diff mercurial/wireprotoserver.py @ 36867:a88d68dc3ee8

hgweb: create dedicated type for WSGI responses

We have refactored the request side of WSGI processing into a dedicated
type. Now let's do the same thing for the response side.

We invent a ``wsgiresponse`` type. It takes an instance of a
request (for consulation) and the WSGI application's "start_response"
handler.

The type basically allows setting the HTTP status line, response
headers, and the response body.

The WSGI application calls sendresponse() to start sending output.
Output is emitted as a generator to be fed through the WSGI application.
According to PEP 3333, this is the preferred way for output to be
transmitted. (Our legacy ``wsgirequest`` exposed a write() to send
data. We do not wish to support this API because it isn't recommended
by PEP 3333.)

The wire protocol code has been ported to use the new API.

Differential Revision: https://phab.mercurial-scm.org/D2775

--- a/mercurial/wireprotoserver.py	Sat Mar 10 11:15:05 2018 -0800
+++ b/mercurial/wireprotoserver.py	Sat Mar 10 11:23:05 2018 -0800
@@ -149,7 +149,7 @@
 def iscmd(cmd):
     return cmd in wireproto.commands
 
-def handlewsgirequest(rctx, wsgireq, req, checkperm):
+def handlewsgirequest(rctx, wsgireq, req, res, checkperm):
     """Possibly process a wire protocol request.
 
     If the current request is a wire protocol request, the request is
@@ -157,10 +157,10 @@
 
     ``wsgireq`` is a ``wsgirequest`` instance.
     ``req`` is a ``parsedrequest`` instance.
+    ``res`` is a ``wsgiresponse`` instance.
 
-    Returns a 2-tuple of (bool, response) where the 1st element indicates
-    whether the request was handled and the 2nd element is a return
-    value for a WSGI application (often a generator of bytes).
+    Returns a bool indicating if the request was serviced. If set, the caller
+    should stop processing the request, as a response has already been issued.
     """
     # Avoid cycle involving hg module.
     from .hgweb import common as hgwebcommon
@@ -171,7 +171,7 @@
     # string parameter. If it isn't present, this isn't a wire protocol
     # request.
     if 'cmd' not in req.querystringdict:
-        return False, None
+        return False
 
     cmd = req.querystringdict['cmd'][0]
 
@@ -183,18 +183,19 @@
     # known wire protocol commands and it is less confusing for machine
     # clients.
     if not iscmd(cmd):
-        return False, None
+        return False
 
     # The "cmd" query string argument is only valid on the root path of the
     # repo. e.g. ``/?cmd=foo``, ``/repo?cmd=foo``. URL paths within the repo
     # like ``/blah?cmd=foo`` are not allowed. So don't recognize the request
     # in this case. We send an HTTP 404 for backwards compatibility reasons.
     if req.dispatchpath:
-        res = _handlehttperror(
-            hgwebcommon.ErrorResponse(hgwebcommon.HTTP_NOT_FOUND), wsgireq,
-            req)
-
-        return True, res
+        res.status = hgwebcommon.statusmessage(404)
+        res.headers['Content-Type'] = HGTYPE
+        # TODO This is not a good response to issue for this request. This
+        # is mostly for BC for now.
+        res.setbodybytes('0\n%s\n' % b'Not Found')
+        return True
 
     proto = httpv1protocolhandler(wsgireq, req, repo.ui,
                                   lambda perm: checkperm(rctx, wsgireq, perm))
@@ -204,11 +205,16 @@
     # exception here. So consider refactoring into a exception type that
     # is associated with the wire protocol.
     try:
-        res = _callhttp(repo, wsgireq, req, proto, cmd)
+        _callhttp(repo, wsgireq, req, res, proto, cmd)
     except hgwebcommon.ErrorResponse as e:
-        res = _handlehttperror(e, wsgireq, req)
+        for k, v in e.headers:
+            res.headers[k] = v
+        res.status = hgwebcommon.statusmessage(e.code, pycompat.bytestr(e))
+        # TODO This response body assumes the failed command was
+        # "unbundle." That assumption is not always valid.
+        res.setbodybytes('0\n%s\n' % pycompat.bytestr(e))
 
