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conflicts.rs
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conflicts.rs
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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::io::{Read, Write};
use std::iter::zip;
use futures::{try_join, Stream, StreamExt, TryStreamExt};
use itertools::Itertools;
use regex::bytes::{Regex, RegexBuilder};
use crate::backend::{BackendError, BackendResult, CommitId, FileId, SymlinkId, TreeId, TreeValue};
use crate::diff::{Diff, DiffHunk};
use crate::files;
use crate::files::{ContentHunk, MergeResult};
use crate::merge::{Merge, MergeBuilder, MergedTreeValue};
use crate::merged_tree::{TreeDiffEntry, TreeDiffStream};
use crate::repo_path::{RepoPath, RepoPathBuf};
use crate::store::Store;
const CONFLICT_START_LINE: &[u8] = b"<<<<<<<";
const CONFLICT_END_LINE: &[u8] = b">>>>>>>";
const CONFLICT_DIFF_LINE: &[u8] = b"%%%%%%%";
const CONFLICT_MINUS_LINE: &[u8] = b"-------";
const CONFLICT_PLUS_LINE: &[u8] = b" ";
const CONFLICT_START_LINE_CHAR: u8 = CONFLICT_START_LINE[0];
const CONFLICT_END_LINE_CHAR: u8 = CONFLICT_END_LINE[0];
const CONFLICT_DIFF_LINE_CHAR: u8 = CONFLICT_DIFF_LINE[0];
const CONFLICT_MINUS_LINE_CHAR: u8 = CONFLICT_MINUS_LINE[0];
const CONFLICT_PLUS_LINE_CHAR: u8 = CONFLICT_PLUS_LINE[0];
/// A conflict marker is one of the separators, optionally followed by a space
/// and some text.
// TODO: All the `{7}` could be replaced with `{7,}` to allow longer
// separators. This could be useful to make it possible to allow conflict
// markers inside the text of the conflicts.
static CONFLICT_MARKER_REGEX: once_cell::sync::Lazy<Regex> = once_cell::sync::Lazy::new(|| {
RegexBuilder::new(r"^(<{7}|>{7}|%{7}|\-{7}|\ {7})( .*)?$")
.multi_line(true)
.build()
.unwrap()
});
fn write_diff_hunks(hunks: &[DiffHunk], file: &mut dyn Write) -> std::io::Result<()> {
for hunk in hunks {
match hunk {
DiffHunk::Matching(content) => {
for line in content.split_inclusive(|b| *b == b'\n') {
file.write_all(b" ")?;
file.write_all(line)?;
}
}
DiffHunk::Different(content) => {
for line in content[0].split_inclusive(|b| *b == b'\n') {
file.write_all(b"-")?;
file.write_all(line)?;
}
for line in content[1].split_inclusive(|b| *b == b'\n') {
file.write_all(b" ")?;
file.write_all(line)?;
}
}
}
}
Ok(())
}
async fn get_file_contents(
store: &Store,
path: &RepoPath,
term: &Option<FileId>,
) -> BackendResult<ContentHunk> {
match term {
Some(id) => {
let mut content = vec![];
store
.read_file_async(path, id)
.await?
.read_to_end(&mut content)
.map_err(|err| BackendError::ReadFile {
path: path.to_owned(),
id: id.clone(),
source: err.into(),
})?;
Ok(ContentHunk(content))
}
// If the conflict had removed the file on one side, we pretend that the file
// was empty there.
None => Ok(ContentHunk(vec![])),
}
}
pub async fn extract_as_single_hunk(
merge: &Merge<Option<FileId>>,
store: &Store,
path: &RepoPath,
) -> BackendResult<Merge<ContentHunk>> {
let builder: MergeBuilder<ContentHunk> = futures::stream::iter(merge.iter())
.then(|term| get_file_contents(store, path, term))
.try_collect()
.await?;
Ok(builder.build())
}
/// A type similar to `MergedTreeValue` but with associated data to include in
/// e.g. the working copy or in a diff.
pub enum MaterializedTreeValue {
Absent,
AccessDenied(Box<dyn std::error::Error Send Sync>),
File {
id: FileId,
executable: bool,
reader: Box<dyn Read>,
},
Symlink {
id: SymlinkId,
target: String,
},
Conflict {
id: MergedTreeValue,
contents: Vec<u8>,
executable: bool,
},
GitSubmodule(CommitId),
Tree(TreeId),
}
impl MaterializedTreeValue {
pub fn is_absent(&self) -> bool {
matches!(self, MaterializedTreeValue::Absent)
}
pub fn is_present(&self) -> bool {
!self.is_absent()
}
}
/// Reads the data associated with a `MergedTreeValue` so it can be written to
/// e.g. the working copy or diff.
