Add async_iterator util (home-assistant#153194)

Author: emontnemery

homeassistant/components/backup/http.py

@@ -17,6 +17,7 @@
 from homeassistant.exceptions import HomeAssistantError
 from homeassistant.helpers import frame
 from homeassistant.util import slugify
+from homeassistant.util.async_iterator import AsyncIteratorReader, AsyncIteratorWriter
 
 from . import util
 from .agent import BackupAgent
@@ -144,15 +145,15 @@ async def _send_backup_with_password(
                 return Response(status=HTTPStatus.NOT_FOUND)
         else:
             stream = await agent.async_download_backup(backup_id)
-            reader = cast(IO[bytes], util.AsyncIteratorReader(hass, stream))
+            reader = cast(IO[bytes], AsyncIteratorReader(hass.loop, stream))
 
         worker_done_event = asyncio.Event()
 
         def on_done(error: Exception | None) -> None:
             """Call by the worker thread when it's done."""
             hass.loop.call_soon_threadsafe(worker_done_event.set)
 
-        stream = util.AsyncIteratorWriter(hass)
+        stream = AsyncIteratorWriter(hass.loop)
         worker = threading.Thread(
             target=util.decrypt_backup,
             args=[backup, reader, stream, password, on_done, 0, []],

homeassistant/components/backup/manager.py

@@ -38,6 +38,7 @@
 )
 from homeassistant.helpers.json import json_bytes
 from homeassistant.util import dt as dt_util, json as json_util
+from homeassistant.util.async_iterator import AsyncIteratorReader
 
 from . import util as backup_util
 from .agent import (
@@ -72,7 +73,6 @@
 )
 from .store import BackupStore
 from .util import (
-    AsyncIteratorReader,
     DecryptedBackupStreamer,
     EncryptedBackupStreamer,
     make_backup_dir,
@@ -1525,7 +1525,7 @@ async def async_can_decrypt_on_download(
             reader = await self.hass.async_add_executor_job(open, path.as_posix(), "rb")
         else:
             backup_stream = await agent.async_download_backup(backup_id)
-            reader = cast(IO[bytes], AsyncIteratorReader(self.hass, backup_stream))
+            reader = cast(IO[bytes], AsyncIteratorReader(self.hass.loop, backup_stream))
         try:
             await self.hass.async_add_executor_job(
                 validate_password_stream, reader, password

homeassistant/components/backup/util.py

@@ -4,7 +4,6 @@
 
 import asyncio
 from collections.abc import AsyncIterator, Callable, Coroutine
-from concurrent.futures import CancelledError, Future
 import copy
 from dataclasses import dataclass, replace
 from io import BytesIO
@@ -14,7 +13,7 @@
 from queue import SimpleQueue
 import tarfile
 import threading
-from typing import IO, Any, Self, cast
+from typing import IO, Any, cast
 
 import aiohttp
 from securetar import SecureTarError, SecureTarFile, SecureTarReadError
@@ -23,6 +22,11 @@
 from homeassistant.core import HomeAssistant
 from homeassistant.exceptions import HomeAssistantError
 from homeassistant.util import dt as dt_util
+from homeassistant.util.async_iterator import (
+    Abort,
+    AsyncIteratorReader,
+    AsyncIteratorWriter,
+)
 from homeassistant.util.json import JsonObjectType, json_loads_object
 
 from .const import BUF_SIZE, LOGGER
@@ -59,12 +63,6 @@ class BackupEmpty(DecryptError):
     _message = "No tar files found in the backup."
 