-    return True, res
+    return True
 
 def _httpresponsetype(ui, req, prefer_uncompressed):
     """Determine the appropriate response type and compression settings.
@@ -250,7 +256,10 @@
     opts = {'level': ui.configint('server', 'zliblevel')}
     return HGTYPE, util.compengines['zlib'], opts
 
-def _callhttp(repo, wsgireq, req, proto, cmd):
+def _callhttp(repo, wsgireq, req, res, proto, cmd):
+    # Avoid cycle involving hg module.
+    from .hgweb import common as hgwebcommon
+
     def genversion2(gen, engine, engineopts):
         # application/mercurial-0.2 always sends a payload header
         # identifying the compression engine.
@@ -262,26 +271,35 @@
         for chunk in gen:
             yield chunk
 
+    def setresponse(code, contenttype, bodybytes=None, bodygen=None):
+        if code == HTTP_OK:
+            res.status = '200 Script output follows'
+        else:
+            res.status = hgwebcommon.statusmessage(code)
+
+        res.headers['Content-Type'] = contenttype
+
+        if bodybytes is not None:
+            res.setbodybytes(bodybytes)
+        if bodygen is not None:
+            res.setbodygen(bodygen)
+
     if not wireproto.commands.commandavailable(cmd, proto):
-        wsgireq.respond(HTTP_OK, HGERRTYPE,
-                        body=_('requested wire protocol command is not '
-                               'available over HTTP'))
-        return []
+        setresponse(HTTP_OK, HGERRTYPE,
+                    _('requested wire protocol command is not available over '
+                      'HTTP'))
+        return
 
     proto.checkperm(wireproto.commands[cmd].permission)
 
     rsp = wireproto.dispatch(repo, proto, cmd)
 
     if isinstance(rsp, bytes):
-        wsgireq.respond(HTTP_OK, HGTYPE, body=rsp)
-        return []
+        setresponse(HTTP_OK, HGTYPE, bodybytes=rsp)
     elif isinstance(rsp, wireprototypes.bytesresponse):
-        wsgireq.respond(HTTP_OK, HGTYPE, body=rsp.data)
-        return []
+        setresponse(HTTP_OK, HGTYPE, bodybytes=rsp.data)
     elif isinstance(rsp, wireprototypes.streamreslegacy):
-        gen = rsp.gen
-        wsgireq.respond(HTTP_OK, HGTYPE)
-        return gen
+        setresponse(HTTP_OK, HGTYPE, bodygen=rsp.gen)
     elif isinstance(rsp, wireprototypes.streamres):
         gen = rsp.gen
 
@@ -294,30 +312,18 @@
         if mediatype == HGTYPE2:
             gen = genversion2(gen, engine, engineopts)
 
-        wsgireq.respond(HTTP_OK, mediatype)
-        return gen
+        setresponse(HTTP_OK, mediatype, bodygen=gen)
     elif isinstance(rsp, wireprototypes.pushres):
         rsp = '%d\n%s' % (rsp.res, rsp.output)
-        wsgireq.respond(HTTP_OK, HGTYPE, body=rsp)
-        return []
+        setresponse(HTTP_OK, HGTYPE, bodybytes=rsp)
     elif isinstance(rsp, wireprototypes.pusherr):
         rsp = '0\n%s\n' % rsp.res
-        wsgireq.respond(HTTP_OK, HGTYPE, body=rsp)
-        return []
+        res.drain = True
+        setresponse(HTTP_OK, HGTYPE, bodybytes=rsp)
     elif isinstance(rsp, wireprototypes.ooberror):
-        rsp = rsp.message
-        wsgireq.respond(HTTP_OK, HGERRTYPE, body=rsp)
-        return []
-    raise error.ProgrammingError('hgweb.protocol internal failure', rsp)
-
-def _handlehttperror(e, wsgireq, req):
-    """Called when an ErrorResponse is raised during HTTP request processing."""
-
-    # TODO This response body assumes the failed command was
-    # "unbundle." That assumption is not always valid.
-    wsgireq.respond(e, HGTYPE, body='0\n%s\n' % pycompat.bytestr(e))
-
-    return ''
+        setresponse(HTTP_OK, HGERRTYPE, bodybytes=rsp.message)
+    else:
+        raise error.ProgrammingError('hgweb.protocol internal failure', rsp)
 
 def _sshv1respondbytes(fout, value):
     """Send a bytes response for protocol version 1."""