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// Copyright 2020 The Jujutsu Authors//// 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. #![allow(missing_docs)] use std::any::Any;use std::collections::HashSet;use std::fmt::Debug;use std::fmt::Error;use std::fmt::Formatter;use std::fs;use std::io;use std::io::Cursor;use std::io::Read;use std::path::Path;use std::path::PathBuf;use std::process::Command;use std::process::ExitStatus;use std::str;use std::sync::Arc;use std::sync::Mutex;use std::sync::MutexGuard;use std::time::SystemTime; use async_trait::async_trait;use futures::stream::BoxStream;use gix::bstr::BString;use gix::objs::CommitRef;use gix::objs::CommitRefIter;use gix::objs::WriteTo;use itertools::Itertools;use pollster::FutureExt;use prost::Message;use smallvec::SmallVec;use thiserror::Error; use crate::backend::make_root_commit;use crate::backend::Backend;use crate::backend::BackendError;use crate::backend::BackendInitError;use crate::backend::BackendLoadError;use crate::backend::BackendResult;use crate::backend::ChangeId;use crate::backend::Commit;use crate::backend::CommitId;use crate::backend::Conflict;use crate::backend::ConflictId;use crate::backend::ConflictTerm;use crate::backend::CopyRecord;use crate::backend::FileId;use crate::backend::MergedTreeId;use crate::backend::MillisSinceEpoch;use crate::backend::SecureSig;use crate::backend::Signature;use crate::backend::SigningFn;use crate::backend::SymlinkId;use crate::backend::Timestamp;use crate::backend::Tree;use crate::backend::TreeId;use crate::backend::TreeValue;use crate::file_util::IoResultExt as _;use crate::file_util::PathError;use crate::index::Index;use crate::lock::FileLock;use crate::merge::Merge;use crate::merge::MergeBuilder;use crate::object_id::ObjectId;use crate::repo_path::RepoPath;use crate::repo_path::RepoPathBuf;use crate::repo_path::RepoPathComponentBuf;use crate::settings::UserSettings;use crate::stacked_table::MutableTable;use crate::stacked_table::ReadonlyTable;use crate::stacked_table::TableSegment;use crate::stacked_table::TableStore;use crate::stacked_table::TableStoreError; const HASH_LENGTH: usize = 20;const CHANGE_ID_LENGTH: usize = 16;/// Ref namespace used only for preventing GC.const NO_GC_REF_NAMESPACE: &str = "refs/jj/keep/";const CONFLICT_SUFFIX: &str = ".jjconflict"; const JJ_TREES_COMMIT_HEADER: &[u8] = b"jj:trees"; #[derive(Debug, Error)]pub enum GitBackendInitError {    #[error("Failed to initialize git repository")]    InitRepository(#[source] gix::init::Error),    #[error("Failed to open git repository")]    OpenRepository(#[source] gix::open::Error),    #[error(transparent)]    Path(PathError),} impl From<Box<GitBackendInitError>> for BackendInitError {    fn from(err: Box<GitBackendInitError>) -> Self {        BackendInitError(err)    }} #[derive(Debug, Error)]pub enum GitBackendLoadError {    #[error("Failed to open git repository")]    OpenRepository(#[source] gix::open::Error),    #[error(transparent)]    Path(PathError),} impl From<Box<GitBackendLoadError>> for BackendLoadError {    fn from(err: Box<GitBackendLoadError>) -> Self {        BackendLoadError(err)    }} /// `GitBackend`-specific error that may occur after the backend is loaded.#[derive(Debug, Error)]pub enum GitBackendError {    #[error("Failed to read non-git metadata")]    ReadMetadata(#[source] TableStoreError),    #[error("Failed to write non-git metadata")]    WriteMetadata(#[source] TableStoreError),} impl From<GitBackendError> for BackendError {    fn from(err: GitBackendError) -> Self {        BackendError::Other(err.into())    }} #[derive(Debug, Error)]pub enum GitGcError {    #[error("Failed to run git gc command")]    GcCommand(#[source] std::io::Error),    #[error("git gc command exited with an error: {0}")]    GcCommandErrorStatus(ExitStatus),} pub struct GitBackend {    // While gix::Repository can be created from gix::ThreadSafeRepository, it's    // cheaper to cache the thread-local instance behind a mutex than creating    // one for each backend method call. Our GitBackend is most likely to be    // used in a single-threaded context.    base_repo: gix::ThreadSafeRepository,    repo: Mutex<gix::Repository>,    root_commit_id: CommitId,    root_change_id: ChangeId,    empty_tree_id: TreeId,    extra_metadata_store: TableStore,    cached_extra_metadata: Mutex<Option<Arc<ReadonlyTable>>>,} impl GitBackend {    pub fn name() -> &'static str {        "git"    }     fn new(base_repo: gix::ThreadSafeRepository, extra_metadata_store: TableStore) -> Self {        let repo = Mutex::new(base_repo.to_thread_local());        let root_commit_id = CommitId::from_bytes(&[0; HASH_LENGTH]);        let root_change_id = ChangeId::from_bytes(&[0; CHANGE_ID_LENGTH]);        let empty_tree_id = TreeId::from_hex("4b825dc642cb6eb9a060e54bf8d69288fbee4904");        GitBackend {            base_repo,            repo,            root_commit_id,            root_change_id,            empty_tree_id,            extra_metadata_store,            cached_extra_metadata: Mutex::new(None),        }    }     pub fn init_internal(        settings: &UserSettings,        store_path: &Path,    ) -> Result<Self, Box<GitBackendInitError>> {        let git_repo_path = Path::new("git");        let git_repo = gix::ThreadSafeRepository::init_opts(            store_path.join(git_repo_path),            gix::create::Kind::Bare,            gix::create::Options::default(),            gix_open_opts_from_settings(settings),        )        .map_err(GitBackendInitError::InitRepository)?;        Self::init_with_repo(store_path, git_repo_path, git_repo)    }     /// Initializes backend by creating a new Git repo at the specified    /// workspace path. The workspace directory must exist.    pub fn init_colocated(        settings: &UserSettings,        store_path: &Path,        workspace_root: &Path,    ) -> Result<Self, Box<GitBackendInitError>> {        let canonical_workspace_root = {            let path = store_path.join(workspace_root);            path.canonicalize()                .context(&path)                .map_err(GitBackendInitError::Path)?        };        let git_repo = gix::ThreadSafeRepository::init_opts(            canonical_workspace_root,            gix::create::Kind::WithWorktree,            gix::create::Options::default(),            gix_open_opts_from_settings(settings),        )        .map_err(GitBackendInitError::InitRepository)?;        let git_repo_path = workspace_root.join(".git");        Self::init_with_repo(store_path, &git_repo_path, git_repo)    }     /// Initializes backend with an existing Git repo at the specified path.    pub fn init_external(        settings: &UserSettings,        store_path: &Path,        git_repo_path: &Path,    ) -> Result<Self, Box<GitBackendInitError>> {        let canonical_git_repo_path = {            let path = store_path.join(git_repo_path);            canonicalize_git_repo_path(&path)                .context(&path)                .map_err(GitBackendInitError::Path)?        };        let git_repo = gix::ThreadSafeRepository::open_opts(            canonical_git_repo_path,            gix_open_opts_from_settings(settings),        )        .map_err(GitBackendInitError::OpenRepository)?;        Self::init_with_repo(store_path, git_repo_path, git_repo)    }     fn init_with_repo(        store_path: &Path,        git_repo_path: &Path,        git_repo: gix::ThreadSafeRepository,    ) -> Result<Self, Box<GitBackendInitError>> {        let extra_path = store_path.join("extra");        fs::create_dir(&extra_path)            .context(&extra_path)            .map_err(GitBackendInitError::Path)?;        let target_path = store_path.join("git_target");        if cfg!(windows) && git_repo_path.is_relative() {            // When a repository is created in Windows, format the path with *forward            // slashes* and not backwards slashes. This makes it possible to use the same            // repository under Windows Subsystem for Linux.            //            // This only works for relative paths. If the path is absolute, there's not much            // we can do, and it simply won't work inside and outside WSL at the same time.            let git_repo_path_string = git_repo_path                .components()                .map(|component| component.as_os_str().to_str().unwrap().to_owned())                .join("/");            fs::write(&target_path, git_repo_path_string.as_bytes())                .context(&target_path)                .map_err(GitBackendInitError::Path)?;        } else {            fs::write(&target_path, git_repo_path.to_str().unwrap().as_bytes())                .context(&target_path)                .map_err(GitBackendInitError::Path)?;        };        let extra_metadata_store = TableStore::init(extra_path, HASH_LENGTH);        Ok(GitBackend::new(git_repo, extra_metadata_store))    }     pub fn load(        settings: &UserSettings,        store_path: &Path,    ) -> Result<Self, Box<GitBackendLoadError>> {        let git_repo_path = {            let target_path = store_path.join("git_target");            let git_repo_path_str = fs::read_to_string(&target_path)                .context(&target_path)                .map_err(GitBackendLoadError::Path)?;            let git_repo_path = store_path.join(git_repo_path_str);            canonicalize_git_repo_path(&git_repo_path)                .context(&git_repo_path)                .map_err(GitBackendLoadError::Path)?        };        let repo = gix::ThreadSafeRepository::open_opts(            git_repo_path,            gix_open_opts_from_settings(settings),        )        .map_err(GitBackendLoadError::OpenRepository)?;        let extra_metadata_store = TableStore::load(store_path.join("extra"), HASH_LENGTH);        Ok(GitBackend::new(repo, extra_metadata_store))    }     fn lock_git_repo(&self) -> MutexGuard<'_, gix::Repository> {        self.repo.lock().unwrap()    }     /// Returns new thread-local instance to access to the underlying Git repo.    pub fn git_repo(&self) -> gix::Repository {        self.base_repo.to_thread_local()    }     /// Creates new owned git repository instance.    pub fn open_git_repo(&self) -> Result<git2::Repository, git2::Error> {        git2::Repository::open(self.git_repo_path())    }     /// Path to the `.git` directory or the repository itself if it's bare.    pub fn git_repo_path(&self) -> &Path {        self.base_repo.path()    }     /// Path to the working directory if the repository isn't bare.    pub fn git_workdir(&self) -> Option<&Path> {        self.base_repo.work_dir()    }     fn cached_extra_metadata_table(&self) -> BackendResult<Arc<ReadonlyTable>> {        let mut locked_head = self.cached_extra_metadata.lock().unwrap();        match locked_head.as_ref() {            Some(head) => Ok(head.clone()),            None => {                let table = self                    .extra_metadata_store                    .get_head()                    .map_err(GitBackendError::ReadMetadata)?;                *locked_head = Some(table.clone());                Ok(table)            }        }    }     fn read_extra_metadata_table_locked(&self) -> BackendResult<(Arc<ReadonlyTable>, FileLock)> {        let table = self            .extra_metadata_store            .get_head_locked()            .map_err(GitBackendError::ReadMetadata)?;        Ok(table)    }     fn save_extra_metadata_table(        &self,        mut_table: MutableTable,        _table_lock: &FileLock,    ) -> BackendResult<()> {        let table = self            .extra_metadata_store            .save_table(mut_table)            .map_err(GitBackendError::WriteMetadata)?;        // Since the parent table was the head, saved table are likely to be new head.        // If it's not, cache will be reloaded when entry can't be found.        *self.cached_extra_metadata.lock().unwrap() = Some(table);        Ok(())    }     /// Imports the given commits and ancestors from the backing Git repo.    ///    /// The `head_ids` may contain commits that have already been imported, but    /// the caller should filter them out to eliminate redundant I/O processing.    #[tracing::instrument(skip(self, head_ids))]    pub fn import_head_commits<'a>(        &self,        head_ids: impl IntoIterator<Item = &'a CommitId>,    ) -> BackendResult<()> {        self.import_head_commits_with_tree_conflicts(head_ids, true)    }     fn import_head_commits_with_tree_conflicts<'a>(        &self,        head_ids: impl IntoIterator<Item = &'a CommitId>,        uses_tree_conflict_format: bool,    ) -> BackendResult<()> {        let head_ids: HashSet<&CommitId> = head_ids            .into_iter()            .filter(|&id| *id != self.root_commit_id)            .collect();        if head_ids.is_empty() {            return Ok(());        }         // Create no-gc ref even if known to the extras table. Concurrent GC        // process might have deleted the no-gc ref.        let locked_repo = self.lock_git_repo();        locked_repo            .edit_references(head_ids.iter().copied().map(to_no_gc_ref_update))            .map_err(|err| BackendError::Other(Box::new(err)))?;         // These commits are imported from Git. Make our change ids persist (otherwise        // future write_commit() could reassign new change id.)        tracing::debug!