1. mp.set_start_method('spawn') commented out from scripts/uncloud

2. uncloud.shared moved under uncloud.common
3. Refactoring in etcd_wrapper e.g timeout mechanism removed and few other things
4. uncloud-{scheduler,host} now better handle etcd events in their block state (waiting for requests to come)

uncloud/common/etcd_wrapper.py

@@ -1,24 +1,21 @@
 import etcd3
 import json
-import queue
-import copy
-from uncloud import UncloudException
 
-from collections import namedtuple
 from functools import wraps
 
-from . import logger
-
-PseudoEtcdMeta = namedtuple("PseudoEtcdMeta", ["key"])
+from uncloud import UncloudException
+from uncloud.common import logger
 
 
 class EtcdEntry:
-    # key: str
-    # value: str
-
-    def __init__(self, meta, value, value_in_json=False):
-        self.key = meta.key.decode("utf-8")
-        self.value = value.decode("utf-8")
+    def __init__(self, meta_or_key, value, value_in_json=False):
+        if hasattr(meta_or_key, 'key'):
+            # if meta has attr 'key' then get it
+            self.key = meta_or_key.key.decode('utf-8')
+        else:
+            # otherwise meta is the 'key'
+            self.key = meta_or_key
+        self.value = value.decode('utf-8')
 
         if value_in_json:
             self.value = json.loads(self.value)
@@ -29,18 +26,12 @@ def readable_errors(func):
     def wrapper(*args, **kwargs):
         try:
             return func(*args, **kwargs)
-        except etcd3.exceptions.ConnectionFailedError as err:
-            raise UncloudException(
-                "Cannot connect to etcd: is etcd running as configured in uncloud.conf?"
-            )
+        except etcd3.exceptions.ConnectionFailedError:
+            raise UncloudException('Cannot connect to etcd: is etcd running as configured in uncloud.conf?')
         except etcd3.exceptions.ConnectionTimeoutError as err:
-            raise etcd3.exceptions.ConnectionTimeoutError(
-                "etcd connection timeout."
-            ) from err
+            raise etcd3.exceptions.ConnectionTimeoutError('etcd connection timeout.') from err
         except Exception:
-            logger.exception(
-                "Some etcd error occured. See syslog for details."
-            )
+            logger.exception('Some etcd error occured. See syslog for details.')
 
     return wrapper
 
@@ -64,55 +55,39 @@ class Etcd3Wrapper:
             _value = json.dumps(_value)
 
         if not isinstance(_key, str):
-            _key = _key.decode("utf-8")
+            _key = _key.decode('utf-8')
 
         return self.client.put(_key, _value, **kwargs)
 
     @readable_errors
-    def get_prefix(self, *args, value_in_json=False, **kwargs):
-        r = self.client.get_prefix(*args, **kwargs)
-        for entry in r:
-            e = EtcdEntry(*entry[::-1], value_in_json=value_in_json)
-            if e.value:
-                yield e
+    def get_prefix(self, *args, value_in_json=False, raise_exception=True, **kwargs):
+        try:
+            event_iterator = self.client.get_prefix(*args, **kwargs)
+            for e in event_iterator:
+                yield EtcdEntry(*e[::-1], value_in_json=value_in_json)
+        except Exception as err:
+            if raise_exception:
+                raise Exception('Exception in etcd_wrapper.get_prefix') from err
+            else:
+                logger.exception('Error in etcd_wrapper')
+                return iter([])
 
     @readable_errors
-    def watch_prefix(self, key, timeout=0, value_in_json=False):
-        timeout_event = EtcdEntry(
-            PseudoEtcdMeta(key=b"TIMEOUT"),
-            value=str.encode(
-                json.dumps({"status": "TIMEOUT", "type": "TIMEOUT"})
-            ),
-            value_in_json=value_in_json,
-        )
-
-        event_queue = queue.Queue()
-
-        def add_event_to_queue(event):
-            if hasattr(event, "events"):
-                for e in event.events:
-                    if e.value:
-                        event_queue.put(
-                            EtcdEntry(
-                                e, e.value, value_in_json=value_in_json
-                            )
-                        )
-
-        self.client.add_watch_prefix_callback(key, add_event_to_queue)
-
-        while True:
-            try:
-                while True:
-                    v = event_queue.get(timeout=timeout)
-                    yield v
-            except queue.Empty:
-                event_queue.put(copy.deepcopy(timeout_event))
-
-
-class PsuedoEtcdEntry(EtcdEntry):
-    def __init__(self, key, value, value_in_json=False):
-        super().__init__(
-            PseudoEtcdMeta(key=key.encode("utf-8")),
-            value,
-            value_in_json=value_in_json,
-        )
+    def watch_prefix(self, key, raise_exception=True, value_in_json=False):
+        try:
+            event_iterator, cancel = self.client.watch_prefix(key)
+            for e in event_iterator:
+                if hasattr(e, '_event'):
+                    e = e._event
+                    if e.type == e.PUT:
+                        yield EtcdEntry(e.kv.key, e.kv.value, value_in_json=value_in_json)
+        except Exception as err:
+            if raise_exception:
+                raise Exception('Exception in etcd_wrapper.get_prefix') from err
+            else:
+                logger.exception('Error in etcd_wrapper.watch_prefix')
+                try:
+                    cancel()
+                except Exception:
+                    pass
+                return iter([])