add event + event handlers for custom logging (#942)

Summary: Pull Request resolved: #942

Reviewed By: diego-urgell

Differential Revision: D65491587

fbshipit-source-id: ca29d91f1aae2acca17f286ab4226590857b8c28

Author: JKSenthil

torchtnt/utils/event.py

@@ -0,0 +1,25 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+from dataclasses import dataclass, field
+from typing import Dict, Union
+
+EventMetadataValue = Union[str, int, float, bool, None]
+
+
+@dataclass
+class Event:
+    """
+    The class represents the generic event that occurs during a TorchTNT
+    loop. The event can be any kind of meaningful action.
+
+    Args:
+        name: event name.
+        metadata: additional data that is associated with the event.
+    """
+
+    name: str
+    metadata: Dict[str, EventMetadataValue] = field(default_factory=dict)

torchtnt/utils/event_handlers.py

@@ -0,0 +1,85 @@
+#!/usr/bin/env python3
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+import logging
+import random
+from contextlib import contextmanager
+from functools import lru_cache
+from typing import Dict, Generator, List, Optional
+
+import importlib_metadata
+from typing_extensions import Protocol, runtime_checkable
+
+from .event import Event
+
+logger: logging.Logger = logging.getLogger(__name__)
+
+
+@runtime_checkable
+class EventHandler(Protocol):
+    def handle_event(self, event: Event) -> None: ...
+
+
+_log_handlers: List[EventHandler] = []
+
+
+@lru_cache(maxsize=None)
+def get_event_handlers() -> List[EventHandler]:
+    global _log_handlers
+
+    # Registered event handlers through entry points
+    eps = importlib_metadata.entry_points(group="tnt_event_handlers")
+    for entry in eps:
+        logger.debug(
+            f"Attempting to register event handler {entry.name}: {entry.value}"
+        )
+        factory = entry.load()
+        handler = factory()
+
+        if not isinstance(handler, EventHandler):
+            raise RuntimeError(
+                f"The factory function for {({entry.value})} "
+                "did not return a EventHandler object."
+            )
+        _log_handlers.append(handler)
+    return _log_handlers
+
+
+def log_event(event: Event) -> None:
+    """
+    Handle an event.
+
+    Args:
+        event: The event to handle.
+    """
+
+    for handler in get_event_handlers():
+        handler.handle_event(event)
+
+
+@contextmanager
+def log_interval(
+    name: str, metadata: Optional[Dict[str, str]] = None
+) -> Generator[None, None, None]:
+    unique_id = _generate_random_int64()
+    if metadata is None:
+        metadata = {}
+    metadata.update({"action": "start", "unique_id": unique_id})
+    start_event = Event(name=name, metadata=metadata)
+    log_event(start_event)
+
+    yield
+
+    metadata["action"] = "end"
+    end_event = Event(name=name, metadata=metadata)
+    log_event(end_event)
+
+
+def _generate_random_int64() -> int:
+    # avoid being influenced by externally set seed
+    local_random = random.Random()
+    return local_random.randint(0, 2**63 - 1)