC"), nullable=False),
pa.field("value", pa.float64(), nullable=False),
]
),
)
class InsertSubscription(DynamicInput):
def __init__(
self,
selector_fn,
selector_refresh_interval=60 * 60 * 6,
heartbeat_interval=None,
profile=None,
conn_str=None,
apikey=None,
):
self._selector_fn = selector_fn
self._conn_str = conn_str
self._apikey = apikey
self._profile = profile
self._selector_refresh_interval = selector_refresh_interval
self._heartbeat_interval = heartbeat_interval
class Source(StatelessSource):
def __init__(
self,
db,
selector_fn,
selector_refresh_interval,
heartbeat_interval,
worker_index,
worker_count,
):
self._db = db
self._selector_fn = selector_fn
self._worker_index = worker_index
self._worker_count = worker_count
self._selector_refresh_interval = selector_refresh_interval
self._heartbeat_interval = heartbeat_interval
self._read_worker_exception = None
self._background_worker_exception = None
self._del_event = threading.Event()
self._update_queue = queue.Queue(1)
self._data_queue = queue.Queue(512)
# self is wrapped in a weakref with the worker threads so
# that the worker threads keep self alive.
def read_worker(self, data):
try:
# Avoid exessive weakref lookups
# by doing the lookup upfront initially.
del_event = self._del_event
data_queue = self._data_queue
for dat in data:
if del_event.is_set():
return
data_queue.put(dat)
except Exception as e:
self._read_worker_exception = e
# Self is a weakref, same as above.
def background_worker(self):
try:
# Avoid exessive weakref lookups
# by doing the lookup upfront initially.
db = self._db
del_event = self._del_event
selector_fn = self._selector_fn
worker_index = self._worker_index
worker_count = self._worker_count
data_queue = self._data_queue
heartbeat_interval = self._heartbeat_interval
last_heartbeat = time.monotonic()
selector_refresh_interval = self._selector_refresh_interval
last_selector_refresh = time.monotonic() - selector_refresh_interval
current_uuids = set()
while True:
now = time.monotonic()
if (now - last_selector_refresh) >= selector_refresh_interval:
last_selector_refresh = now
next_uuids = {
uuid
for uuid in selector_fn(db)
if uuid.int % worker_count == worker_index
}
added_uuids = next_uuids - current_uuids
removed_uuids = current_uuids - next_uuids
if len(added_uuids) != 0 or len(removed_uuids) != 0:
self._update_queue.put([added_uuids, removed_uuids])
current_uuids = next_uuids
if (
heartbeat_interval is not None
and (now - last_heartbeat) >= heartbeat_interval
):
last_heartbeat = now
for uuid in current_uuids:
while not del_event.is_set():
try:
data_queue.put((uuid, _empty_values), 0.1)
break
except queue.Full:
pass
if del_event.wait(1.0):
return
except Exception as e:
self._background_worker_exception = e
weakself = weakref.proxy(self)
data = db.ep.subscribe(self._update_queue)
self._background_worker = threading.Thread(
target=background_worker, args=[weakself], daemon=True
)
self._read_worker = threading.Thread(
target=read_worker, args=[weakself, data], daemon=True
)
self._background_worker.start()
self._read_worker.start()
def next(self):
# Check if the selector thread has died.
background_worker_exception = self._background_worker_exception
if background_worker_exception is not None:
raise background_worker_exception
try:
return self._data_queue.get_nowait()
except queue.Empty:
# Check if the reason no data arrived is because
# the reader thead has died.
read_worker_exception = self._read_worker_exception
if read_worker_exception is not None:
raise read_worker_exception
return None
def __del__(self):
# Signal workers to exit.
self._del_event.set()
# Signal the end of the subscription.
self._update_queue.put(None)
def build(self, worker_index, worker_count):
db = btrdb.connect(
profile=self._profile,
conn_str=self._conn_str,
apikey=self._apikey,
)
return InsertSubscription.Source(
db,
self._selector_fn,
self._selector_refresh_interval,
self._heartbeat_interval,
worker_index,
worker_count,
)