bitbake: fetch/git: add support for keeping extra refs for shallow

By default, all unused refs (branches & tags) are removed from the repository,
as shallow processing scales with the number of refs it has to process. Add
the ability to explicitly specify additional refs to keep. This is
particularly useful for recipes with custom checkout processes, or whose
git-based versioning requires a tag be available (i.e. for `git describe
--tags`). The new `BB_GIT_SHALLOW_EXTRA_REFS` variable is a space-separated
list of refs, fully specified, and support wildcards.

Example usages:

    BB_GIT_SHALLOW_EXTRA_REFS = "refs/tags/v1.0"
    BB_GIT_SHALLOW_EXTRA_REFS += "refs/heads/*"

(Bitbake rev: 1771934cd9f8b5847c6fcae0a906fb99d6b0db16)

Signed-off-by: Christopher Larson <chris_larson@mentor.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/fetch2/git.py

@@ -72,6 +72,7 @@ Supported SRC_URI options are:
 
 import collections
 import errno
+import fnmatch
 import os
 import re
 import subprocess
@@ -180,6 +181,7 @@ class Git(FetchMethod):
             ud.cloneflags += " --mirror"
 
         ud.shallow = d.getVar("BB_GIT_SHALLOW") == "1"
+        ud.shallow_extra_refs = (d.getVar("BB_GIT_SHALLOW_EXTRA_REFS") or "").split()
 
         depth_default = d.getVar("BB_GIT_SHALLOW_DEPTH")
         if depth_default is not None:
@@ -265,8 +267,13 @@ class Git(FetchMethod):
                 if depth:
                     tarballname = "%s-%s" % (tarballname, depth)
 
+            shallow_refs = []
             if not ud.nobranch:
-                tarballname = "%s_%s" % (tarballname, "_".join(sorted(ud.branches.values())).replace('/', '.'))
+                shallow_refs.extend(ud.branches.values())
+            if ud.shallow_extra_refs:
+                shallow_refs.extend(r.replace('refs/heads/', '').replace('*', 'ALL') for r in ud.shallow_extra_refs)
+            if shallow_refs:
+                tarballname = "%s_%s" % (tarballname, "_".join(sorted(shallow_refs)).replace('/', '.'))
 
             fetcher = self.__class__.__name__.lower()
             ud.shallowtarball = '%sshallow_%s.tar.gz' % (fetcher, tarballname)
@@ -408,6 +415,19 @@ class Git(FetchMethod):
         # Map srcrev+depths to revisions
         shallow_revisions = runfetchcmd("%s rev-parse %s" % (ud.basecmd, " ".join(to_parse)), d, workdir=dest).splitlines()
 
+        # Apply extra ref wildcards
+        all_refs = runfetchcmd('%s for-each-ref "--format=%%(refname)"' % ud.basecmd,
+                               d, workdir=dest).splitlines()
+        for r in ud.shallow_extra_refs:
+            if not ud.bareclone:
+                r = r.replace('refs/heads/', 'refs/remotes/origin/')
+
+            if '*' in r:
+                matches = filter(lambda a: fnmatch.fnmatchcase(a, r), all_refs)
+                shallow_branches.extend(matches)
+            else:
+                shallow_branches.append(r)
+
         # Make the repository shallow
         shallow_cmd = ['git', 'make-shallow', '-s']
         for b in shallow_branches:

bitbake/lib/bb/tests/fetch.py

@@ -1293,6 +1293,48 @@ class GitShallowTest(FetcherTest):
         with self.assertRaises(bb.fetch2.FetchError):
             self.fetch()
 
+    def test_shallow_extra_refs(self):
+        self.add_empty_file('a')
+        self.add_empty_file('b')
+        self.git('branch a_branch', cwd=self.srcdir)
+        self.assertRefs(['master', 'a_branch'], cwd=self.srcdir)
+        self.assertRevCount(2, cwd=self.srcdir)
+
+        self.d.setVar('BB_GIT_SHALLOW_EXTRA_REFS', 'refs/heads/a_branch')
+        self.fetch_shallow()
+
+        self.assertRefs(['master', 'origin/master', 'origin/a_branch'])
+        self.assertRevCount(1)
+
+    def test_shallow_extra_refs_wildcard(self):
+        self.add_empty_file('a')
+        self.add_empty_file('b')
+        self.git('branch a_branch', cwd=self.srcdir)
+        self.git('tag v1.0', cwd=self.srcdir)
+        self.assertRefs(['master', 'a_branch', 'v1.0'], cwd=self.srcdir)
+        self.assertRevCount(2, cwd=self.srcdir)
+
+        self.d.setVar('BB_GIT_SHALLOW_EXTRA_REFS', 'refs/tags/*')
+        self.fetch_shallow()
+
+        self.assertRefs(['master', 'origin/master', 'v1.0'])
+        self.assertRevCount(1)
+
+    def test_shallow_missing_extra_refs(self):
+        self.add_empty_file('a')
+        self.add_empty_file('b')
+
+        self.d.setVar('BB_GIT_SHALLOW_EXTRA_REFS', 'refs/heads/foo')
+        with self.assertRaises(bb.fetch2.FetchError):
+            self.fetch()
+
+    def test_shallow_missing_extra_refs_wildcard(self):
+        self.add_empty_file('a')
+        self.add_empty_file('b')
+
+        self.d.setVar('BB_GIT_SHALLOW_EXTRA_REFS', 'refs/tags/*')
+        self.fetch()
+
     if os.environ.get("BB_SKIP_NETTESTS") == "yes":
         print("Unset BB_SKIP_NETTESTS to run network tests")
     else: