// Copyright 2023 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::cmp::max;use std::collections::BTreeMap;use std::io;use std::io::Write;use std::ops::Bound;use std::path::Path;use std::sync::Arc; use blake2::Blake2b512;use digest::Digest;use itertools::Itertools;use smallvec::SmallVec;use tempfile::NamedTempFile; use super::composite::{AsCompositeIndex, ChangeIdIndexImpl, CompositeIndex, IndexSegment};use super::entry::{IndexPosition, LocalPosition, SmallIndexPositionsVec};use super::readonly::{DefaultReadonlyIndex, ReadonlyIndexSegment};use crate::backend::{ChangeId, CommitId};use crate::commit::Commit;use crate::file_util::persist_content_addressed_temp_file;use crate::index::{AllHeadsForGcUnsupported, ChangeIdIndex, Index, MutableIndex, ReadonlyIndex};use crate::object_id::{HexPrefix, ObjectId, PrefixResolution};use crate::revset::{ResolvedExpression, Revset, RevsetEvaluationError};use crate::store::Store; #[derive(Debug)]struct MutableGraphEntry {    commit_id: CommitId,    change_id: ChangeId,    generation_number: u32,    parent_positions: SmallIndexPositionsVec,} pub(super) struct MutableIndexSegment {    parent_file: Option<Arc<ReadonlyIndexSegment>>,    num_parent_commits: u32,    commit_id_length: usize,    change_id_length: usize,    graph: Vec<MutableGraphEntry>,    commit_lookup: BTreeMap<CommitId, IndexPosition>,} impl MutableIndexSegment {    pub(super) fn full(commit_id_length: usize, change_id_length: usize) -> Self {        Self {            parent_file: None,            num_parent_commits: 0,            commit_id_length,            change_id_length,            graph: vec![],            commit_lookup: BTreeMap::new(),        }    }     pub(super) fn incremental(parent_file: Arc<ReadonlyIndexSegment>) -> Self {        let num_parent_commits = parent_file.as_composite().num_commits();        let commit_id_length = parent_file.commit_id_length();        let change_id_length = parent_file.change_id_length();        Self {            parent_file: Some(parent_file),            num_parent_commits,            commit_id_length,            change_id_length,            graph: vec![],            commit_lookup: BTreeMap::new(),        }    }     pub(super) fn as_composite(&self) -> CompositeIndex {        CompositeIndex::new(self)    }     pub(super) fn add_commit(&mut self, commit: &Commit) {        self.add_commit_data(            commit.id().clone(),            commit.change_id().clone(),            commit.parent_ids(),        );    }     pub(super) fn add_commit_data(        &mut self,        commit_id: CommitId,        change_id: ChangeId,        parent_ids: &[CommitId],    ) {        if self.as_composite().has_id(&commit_id) {            return;        }        let mut entry = MutableGraphEntry {            commit_id,            change_id,            generation_number: 0,            parent_positions: SmallVec::new(),        };        for parent_id in parent_ids {            let parent_entry = self                .as_composite()                .entry_by_id(parent_id)                .expect("parent commit is not indexed");            entry.generation_number = max(                entry.generation_number,                parent_entry.generation_number() + 1,            );            entry.parent_positions.push(parent_entry.position());        }        self.commit_lookup.insert(            entry.commit_id.clone(),            IndexPosition(u32::try_from(self.graph.len()).unwrap() + self.num_parent_commits),        );        self.graph.push(entry);    }     pub(super) fn add_commits_from(&mut self, other_segment: &dyn IndexSegment) {        let other = CompositeIndex::new(other_segment);        for pos in other_segment.num_parent_commits()..other.num_commits() {            let entry = other.entry_by_pos(IndexPosition(pos));            let parent_ids = entry.parents().map(|entry| entry.commit_id()).collect_vec();            self.add_commit_data(entry.commit_id(), entry.change_id(), &parent_ids);        }    }     pub(super) fn merge_in(&mut self, other: Arc<ReadonlyIndexSegment>) {        let mut maybe_own_ancestor = self.parent_file.clone();        let mut maybe_other_ancestor = Some(other);        let mut files_to_add = vec![];        loop {            if maybe_other_ancestor.is_none() {                break;            }            let other_ancestor = maybe_other_ancestor.as_ref().unwrap();            if maybe_own_ancestor.is_none() {                files_to_add.push(other_ancestor.clone());                maybe_other_ancestor = other_ancestor.parent_file().cloned();                continue;            }            let own_ancestor = maybe_own_ancestor.as_ref().unwrap();            if own_ancestor.name() == other_ancestor.name() {                break;            }            if own_ancestor.as_composite().num_commits()                < other_ancestor.as_composite().num_commits()            {                files_to_add.push(other_ancestor.clone());                maybe_other_ancestor = other_ancestor.parent_file().cloned();            } else {                maybe_own_ancestor = own_ancestor.parent_file().cloned();            }        }         for file in files_to_add.iter().rev() {            self.add_commits_from(file.as_ref());        }    }     fn serialize_parent_filename(&self, buf: &mut Vec<u8>) {        if let Some(parent_file) = &self.parent_file {            buf.extend(                u32::try_from(parent_file.name().len())                    .unwrap()                    .to_le_bytes(),            );            buf.extend_from_slice(parent_file.name().as_bytes());        } else {            buf.extend(0_u32.to_le_bytes());        }    }     fn serialize_local_entries(&self, buf: &mut Vec<u8>) {        assert_eq!(self.graph.len(), self.commit_lookup.len());         let num_commits = u32::try_from(self.graph.len()).unwrap();        buf.extend(num_commits.to_le_bytes());        // We'll write the actual value later        let parent_overflow_offset = buf.len();        buf.extend(0_u32.to_le_bytes());         let mut parent_overflow = vec![];        for entry in &self.graph {            let flags = 0_u32;            buf.extend(flags.to_le_bytes());             buf.extend(entry.generation_number.to_le_bytes());             buf.extend(                u32::try_from(entry.parent_positions.len())                    .unwrap()                    .to_le_bytes(),            );            let mut parent1_pos = IndexPosition(0);            let parent_overflow_pos = u32::try_from(parent_overflow.len()).unwrap();            for (i, parent_pos) in entry.parent_positions.iter().enumerate() {                if i == 0 {                    parent1_pos = *parent_pos;                } else {                    parent_overflow.push(*parent_pos);                }            }            buf.extend(parent1_pos.0.to_le_bytes());            buf.extend(parent_overflow_pos.to_le_bytes());             assert_eq!(entry.change_id.as_bytes().len(), self.change_id_length);            buf.extend_from_slice(entry.change_id.as_bytes());             assert_eq!(entry.commit_id.as_bytes().len(), self.commit_id_length);            buf.extend_from_slice(entry.commit_id.as_bytes());        }         for (commit_id, pos) in &self.commit_lookup {            buf.extend_from_slice(commit_id.as_bytes());            buf.extend(pos.0.to_le_bytes());        }         buf[parent_overflow_offset..][..4]            .copy_from_slice(&u32::try_from(parent_overflow.len()).unwrap().to_le_bytes());        for parent_pos in parent_overflow {            buf.extend(parent_pos.0.to_le_bytes());        }    }     /// If the MutableIndex has more than half the commits of its parent    /// ReadonlyIndex, return MutableIndex with the commits from both. This    /// is done recursively, so the stack of index files has O(log n) files.    