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git_store.rs
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git_store.rs
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// Copyright 2020 Google LLC
//
// 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
//
// https://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.
use std::fmt::{Debug, Error, Formatter};
use std::io::Cursor;
use std::io::Read;
use std::path::PathBuf;
use std::sync::Mutex;
use std::time::Duration;
use git2::Oid;
use protobuf::Message;
use crate::repo_path::{DirRepoPath, FileRepoPath};
use crate::store::{
ChangeId, Commit, CommitId, Conflict, ConflictId, ConflictPart, FileId, MillisSinceEpoch,
Signature, Store, StoreError, StoreResult, SymlinkId, Timestamp, Tree, TreeId, TreeValue,
};
use backoff::{ExponentialBackoff, Operation};
use std::ops::Deref;
const COMMITS_NOTES_REF: &str = "refs/notes/jj/commits";
const CONFLICTS_NOTES_REF: &str = "refs/notes/jj/conflicts";
const CONFLICT_SUFFIX: &str = ".jjconflict";
impl From<git2::Error> for StoreError {
fn from(err: git2::Error) -> Self {
match err.code() {
git2::ErrorCode::NotFound => StoreError::NotFound,
_other => StoreError::Other(err.to_string()),
}
}
}
pub struct GitStore {
repo: Mutex<git2::Repository>,
empty_tree_id: TreeId,
}
impl GitStore {
pub fn load(path: PathBuf) -> Self {
let repo = Mutex::new(git2::Repository::open(path).unwrap());
let empty_tree_id =
TreeId(hex::decode("4b825dc642cb6eb9a060e54bf8d69288fbee4904").unwrap());
GitStore {
repo,
empty_tree_id,
}
}
}
fn signature_from_git(signature: git2::Signature) -> Signature {
let name = signature.name().unwrap_or("<no name>").to_owned();
let email = signature.email().unwrap_or("<no email>").to_owned();
let timestamp = MillisSinceEpoch((signature.when().seconds() * 1000) as u64);
let tz_offset = signature.when().offset_minutes();
Signature {
name,
email,
timestamp: Timestamp {
timestamp,
tz_offset,
},
}
}
fn signature_to_git(signature: &Signature) -> git2::Signature {
let name = &signature.name;
let email = &signature.email;
let time = git2::Time::new(
(signature.timestamp.timestamp.0 / 1000) as i64,
signature.timestamp.tz_offset,
);
git2::Signature::new(&name, &email, &time).unwrap()
}
fn serialize_note(commit: &Commit) -> String {
let mut proto = crate::protos::store::Commit::new();
proto.is_open = commit.is_open;
proto.is_pruned = commit.is_pruned;
proto.change_id = commit.change_id.0.to_vec();
for predecessor in &commit.predecessors {
proto.predecessors.push(predecessor.0.to_vec());
}
let bytes = proto.write_to_bytes().unwrap();
hex::encode(bytes)
}
fn deserialize_note(commit: &mut Commit, note: &str) {
let bytes = hex::decode(note).unwrap();
let mut cursor = Cursor::new(bytes);
let proto: crate::protos::store::Commit = protobuf::parse_from_reader(&mut cursor).unwrap();
commit.is_open = proto.is_open;
commit.is_pruned = proto.is_pruned;
commit.change_id = ChangeId(proto.change_id);
for predecessor in &proto.predecessors {
commit.predecessors.push(CommitId(predecessor.clone()));
}
}
fn write_note(
git_repo: &git2::Repository,
committer: &git2::Signature,
notes_ref: &str,
oid: git2::Oid,
note: &str,
) -> Result<(), git2::Error> {
// It seems that libgit2 doesn't retry when .git/refs/notes/jj/commits.lock
// already exists, so we do the retrying ourselves.
