add batch

layercake/layercake/batch.py

@@ -0,0 +1,118 @@
+import inspect
+import logging
+from contextlib import AbstractContextManager
+from enum import Enum
+from typing import Any, Callable, NamedTuple, Self, Sequence
+
+logger = logging.getLogger(__name__)
+logging.basicConfig(level=logging.INFO)
+
+
+class Status(Enum):
+    SUCCESS = 'success'
+    FAIL = 'fail'
+
+
+class Result(NamedTuple):
+    status: Status
+    cause: Any
+    record: Any
+
+
+class BatchProcessor(AbstractContextManager):
+    """
+    This class provides a structured way to process a sequence of records,
+    capturing both successful and failed executions along with exception details.
+
+    Batch processing utility inspired by AWS Lambda Powertools for Python:
+    https://github.com/aws-powertools/powertools-lambda-python/blob/develop/aws_lambda_powertools/utilities/batch/base.py
+
+    Attributes
+    ----------
+    successes : list
+        List of successfully processed records.
+    failures : list
+        List of records that failed to process.
+    exceptions : list
+        List of exceptions raised during processing.
+
+    Examples
+    --------
+    >>> def handler(record, context):
+    ...     if record % 2 == 0:
+    ...         return record * 2
+    ...     else:
+    ...         raise ValueError("Odd number not allowed")
+    ...
+    >>> records = [1, 2, 3, 4]
+    >>> processor = BatchProcessor()
+    >>> with processor(records, handler) as p:
+    ...     results = p.process()
+    ...
+    >>> for result in results:
+    ...     print(result.status, result.cause, result.record)
+    Status.FAIL ValueError: Odd number not allowed 1
+    Status.SUCCESS 4 2
+    Status.FAIL ValueError: Odd number not allowed 3
+    Status.SUCCESS 8 4
+    """
+
+    def __init__(self) -> None:
+        self.successes: list[Any] = []
+        self.failures: list[Any] = []
+        self.exceptions: list[BaseException] = []
+
+    def __call__(
+        self,
+        records: Sequence[Any],
+        handler: Callable[..., Any],
+        context: dict[str, Any] | None = None,
+    ) -> Self:
+        self.records = records
+        self.handler = handler
+
+        if context is None:
+            self._handler_accepts_context = False
+        else:
+            self.context = context
+            self._handler_accepts_context = (
+                'context' in inspect.signature(self.handler).parameters
+            )
+
+        return self
+
+    def __enter__(self):
+        """Remove results from previous execution."""
+        self.successes.clear()
+        self.failures.clear()
+        self.exceptions.clear()
+
+        return self
+
+    def __exit__(self, *exc_details) -> None:
+        pass
+
+    def process(self) -> Sequence[Result]:
+        return tuple(self._process_record(record) for record in self.records)
+
+    def _process_record(self, record: Any) -> Result:
+        """
+        Processes a single record using the handler function with optional context.
+        Returns a Result indicating success or failure.
+        """
+        try:
+            if self._handler_accepts_context:
+                result = self.handler(record, self.context)
+            else:
+                result = self.handler(record)
+
+            self.successes.append(record)
+            return Result(Status.SUCCESS, result, record)
+        except Exception as exc:
+            exc_str = f'{type(exc).__name__}: {exc}'
+            logger.debug(f'Record processing exception: {exc_str}')
+
+            self.exceptions.append(exc)
+            self.failures.append(record)
+
+            return Result(Status.FAIL, exc_str, record)

layercake/layercake/strutils.py

@@ -0,0 +1,18 @@
+import hashlib
+
+
+def first_word(s: str) -> str:
+    """Returns the first word from a string."""
+    return s.split(' ', 1)[0]
+
+
+def truncate_str(s: str, maxlen: int = 30) -> str:
+    """Truncates a string to fit within a maximum length, adding '...' if truncated."""
+    if len(s) <= maxlen:
+        return s
+    return s[: maxlen - 3] + '...'
+
+
+def md5_hash(s: str) -> str:
+    """Computes the MD5 hash of a string."""
+    return hashlib.md5(s.encode()).hexdigest()

layercake/pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "layercake"
-version = "0.2.15"
+version = "0.2.17"
 description = "Packages shared dependencies to optimize deployment and ensure consistency across functions."
 readme = "README.md"
 authors = [

layercake/tests/test_batch.py

@@ -0,0 +1,56 @@
+from layercake.batch import BatchProcessor, Result, Status
+
+processor = BatchProcessor()
+
+
+def test_batch():
+    def record_handler(record: bool):
+        if record:
+            return True
+        raise ValueError('Invalid record')
+
+    records = (
+        True,
+        True,
+        False,
+    )
+
+    with processor(records=records, handler=record_handler) as p:
+        processed_messages = p.process()
+
+        assert processed_messages == (
+            Result(Status.SUCCESS, True, True),
+            Result(Status.SUCCESS, True, True),
+            Result(Status.FAIL, 'ValueError: Invalid record', False),
+        )
+
+    assert processor.successes == [True, True]
+    assert processor.failures == [False]
+
+    with processor(records=(False,), handler=record_handler):
+        processed_messages = processor.process()
+
+        assert processed_messages == (
+            Result(Status.FAIL, 'ValueError: Invalid record', False),
+        )
+
+    assert processor.successes == []
+    assert processor.failures == [False]
+
+
+def test_batch_context():
+    def record_handler(val: int, context: dict):
+        return val * context['multiplier']
+
+    with processor(
+        records=(2, 3, 4),
+        handler=record_handler,
+        context={'multiplier': 2},
+    ):
+        processed_messages = processor.process()
+
+        assert processed_messages == (
+            Result(Status.SUCCESS, 4, 2),
+            Result(Status.SUCCESS, 6, 3),
+            Result(Status.SUCCESS, 8, 4),
+        )

layercake/uv.lock

@@ -589,7 +589,7 @@ wheels = [
 
 [[package]]
 name = "layercake"
-version = "0.2.14"
+version = "0.2.17"
 source = { editable = "." }
 dependencies = [
     { name = "arnparse" },