#[cfg(test)]
#[macro_use]
mod tests_support;
#[cfg(test)]
mod tests;
use crate::utils::hg_path::HgPath;
use crate::utils::hg_path::HgPathBuf;
use crate::Revision;
use crate::NULL_REVISION;
use bytes_cast::{unaligned, BytesCast};
use im_rc::ordmap::Entry;
use im_rc::ordmap::OrdMap;
use im_rc::OrdSet;
use std::cmp::Ordering;
use std::collections::HashMap;
pub type PathCopies = HashMap<HgPathBuf, HgPathBuf>;
type PathToken = usize;
#[derive(Clone, Debug)]
struct CopySource {
/// revision at which the copy information was added
rev: Revision,
/// the copy source, (Set to None in case of deletion of the associated
/// key)
path: Option<PathToken>,
/// a set of previous `CopySource.rev` value directly or indirectly
/// overwritten by this one.
overwritten: OrdSet<Revision>,
}
impl CopySource {
/// create a new CopySource
///
/// Use this when no previous copy source existed.
fn new(rev: Revision, path: Option<PathToken>) -> Self {
Self {
rev,
path,
overwritten: OrdSet::new(),
}
}
/// create a new CopySource from merging two others
///
/// Use this when merging two InternalPathCopies requires active merging of
/// some entries.
fn new_from_merge(rev: Revision, winner: &Self, loser: &Self) -> Self {
let mut overwritten = OrdSet::new();
overwritten.extend(winner.overwritten.iter().copied());
overwritten.extend(loser.overwritten.iter().copied());
overwritten.insert(winner.rev);
overwritten.insert(loser.rev);
Self {
rev,
path: winner.path,
overwritten: overwritten,
}
}
/// Update the value of a pre-existing CopySource
///
/// Use this when recording copy information from parent → child edges
fn overwrite(&mut self, rev: Revision, path: Option<PathToken>) {
self.overwritten.insert(self.rev);
self.rev = rev;
self.path = path;
}
/// Mark pre-existing copy information as "dropped" by a file deletion
///
/// Use this when recording copy information from parent → child edges
fn mark_delete(&mut self, rev: Revision) {
self.overwritten.insert(self.rev);
self.rev = rev;
self.path = None;
}
/// Mark pre-existing copy information as "dropped" by a file deletion
///
/// Use this when recording copy information from parent → child edges
fn mark_delete_with_pair(&mut self, rev: Revision, other: &Self) {
self.overwritten.insert(self.rev);
if other.rev != rev {
self.overwritten.insert(other.rev);
}
self.overwritten.extend(other.overwritten.iter().copied());
self.rev = rev;
self.path = None;
}
fn is_overwritten_by(&self, other: &Self) -> bool {
other.overwritten.contains(&self.rev)
}
}
// For the same "dest", content generated for a given revision will always be
// the same.
impl PartialEq for CopySource {
fn eq(&self, other: &Self) -> bool {
#[cfg(debug_assertions)]
{
if self.rev == other.rev {
debug_assert!(self.path == other.path);
debug_assert!(self.overwritten == other.overwritten);
}
}
self.rev == other.rev
}
}
/// maps CopyDestination to Copy Source (+ a "timestamp" for the operation)
type InternalPathCopies = OrdMap<PathToken, CopySource>;
/// Represent active changes that affect the copy tracing.
enum Action<'a> {
/// The parent ? children edge is removing a file
///
/// (actually, this could be the edge from the other parent, but it does
/// not matters)
Removed(&'a HgPath),
/// The parent ? children edge introduce copy information between (dest,
/// source)
CopiedFromP1(&'a HgPath, &'a HgPath),
CopiedFromP2(&'a HgPath, &'a HgPath),
}
/// This express the possible "special" case we can get in a merge
///
/// See mercurial/metadata.py for details on these values.
#[derive(PartialEq)]
enum MergeCase {
/// Merged: file had history on both side that needed to be merged
Merged,
/// Salvaged: file was candidate for deletion, but survived the merge
Salvaged,
/// Normal: Not one of the two cases above
Normal,
}
const COPY_MASK: u8 = 3;
const P1_COPY: u8 = 2;
const P2_COPY: u8 = 3;
const ACTION_MASK: u8 = 28;
const REMOVED: u8 = 12;
const MERGED: u8 = 8;
const SALVAGED: u8 = 16;
#[derive(BytesCast)]
#[repr(C)]
struct ChangedFilesIndexEntry {
flags: u8,
/// Only the end position is stored. The start is at the end of the
/// previous entry.
destination_path_end_position: unaligned::U32Be,
source_index_entry_position: unaligned::U32Be,
}
fn _static_assert_size_of() {
let _ = std::mem::transmute::<ChangedFilesIndexEntry, [u8; 9]>;
}
/// Represents the files affected by a changeset.
///
/// This holds a subset of `mercurial.metadata.ChangingFiles` as we do not need
/// all the data categories tracked by it.
pub struct ChangedFiles<'a> {
index: &'a [ChangedFilesIndexEntry],
paths: &'a [u8],
}
impl<'a> ChangedFiles<'a> {
pub fn new(data: &'a [u8]) -> Self {
let (header, rest) = unaligned::U32Be::from_bytes(data).unwrap();
let nb_index_entries = header.get() as usize;
let (index, paths) =
ChangedFilesIndexEntry::slice_from_bytes(rest, nb_index_entries)
.unwrap();
Self { index, paths }
}
pub fn new_empty() -> Self {
ChangedFiles {
index: &[],
paths: &[],
}
}
/// Internal function to return the filename of the entry at a given index
fn path(&self, idx: usize) -> &HgPath {
let start = if idx == 0 {
0
} else {
self.index[idx - 1].destination_path_end_position.get() as usize
};
let end = self.index[idx].destination_path_end_position.get() as usize;
HgPath::new(&self.paths[start..end])
}
/// Return an iterator over all the `Action` in this instance.
fn iter_actions(&self) -> impl Iterator<Item = Action> {
self.index.iter().enumerate().flat_map(move |(idx, entry)| {
let path = self.path(idx);
if (entry.flags & ACTION_MASK) == REMOVED {
Some(Action::Removed(path))
} else if (entry.flags & COPY_MASK) == P1_COPY {
let source_idx =
entry.source_index_entry_position.get() as usize;
Some(Action::CopiedFromP1(path, self.path(source_idx)))
} else if (entry.flags & COPY_MASK) == P2_COPY {
let source_idx =
entry.source_index_entry_position.get() as usize;
Some(Action::CopiedFromP2(path, self.path(source_idx)))
} else {
None
}
})
}
/// return the MergeCase value associated with a filename
fn get_merge_case(&self, path: &HgPath) -> MergeCase {
if self.index.is_empty() {
return MergeCase::Normal;
}
let mut low_part = 0;
let mut high_part = self.index.len();
while low_part < high_part {
let cursor = (low_part + high_part - 1) / 2;
match path.cmp(self.path(cursor)) {
Ordering::Less => low_part = cursor + 1,
Ordering::Greater => high_part = cursor,
Ordering::Equal => {
return match self.index[cursor].flags & ACTION_MASK {
MERGED => MergeCase::Merged,
SALVAGED => MergeCase::Salvaged,
_ => MergeCase::Normal,
};
}
}
}
MergeCase::Normal
}
}
/// A small "tokenizer" responsible of turning full HgPath into lighter
/// PathToken
///
/// Dealing with small object, like integer is much faster, so HgPath input are
/// turned into integer "PathToken" and converted back in the end.