 
-class AbortCipher(HomeAssistantError):
-    """Abort the cipher operation."""
-
-    _message = "Abort cipher operation."
-
-
 def make_backup_dir(path: Path) -> None:
     """Create a backup directory if it does not exist."""
     path.mkdir(exist_ok=True)
@@ -166,106 +164,6 @@ def validate_password(path: Path, password: str | None) -> bool:
     return False
 
 
-class AsyncIteratorReader:
-    """Wrap an AsyncIterator."""
-
-    def __init__(self, hass: HomeAssistant, stream: AsyncIterator[bytes]) -> None:
-        """Initialize the wrapper."""
-        self._aborted = False
-        self._hass = hass
-        self._stream = stream
-        self._buffer: bytes | None = None
-        self._next_future: Future[bytes | None] | None = None
-        self._pos: int = 0
-
-    async def _next(self) -> bytes | None:
-        """Get the next chunk from the iterator."""
-        return await anext(self._stream, None)
-
-    def abort(self) -> None:
-        """Abort the reader."""
-        self._aborted = True
-        if self._next_future is not None:
-            self._next_future.cancel()
-
-    def read(self, n: int = -1, /) -> bytes:
-        """Read data from the iterator."""
-        result = bytearray()
-        while n < 0 or len(result) < n:
-            if not self._buffer:
-                self._next_future = asyncio.run_coroutine_threadsafe(
-                    self._next(), self._hass.loop
-                )
-                if self._aborted:
-                    self._next_future.cancel()
-                    raise AbortCipher
-                try:
-                    self._buffer = self._next_future.result()
-                except CancelledError as err:
-                    raise AbortCipher from err
-                self._pos = 0
-            if not self._buffer:
-                # The stream is exhausted
-                break
-            chunk = self._buffer[self._pos : self._pos + n]
-            result.extend(chunk)
-            n -= len(chunk)
-            self._pos += len(chunk)
-            if self._pos == len(self._buffer):
-                self._buffer = None
-        return bytes(result)
-
-    def close(self) -> None:
-        """Close the iterator."""
-
-
-class AsyncIteratorWriter:
-    """Wrap an AsyncIterator."""
-
-    def __init__(self, hass: HomeAssistant) -> None:
-        """Initialize the wrapper."""
-        self._aborted = False
-        self._hass = hass
-        self._pos: int = 0
-        self._queue: asyncio.Queue[bytes | None] = asyncio.Queue(maxsize=1)
-        self._write_future: Future[bytes | None] | None = None
-
-    def __aiter__(self) -> Self:
-        """Return the iterator."""
-        return self
-
-    async def __anext__(self) -> bytes:
-        """Get the next chunk from the iterator."""
-        if data := await self._queue.get():
-            return data
-        raise StopAsyncIteration
-
-    def abort(self) -> None:
-        """Abort the writer."""
-        self._aborted = True
-        if self._write_future is not None:
-            self._write_future.cancel()
-
-    def tell(self) -> int:
-        """Return the current position in the iterator."""
-        return self._pos
-
-    def write(self, s: bytes, /) -> int:
-        """Write data to the iterator."""
-        self._write_future = asyncio.run_coroutine_threadsafe(
-            self._queue.put(s), self._hass.loop
-        )
-        if self._aborted:
-            self._write_future.cancel()
-            raise AbortCipher
-        try:
-            self._write_future.result()
-        except CancelledError as err:
-            raise AbortCipher from err
-        self._pos += len(s)
-        return len(s)
-
-
 def validate_password_stream(
     input_stream: IO[bytes],
     password: str | None,
@@ -342,7 +240,7 @@ def decrypt_backup(
         finally:
             # Write an empty chunk to signal the end of the stream
             output_stream.write(b"")
-    except AbortCipher:
+    except Abort:
         LOGGER.debug("Cipher operation aborted")
     finally:
         on_done(error)
@@ -430,7 +328,7 @@ def encrypt_backup(
         finally:
             # Write an empty chunk to signal the end of the stream
             output_stream.write(b"")
-    except AbortCipher:
+    except Abort:
         LOGGER.debug("Cipher operation aborted")
     finally:
         on_done(error)
@@ -557,8 +455,8 @@ def on_done(error: Exception | None) -> None:
             self._hass.loop.call_soon_threadsafe(worker_status.done.set)
 
         stream = await self._open_stream()
-        reader = AsyncIteratorReader(self._hass, stream)
-        writer = AsyncIteratorWriter(self._hass)
+        reader = AsyncIteratorReader(self._hass.loop, stream)
+        writer = AsyncIteratorWriter(self._hass.loop)
         worker = threading.Thread(
             target=self._cipher_func,
             args=[

