X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/3957f3dbb398a1039c8ebb12a008bf9a7f17a4f0..07ad618c10f03f9d24970670f991791d4bd22b62:/sdk/python/arvados/events.py diff --git a/sdk/python/arvados/events.py b/sdk/python/arvados/events.py index 7e8cdc3282..df5b3e7dee 100644 --- a/sdk/python/arvados/events.py +++ b/sdk/python/arvados/events.py @@ -1,43 +1,60 @@ -from ws4py.client.threadedclient import WebSocketClient -import threading +import arvados +import config +import errors + +import logging import json -import os +import threading import time -import ssl +import os import re -import config -import logging -import arvados +import ssl +from ws4py.client.threadedclient import WebSocketClient _logger = logging.getLogger('arvados.events') class EventClient(WebSocketClient): - def __init__(self, url, filters, on_event): - # Prefer system's CA certificates (if available) - ssl_options = {} - certs_path = '/etc/ssl/certs/ca-certificates.crt' - if os.path.exists(certs_path): - ssl_options['ca_certs'] = certs_path + def __init__(self, url, filters, on_event, last_log_id): + ssl_options = {'ca_certs': arvados.util.ca_certs_path()} if config.flag_is_true('ARVADOS_API_HOST_INSECURE'): ssl_options['cert_reqs'] = ssl.CERT_NONE else: ssl_options['cert_reqs'] = ssl.CERT_REQUIRED + + # Warning: If the host part of url resolves to both IPv6 and + # IPv4 addresses (common with "localhost"), only one of them + # will be attempted -- and it might not be the right one. See + # ws4py's WebSocketBaseClient.__init__. super(EventClient, self).__init__(url, ssl_options=ssl_options) self.filters = filters self.on_event = on_event + self.stop = threading.Event() + self.last_log_id = last_log_id def opened(self): - self.subscribe(self.filters) + self.subscribe(self.filters, self.last_log_id) def received_message(self, m): self.on_event(json.loads(str(m))) - def close_connection(self): - try: - self.sock.shutdown(socket.SHUT_RDWR) - self.sock.close() - except: - pass + def closed(self, code, reason=None): + self.stop.set() + + def close(self, code=1000, reason=''): + """Close event client and wait for it to finish.""" + + # parent close() method sends a asynchronous "closed" event to the server + super(EventClient, self).close(code, reason) + + # if server doesn't respond by finishing the close handshake, we'll be + # stuck in limbo forever. We don't need to wait for the server to + # respond to go ahead and actually close the socket. + self.close_connection() + + # wait for websocket thread to finish up (closed() is called by + # websocket thread in as part of terminate()) + while not self.stop.is_set(): + self.stop.wait(1) def subscribe(self, filters, last_log_id=None): m = {"method": "subscribe", "filters": filters} @@ -49,7 +66,7 @@ class EventClient(WebSocketClient): self.send(json.dumps({"method": "unsubscribe", "filters": filters})) class PollClient(threading.Thread): - def __init__(self, api, filters, on_event, poll_time): + def __init__(self, api, filters, on_event, poll_time, last_log_id): super(PollClient, self).__init__() self.api = api if filters: @@ -58,28 +75,37 @@ class PollClient(threading.Thread): self.filters = [[]] self.on_event = on_event self.poll_time = poll_time + self.daemon = True self.stop = threading.Event() + self.last_log_id = last_log_id def run(self): self.id = 0 - for f in self.filters: - items = self.api.logs().list(limit=1, order="id desc", filters=f).execute()['items'] - if items: - if items[0]['id'] > self.id: - self.id = items[0]['id'] + if self.last_log_id != None: + self.id = self.last_log_id + else: + for f in self.filters: + items = self.api.logs().list(limit=1, order="id desc", filters=f).execute()['items'] + if items: + if items[0]['id'] > self.id: + self.id = items[0]['id'] self.on_event({'status': 200}) while not self.stop.isSet(): max_id = self.id + moreitems = False for f in self.filters: - items = self.api.logs().list(order="id asc", filters=f+[["id", ">", str(self.id)]]).execute()['items'] - for i in items: + items = self.api.logs().list(order="id asc", filters=f+[["id", ">", str(self.id)]]).execute() + for i in items["items"]: if i['id'] > max_id: max_id = i['id'] self.on_event(i) + if items["items_available"] > len(items["items"]): + moreitems = True self.id = max_id - self.stop.wait(self.poll_time) + if not moreitems: + self.stop.wait(self.poll_time) def run_forever(self): # Have to poll here, otherwise KeyboardInterrupt will never get processed. @@ -87,6 +113,8 @@ class PollClient(threading.Thread): self.stop.wait(1) def close(self): + """Close poll client and wait for it to finish.""" + self.stop.set() try: self.join() @@ -105,29 +133,48 @@ class PollClient(threading.Thread): del self.filters[self.filters.index(filters)] -def subscribe(api, filters, on_event, poll_fallback=15): - ''' - api: Must be a newly created from arvados.api(cache=False), not shared with the caller, as it may be used by a background thread. - filters: Initial subscription filters. - on_event: The callback when a message is received - poll_fallback: If websockets are not available, fall back to polling every N seconds. If poll_fallback=False, this will return None if websockets are not available. - ''' - ws = None - if 'websocketUrl' in api._rootDesc: +def _subscribe_websocket(api, filters, on_event, last_log_id=None): + endpoint = api._rootDesc.get('websocketUrl', None) + if not endpoint: + raise errors.FeatureNotEnabledError( + "Server does not advertise a websocket endpoint") + try: + uri_with_token = "{}?api_token={}".format(endpoint, api.api_token) + client = EventClient(uri_with_token, filters, on_event, last_log_id) + ok = False try: - url = "{}?api_token={}".format(api._rootDesc['websocketUrl'], api.api_token) - ws = EventClient(url, filters, on_event) - ws.connect() - return ws - except Exception as e: - _logger.warn("Got exception %s trying to connect to websockets at %s" % (e, api._rootDesc['websocketUrl'])) - if ws: - ws.close_connection() - if poll_fallback: - _logger.warn("Websockets not available, falling back to log table polling") - p = PollClient(api, filters, on_event, poll_fallback) - p.start() - return p - else: - _logger.error("Websockets not available") - return None + client.connect() + ok = True + return client + finally: + if not ok: + client.close_connection() + except: + _logger.warn("Failed to connect to websockets on %s" % endpoint) + raise + + +def subscribe(api, filters, on_event, poll_fallback=15, last_log_id=None): + """ + :api: + a client object retrieved from arvados.api(). The caller should not use this client object for anything else after calling subscribe(). + :filters: + Initial subscription filters. + :on_event: + The callback when a message is received. + :poll_fallback: + If websockets are not available, fall back to polling every N seconds. If poll_fallback=False, this will return None if websockets are not available. + :last_log_id: + Log rows that are newer than the log id + """ + + if not poll_fallback: + return _subscribe_websocket(api, filters, on_event, last_log_id) + + try: + return _subscribe_websocket(api, filters, on_event, last_log_id) + except Exception as e: + _logger.warn("Falling back to polling after websocket error: %s" % e) + p = PollClient(api, filters, on_event, poll_fallback, last_log_id) + p.start() + return p