bpo-41002: Optimize HTTPResponse.read with a given amount (GH-20943)

I've done the implementation for both non-chunked and chunked reads. I haven't benchmarked chunked reads because I don't currently have a convenient way to generate a high-bandwidth chunked stream, but I don't see any reason that it shouldn't enjoy the same benefits that the non-chunked case does. I've used the benchmark attached to the bpo bug to verify that performance now matches the unsized read case.

Automerge-Triggered-By: @methane

1 files changed, 27 insertions, 0 deletions

diff --git a/Lib/test/test_httplib.py b/Lib/test/test_httplib.py
index e95487bcd4..e909980d23 100644
--- a/Lib/test/test_httplib.py
+++ b/Lib/test/test_httplib.py
@@ -569,6 +569,33 @@ class BasicTest(TestCase):
         resp.close()
         self.assertTrue(resp.closed)
 
+    def test_partial_reads_past_end(self):
+        # if we have Content-Length, clip reads to the end
+        body = "HTTP/1.1 200 Ok\r\nContent-Length: 4\r\n\r\nText"
+        sock = FakeSocket(body)
+        resp = client.HTTPResponse(sock)
+        resp.begin()
+        self.assertEqual(resp.read(10), b'Text')
+        self.assertTrue(resp.isclosed())
+        self.assertFalse(resp.closed)
+        resp.close()
+        self.assertTrue(resp.closed)
+
+    def test_partial_readintos_past_end(self):
+        # if we have Content-Length, clip readintos to the end
+        body = "HTTP/1.1 200 Ok\r\nContent-Length: 4\r\n\r\nText"
+        sock = FakeSocket(body)
+        resp = client.HTTPResponse(sock)
+        resp.begin()
+        b = bytearray(10)
+        n = resp.readinto(b)
+        self.assertEqual(n, 4)
+        self.assertEqual(bytes(b)[:4], b'Text')
+        self.assertTrue(resp.isclosed())
+        self.assertFalse(resp.closed)
+        resp.close()
+        self.assertTrue(resp.closed)
+
     def test_partial_reads_no_content_length(self):
         # when no length is present, the socket should be gracefully closed when
         # all data was read