# HG changeset patch
# User Augie Fackler <augie@google.com>
# Date 2018-04-11 18:39:49
# Node ID 192b7ad06932682fa7f87e44f10a85bfabb4f7a7
# Parent  b94fecf4cd8c64dc00a2fba35a6d771cbf568e16

keepalive: rewrite readinto() to not use read()

It turns out http.client on Python 3 sometimes uses readinto() in the
implementation of read(). Unfortunately, Python 2 doesn't have a
readinto() in httplib's client, so we have to support both codepaths.

Subclassing is bad, folks.

Differential Revision: https://phab.mercurial-scm.org/D3246

diff --git a/mercurial/keepalive.py b/mercurial/keepalive.py
--- a/mercurial/keepalive.py
+++ b/mercurial/keepalive.py
@@ -384,6 +384,7 @@ class HTTPResponse(httplib.HTTPResponse)
         self._connection = None # (same)
 
     _raw_read = httplib.HTTPResponse.read
+    _raw_readinto = getattr(httplib.HTTPResponse, 'readinto', None)
 
     def close(self):
         if self.fp:
@@ -523,12 +524,24 @@ class HTTPResponse(httplib.HTTPResponse)
         return list
 
     def readinto(self, dest):
-        res = self.read(len(dest))
-        if not res:
-            return 0
-
-        dest[0:len(res)] = res
-        return len(res)
+        if self._raw_readinto is None:
+            res = self.read(len(dest))
+            if not res:
+                return 0
+            dest[0:len(res)] = res
+            return len(res)
+        total = len(dest)
+        have = len(self._rbuf)
+        if have >= total:
+            dest[0:total] = self._rbuf[:total]
+            self._rbuf = self._rbuf[total:]
+            return total
+        mv = memoryview(dest)
+        got = self._raw_readinto(mv[have:total])
+        dest[0:have] = self._rbuf
+        got += len(self._rbuf)
+        self._rbuf = ''
+        return got
 
 def safesend(self, str):
     """Send `str' to the server.