#[derive(Clone, Debug, Default)]
struct TwoWayPathMap {
token: HashMap<HgPathBuf, PathToken>,
path: Vec<HgPathBuf>,
}
impl TwoWayPathMap {
fn tokenize(&mut self, path: &HgPath) -> PathToken {
match self.token.get(path) {
Some(a) => *a,
None => {
let a = self.token.len();
let buf = path.to_owned();
self.path.push(buf.clone());
self.token.insert(buf, a);
a
}
}
}
fn untokenize(&self, token: PathToken) -> &HgPathBuf {
assert!(token < self.path.len(), "Unknown token: {}", token);
&self.path[token]
}
}
/// Same as mercurial.copies._combine_changeset_copies, but in Rust.
pub struct CombineChangesetCopies {
all_copies: HashMap<Revision, InternalPathCopies>,
path_map: TwoWayPathMap,
children_count: HashMap<Revision, usize>,
}
impl CombineChangesetCopies {
pub fn new(children_count: HashMap<Revision, usize>) -> Self {
Self {
all_copies: HashMap::new(),
path_map: TwoWayPathMap::default(),
children_count,
}
}
/// Combined the given `changes` data specific to `rev` with the data
/// previously given for its parents (and transitively, its ancestors).
pub fn add_revision(
&mut self,
rev: Revision,
p1: Revision,
p2: Revision,
changes: ChangedFiles<'_>,
) {
self.add_revision_inner(rev, p1, p2, changes.iter_actions(), |path| {
changes.get_merge_case(path)
})
}
/// Separated out from `add_revsion` so that unit tests can call this
/// without synthetizing a `ChangedFiles` in binary format.
fn add_revision_inner<'a>(
&mut self,
rev: Revision,
p1: Revision,
p2: Revision,
copy_actions: impl Iterator<Item = Action<'a>>,
get_merge_case: impl Fn(&HgPath) -> MergeCase + Copy,
) {
// Retrieve data computed in a previous iteration
let p1_copies = match p1 {
NULL_REVISION => None,
_ => get_and_clean_parent_copies(
&mut self.all_copies,
&mut self.children_count,
p1,
), // will be None if the vertex is not to be traversed
};
let p2_copies = match p2 {
NULL_REVISION => None,
_ => get_and_clean_parent_copies(
&mut self.all_copies,
&mut self.children_count,
p2,
), // will be None if the vertex is not to be traversed
};
// combine it with data for that revision
let (p1_copies, p2_copies) = chain_changes(
&mut self.path_map,
p1_copies,
p2_copies,
copy_actions,
rev,
);
let copies = match (p1_copies, p2_copies) {
(None, None) => None,
(c, None) => c,
(None, c) => c,
(Some(p1_copies), Some(p2_copies)) => Some(merge_copies_dict(
&self.path_map,
rev,
p2_copies,
p1_copies,
get_merge_case,
)),
};
if let Some(c) = copies {
self.all_copies.insert(rev, c);
}
}
/// Drop intermediate data (such as which revision a copy was from) and
/// return the final mapping.
pub fn finish(mut self, target_rev: Revision) -> PathCopies {
let tt_result = self
.all_copies
.remove(&target_rev)
.expect("target revision was not processed");
let mut result = PathCopies::default();
for (dest, tt_source) in tt_result {
if let Some(path) = tt_source.path {
let path_dest = self.path_map.untokenize(dest).to_owned();
let path_path = self.path_map.untokenize(path).to_owned();
result.insert(path_dest, path_path);
}
}
result
}
}
/// fetch previous computed information
///
/// If no other children are expected to need this information, we drop it from
/// the cache.
///
/// If parent is not part of the set we are expected to walk, return None.
fn get_and_clean_parent_copies(
all_copies: &mut HashMap<Revision, InternalPathCopies>,
children_count: &mut HashMap<Revision, usize>,
parent_rev: Revision,
) -> Option<InternalPathCopies> {
let count = children_count.get_mut(&parent_rev)?;
*count -= 1;
if *count == 0 {
match all_copies.remove(&parent_rev) {
Some(c) => Some(c),
None => Some(InternalPathCopies::default()),
}
} else {
match all_copies.get(&parent_rev) {
Some(c) => Some(c.clone()),
None => Some(InternalPathCopies::default()),
}
}
}
/// Combine ChangedFiles with some existing PathCopies information and return
/// the result
fn chain_changes<'a>(
path_map: &mut TwoWayPathMap,
base_p1_copies: Option<InternalPathCopies>,
base_p2_copies: Option<InternalPathCopies>,
copy_actions: impl Iterator<Item = Action<'a>>,
current_rev: Revision,
) -> (Option<InternalPathCopies>, Option<InternalPathCopies>) {
// Fast path the "nothing to do" case.
