feat: events (#357)

Author: sighphyre

UnleashClient/__init__.py

@@ -24,7 +24,12 @@
     SDK_NAME,
     SDK_VERSION,
 )
-from UnleashClient.events import UnleashEvent, UnleashEventType
+from UnleashClient.events import (
+    BaseEvent,
+    UnleashEvent,
+    UnleashEventType,
+    UnleashReadyEvent,
+)
 from UnleashClient.loader import load_features
 from UnleashClient.periodic_tasks import (
     aggregate_and_send_metrics,
@@ -46,6 +51,37 @@
 ]
 
 
+def build_ready_callback(
+    event_callback: Optional[Callable[[BaseEvent], None]] = None,
+) -> Optional[Callable]:
+    """
+    Builds a callback function that can be used to notify when the Unleash client is ready.
+    """
+
+    if not event_callback:
+        return None
+
+    already_fired = False
+
+    def ready_callback() -> None:
+        """
+        Callback function to notify that the Unleash client is ready.
+        This will only call the event_callback once.
+        """
+        nonlocal already_fired
+        if already_fired:
+            return
+        if event_callback:
+            event = UnleashReadyEvent(
+                event_type=UnleashEventType.READY,
+                event_id=uuid.uuid4(),
+            )
+            already_fired = True
+            event_callback(event)
+
+    return ready_callback
+
+
 # pylint: disable=dangerous-default-value
 class UnleashClient:
     """
@@ -99,7 +135,7 @@ def __init__(
         scheduler: Optional[BaseScheduler] = None,
         scheduler_executor: Optional[str] = None,
         multiple_instance_mode: InstanceAllowType = InstanceAllowType.WARN,
-        event_callback: Optional[Callable[[UnleashEvent], None]] = None,
+        event_callback: Optional[Callable[[BaseEvent], None]] = None,
     ) -> None:
         custom_headers = custom_headers or {}
         custom_options = custom_options or {}
@@ -132,6 +168,7 @@ def __init__(
         self.unleash_project_name = project_name
         self.unleash_verbose_log_level = verbose_log_level
         self.unleash_event_callback = event_callback
+        self._ready_callback = build_ready_callback(event_callback)
 
         self._do_instance_check(multiple_instance_mode)
 
@@ -283,12 +320,15 @@ def initialize_client(self, fetch_toggles: bool = True) -> None:
                         "request_timeout": self.unleash_request_timeout,
                         "request_retries": self.unleash_request_retries,
                         "project": self.unleash_project_name,
+                        "event_callback": self.unleash_event_callback,
+                        "ready_callback": self._ready_callback,
                     }
                     job_func: Callable = fetch_and_load_features
                 else:
                     job_args = {
                         "cache": self.cache,
                         "engine": self.engine,
+                        "ready_callback": self._ready_callback,
                     }
                     job_func = load_features
 

UnleashClient/events.py

@@ -1,5 +1,6 @@
 from dataclasses import dataclass
 from enum import Enum
+from json import loads
 from typing import Optional
 from uuid import UUID
 
@@ -11,17 +12,51 @@ class UnleashEventType(Enum):
 
     FEATURE_FLAG = "feature_flag"
     VARIANT = "variant"
+    FETCHED = "fetched"
+    READY = "ready"
 
 
 @dataclass
-class UnleashEvent:
+class BaseEvent:
     """
-    Dataclass capturing information from an Unleash feature flag or variant check.
+    Base event type for all events in the Unleash client.
     """
 
     event_type: UnleashEventType
     event_id: UUID
+
+
+@dataclass
+class UnleashEvent(BaseEvent):
+    """
+    Dataclass capturing information from an Unleash feature flag or variant check.
+    """
+
     context: dict
     enabled: bool
     feature_name: str
     variant: Optional[str] = ""
+
+
+@dataclass
+class UnleashReadyEvent(BaseEvent):
+    """
+    Event indicating that the Unleash client is ready.
+    """
+
+    pass
+
+
+@dataclass
+class UnleashFetchedEvent(BaseEvent):
+    """
+    Event indicating that the Unleash client has fetched feature flags.
+    """
+
+    raw_features: str
+
+    @property
+    def features(self) -> dict:
+        if not hasattr(self, "_parsed_payload"):
+            self._parsed_payload = loads(self.raw_features)["features"]
+        return self._parsed_payload