(            heads_count = head_ids.len(),            "import extra metadata entries"        );        let (table, table_lock) = self.read_extra_metadata_table_locked()?;        let mut mut_table = table.start_mutation();        import_extra_metadata_entries_from_heads(            &locked_repo,            &mut mut_table,            &table_lock,            &head_ids,            uses_tree_conflict_format,        )?;        self.save_extra_metadata_table(mut_table, &table_lock)    }     fn read_file_sync(&self, id: &FileId) -> BackendResult<Box<dyn Read>> {        let git_blob_id = validate_git_object_id(id)?;        let locked_repo = self.lock_git_repo();        let mut blob = locked_repo            .find_object(git_blob_id)            .map_err(|err| map_not_found_err(err, id))?            .try_into_blob()            .map_err(|err| to_read_object_err(err, id))?;        Ok(Box::new(Cursor::new(blob.take_data())))    }     fn new_diff_platform(&self) -> BackendResult<gix::diff::blob::Platform> {        let attributes = gix::worktree::Stack::new(            Path::new(""),            gix::worktree::stack::State::AttributesStack(Default::default()),            gix::worktree::glob::pattern::Case::Sensitive,            Vec::new(),            Vec::new(),        );        let filter = gix::diff::blob::Pipeline::new(            Default::default(),            gix_filter::Pipeline::new(                self.git_repo()                    .command_context()                    .map_err(|err| BackendError::Other(Box::new(err)))?,                Default::default(),            ),            Vec::new(),            Default::default(),        );        Ok(gix::diff::blob::Platform::new(            Default::default(),            filter,            gix::diff::blob::pipeline::Mode::ToGit,            attributes,        ))    }     fn read_tree_for_commit<'repo>(        &self,        repo: &'repo gix::Repository,        id: &CommitId,    ) -> BackendResult<gix::Tree<'repo>> {        let tree = self.read_commit(id).block_on()?.root_tree.to_merge();        // TODO(kfm): probably want to do something here if it is a merge        let tree_id = tree.first().clone();        let gix_id = validate_git_object_id(&tree_id)?;        repo.find_object(gix_id)            .map_err(|err| map_not_found_err(err, &tree_id))?            .try_into_tree()            .map_err(|err| to_read_object_err(err, &tree_id))    }} /// Canonicalizes the given `path` except for the last `".git"` component.////// The last path component matters when opening a Git repo without `core.bare`/// config. This config is usually set, but the "repo" tool will set up such/// repositories and symlinks. Opening such repo with fully-canonicalized path/// would turn a colocated Git repo into a bare repo.pub fn canonicalize_git_repo_path(path: &Path) -> io::Result<PathBuf> {    if path.ends_with(".git") {        let workdir = path.parent().unwrap();        workdir.canonicalize().map(|dir| dir.join(".git"))    } else {        path.canonicalize()    }} fn gix_open_opts_from_settings(settings: &UserSettings) -> gix::open::Options {    let user_name = settings.user_name();    let user_email = settings.user_email();    gix::open::Options::default()        .config_overrides([            // Committer has to be configured to record reflog. Author isn't            // needed, but let's copy the same values.            format!("author.name={user_name}"),            format!("author.email={user_email}"),            format!("committer.name={user_name}"),            format!("committer.email={user_email}"),        ])        // The git_target path should point the repository, not the working directory.        .open_path_as_is(true)} /// Reads the `jj:trees` header from the commit.fn root_tree_from_header(git_commit: &CommitRef) -> Result<Option<MergedTreeId>, ()> {    for (key, value) in &git_commit.extra_headers {        if *key == JJ_TREES_COMMIT_HEADER {

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