pub async fn materialize_tree_value(
store: &Store,
path: &RepoPath,
value: MergedTreeValue,
) -> BackendResult<MaterializedTreeValue> {
match materialize_tree_value_no_access_denied(store, path, value).await {
Err(BackendError::ReadAccessDenied { source, .. }) => {
Ok(MaterializedTreeValue::AccessDenied(source))
}
result => result,
}
}
async fn materialize_tree_value_no_access_denied(
store: &Store,
path: &RepoPath,
value: MergedTreeValue,
) -> BackendResult<MaterializedTreeValue> {
match value.into_resolved() {
Ok(None) => Ok(MaterializedTreeValue::Absent),
Ok(Some(TreeValue::File { id, executable })) => {
let reader = store.read_file_async(path, &id).await?;
Ok(MaterializedTreeValue::File {
id,
executable,
reader,
})
}
Ok(Some(TreeValue::Symlink(id))) => {
let target = store.read_symlink_async(path, &id).await?;
Ok(MaterializedTreeValue::Symlink { id, target })
}
Ok(Some(TreeValue::GitSubmodule(id))) => Ok(MaterializedTreeValue::GitSubmodule(id)),
Ok(Some(TreeValue::Tree(id))) => Ok(MaterializedTreeValue::Tree(id)),
Ok(Some(TreeValue::Conflict(_))) => {
panic!("cannot materialize legacy conflict object at path {path:?}");
}
Err(conflict) => {
let mut contents = vec![];
if let Some(file_merge) = conflict.to_file_merge() {
let file_merge = file_merge.simplify();
let content = extract_as_single_hunk(&file_merge, store, path).await?;
materialize_merge_result(&content, &mut contents)
.expect("Failed to materialize conflict to in-memory buffer");
} else {
// Unless all terms are regular files, we can't do much better than to try to
// describe the merge.
conflict
.describe(&mut contents)
.expect("Failed to materialize conflict to in-memory buffer");
}
let executable = if let Some(merge) = conflict.to_executable_merge() {
merge.resolve_trivial().copied().unwrap_or_default()
} else {
false
};
Ok(MaterializedTreeValue::Conflict {
id: conflict,
contents,
executable,
})
}
}
}
pub fn materialize_merge_result(
single_hunk: &Merge<ContentHunk>,
output: &mut dyn Write,
) -> std::io::Result<()> {
let merge_result = files::merge(single_hunk);
match merge_result {
MergeResult::Resolved(content) => {
output.write_all(&content.0)?;
}
MergeResult::Conflict(hunks) => {
let num_conflicts = hunks
.iter()
.filter(|hunk| hunk.as_resolved().is_none())
.count();
let mut conflict_index = 0;
for hunk in hunks {
if let Some(content) = hunk.as_resolved() {
output.write_all(&content.0)?;
} else {
conflict_index = 1;
output.write_all(CONFLICT_START_LINE)?;
output.write_all(
format!(" Conflict {conflict_index} of {num_conflicts}\n").as_bytes(),
)?;
let mut add_index = 0;
for (base_index, left) in hunk.removes().enumerate() {
// The vast majority of conflicts one actually tries to
// resolve manually have 1 base.
let base_str = if hunk.removes().len() == 1 {
"base".to_string()
} else {
format!("base #{}", base_index 1)
};
let right1 = if let Some(right1) = hunk.get_add(add_index) {
right1
} else {
// If we have no more positive terms, emit the remaining negative
// terms as snapshots.
output.write_all(CONFLICT_MINUS_LINE)?;
output.write_all(format!(" Contents of {base_str}\n").as_bytes())?;
output.write_all(&left.0)?;
continue;
};
let diff1 = Diff::by_line([&left.0, &right1.0]).hunks().collect_vec();
// Check if the diff against the next positive term is better. Since
// we want to preserve the order of the terms, we don't match against
// any later positive terms.
if let Some(right2) = hunk.get_add(add_index 1) {
let diff2 = Diff::by_line([&left.0, &right2.0]).hunks().collect_vec();
if diff_size(&diff2) < diff_size(&diff1) {
// If the next positive term is a better match, emit
// the current positive term as a snapshot and the next
// positive term as a diff.