if let (None, None) = (&base_p1_copies, &base_p2_copies) {
return (None, None);
}
let mut p1_copies = base_p1_copies.clone();
let mut p2_copies = base_p2_copies.clone();
for action in copy_actions {
match action {
Action::CopiedFromP1(path_dest, path_source) => {
match &mut p1_copies {
None => (), // This is not a vertex we should proceed.
Some(copies) => add_one_copy(
current_rev,
path_map,
copies,
base_p1_copies.as_ref().unwrap(),
path_dest,
path_source,
),
}
}
Action::CopiedFromP2(path_dest, path_source) => {
match &mut p2_copies {
None => (), // This is not a vertex we should proceed.
Some(copies) => add_one_copy(
current_rev,
path_map,
copies,
base_p2_copies.as_ref().unwrap(),
path_dest,
path_source,
),
}
}
Action::Removed(deleted_path) => {
// We must drop copy information for removed file.
//
// We need to explicitly record them as dropped to
// propagate this information when merging two
// InternalPathCopies object.
let deleted = path_map.tokenize(deleted_path);
let p1_entry = match &mut p1_copies {
None => None,
Some(copies) => match copies.entry(deleted) {
Entry::Occupied(e) => Some(e),
Entry::Vacant(_) => None,
},
};
let p2_entry = match &mut p2_copies {
None => None,
Some(copies) => match copies.entry(deleted) {
Entry::Occupied(e) => Some(e),
Entry::Vacant(_) => None,
},
};
match (p1_entry, p2_entry) {
(None, None) => (),
(Some(mut e), None) => {
e.get_mut().mark_delete(current_rev)
}
(None, Some(mut e)) => {
e.get_mut().mark_delete(current_rev)
}
(Some(mut e1), Some(mut e2)) => {
let cs1 = e1.get_mut();
let cs2 = e2.get();
if cs1 == cs2 {
cs1.mark_delete(current_rev);
} else {
cs1.mark_delete_with_pair(current_rev, &cs2);
}
e2.insert(cs1.clone());
}
}
}
}
}
(p1_copies, p2_copies)
}
// insert one new copy information in an InternalPathCopies
//
// This deal with chaining and overwrite.
fn add_one_copy(
current_rev: Revision,
path_map: &mut TwoWayPathMap,
copies: &mut InternalPathCopies,
base_copies: &InternalPathCopies,
path_dest: &HgPath,
path_source: &HgPath,
) {
let dest = path_map.tokenize(path_dest);
let source = path_map.tokenize(path_source);
let entry;
if let Some(v) = base_copies.get(&source) {
entry = match &v.path {
Some(path) => Some((*(path)).to_owned()),
None => Some(source.to_owned()),
}
} else {
entry = Some(source.to_owned());
}
// Each new entry is introduced by the children, we
// record this information as we will need it to take
// the right decision when merging conflicting copy
// information. See merge_copies_dict for details.
match copies.entry(dest) {
Entry::Vacant(slot) => {
let ttpc = CopySource::new(current_rev, entry);
slot.insert(ttpc);
}
Entry::Occupied(mut slot) => {
let ttpc = slot.get_mut();
ttpc.overwrite(current_rev, entry);
}
}
}
/// merge two copies-mapping together, minor and major
///
/// In case of conflict, value from "major" will be picked, unless in some
/// cases. See inline documentation for details.
