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jj/lib/src/commit.rs
Martin von Zweigbergk 0108673087 backend: let each backend handle root commit on write
This moves the logic for handling the root commit when writing commits
from `CommitBuilder` into the individual backends. It always bothered
me a bit that the `commit::Commit` wrapper had a different idea of the
number of parents than the wrapped `backend::Commit` had.

With this change, the `LocalBackend` will now write the root commit in
the list of parents if it's there in the argument to
`write_commit()`. Note that root commit itself won't be written. The
main argument for not writing it is that we can then keep the fake
all-zeros hash for it. One argument for writing it, if we were to do
so, is that it would make the set of written objects consistent, so
any future processing of them (such as GC) doesn't have to know to
ignore the root commit in the list of parents.

We still treat the two backends the same, so the user won't be allowed
to create merges including the root commit even when using the
`LocalBackend`.
2022-09-20 21:20:57 -07:00

141 lines
3.4 KiB
Rust

// 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::cmp::Ordering;
use std::fmt::{Debug, Error, Formatter};
use std::hash::{Hash, Hasher};
use std::sync::Arc;
use crate::backend;
use crate::backend::{ChangeId, CommitId, Signature, TreeId};
use crate::repo_path::RepoPath;
use crate::store::Store;
use crate::tree::Tree;
#[derive(Clone)]
pub struct Commit {
store: Arc<Store>,
id: CommitId,
data: Arc<backend::Commit>,
}
impl Debug for Commit {
fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
f.debug_struct("Commit").field("id", &self.id).finish()
}
}
impl PartialEq for Commit {
fn eq(&self, other: &Self) -> bool {
self.id == other.id
}
}
impl Eq for Commit {}
impl Ord for Commit {
fn cmp(&self, other: &Self) -> Ordering {
self.id.cmp(&other.id)
}
}
impl PartialOrd for Commit {
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
Some(self.id.cmp(&other.id))
}
}
impl Hash for Commit {
fn hash<H: Hasher>(&self, state: &mut H) {
self.id.hash(state)
}
}
impl Commit {
pub fn new(store: Arc<Store>, id: CommitId, data: Arc<backend::Commit>) -> Self {
Commit { store, id, data }
}
pub fn store(&self) -> &Arc<Store> {
&self.store
}
pub fn id(&self) -> &CommitId {
&self.id
}
pub fn parent_ids(&self) -> Vec<CommitId> {
self.data.parents.clone()
}
pub fn parents(&self) -> Vec<Commit> {
let mut parents = Vec::new();
for parent in &self.data.parents {
parents.push(self.store.get_commit(parent).unwrap());
}
parents
}
pub fn predecessor_ids(&self) -> Vec<CommitId> {
self.data.predecessors.clone()
}
pub fn predecessors(&self) -> Vec<Commit> {
let mut predecessors = Vec::new();
for predecessor in &self.data.predecessors {
predecessors.push(self.store.get_commit(predecessor).unwrap());
}
predecessors
}
pub fn tree(&self) -> Tree {
self.store
.get_tree(&RepoPath::root(), &self.data.root_tree)
.unwrap()
}
pub fn tree_id(&self) -> &TreeId {
&self.data.root_tree
}
pub fn change_id(&self) -> &ChangeId {
&self.data.change_id
}
pub fn store_commit(&self) -> &backend::Commit {
&self.data
}
pub fn is_open(&self) -> bool {
self.data.is_open
}
pub fn is_empty(&self) -> bool {
let parents = self.parents();
// TODO: Perhaps the root commit should also be considered empty.
parents.len() == 1 && parents[0].tree_id() == self.tree_id()
}
pub fn description(&self) -> &str {
&self.data.description
}
pub fn author(&self) -> &Signature {
&self.data.author
}
pub fn committer(&self) -> &Signature {
&self.data.committer
}
}