output.write_all(CONFLICT_PLUS_LINE)?;
output.write_all(
format!(" Contents of side #{}\n", add_index 1).as_bytes(),
)?;
output.write_all(&right1.0)?;
output.write_all(CONFLICT_DIFF_LINE)?;
output.write_all(
format!(
" Changes from {base_str} to side #{}\n",
add_index 2
)
.as_bytes(),
)?;
write_diff_hunks(&diff2, output)?;
add_index = 2;
continue;
}
}
output.write_all(CONFLICT_DIFF_LINE)?;
output.write_all(
format!(" Changes from {base_str} to side #{}\n", add_index 1)
.as_bytes(),
)?;
write_diff_hunks(&diff1, output)?;
add_index = 1;
}
// Emit the remaining positive terms as snapshots.
for (add_index, slice) in hunk.adds().enumerate().skip(add_index) {
output.write_all(CONFLICT_PLUS_LINE)?;
output.write_all(
format!(" Contents of side #{}\n", add_index 1).as_bytes(),
)?;
output.write_all(&slice.0)?;
}
output.write_all(CONFLICT_END_LINE)?;
output.write_all(
format!(" Conflict {conflict_index} of {num_conflicts} ends\n").as_bytes(),
)?;
}
}
}
}
Ok(())
}
fn diff_size(hunks: &[DiffHunk]) -> usize {
hunks
.iter()
.map(|hunk| match hunk {
DiffHunk::Matching(_) => 0,
DiffHunk::Different(slices) => slices.iter().map(|slice| slice.len()).sum(),
})
.sum()
}
pub struct MaterializedTreeDiffEntry {
pub source: RepoPathBuf,
pub target: RepoPathBuf,
pub value: BackendResult<(MaterializedTreeValue, MaterializedTreeValue)>,
}
pub fn materialized_diff_stream<'a>(
store: &'a Store,
tree_diff: TreeDiffStream<'a>,
) -> impl Stream<Item = MaterializedTreeDiffEntry> 'a {
tree_diff
.map(
|TreeDiffEntry {
source,
target,
value,
}| async {
match value {
Err(err) => MaterializedTreeDiffEntry {
source,
target,
value: Err(err),
},
Ok((before, after)) => {
let before_future = materialize_tree_value(store, &source, before);
let after_future = materialize_tree_value(store, &target, after);
let values = try_join!(before_future, after_future);
MaterializedTreeDiffEntry {
source,
target,
value: values,
}
}
}
},
)
.buffered((store.concurrency() / 2).max(1))
}
/// Parses conflict markers from a slice. Returns None if there were no valid
/// conflict markers. The caller has to provide the expected number of merge
/// sides (adds). Conflict markers that are otherwise valid will be considered
/// invalid if they don't have the expected arity.
// TODO: "parse" is not usually the opposite of "materialize", so maybe we
// should rename them to "serialize" and "deserialize"?
pub fn parse_conflict(input: &[u8], num_sides: usize) -> Option<Vec<Merge<ContentHunk>>> {
if input.is_empty() {
return None;
}
let mut hunks = vec![];
let mut pos = 0;
let mut resolved_start = 0;
let mut conflict_start = None;
let mut conflict_start_len = 0;
for line in input.split_inclusive(|b| *b == b'\n') {
if CONFLICT_MARKER_REGEX.is_match_at(line, 0) {
if line[0] == CONFLICT_START_LINE_CHAR {
conflict_start = Some(pos);
conflict_start_len = line.len();
} else if conflict_start.is_some() && line[0] == CONFLICT_END_LINE_CHAR {
let conflict_body = &input[conflict_start.unwrap() conflict_start_len..pos];
let hunk = parse_conflict_hunk(conflict_body);
if hunk.num_sides() == num_sides {
let resolved_slice = &input[resolved_start..conflict_start.unwrap()];
if !resolved_slice.is_empty() {
hunks.push(Merge::resolved(ContentHunk(resolved_slice.to_vec())));
}
hunks.push(hunk);
resolved_start = pos line.len();
}
conflict_start = None;
}
}
pos = line.len();
}
if hunks.is_empty() {
None
} else {
if resolved_start < input.len() {
hunks.push(Merge::resolved(ContentHunk(
input[resolved_start..].to_vec(),
)));
}
Some(hunks)
}
}
fn parse_conflict_hunk(input: &[u8]) -> Merge<ContentHunk> {
enum State {
Diff,
Minus,
Plus,
Unknown,
}
let mut state = State::Unknown;
let mut removes = vec![];
let mut adds = vec![];
for line in input.split_inclusive(|b| *b == b'\n') {
if CONFLICT_MARKER_REGEX.is_match_at(line, 0) {
match line[0] {
CONFLICT_DIFF_LINE_CHAR => {
state = State::Diff;
removes.push(ContentHunk(vec![]));
adds.push(ContentHunk(vec![]));
continue;
}
CONFLICT_MINUS_LINE_CHAR => {
state = State::Minus;
removes.push(ContentHunk(vec![]));
continue;
}
CONFLICT_PLUS_LINE_CHAR => {