fn merge_copies_dict(
path_map: &TwoWayPathMap,
current_merge: Revision,
minor: InternalPathCopies,
major: InternalPathCopies,
get_merge_case: impl Fn(&HgPath) -> MergeCase + Copy,
) -> InternalPathCopies {
use crate::utils::{ordmap_union_with_merge, MergeResult};
ordmap_union_with_merge(minor, major, |&dest, src_minor, src_major| {
let (pick, overwrite) = compare_value(
current_merge,
|| get_merge_case(path_map.untokenize(dest)),
src_minor,
src_major,
);
if overwrite {
let (winner, loser) = match pick {
MergePick::Major | MergePick::Any => (src_major, src_minor),
MergePick::Minor => (src_minor, src_major),
};
MergeResult::UseNewValue(CopySource::new_from_merge(
current_merge,
winner,
loser,
))
} else {
match pick {
MergePick::Any | MergePick::Major => {
MergeResult::UseRightValue
}
MergePick::Minor => MergeResult::UseLeftValue,
}
}
})
}
/// represent the side that should prevail when merging two
/// InternalPathCopies
#[derive(Debug, PartialEq)]
enum MergePick {
/// The "major" (p1) side prevails
Major,
/// The "minor" (p2) side prevails
Minor,
/// Any side could be used (because they are the same)
Any,
}
/// decide which side prevails in case of conflicting values
#[allow(clippy::if_same_then_else)]
fn compare_value(
current_merge: Revision,
merge_case_for_dest: impl Fn() -> MergeCase,
src_minor: &CopySource,
src_major: &CopySource,
) -> (MergePick, bool) {
if src_major == src_minor {
(MergePick::Any, false)
} else if src_major.rev == current_merge {
// minor is different according to per minor == major check earlier
debug_assert!(src_minor.rev != current_merge);
// The last value comes the current merge, this value -will- win
// eventually.
(MergePick::Major, true)
} else if src_minor.rev == current_merge {
// The last value comes the current merge, this value -will- win
// eventually.
(MergePick::Minor, true)
} else if src_major.path == src_minor.path {
debug_assert!(src_major.rev != src_major.rev);
// we have the same value, but from other source;
if src_major.is_overwritten_by(src_minor) {
(MergePick::Minor, false)
} else if src_minor.is_overwritten_by(src_major) {
(MergePick::Major, false)
} else {
(MergePick::Any, true)
}
} else {
debug_assert!(src_major.rev != src_major.rev);
let action = merge_case_for_dest();
if src_minor.path.is_some()
&& src_major.path.is_none()
&& action == MergeCase::Salvaged
{
// If the file is "deleted" in the major side but was
// salvaged by the merge, we keep the minor side alive
(MergePick::Minor, true)
} else if src_major.path.is_some()
&& src_minor.path.is_none()
&& action == MergeCase::Salvaged
{
// If the file is "deleted" in the minor side but was
// salvaged by the merge, unconditionnaly preserve the
// major side.
(MergePick::Major, true)
} else if src_minor.is_overwritten_by(src_major) {
// The information from the minor version are strictly older than
// the major version
if action == MergeCase::Merged {
// If the file was actively merged, its means some non-copy
// activity happened on the other branch. It
// mean the older copy information are still relevant.
//
// The major side wins such conflict.
(MergePick::Major, true)
} else {
// No activity on the minor branch, pick the newer one.
(MergePick::Major, false)
}
} else if src_major.is_overwritten_by(src_minor) {
if action == MergeCase::Merged {
// If the file was actively merged, its means some non-copy
// activity happened on the other branch. It
// mean the older copy information are still relevant.
//
// The major side wins such conflict.
(MergePick::Major, true)
} else {
// No activity on the minor branch, pick the newer one.
(MergePick::Minor, false)
}
} else if src_minor.path.is_none() {
// the minor side has no relevant information, pick the alive one
(MergePick::Major, true)
} else if src_major.path.is_none() {
// the major side has no relevant information, pick the alive one
(MergePick::Minor, true)
} else {
// by default the major side wins
(MergePick::Major, true)
}
}
}