// TODO: Report this to libgit2.
let notes_ref_lock = format!("{}.lock", notes_ref);
let mut try_write_note = || {
let note_status = git_repo.note(&committer, &committer, Some(notes_ref), oid, note, false);
match note_status {
Err(err) if err.message().contains(¬es_ref_lock) => {
Err(backoff::Error::Transient(err))
}
Err(err) => Err(backoff::Error::Permanent(err)),
Ok(_) => Ok(()),
}
};
let mut backoff = ExponentialBackoff::default();
backoff.initial_interval = Duration::from_millis(1);
backoff.max_elapsed_time = Some(Duration::from_secs(10));
try_write_note
.retry(&mut backoff)
.map_err(|err| match err {
backoff::Error::Permanent(err) => err,
backoff::Error::Transient(err) => err,
})?;
Ok(())
}
impl Debug for GitStore {
fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
f.debug_struct("GitStore")
.field("path", &self.repo.lock().unwrap().path())
.finish()
}
}
impl Store for GitStore {
fn hash_length(&self) -> usize {
20
}
fn git_repo(&self) -> Option<git2::Repository> {
let path = self.repo.lock().unwrap().path().to_owned();
Some(git2::Repository::open(&path).unwrap())
}
fn read_file(&self, _path: &FileRepoPath, id: &FileId) -> StoreResult<Box<dyn Read>> {
if id.0.len() != self.hash_length() {
return Err(StoreError::NotFound);
}
let locked_repo = self.repo.lock().unwrap();
let blob = locked_repo
.find_blob(Oid::from_bytes(id.0.as_slice()).unwrap())
.unwrap();
let content = blob.content().to_owned();
Ok(Box::new(Cursor::new(content)))
}
fn write_file(&self, _path: &FileRepoPath, contents: &mut dyn Read) -> StoreResult<FileId> {
let mut bytes = Vec::new();
contents.read_to_end(&mut bytes).unwrap();
let locked_repo = self.repo.lock().unwrap();
let oid = locked_repo.blob(bytes.as_slice()).unwrap();
Ok(FileId(oid.as_bytes().to_vec()))
}
fn read_symlink(&self, _path: &FileRepoPath, id: &SymlinkId) -> Result<String, StoreError> {
if id.0.len() != self.hash_length() {
return Err(StoreError::NotFound);
}
let locked_repo = self.repo.lock().unwrap();
let blob = locked_repo
.find_blob(Oid::from_bytes(id.0.as_slice()).unwrap())
.unwrap();
let target = String::from_utf8(blob.content().to_owned()).unwrap();
Ok(target)
}
fn write_symlink(&self, _path: &FileRepoPath, target: &str) -> Result<SymlinkId, StoreError> {
let locked_repo = self.repo.lock().unwrap();
let oid = locked_repo.blob(target.as_bytes()).unwrap();
Ok(SymlinkId(oid.as_bytes().to_vec()))
}
fn empty_tree_id(&self) -> &TreeId {
&self.empty_tree_id
}
fn read_tree(&self, _path: &DirRepoPath, id: &TreeId) -> StoreResult<Tree> {
if id == &self.empty_tree_id {
return Ok(Tree::default());
}
if id.0.len() != self.hash_length() {
return Err(StoreError::NotFound);
}
let locked_repo = self.repo.lock().unwrap();
let git_tree = locked_repo
.find_tree(Oid::from_bytes(id.0.as_slice()).unwrap())
.unwrap();
let mut tree = Tree::default();
for entry in git_tree.iter() {
let name = entry.name().unwrap();
let (name, value) = match entry.kind().unwrap() {
git2::ObjectType::Tree => {
let id = TreeId(entry.id().as_bytes().to_vec());
(entry.name().unwrap(), TreeValue::Tree(id))
}
git2::ObjectType::Blob => match entry.filemode() {
0o100644 => {
let id = FileId(entry.id().as_bytes().to_vec());
if name.ends_with(CONFLICT_SUFFIX) {
(
&name[0..name.len() - CONFLICT_SUFFIX.len()],
TreeValue::Conflict(ConflictId(entry.id().as_bytes().to_vec())),
)
} else {
(
name,
TreeValue::Normal {
id,
executable: false,
},
)
}
}
0o100755 => {
let id = FileId(entry.id().as_bytes().to_vec());
(
name,
TreeValue::Normal {
id,
executable: true,
},
)
}
0o120000 => {
let id = SymlinkId(entry.id().as_bytes().to_vec());
(name, TreeValue::Symlink(id))
}
mode => panic!("unexpected file mode {:?}", mode),
},
git2::ObjectType::Commit => {
let id = CommitId(entry.id().as_bytes().to_vec());
(name, TreeValue::GitSubmodule(id))
}
kind => panic!("unexpected object type {:?}", kind),
};
tree.set(name.to_string(), value);
}
Ok(tree)
}
fn write_tree(&self, _path: &DirRepoPath, contents: &Tree) -> StoreResult<TreeId> {
let locked_repo = self.repo.lock().unwrap();