state = State::Plus;
adds.push(ContentHunk(vec![]));
continue;
}
_ => {}
}
};
match state {
State::Diff => {
if let Some(rest) = line.strip_prefix(b"-") {
removes.last_mut().unwrap().0.extend_from_slice(rest);
} else if let Some(rest) = line.strip_prefix(b" ") {
adds.last_mut().unwrap().0.extend_from_slice(rest);
} else if let Some(rest) = line.strip_prefix(b" ") {
removes.last_mut().unwrap().0.extend_from_slice(rest);
adds.last_mut().unwrap().0.extend_from_slice(rest);
} else {
// Doesn't look like a conflict
return Merge::resolved(ContentHunk(vec![]));
}
}
State::Minus => {
removes.last_mut().unwrap().0.extend_from_slice(line);
}
State::Plus => {
adds.last_mut().unwrap().0.extend_from_slice(line);
}
State::Unknown => {
// Doesn't look like a conflict
return Merge::resolved(ContentHunk(vec![]));
}
}
}
Merge::from_removes_adds(removes, adds)
}
/// Parses conflict markers in `content` and returns an updated version of
/// `file_ids` with the new contents. If no (valid) conflict markers remain, a
/// single resolves `FileId` will be returned.
pub async fn update_from_content(
file_ids: &Merge<Option<FileId>>,
store: &Store,
path: &RepoPath,
content: &[u8],
) -> BackendResult<Merge<Option<FileId>>> {
let simplified_file_ids = file_ids.clone().simplify();
let simplified_file_ids = &simplified_file_ids;
// First check if the new content is unchanged compared to the old content. If
// it is, we don't need parse the content or write any new objects to the
// store. This is also a way of making sure that unchanged tree/file
// conflicts (for example) are not converted to regular files in the working
// copy.
let mut old_content = Vec::with_capacity(content.len());
let merge_hunk = extract_as_single_hunk(simplified_file_ids, store, path).await?;
materialize_merge_result(&merge_hunk, &mut old_content).unwrap();
if content == old_content {
return Ok(file_ids.clone());
}
// Parse conflicts from the new content using the arity of the simplified
// conflicts initially. If unsuccessful, attempt to parse conflicts from with
// the arity of the unsimplified conflicts since such a conflict may be
// present in the working copy if written by an earlier version of jj.
let (used_file_ids, hunks) = 'hunks: {
if let Some(hunks) = parse_conflict(content, simplified_file_ids.num_sides()) {
break 'hunks (simplified_file_ids, hunks);
};
if simplified_file_ids.num_sides() != file_ids.num_sides() {
if let Some(hunks) = parse_conflict(content, file_ids.num_sides()) {
break 'hunks (file_ids, hunks);
};
};
// Either there are no markers or they don't have the expected arity
let file_id = store.write_file(path, &mut &content[..])?;
return Ok(Merge::normal(file_id));
};
let mut contents = used_file_ids.map(|_| vec![]);
for hunk in hunks {
if let Some(slice) = hunk.as_resolved() {
for content in contents.iter_mut() {
content.extend_from_slice(&slice.0);
}
} else {
for (content, slice) in zip(contents.iter_mut(), hunk.into_iter()) {
content.extend(slice.0);
}
}
}
// If the user edited the empty placeholder for an absent side, we consider the
// conflict resolved.
if zip(contents.iter(), used_file_ids.iter())
.any(|(content, file_id)| file_id.is_none() && !content.is_empty())
{
let file_id = store.write_file(path, &mut &content[..])?;
return Ok(Merge::normal(file_id));
}
// Now write the new files contents we found by parsing the file with conflict
// markers.
let new_file_ids: Vec<Option<FileId>> = zip(contents.iter(), used_file_ids.iter())
.map(|(content, file_id)| -> BackendResult<Option<FileId>> {
match file_id {
Some(_) => {
let file_id = store.write_file(path, &mut content.as_slice())?;
Ok(Some(file_id))
}
None => {
// The missing side of a conflict is still represented by
// the empty string we materialized it as
Ok(None)
}
}
})
.try_collect()?;
// If the conflict was simplified, expand the conflict to the original
// number of sides.
let new_file_ids = if new_file_ids.len() != file_ids.iter().len() {
file_ids
.clone()
.update_from_simplified(Merge::from_vec(new_file_ids))
} else {
Merge::from_vec(new_file_ids)
};
Ok(new_file_ids)
}