Support zerocopy send

docs/server-behavior.md

@@ -56,6 +56,12 @@ Applications should generally treat `HEAD` requests in the same manner as `GET`
 
 One exception to this might be if your application serves large file downloads, in which case you might wish to only generate the response headers.
 
+### Zero copy send
+
+Uvicorn supports [ASGI Zero Copy Send Extension](https://asgi.readthedocs.io/en/latest/extensions.html#zero-copy-send). Using the method specified by the extension, you can call the zero-copy interface of the operating system to send files.
+
+Note: This is currently only available on Python3.7+. And it is temporarily unavailable with uvloop because [uvloop#228](https://github.com/MagicStack/uvloop/issues/228).
+
 ---
 
 ## Timeouts

scripts/coverage

@@ -8,4 +8,4 @@ export SOURCE_FILES="uvicorn tests"
 
 set -x
 
-${PREFIX}coverage report --show-missing --skip-covered --fail-under=96.93
+${PREFIX}coverage report --show-missing --skip-covered --fail-under=96.69

tests/protocols/test_http.py

@@ -1,10 +1,14 @@
 import asyncio
 import contextlib
 import logging
+import os
+import sys
 
+import httpx
 import pytest
 
 from tests.response import Response
+from tests.utils import run_server
 from uvicorn.config import Config
 from uvicorn.main import ServerState
 from uvicorn.protocols.http.h11_impl import H11Protocol
@@ -123,6 +127,9 @@ def clear_buffer(self):
  def set_protocol(self, protocol):
  pass
 
+ def set_write_buffer_limits(self, high=None, low=None):
+ pass
+
 
 class MockLoop(asyncio.AbstractEventLoop):
  def __init__(self, event_loop):
@@ -744,3 +751,43 @@ def test_invalid_http_request(request_line, protocol_cls, caplog, event_loop):
  protocol.data_received(request)
  assert not protocol.transport.buffer
  assert "Invalid HTTP request received." in caplog.messages
+
+
+@pytest.mark.skipif(
+ sys.version_info[:2] < (3, 7),
+ not hasattr(os, "sendfile"),
+ reason="Sendfile only available in python3.7+",
+)
+@pytest.mark.parametrize("http", ["h11", "httptools"])
+@pytest.mark.parametrize("loop", ["asyncio"])
+@pytest.mark.asyncio
+async def test_sendfile(http, loop):
+ async def app(scope, receive, send):
+ with open("./README.md", "rb") as file:
+ content_length = len(file.read())
+ file.seek(0, 0)
+ await send(
+ {
+ "type": "http.response.start",
+ "status": 200,
+ "headers": [
+ (b"Content-Length", str(content_length).encode("ascii")),
+ (b"Content-Type", b"text/plain; charset=utf8"),
+ ],
+ }
+ )
+ await send(
+ {
+ "type": "http.response.zerocopysend",
+ "file": file.fileno(),
+ }
+ )
+
+ config = Config(app=app, http=http, loop=loop, limit_max_requests=1)
+ async with run_server(config):
+ with open("./README.md", "rb") as file:
+ file_content = file.read()
+
+ async with httpx.AsyncClient() as client:
+ response = await client.get("http://127.0.0.1:8000")
+ assert response.content == file_content

uvicorn/protocols/http/h11_impl.py

@@ -1,6 +1,7 @@
 import asyncio
 import http
 import logging
+import os
 from urllib.parse import unquote
 
 import h11
@@ -12,6 +13,7 @@
  FlowControl,
  service_unavailable,
 )
+from uvicorn.protocols.http.sendfile import can_sendfile
 from uvicorn.protocols.utils import (
  get_client_addr,
  get_local_addr,
@@ -76,6 +78,7 @@ def connection_made(self, transport):
  self.connections.add(self)
 
  self.transport = transport
+ self.allow_sendfile = can_sendfile(self.loop) and not is_ssl(self.transport)
  self.flow = FlowControl(transport)
  self.server = get_local_addr(transport)
  self.client = get_remote_addr(transport)
@@ -165,6 +168,9 @@ def handle_events(self):
  "query_string": query_string,
  "headers": self.headers,
  }
+ if self.allow_sendfile: # pragma: no cover
+ extensions = self.scope.setdefault("extensions", {})
+ extensions["http.response.zerocopysend"] = {}
 
  for name, value in self.headers:
  if name == b"connection":
@@ -185,6 +191,8 @@ def handle_events(self):
  app = self.app
 