UnleashClient/loader.py

@@ -1,3 +1,5 @@
+from typing import Callable, Optional
+
 from yggdrasil_engine.engine import UnleashEngine
 
 from UnleashClient.cache import BaseCache
@@ -8,6 +10,7 @@
 def load_features(
     cache: BaseCache,
     engine: UnleashEngine,
+    ready_callback: Optional[Callable] = None,
 ) -> None:
     """
     Caching
@@ -27,6 +30,8 @@ def load_features(
 
     try:
         warnings = engine.take_state(feature_provisioning)
+        if ready_callback:
+            ready_callback()
         if warnings:
             LOGGER.warning(
                 "Some features were not able to be parsed correctly, they may not evaluate as expected"

UnleashClient/periodic_tasks/fetch_and_load.py

@@ -1,10 +1,12 @@
-from typing import Optional
+import uuid
+from typing import Callable, Optional
 
 from yggdrasil_engine.engine import UnleashEngine
 
 from UnleashClient.api import get_feature_toggles
 from UnleashClient.cache import BaseCache
 from UnleashClient.constants import ETAG, FEATURES_URL
+from UnleashClient.events import UnleashEventType, UnleashFetchedEvent
 from UnleashClient.loader import load_features
 from UnleashClient.utils import LOGGER
 
@@ -20,6 +22,8 @@ def fetch_and_load_features(
     request_retries: int,
     engine: UnleashEngine,
     project: Optional[str] = None,
+    event_callback: Optional[Callable] = None,
+    ready_callback: Optional[Callable] = None,
 ) -> None:
     (state, etag) = get_feature_toggles(
         url,
@@ -44,3 +48,14 @@ def fetch_and_load_features(
         cache.set(ETAG, etag)
 
     load_features(cache, engine)
+
+    if state:
+        if event_callback:
+            event = UnleashFetchedEvent(
+                event_type=UnleashEventType.FETCHED,
+                event_id=uuid.uuid4(),
+                raw_features=state,
+            )
+            event_callback(event)
+        if ready_callback:
+            ready_callback()

tests/unit_tests/test_client.py

@@ -891,28 +891,24 @@ def test_multiple_instances_are_unique_on_api_key(caplog):
 @responses.activate
 def test_signals_feature_flag(cache):
     # Set up API
-    responses.add(responses.POST, URL + REGISTER_URL, json={}, status=202)
     responses.add(
         responses.GET, URL + FEATURES_URL, json=MOCK_FEATURE_RESPONSE, status=200
     )
-    responses.add(responses.POST, URL + METRICS_URL, json={}, status=202)
+    flag_event = None
+    variant_event = None
 
     # Set up signals
     send_data = signal("send-data")
 
     @send_data.connect
     def receive_data(sender, **kw):
-        print("Caught signal from %r, data %r" % (sender, kw))
-
+        #  variant_event
         if kw["data"].event_type == UnleashEventType.FEATURE_FLAG:
-            assert kw["data"].feature_name == "testFlag"
-            assert kw["data"].enabled
+            nonlocal flag_event
+            flag_event = kw["data"]
         elif kw["data"].event_type == UnleashEventType.VARIANT:
-            assert kw["data"].feature_name == "testVariations"
-            assert kw["data"].enabled
-            assert kw["data"].variant == "VarA"
-
-        raise Exception("Random!")
+            nonlocal variant_event
+            variant_event = kw["data"]
 
     def example_callback(event: UnleashEvent):
         send_data.send("anonymous", data=event)
@@ -922,7 +918,8 @@ def example_callback(event: UnleashEvent):
         URL,
         APP_NAME,
         refresh_interval=REFRESH_INTERVAL,
-        metrics_interval=METRICS_INTERVAL,
+        disable_registration=True,
+        disable_metrics=True,
         cache=cache,
         event_callback=example_callback,
     )
@@ -935,6 +932,121 @@ def example_callback(event: UnleashEvent):
     variant = unleash_client.get_variant("testVariations", context={"userId": "2"})
     assert variant["name"] == "VarA"
 