fn maybe_squash_with_ancestors(self) -> MutableIndexSegment {        let mut num_new_commits = self.num_local_commits();        let mut files_to_squash = vec![];        let mut base_parent_file = None;        for parent_file in self.as_composite().ancestor_files_without_local() {            // TODO: We should probably also squash if the parent file has less than N            // commits, regardless of how many (few) are in `self`.            if 2 * num_new_commits < parent_file.num_local_commits() {                base_parent_file = Some(parent_file.clone());                break;            }            num_new_commits += parent_file.num_local_commits();            files_to_squash.push(parent_file.clone());        }         if files_to_squash.is_empty() {            return self;        }         let mut squashed = if let Some(parent_file) = base_parent_file {            MutableIndexSegment::incremental(parent_file)        } else {            MutableIndexSegment::full(self.commit_id_length, self.change_id_length)        };        for parent_file in files_to_squash.iter().rev() {            squashed.add_commits_from(parent_file.as_ref());        }        squashed.add_commits_from(&self);        squashed    }     pub(super) fn save_in(self, dir: &Path) -> io::Result<Arc<ReadonlyIndexSegment>> {        if self.num_local_commits() == 0 && self.parent_file.is_some() {            return Ok(self.parent_file.unwrap());        }         let mut buf = Vec::new();        self.serialize_parent_filename(&mut buf);        let local_entries_offset = buf.len();        self.serialize_local_entries(&mut buf);        let mut hasher = Blake2b512::new();        hasher.update(&buf);        let index_file_id_hex = hex::encode(hasher.finalize());        let index_file_path = dir.join(&index_file_id_hex);         let mut temp_file = NamedTempFile::new_in(dir)?;        let file = temp_file.as_file_mut();        file.write_all(&buf)?;        persist_content_addressed_temp_file(temp_file, index_file_path)?;         Ok(ReadonlyIndexSegment::load_with_parent_file(            &mut &buf[local_entries_offset..],            index_file_id_hex,            self.parent_file,            self.commit_id_length,            self.change_id_length,        )        .expect("in-memory index data should be valid and readable"))    }} impl IndexSegment for MutableIndexSegment {    fn num_parent_commits(&self) -> u32 {        self.num_parent_commits    }     fn num_local_commits(&self) -> u32 {        self.graph.len().try_into().unwrap()    }     fn parent_file(&self) -> Option<&Arc<ReadonlyIndexSegment>> {        self.parent_file.as_ref()    }     fn name(&self) -> Option<String> {        None    }     fn commit_id_to_pos(&self, commit_id: &CommitId) -> Option<IndexPosition> {        self.commit_lookup.get(commit_id).cloned()    }     fn resolve_neighbor_commit_ids(        &self,        commit_id: &CommitId,    ) -> (Option<CommitId>, Option<CommitId>) {        let prev_id = self            .commit_lookup            .range((Bound::Unbounded, Bound::Excluded(commit_id)))            .next_back()            .map(|(id, _)| id.clone());        let next_id = self            .commit_lookup            .range((Bound::Excluded(commit_id), Bound::Unbounded))            .next()            .map(|(id, _)| id.clone());        (prev_id, next_id)    }     fn resolve_commit_id_prefix(&self, prefix: &HexPrefix) -> PrefixResolution<CommitId> {        let min_bytes_prefix = CommitId::from_bytes(prefix.min_prefix_bytes());        let mut matches = self            .commit_lookup            .range((Bound::Included(&min_bytes_prefix), Bound::Unbounded))            .map(|(id, _pos)| id)            .take_while(|&id| prefix.matches(id))            .fuse();        match (matches.next(), matches.next()) {            (Some(id), None) => PrefixResolution::SingleMatch(id.clone()),            (Some(_), Some(_)) => PrefixResolution::AmbiguousMatch,            (None, _) => PrefixResolution::NoMatch,        }    }     fn generation_number(&self, local_pos: LocalPosition) -> u32 {        self.graph[local_pos.0 as usize].generation_number    }     fn commit_id(&self, local_pos: LocalPosition) -> CommitId {        self.graph[local_pos.0 as usize].commit_id.clone()    }     fn change_id(&self, local_pos: LocalPosition) -> ChangeId {        self.graph[local_pos.0 as usize].change_id.clone()    }     fn num_parents(&self, local_pos: LocalPosition) -> u32 {        self.graph[local_pos.0 as usize]            .parent_positions            .len()            .try_into()            .unwrap()    }     fn parent_positions(&self, local_pos: LocalPosition) -> SmallIndexPositionsVec {        self.graph[local_pos.0 as usize].parent_positions.clone()    }} /// In-memory mutable records for the on-disk commit index backend.pub struct DefaultMutableIndex(MutableIndexSegment); impl DefaultMutableIndex {    pub(crate) fn full(commit_id_length: usize, change_id_length: usize) -> Self {        let mutable_segment = MutableIndexSegment::full(commit_id_length, change_id_length);        DefaultMutableIndex(mutable_segment)    }     pub(super) fn incremental(parent_file: Arc<ReadonlyIndexSegment>) -> Self {        let mutable_segment = MutableIndexSegment::incremental(parent_file);        DefaultMutableIndex(mutable_segment)    }     #[cfg(test)]    pub(crate) fn add_commit_data(        &mut self,        commit_id: CommitId,        change_id: ChangeId,        parent_ids: &[CommitId],    ) {        self.0.add_commit_data(commit_id, change_id, parent_ids);    }     pub(super) fn squash_and_save_in(self, dir: &Path) -> io::Result<Arc<ReadonlyIndexSegment>> {        self.0.maybe_squash_with_ancestors().save_in(dir)    }} impl AsCompositeIndex for DefaultMutableIndex {    fn as_composite(&self) -> CompositeIndex<'_> {        self.0.as_composite()    }} impl Index for DefaultMutableIndex {    fn shortest_unique_commit_id_prefix_len(&self, commit_id: &CommitId) -> usize {        self.as_composite()            .shortest_unique_commit_id_prefix_len(commit_id)    }     fn resolve_commit_id_prefix(&self, prefix: &HexPrefix) -> PrefixResolution<CommitId> {        self.as_composite().resolve_commit_id_prefix(prefix)    }     fn has_id(&self, commit_id: &CommitId) -> bool {        self.as_composite().has_id(commit_id)    }     fn is_ancestor(&self, ancestor_id: &CommitId, descendant_id: &CommitId) -> bool {        self.as_composite().is_ancestor(ancestor_id, descendant_id)    }     fn common_ancestors(&self, set1: &[CommitId], set2: &[CommitId]) -> Vec<CommitId> {        self.as_composite().common_ancestors(set1, set2)    }     fn all_heads_for_gc(        &self,    ) -> Result<Box<dyn Iterator<Item = CommitId> + '_>, AllHeadsForGcUnsupported> {        Ok(Box::new(self.as_composite().all_heads()))    }     fn heads(&self, candidates: &mut dyn Iterator<Item = &CommitId>) -> Vec<CommitId> {        self.as_composite().heads(candidates)    }     fn topo_order(&self, input: &mut dyn Iterator<Item = &CommitId>) -> Vec<CommitId> {        self.as_composite().topo_order(input)    }     fn evaluate_revset<'index>(        &'index self,        expression: &ResolvedExpression,        store: &Arc<Store>,    ) -> Result<Box<dyn Revset + 'index>, RevsetEvaluationError> {        self.as_composite().evaluate_revset(expression, store)    }} impl MutableIndex for DefaultMutableIndex {    fn as_any(&self) -> &dyn Any {        self    }     fn into_any(self: Box<Self>) -> Box<dyn Any> {        Box::new(*self)    }     fn as_index(&self) -> &dyn Index {        self    }     fn change_id_index(        &self,        heads: &mut dyn Iterator<Item = &CommitId>,    ) -> Box<dyn ChangeIdIndex + '_> {        Box::new(ChangeIdIndexImpl::new(self, heads))    }     fn add_commit(&mut self, commit: &Commit) {        self.0.add_commit(commit);    }     fn merge_in(&mut self, other: &dyn ReadonlyIndex) {        let other = other            .as_any()            .downcast_ref::<DefaultReadonlyIndex>()            .expect("index to merge in must be a DefaultReadonlyIndex");        self.0.merge_in(other.as_segment().clone());    }}