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# Copyright (C) 2009 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import os
from git_command import git_require
from git_command import GitCommand
import platform_utils
from repo_trace import Trace
HEAD = "HEAD"
R_CHANGES = "refs/changes/"
R_HEADS = "refs/heads/"
R_TAGS = "refs/tags/"
R_PUB = "refs/published/"
R_WORKTREE = "refs/worktree/"
R_WORKTREE_M = R_WORKTREE + "m/"
R_M = "refs/remotes/m/"
class GitRefs:
def __init__(self, gitdir):
self._gitdir = gitdir
self._phyref = None
self._symref = None
self._mtime = {}
@property
def all(self):
self._EnsureLoaded()
return self._phyref
@property
def head(self) -> str:
"""Return HEAD's symbolic target or detached object ID."""
self._EnsureLoaded()
return self._symref.get(HEAD) or self._phyref.get(HEAD, "")
@property
def is_loaded(self) -> bool:
"""Whether a ref snapshot has already been loaded."""
return self._phyref is not None
def get(self, name):
try:
return self.all[name]
except KeyError:
return ""
def deleted(self, name):
if self._phyref is not None:
if name in self._phyref:
del self._phyref[name]
if name in self._symref:
del self._symref[name]
if name in self._mtime:
del self._mtime[name]
def symref(self, name):
try:
self._EnsureLoaded()
return self._symref[name]
except KeyError:
return ""
def _EnsureLoaded(self):
if self._phyref is None or self._NeedUpdate():
self._LoadAll()
def _NeedUpdate(self):
with Trace(": scan refs %s", self._gitdir):
for name, mtime in self._mtime.items():
try:
if mtime != os.path.getmtime(
os.path.join(self._gitdir, name)
):
return True
except OSError:
return True
return False
def _LoadAll(self):
with Trace(": load refs %s", self._gitdir):
self._phyref = {}
self._symref = {}
self._mtime = {}
root_refs_loaded = self._ReadRefs()
if not root_refs_loaded or (
HEAD not in self._phyref and HEAD not in self._symref
):
# --include-root-refs does not report an unborn HEAD.
self._ReadSymbolicRef(HEAD)
scan = self._symref
attempts = 0
while scan and attempts < 5:
scan_next = {}
for name, dest in scan.items():
if dest in self._phyref:
self._phyref[name] = self._phyref[dest]
else:
scan_next[name] = dest
scan = scan_next
attempts += 1
self._TrackMtime(HEAD)
self._TrackMtime("config")
self._TrackMtime("packed-refs")
self._TrackTreeMtimes("refs")
self._TrackTreeMtimes("reftable")
@staticmethod
def _IsNullRef(ref_id: str) -> bool:
"""Check if a ref_id is a null object ID."""
return ref_id and all(ch == "0" for ch in ref_id)
def _ReadRefs(self) -> bool:
"""Read all references using git for-each-ref.
Returns:
Whether root refs, including HEAD when it exists, were loaded.
"""
include_root_refs = git_require((2, 45, 0))
cmd = [
"for-each-ref",
"--format=%(objectname)%00%(refname)%00%(symref)",
]
if include_root_refs:
cmd.insert(1, "--include-root-refs")
# Avoid caching volatile root refs such as ORIG_HEAD. HEAD and
# refs/* are the only namespaces GitRefs exposes to callers.
cmd.extend([HEAD, "refs"])
p = GitCommand(
None,
cmd,
capture_stdout=True,
capture_stderr=True,
bare=True,
gitdir=self._gitdir,
)
if p.Wait() != 0:
return False
for line in p.stdout.splitlines():
ref_id, name, symref = line.split("\0")
if symref:
self._symref[name] = symref
elif ref_id and not self._IsNullRef(ref_id):
self._phyref[name] = ref_id
return include_root_refs
def _ReadSymbolicRef(self, name: str) -> None:
"""Read a symbolic reference."""
p = GitCommand(
None,
["symbolic-ref", "-q", name],
capture_stdout=True,
capture_stderr=True,
bare=True,
gitdir=self._gitdir,
)
if p.Wait() == 0:
ref = p.stdout.strip()
if ref:
self._symref[name] = ref
return
p = GitCommand(
None,
["rev-parse", "--verify", "-q", name],
capture_stdout=True,
capture_stderr=True,
bare=True,
gitdir=self._gitdir,
)
if p.Wait() == 0:
ref_id = p.stdout.strip()
if ref_id:
self._phyref[name] = ref_id
def _TrackMtime(self, name: str) -> None:
"""Track the modification time of a specific gitdir path."""
path = os.path.join(self._gitdir, name)
try:
self._mtime[name] = os.path.getmtime(path)
except OSError:
return
def _TrackTreeMtimes(self, root: str) -> None:
"""Recursively track modification times for a directory tree."""
root_path = os.path.join(self._gitdir, root)
try:
if not platform_utils.isdir(root_path):
return
except OSError:
return
to_scan = [root]
while to_scan:
name = to_scan.pop()
self._TrackMtime(name)
path = os.path.join(self._gitdir, name)
if not platform_utils.isdir(path):
continue
for child in platform_utils.listdir(path):
child_name = os.path.join(name, child)
child_path = os.path.join(self._gitdir, child_name)
if platform_utils.isdir(child_path):
to_scan.append(child_name)
else:
self._TrackMtime(child_name)
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