homeassistant/util/async_iterator.py

@@ -0,0 +1,134 @@
+"""Async iterator utilities."""
+
+from __future__ import annotations
+
+import asyncio
+from collections.abc import AsyncIterator
+from concurrent.futures import CancelledError, Future
+from typing import Self
+
+
+class Abort(Exception):
+    """Raised when abort is requested."""
+
+
+class AsyncIteratorReader:
+    """Allow reading from an AsyncIterator using blocking I/O.
+
+    The class implements a blocking read method reading from the async iterator,
+    and a close method.
+
+    In addition, the abort method can be used to abort any ongoing read operation.
+    """
+
+    def __init__(
+        self,
+        loop: asyncio.AbstractEventLoop,
+        stream: AsyncIterator[bytes],
+    ) -> None:
+        """Initialize the wrapper."""
+        self._aborted = False
+        self._loop = loop
+        self._stream = stream
+        self._buffer: bytes | None = None
+        self._next_future: Future[bytes | None] | None = None
+        self._pos: int = 0
+
+    async def _next(self) -> bytes | None:
+        """Get the next chunk from the iterator."""
+        return await anext(self._stream, None)
+
+    def abort(self) -> None:
+        """Abort the reader."""
+        self._aborted = True
+        if self._next_future is not None:
+            self._next_future.cancel()
+
+    def read(self, n: int = -1, /) -> bytes:
+        """Read up to n bytes of data from the iterator.
+
+        The read method returns 0 bytes when the iterator is exhausted.
+        """
+        result = bytearray()
+        while n < 0 or len(result) < n:
+            if not self._buffer:
+                self._next_future = asyncio.run_coroutine_threadsafe(
+                    self._next(), self._loop
+                )
+                if self._aborted:
+                    self._next_future.cancel()
+                    raise Abort
+                try:
+                    self._buffer = self._next_future.result()
+                except CancelledError as err:
+                    raise Abort from err
+                self._pos = 0
+            if not self._buffer:
+                # The stream is exhausted
+                break
+            chunk = self._buffer[self._pos : self._pos + n]
+            result.extend(chunk)
+            n -= len(chunk)
+            self._pos += len(chunk)
+            if self._pos == len(self._buffer):
+                self._buffer = None
+        return bytes(result)
+
+    def close(self) -> None:
+        """Close the iterator."""
+
+
+class AsyncIteratorWriter:
+    """Allow writing to an AsyncIterator using blocking I/O.
+
+    The class implements a blocking write method writing to the async iterator,
+    as well as a close and tell methods.
+
+    In addition, the abort method can be used to abort any ongoing write operation.
+    """
+
+    def __init__(self, loop: asyncio.AbstractEventLoop) -> None:
+        """Initialize the wrapper."""
+        self._aborted = False
+        self._loop = loop
+        self._pos: int = 0
+        self._queue: asyncio.Queue[bytes | None] = asyncio.Queue(maxsize=1)
+        self._write_future: Future[bytes | None] | None = None
+
+    def __aiter__(self) -> Self:
+        """Return the iterator."""
+        return self
+
+    async def __anext__(self) -> bytes:
+        """Get the next chunk from the iterator."""
+        if data := await self._queue.get():
+            return data
+        raise StopAsyncIteration
+
+    def abort(self) -> None:
+        """Abort the writer."""
+        self._aborted = True
+        if self._write_future is not None:
+            self._write_future.cancel()
+
+    def tell(self) -> int:
+        """Return the current position in the iterator."""
+        return self._pos
+
+    def write(self, s: bytes, /) -> int:
+        """Write data to the iterator.
+
+        To signal the end of the stream, write a zero-length bytes object.
+        """
+        self._write_future = asyncio.run_coroutine_threadsafe(
+            self._queue.put(s), self._loop
+        )
+        if self._aborted:
+            self._write_future.cancel()
+            raise Abort
+        try:
+            self._write_future.result()
+        except CancelledError as err:
+            raise Abort from err
+        self._pos += len(s)
+        return len(s)