+    assert flag_event.feature_name == "testFlag"
+    assert flag_event.enabled
+
+    assert variant_event.feature_name == "testVariations"
+    assert variant_event.enabled
+    assert variant_event.variant == "VarA"
+
+
+@responses.activate
+def test_fetch_signal(cache):
+    # Set up API
+    responses.add(responses.POST, URL + REGISTER_URL, json={}, status=202)
+    responses.add(
+        responses.GET, URL + FEATURES_URL, json=MOCK_FEATURE_RESPONSE, status=200
+    )
+    responses.add(responses.POST, URL + METRICS_URL, json={}, status=202)
+    trapped_event = None
+
+    # Set up signals
+    send_data = signal("send-data")
+
+    @send_data.connect
+    def receive_data(sender, **kw):
+
+        if kw["data"].event_type == UnleashEventType.FETCHED:
+            nonlocal trapped_event
+            trapped_event = kw["data"]
+
+    def example_callback(event: UnleashEvent):
+        send_data.send("anonymous", data=event)
+
+    # Set up Unleash
+    unleash_client = UnleashClient(
+        URL,
+        APP_NAME,
+        refresh_interval=REFRESH_INTERVAL,
+        metrics_interval=METRICS_INTERVAL,
+        cache=cache,
+        event_callback=example_callback,
+    )
+
+    # Create Unleash client and check initial load
+    unleash_client.initialize_client()
+    time.sleep(1)
+
+    assert trapped_event.features[0]["name"] == "testFlag"
+
+
+@responses.activate
+def test_ready_signal(cache):
+    responses.add(
+        responses.GET, URL + FEATURES_URL, json=MOCK_FEATURE_RESPONSE, status=200
+    )
+    trapped_events = 0
+
+    # Set up signals
+    send_data = signal("send-data")
+
+    @send_data.connect
+    def receive_data(sender, **kw):
+        if kw["data"].event_type == UnleashEventType.READY:
+            nonlocal trapped_events
+            trapped_events += 1
+
+    def example_callback(event: UnleashEvent):
+        send_data.send("anonymous", data=event)
+
+    unleash_client = UnleashClient(
+        URL,
+        APP_NAME,
+        refresh_interval=1,  # minimum interval is 1 second
+        disable_metrics=True,
+        disable_registration=True,
+        cache=cache,
+        event_callback=example_callback,
+    )
+
+    unleash_client.initialize_client()
+    time.sleep(2)
+
+    assert trapped_events == 1
+
+
+def test_ready_signal_works_with_bootstrapping():
+    cache = FileCache("MOCK_CACHE")
+    cache.bootstrap_from_dict(MOCK_FEATURE_WITH_DEPENDENCIES_RESPONSE)
+
+    trapped_events = 0
+
+    # Set up signals
+    send_data = signal("send-data")
+
+    @send_data.connect
+    def receive_data(sender, **kw):
+        if kw["data"].event_type == UnleashEventType.READY:
+            nonlocal trapped_events
+            trapped_events += 1
+
+    def example_callback(event: UnleashEvent):
+        send_data.send("anonymous", data=event)
+
+    unleash_client = UnleashClient(
+        url=URL,
+        app_name=APP_NAME,
+        cache=cache,
+        disable_metrics=True,
+        disable_registration=True,
+        event_callback=example_callback,
+    )
+
+    unleash_client.initialize_client(fetch_toggles=False)
+    time.sleep(1)
+
+    assert trapped_events == 1
+
 
 def test_context_handles_numerics():
     cache = FileCache("MOCK_CACHE")