gix_commitgraph/
init.rs

1use crate::{File, Graph, MAX_COMMITS};
2use gix_error::ExnMessageResult;
3use gix_error::{ErrorExt, Exn, Message, ResultExt, message};
4use std::{
5    io::{BufRead, BufReader},
6    path::Path,
7};
8
9/// Instantiate a `Graph` from various sources.
10impl Graph {
11    /// Instantiate a commit graph from `path` which may be a directory containing graph files or the graph file itself.
12    ///
13    /// Filesystem errors retain their [`std::io::Error`] source, including when `path` does not exist.
14    pub fn at(path: &Path) -> ExnMessageResult<Self> {
15        Self::try_from(path)
16    }
17
18    /// Instantiate a commit graph from the directory containing all of its files.
19    pub fn from_commit_graphs_dir(path: &Path) -> ExnMessageResult<Self> {
20        let commit_graphs_dir = path;
21        let chain_file_path = commit_graphs_dir.join("commit-graph-chain");
22        let chain_file = std::fs::File::open(&chain_file_path).or_raise(|| {
23            message!(
24                "Could not open commit-graph chain file at '{}'",
25                chain_file_path.display()
26            )
27        })?;
28        let mut files = Vec::new();
29        for line in BufReader::new(chain_file).lines() {
30            let hash = line.or_raise(|| {
31                message!(
32                    "Could not read from commit-graph file at '{}'",
33                    chain_file_path.display()
34                )
35            })?;
36            let graph_file_path = commit_graphs_dir.join(format!("graph-{hash}.graph"));
37            files.push(
38                File::at(&graph_file_path)
39                    .or_raise(|| message!("Could not open commit-graph file at '{}'", graph_file_path.display()))?,
40            );
41        }
42        Self::new(files)
43    }
44
45    /// Instantiate a commit graph from a `.git/objects/info/commit-graph` or
46    /// `.git/objects/info/commit-graphs/graph-*.graph` file.
47    pub fn from_file(path: &Path) -> ExnMessageResult<Self> {
48        let file = File::at(path).or_raise(|| message!("Could not open commit-graph file at '{}'", path.display()))?;
49        Self::new(vec![file])
50    }
51
52    /// Instantiate a commit graph from an `.git/objects/info` directory.
53    pub fn from_info_dir(info_dir: &Path) -> ExnMessageResult<Self> {
54        Self::from_file(&info_dir.join("commit-graph"))
55            .or_else(|_| Self::from_commit_graphs_dir(&info_dir.join("commit-graphs")))
56    }
57
58    /// Create a new commit graph from a list of `files`.
59    pub fn new(files: Vec<File>) -> ExnMessageResult<Self> {
60        let files = nonempty::NonEmpty::from_vec(files)
61            .ok_or_else(|| message!("Commit-graph must contain at least one file"))?;
62        let num_commits: u64 = files.iter().map(|f| u64::from(f.num_commits())).sum();
63        if num_commits > u64::from(MAX_COMMITS) {
64            return Err(message!(
65                "Commit-graph files contain {num_commits} commits altogether, but only {MAX_COMMITS} commits are allowed"
66            ).into());
67        }
68
69        let mut f1 = files.first();
70        for f2 in files.tail() {
71            if f1.object_hash() != f2.object_hash() {
72                return Err(message!(
73                    "Commit-graph files mismatch: '{path1}' uses hash {hash1:?}, but '{path2}' uses hash {hash2:?}",
74                    path1 = f1.path().display(),
75                    hash1 = f1.object_hash(),
76                    path2 = f2.path().display(),
77                    hash2 = f2.object_hash(),
78                )
79                .into());
80            }
81            f1 = f2;
82        }
83
84        Ok(Self { files })
85    }
86}
87
88impl TryFrom<&Path> for Graph {
89    type Error = Exn<Message>;
90
91    fn try_from(path: &Path) -> std::result::Result<Self, Self::Error> {
92        let metadata = path
93            .metadata()
94            .or_raise(|| message!("Could not access commit-graph path at '{}'", path.display()))?;
95        if metadata.is_file() {
96            // Assume we are looking at `.git/objects/info/commit-graph` or
97            // `.git/objects/info/commit-graphs/graph-*.graph`.
98            Self::from_file(path)
99        } else if metadata.is_dir() {
100            if path.join("commit-graph-chain").is_file() {
101                Self::from_commit_graphs_dir(path)
102            } else {
103                Self::from_info_dir(path)
104            }
105        } else {
106            Err(message!(
107                "Did not find any files that look like commit graphs at '{}'",
108                path.display()
109            )
110            .raise())
111        }
112    }
113}
gix_commitgraph/init.rs

gix_commitgraph/
init.rs