  self.cycle = RequestResponseCycle(
+ loop=self.loop,
+ allow_sendfile=self.allow_sendfile,
  scope=self.scope,
  conn=self.conn,
  transport=self.transport,
@@ -323,6 +331,8 @@ def timeout_keep_alive_handler(self):
 class RequestResponseCycle:
  def __init__(
  self,
+ loop,
+ allow_sendfile,
  scope,
  conn,
  transport,
@@ -334,6 +344,8 @@ def __init__(
  message_event,
  on_response,
  ):
+ self.loop = loop
+ self.allow_sendfile = allow_sendfile
  self.scope = scope
  self.conn = conn
  self.transport = transport
@@ -358,6 +370,11 @@ def __init__(
  self.response_started = False
  self.response_complete = False
 
+ # Sendfile
+ if self.allow_sendfile: # pragma: no cover
+ # Set the buffer to 0 to avoid the problem of sending file before headers.
+ transport.set_write_buffer_limits(0)
+
  # ASGI exception wrapper
  async def run_asgi(self, app):
  try:
@@ -445,20 +462,55 @@ async def send(self, message):
 
  elif not self.response_complete:
  # Sending response body
- if message_type != "http.response.body":
- msg = "Expected ASGI message 'http.response.body', but got '%s'."
- raise RuntimeError(msg % message_type)
-
- body = message.get("body", b"")
- more_body = message.get("more_body", False)
+ use_sendfile = False
+ if message_type == "http.response.body":
+ body = message.get("body", b"")
+ more_body = message.get("more_body", False)
+ elif (
+ self.allow_sendfile and message_type == "http.response.zerocopysend"
+ ): # pragma: no cover
+ file_fd = message["file"]
+ sendfile_offset = message.get("offset", None)
+ if sendfile_offset is None:
+ sendfile_offset = os.lseek(file_fd, 0, os.SEEK_CUR)
+ sendfile_count = message.get("count", None)
+ if sendfile_count is None:
+ sendfile_count = os.stat(file_fd).st_size - sendfile_offset
+ more_body = message.get("more_body", False)
+ use_sendfile = True
+ else:
+ if self.allow_sendfile: # pragma: no cover
+ expect_message_types = (
+ "http.response.body",
+ "http.response.zerocopysend",
+ )
+ else:
+ expect_message_types = ("http.response.body",)
+ msg = "Expected ASGI message %s, but got '%s'."
+ raise RuntimeError(msg % expect_message_types, message_type)
 
  # Write response body
  if self.scope["method"] == "HEAD":
  event = h11.Data(data=b"")
+ output = self.conn.send(event)
+ self.transport.write(output)
+ elif use_sendfile: # pragma: no cover
+ with os.fdopen(os.dup(file_fd), "rb") as file:
+ event = SendfileData(file, sendfile_offset, sendfile_count)
+ for data in self.conn.send_with_data_passthrough(
+ h11.Data(data=event)
+ ):
+ if isinstance(data, SendfileData):
+ await self.flow.drain()
+ await self.loop.sendfile(
+ self.transport, data.file, data.offset, data.count
+ )
+ else:
+ self.transport.write(data)
  else:
  event = h11.Data(data=body)
- output = self.conn.send(event)
- self.transport.write(output)
+  output = self.conn.send(event)
+  self.transport.write(output)
 
  # Handle response completion
  if not more_body:
@@ -505,3 +557,13 @@ async def receive(self):
  self.body = b""
 
  return message
+
+
+class SendfileData:
+ def __init__(self, file, offset, count):
+ self.file = file
+ self.offset = offset
+ self.count = count
+
+ def __len__(self):
+ return self.count

uvicorn/protocols/http/httptools_impl.py

@@ -1,6 +1,7 @@
 import asyncio
 import http
 import logging
+import os
 import re
 import urllib
 from collections import deque
@@ -14,6 +15,7 @@
  FlowControl,
  service_unavailable,
 )
+from uvicorn.protocols.http.sendfile import can_sendfile
 from uvicorn.protocols.utils import (
  get_client_addr,
  get_local_addr,
@@ -85,6 +87,7 @@ def connection_made(self, transport):
  self.connections.add(self)
 
  self.transport = transport
+ self.allow_sendfile = can_sendfile(self.loop) and not is_ssl(self.transport)
  self.flow = FlowControl(transport)
  self.server = get_local_addr(transport)
  self.client = get_remote_addr(transport)
@@ -204,6 +207,9 @@ def on_url(self, url):
  "query_string": parsed_url.query if parsed_url.query else b"",
  "headers": self.headers,
  }
+ if self.allow_sendfile: # pragma: no cover
+ extensions = self.scope.setdefault("extensions", {})
+ extensions["http.response.zerocopysend"] = {}
 
