streamclone: new server config and some API changes for narrow stream clones

This patch introduces a new server config
`experimental.server.stream-narrow-clones` which if set to True will advertise
that the server supports narrow stream clones.

This patch also pass on the includes and excludes from getbundle command to
streamclone generation code.

There is a test added to show that the includepats and excludepats are correctly
passed.

Upcoming patches will implement storage layer filtering for streamclones and
then we can remove the temporary error and plug in the whole logic together to
make narrow stream clones working.

Differential Revision: https://phab.mercurial-scm.org/D5137

tests/test-narrow-clone-stream.t

@@ -0,0 +1,39 b''
+Tests narrow stream clones
+
+  $ . "$TESTDIR/narrow-library.sh"
+
+Server setup
+
+  $ hg init master
+  $ cd master
+  $ mkdir dir
+  $ mkdir dir/src
+  $ cd dir/src
+  $ for x in `$TESTDIR/seq.py 20`; do echo $x > "f$x"; hg add "f$x"; hg commit -m "Commit src $x"; done
+
+  $ cd ..
+  $ mkdir tests
+  $ cd tests
+  $ for x in `$TESTDIR/seq.py 20`; do echo $x > "f$x"; hg add "f$x"; hg commit -m "Commit src $x"; done
+  $ cd ../../..
+
+Trying to stream clone when the server does not support it
+
+  $ hg clone --narrow ssh://user@dummy/master narrow --noupdate --include "dir/src/f10" --stream
+  streaming all changes
+  remote: abort: server does not support narrow stream clones
+  abort: pull failed on remote
+  [255]
+
+Enable stream clone on the server
+
+  $ echo "[server]" >> master/.hg/hgrc
+  $ echo "stream-narrow-clones=True" >> master/.hg/hgrc
+
+Cloning a specific file when stream clone is supported
+
+  $ hg clone --narrow ssh://user@dummy/master narrow --noupdate --include "dir/src/f10" --stream
+  streaming all changes
+  remote: abort: server does not support narrow stream clones
+  abort: pull failed on remote
+  [255]

mercurial/bundle2.py

@@ -1687,7 +1687,18 b' def addpartbundlestream2(bundler, repo, '
     # to avoid compression to consumers of the bundle.
     bundler.prefercompressed = False
 
-    filecount, bytecount, it = streamclone.generatev2(repo)
+    # get the includes and excludes
+    includepats = kwargs.get(r'includepats')
+    excludepats = kwargs.get(r'excludepats')
+
+    narrowstream = repo.ui.configbool('experimental.server',
+                                      'stream-narrow-clones')
+
+    if (includepats or excludepats) and not narrowstream:
+        raise error.Abort(_('server does not support narrow stream clones'))
+
+    filecount, bytecount, it = streamclone.generatev2(repo, includepats,
+                                                      excludepats)
     requirements = _formatrequirementsspec(repo.requirements)
     part = bundler.newpart('stream2', data=it)
     part.addparam('bytecount', '%d' % bytecount, mandatory=True)

mercurial/configitems.py

@@ -610,6 +610,9 b" coreconfigitem('experimental', 'server.f"
 coreconfigitem('experimental', 'server.manifestdata.recommended-batch-size',
     default=100000,
 )
+coreconfigitem('experimental.server', 'stream-narrow-clones',
+    default=False,
+)
 coreconfigitem('experimental', 'single-head-per-branch',
     default=False,
 )

mercurial/streamclone.py

@@ -531,7 +531,7 b' def _emit2(repo, entries, totalfilesize)'
             finally:
                 fp.close()
 
-def generatev2(repo):
+def generatev2(repo, includes, excludes):
     """Emit content for version 2 of a streaming clone.
 
     the data stream consists the following entries:
@@ -544,6 +544,10 b' def generatev2(repo):'
     Returns a 3-tuple of (file count, file size, data iterator).
     """
 
+    # temporarily raise error until we add storage level logic
+    if includes or excludes:
+        raise error.Abort(_("server does not support narrow stream clones"))
+
     with repo.lock():
 
         entries = []