let mut builder = locked_repo.treebuilder(None).unwrap();
for entry in contents.entries() {
let name = entry.name().to_owned();
let (name, id, filemode) = match entry.value() {
TreeValue::Normal {
id,
executable: false,
} => (name, &id.0, 0o100644),
TreeValue::Normal {
id,
executable: true,
} => (name, &id.0, 0o100755),
TreeValue::Symlink(id) => (name, &id.0, 0o120000),
TreeValue::Tree(id) => (name, &id.0, 0o040000),
TreeValue::GitSubmodule(id) => (name, &id.0, 0o160000),
TreeValue::Conflict(id) => (name + CONFLICT_SUFFIX, &id.0, 0o100644),
};
builder
.insert(name, Oid::from_bytes(id).unwrap(), filemode)
.unwrap();
}
let oid = builder.write().unwrap();
Ok(TreeId(oid.as_bytes().to_vec()))
}
fn read_commit(&self, id: &CommitId) -> StoreResult<Commit> {
if id.0.len() != self.hash_length() {
return Err(StoreError::NotFound);
}
let locked_repo = self.repo.lock().unwrap();
let git_commit_id = Oid::from_bytes(id.0.as_slice())?;
let commit = locked_repo.find_commit(git_commit_id)?;
let change_id = ChangeId(id.0.clone().as_slice()[0..16].to_vec());
let parents: Vec<_> = commit
.parent_ids()
.map(|oid| CommitId(oid.as_bytes().to_vec()))
.collect();
let tree_id = TreeId(commit.tree_id().as_bytes().to_vec());
let description = commit.message().unwrap_or("<no message>").to_owned();
let author = signature_from_git(commit.author());
let committer = signature_from_git(commit.committer());
let mut commit = Commit {
parents,
predecessors: vec![],
root_tree: tree_id,
change_id,
description,
author,
committer,
is_open: false,
is_pruned: false,
};
let maybe_note = locked_repo
.find_note(Some(COMMITS_NOTES_REF), git_commit_id)
.ok();
if let Some(note) = maybe_note {
deserialize_note(&mut commit, note.message().unwrap());
}
Ok(commit)
}
fn write_commit(&self, contents: &Commit) -> StoreResult<CommitId> {
// TODO: We shouldn't have to create an in-memory index just to write an
// object...
let locked_repo = self.repo.lock().unwrap();
let git_tree = locked_repo.find_tree(Oid::from_bytes(contents.root_tree.0.as_slice())?)?;
let author = signature_to_git(&contents.author);
let committer = signature_to_git(&contents.committer);
let message = &contents.description;
let mut parents = vec![];
for parent_id in &contents.parents {
let parent_git_commit =
locked_repo.find_commit(Oid::from_bytes(parent_id.0.as_slice())?)?;
parents.push(parent_git_commit);
}
let parent_refs: Vec<_> = parents.iter().collect();
let git_id =
locked_repo.commit(None, &author, &committer, &message, &git_tree, &parent_refs)?;
let id = CommitId(git_id.as_bytes().to_vec());
let note = serialize_note(contents);
// TODO: Include the extra commit data in commit headers instead of a ref.
// Unfortunately, it doesn't seem like libgit2-rs supports that. Perhaps
// we'll have to serialize/deserialize the commit data ourselves.
write_note(
locked_repo.deref(),
&committer,
COMMITS_NOTES_REF,
git_id,
¬e,
)?;
Ok(id)
}
fn read_conflict(&self, id: &ConflictId) -> StoreResult<Conflict> {
let mut file = self.read_file(&FileRepoPath::from("unused"), &FileId(id.0.clone()))?;
let mut data = String::new();
file.read_to_string(&mut data)?;
let json: serde_json::Value = serde_json::from_str(&data).unwrap();
Ok(Conflict {
removes: conflict_part_list_from_json(json.get("removes").unwrap()),
adds: conflict_part_list_from_json(json.get("adds").unwrap()),
})
}
fn write_conflict(&self, conflict: &Conflict) -> StoreResult<ConflictId> {
let json = serde_json::json!({
"removes": conflict_part_list_to_json(&conflict.removes),
"adds": conflict_part_list_to_json(&conflict.adds),
});
let json_string = json.to_string();
let bytes = json_string.as_bytes();
let locked_repo = self.repo.lock().unwrap();
let oid = locked_repo.blob(bytes).unwrap();
let signature = git2::Signature::now("Jujube", "jj@example.com").unwrap();
let note_result = write_note(
locked_repo.deref(),
&signature,
CONFLICTS_NOTES_REF,
oid,
"Conflict object used by Jujube",
);
match note_result {
// It's fine if the conflict already existed (no need to update the note), but
// any other error is unexpected.