  def on_header(self, name: bytes, value: bytes):
  name = name.lower()
@@ -231,6 +237,8 @@ def on_headers_complete(self):
 
  existing_cycle = self.cycle
  self.cycle = RequestResponseCycle(
+ loop=self.loop,
+ allow_sendfile=self.allow_sendfile,
  scope=self.scope,
  transport=self.transport,
  flow=self.flow,
@@ -324,6 +332,8 @@ def timeout_keep_alive_handler(self):
 class RequestResponseCycle:
  def __init__(
  self,
+ loop,
+ allow_sendfile,
  scope,
  transport,
  flow,
@@ -336,6 +346,8 @@ def __init__(
  keep_alive,
  on_response,
  ):
+ self.loop = loop
+ self.allow_sendfile = allow_sendfile
  self.scope = scope
  self.transport = transport
  self.flow = flow
@@ -361,6 +373,11 @@ def __init__(
  self.chunked_encoding = None
  self.expected_content_length = 0
 
+ # Sendfile
+ if self.allow_sendfile: # pragma: no cover
+ # Set the buffer to 0 to avoid the problem of sending file before headers.
+ transport.set_write_buffer_limits(0)
+
  # ASGI exception wrapper
  async def run_asgi(self, app):
  try:
@@ -472,31 +489,72 @@ async def send(self, message):
 
  elif not self.response_complete:
  # Sending response body
- if message_type != "http.response.body":
- msg = "Expected ASGI message 'http.response.body', but got '%s'."
- raise RuntimeError(msg % message_type)
-
- body = message.get("body", b"")
- more_body = message.get("more_body", False)
+ use_sendfile = False
+ if message_type == "http.response.body":
+ body = message.get("body", b"")
+ more_body = message.get("more_body", False)
+ elif (
+ self.allow_sendfile and message_type == "http.response.zerocopysend"
+ ): # pragma: no cover
+ file_fd = message["file"]
+ sendfile_offset = message.get("offset", None)
+ if sendfile_offset is None:
+ sendfile_offset = os.lseek(file_fd, 0, os.SEEK_CUR)
+ sendfile_count = message.get("count", None)
+ if sendfile_count is None:
+ sendfile_count = os.stat(file_fd).st_size - sendfile_offset
+ more_body = message.get("more_body", False)
+ use_sendfile = True
+ else:
+ if self.allow_sendfile: # pragma: no cover
+ expect_message_types = (
+ "http.response.body",
+ "http.response.zerocopysend",
+ )
+ else:
+ expect_message_types = ("http.response.body",)
+ msg = "Expected ASGI message %s, but got '%s'."
+ raise RuntimeError(msg % expect_message_types, message_type)
 
  # Write response body
  if self.scope["method"] == "HEAD":
  self.expected_content_length = 0
  elif self.chunked_encoding:
- if body:
- content = [b"%x\r\n" % len(body), body, b"\r\n"]
- else:
- content = []
- if not more_body:
- content.append(b"0\r\n\r\n")
- self.transport.write(b"".join(content))
+ if not use_sendfile:
+ if body:
+ content = [b"%x\r\n" % len(body), body, b"\r\n"]
+ else:
+ content = []
+ if not more_body:
+ content.append(b"0\r\n\r\n")
+ self.transport.write(b"".join(content))
+ else: # pragma: no cover
+ self.transport.write(b"%x\r\n" % sendfile_count)
+ await self.flow.drain()
+ with os.fdopen(os.dup(file_fd), "rb") as file:
+ await self.loop.sendfile(
+ self.transport, file, sendfile_offset, sendfile_count
+ )
+ if more_body:
+ self.transport.write(b"\r\n")
+ else:
+ self.transport.write(b"\r\n0\r\n\r\n")
  else:
- num_bytes = len(body)
+ if not use_sendfile:
+ num_bytes = len(body)
+ self.transport.write(body)
+ else: # pragma: no cover
+ num_bytes = sendfile_count
+ await self.flow.drain()
+ with os.fdopen(os.dup(file_fd), "rb") as file:
+ await self.loop.sendfile(
+ self.transport, file, sendfile_offset, sendfile_count
+ )
+
  if num_bytes > self.expected_content_length:
  raise RuntimeError("Response content longer than Content-Length")
  else:
  self.expected_content_length -= num_bytes
- self.transport.write(body)
 
  # Handle response completion
  if not more_body: