X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/61cd57499905e8e8cca07c774d1bf8c6bfa069a7..83562734c781379665e3a337bce5b548afc88681:/sdk/python/arvados/events.py

diff --git a/sdk/python/arvados/events.py b/sdk/python/arvados/events.py
index b7d610d66e..09f2a871a9 100644
--- a/sdk/python/arvados/events.py
+++ b/sdk/python/arvados/events.py
@@ -1,30 +1,40 @@
-from ws4py.client.threadedclient import WebSocketClient
-import thread
+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 ssl
+from ws4py.client.threadedclient import WebSocketClient
 
 _logger = logging.getLogger('arvados.events')
 
 class EventClient(WebSocketClient):
     def __init__(self, url, filters, on_event):
-        ssl_options = None
-        if re.match(r'(?i)^(true|1|yes)$',
-                    config.get('ARVADOS_API_HOST_INSECURE', 'no')):
-            ssl_options={'cert_reqs': ssl.CERT_NONE}
+        # 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
+        if config.flag_is_true('ARVADOS_API_HOST_INSECURE'):
+            ssl_options['cert_reqs'] = ssl.CERT_NONE
         else:
-            ssl_options={'cert_reqs': ssl.CERT_REQUIRED}
+            ssl_options['cert_reqs'] = ssl.CERT_REQUIRED
 
-        super(EventClient, self).__init__(url, ssl_options)
+        # 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
 
     def opened(self):
-        self.send(json.dumps({"method": "subscribe", "filters": self.filters}))
+        self.subscribe(self.filters)
 
     def received_message(self, m):
         self.on_event(json.loads(str(m)))
@@ -36,14 +46,108 @@ class EventClient(WebSocketClient):
         except:
             pass
 
-def subscribe(api, filters, on_event):
-    ws = None
+    def subscribe(self, filters, last_log_id=None):
+        m = {"method": "subscribe", "filters": filters}
+        if last_log_id is not None:
+            m["last_log_id"] = last_log_id
+        self.send(json.dumps(m))
+
+    def unsubscribe(self, filters):
+        self.send(json.dumps({"method": "unsubscribe", "filters": filters}))
+
+class PollClient(threading.Thread):
+    def __init__(self, api, filters, on_event, poll_time):
+        super(PollClient, self).__init__()
+        self.api = api
+        if filters:
+            self.filters = [filters]
+        else:
+            self.filters = [[]]
+        self.on_event = on_event
+        self.poll_time = poll_time
+        self.daemon = True
+        self.stop = threading.Event()
+
+    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']
+
+        self.on_event({'status': 200})
+
+        while not self.stop.isSet():
+            max_id = self.id
+            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:
+                    if i['id'] > max_id:
+                        max_id = i['id']
+                    self.on_event(i)
+            self.id = max_id
+            self.stop.wait(self.poll_time)
+
+    def run_forever(self):
+        # Have to poll here, otherwise KeyboardInterrupt will never get processed.
+        while not self.stop.is_set():
+            self.stop.wait(1)
+
+    def close(self):
+        self.stop.set()
+        try:
+            self.join()
+        except RuntimeError:
+            # "join() raises a RuntimeError if an attempt is made to join the
+            # current thread as that would cause a deadlock. It is also an
+            # error to join() a thread before it has been started and attempts
+            # to do so raises the same exception."
+            pass
+
+    def subscribe(self, filters):
+        self.on_event({'status': 200})
+        self.filters.append(filters)
+
+    def unsubscribe(self, filters):
+        del self.filters[self.filters.index(filters)]
+
+
+def _subscribe_websocket(api, filters, on_event):
+    endpoint = api._rootDesc.get('websocketUrl', None)
+    if not endpoint:
+        raise errors.FeatureNotEnabledError(
+            "Server does not advertise a websocket endpoint")
+    uri_with_token = "{}?api_token={}".format(endpoint, api.api_token)
+    client = EventClient(uri_with_token, filters, on_event)
+    ok = False
+    try:
+        client.connect()
+        ok = True
+        return client
+    finally:
+        if not ok:
+            client.close_connection()
+
+def subscribe(api, filters, on_event, poll_fallback=15):
+    """
+    :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.
+    """
+
+    if not poll_fallback:
+        return _subscribe_websocket(api, filters, on_event)
+
     try:
-        url = "{}?api_token={}".format(api._rootDesc['websocketUrl'], config.get('ARVADOS_API_TOKEN'))
-        ws = EventClient(url, filters, on_event)
-        ws.connect()
-        return ws
-    except Exception:
-        if (ws):
-          ws.close_connection()
-        raise
+        return _subscribe_websocket(api, filters, on_event)
+    except Exception as e:
+        _logger.warn("Falling back to polling after websocket error: %s" % e)
+    p = PollClient(api, filters, on_event, poll_fallback)
+    p.start()
+    return p