Err(err) if err.code() != git2::ErrorCode::Exists => {
return Err(StoreError::from(err));
}
_ => {}
}
Ok(ConflictId(oid.as_bytes().to_vec()))
}
}
fn conflict_part_list_to_json(parts: &[ConflictPart]) -> serde_json::Value {
serde_json::Value::Array(parts.iter().map(conflict_part_to_json).collect())
}
fn conflict_part_list_from_json(json: &serde_json::Value) -> Vec<ConflictPart> {
json.as_array()
.unwrap()
.iter()
.map(conflict_part_from_json)
.collect()
}
fn conflict_part_to_json(part: &ConflictPart) -> serde_json::Value {
serde_json::json!({
"value": tree_value_to_json(&part.value),
})
}
fn conflict_part_from_json(json: &serde_json::Value) -> ConflictPart {
let json_value = json.get("value").unwrap();
ConflictPart {
value: tree_value_from_json(json_value),
}
}
fn tree_value_to_json(value: &TreeValue) -> serde_json::Value {
match value {
TreeValue::Normal { id, executable } => serde_json::json!({
"file": {
"id": id.hex(),
"executable": executable,
},
}),
TreeValue::Symlink(id) => serde_json::json!({
"symlink_id": id.hex(),
}),
TreeValue::Tree(id) => serde_json::json!({
"tree_id": id.hex(),
}),
TreeValue::GitSubmodule(id) => serde_json::json!({
"submodule_id": id.hex(),
}),
TreeValue::Conflict(id) => serde_json::json!({
"conflict_id": id.hex(),
}),
}
}
fn tree_value_from_json(json: &serde_json::Value) -> TreeValue {
if let Some(json_file) = json.get("file") {
TreeValue::Normal {
id: FileId(bytes_vec_from_json(json_file.get("id").unwrap())),
executable: json_file.get("executable").unwrap().as_bool().unwrap(),
}
} else if let Some(json_id) = json.get("symlink_id") {
TreeValue::Symlink(SymlinkId(bytes_vec_from_json(json_id)))
} else if let Some(json_id) = json.get("tree_id") {
TreeValue::Tree(TreeId(bytes_vec_from_json(json_id)))
} else if let Some(json_id) = json.get("submodule_id") {
TreeValue::GitSubmodule(CommitId(bytes_vec_from_json(json_id)))
} else if let Some(json_id) = json.get("conflict_id") {
TreeValue::Conflict(ConflictId(bytes_vec_from_json(json_id)))
} else {
panic!("unexpected json value in conflict: {:#?}", json);
}
}
fn bytes_vec_from_json(value: &serde_json::Value) -> Vec<u8> {
hex::decode(value.as_str().unwrap()).unwrap()
}
#[cfg(test)]
mod tests {
use crate::store::{FileId, MillisSinceEpoch};
use super::*;
#[test]
fn read_plain_git_commit() {
let temp_dir = tempfile::tempdir().unwrap();
let git_repo_path = temp_dir.path();
let git_repo = git2::Repository::init(git_repo_path.clone()).unwrap();
// Add a commit with some files in
let blob1 = git_repo.blob(b"content1").unwrap();
let blob2 = git_repo.blob(b"normal").unwrap();
let mut dir_tree_builder = git_repo.treebuilder(None).unwrap();
dir_tree_builder.insert("normal", blob1, 0o100644).unwrap();
dir_tree_builder.insert("symlink", blob2, 0o120000).unwrap();
let dir_tree_id = dir_tree_builder.write().unwrap();
let mut root_tree_builder = git_repo.treebuilder(None).unwrap();
root_tree_builder
.insert("dir", dir_tree_id, 0o040000)
.unwrap();
let root_tree_id = root_tree_builder.write().unwrap();
let git_author = git2::Signature::new(
"git author",
"git.author@example.com",
&git2::Time::new(1000, 60),
)
.unwrap();
let git_committer = git2::Signature::new(
"git committer",
"git.committer@example.com",
&git2::Time::new(2000, -480),
)
.unwrap();
let git_tree = git_repo.find_tree(root_tree_id).unwrap();
let git_commit_id = git_repo
.commit(
None,
&git_author,
&git_committer,
"git commit message",
&git_tree,
&[],
)
.unwrap();
let commit_id = CommitId(git_commit_id.as_bytes().to_vec());
let store = GitStore::load(git_repo_path.to_owned());
let commit = store.read_commit(&commit_id).unwrap();
assert_eq!(
&commit.change_id,
&ChangeId(commit_id.0.as_slice()[0..16].to_vec())
);
assert_eq!(commit.parents, vec![]);
assert_eq!(commit.predecessors, vec![]);
assert_eq!(commit.root_tree.0.as_slice(), root_tree_id.as_bytes());
assert_eq!(commit.is_open, false);
assert_eq!(commit.is_pruned, false);
assert_eq!(commit.description, "git commit message");
assert_eq!(commit.author.name, "git author");
assert_eq!(commit.author.email, "git.author@example.com");
assert_eq!(
commit.author.timestamp.timestamp,
MillisSinceEpoch(1000 * 1000)
);
assert_eq!(commit.author.timestamp.tz_offset, 60);
assert_eq!(commit.committer.name, "git committer");
assert_eq!(commit.committer.email, "git.committer@example.com");
assert_eq!(
commit.committer.timestamp.timestamp,
MillisSinceEpoch(2000 * 1000)
);
assert_eq!(commit.committer.timestamp.tz_offset, -480);
let root_tree = store
.read_tree(
&DirRepoPath::root(),
&TreeId(root_tree_id.as_bytes().to_vec()),
)
.unwrap();
let mut root_entries = root_tree.entries();
let dir = root_entries.next().unwrap();
assert_eq!(root_entries.next(), None);
assert_eq!(dir.name(), "dir");
assert_eq!(
dir.value(),
&TreeValue::Tree(TreeId(dir_tree_id.as_bytes().to_vec()))
);
let dir_tree = store
.read_tree(
&DirRepoPath::from("dir/"),
&TreeId(dir_tree_id.as_bytes().to_vec()),
)
.unwrap();
let mut files = dir_tree.entries();
let normal_file = files.next().unwrap();
let symlink = files.next().unwrap();
assert_eq!(files.next(), None);
assert_eq!(normal_file.name(), "normal");
assert_eq!(
normal_file.value(),
&TreeValue::Normal {
id: FileId(blob1.as_bytes().to_vec()),
executable: false
}
);
assert_eq!(symlink.name(), "symlink");
assert_eq!(
symlink.value(),
&TreeValue::Symlink(SymlinkId(blob2.as_bytes().to_vec()))
);
}
#[test]
fn overlapping_git_commit_id() {
let temp_dir = tempfile::tempdir().unwrap();
let git_repo_path = temp_dir.path();
git2::Repository::init(git_repo_path.clone()).unwrap();
let store = GitStore::load(git_repo_path.to_owned());
let signature = Signature {
name: "Someone".to_string(),
email: "someone@example.com".to_string(),
timestamp: Timestamp {
timestamp: MillisSinceEpoch(0),
tz_offset: 0,
},
};
let commit1 = Commit {
parents: vec![],
predecessors: vec![],
root_tree: store.empty_tree_id().clone(),
change_id: ChangeId(vec![]),
description: "initial".to_string(),
author: signature.clone(),
committer: signature,
is_open: false,
is_pruned: false,
};
let commit_id1 = store.write_commit(&commit1).unwrap();
let mut commit2 = commit1;
commit2.predecessors.push(commit_id1.clone());
let expected_error_message = format!("note for '{}' exists already", commit_id1.hex());
match store.write_commit(&commit2) {
Ok(_) => {
panic!("expectedly successfully wrote two commits with the same git commit object")
}
Err(StoreError::Other(message)) if message.contains(&expected_error_message) => {}
Err(err) => panic!("unexpected error: {:?}", err),
};
}
}