Mercurial > hg
view rust/hg-core/src/revlog/filelog.rs @ 49095:b97835b2e2d4
rust-nodemap: remove unnecessary explicit lifetime
Differential Revision: https://phab.mercurial-scm.org/D12486
author | Martin von Zweigbergk <martinvonz@google.com> |
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date | Fri, 08 Apr 2022 21:34:18 -0700 |
parents | 399439c12223 |
children | 3f86ee422095 |
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use crate::errors::HgError; use crate::repo::Repo; use crate::revlog::path_encode::path_encode; use crate::revlog::revlog::RevlogEntry; use crate::revlog::revlog::{Revlog, RevlogError}; use crate::revlog::NodePrefix; use crate::revlog::Revision; use crate::utils::files::get_path_from_bytes; use crate::utils::hg_path::HgPath; use crate::utils::SliceExt; use std::path::PathBuf; /// A specialized `Revlog` to work with file data logs. pub struct Filelog { /// The generic `revlog` format. revlog: Revlog, } impl Filelog { pub fn open(repo: &Repo, file_path: &HgPath) -> Result<Self, HgError> { let index_path = store_path(file_path, b".i"); let data_path = store_path(file_path, b".d"); let revlog = Revlog::open( &repo.store_vfs(), index_path, Some(&data_path), false, )?; Ok(Self { revlog }) } /// The given node ID is that of the file as found in a filelog, not of a /// changeset. pub fn data_for_node( &self, file_node: impl Into<NodePrefix>, ) -> Result<FilelogRevisionData, RevlogError> { let file_rev = self.revlog.rev_from_node(file_node.into())?; self.data_for_rev(file_rev) } /// The given revision is that of the file as found in a filelog, not of a /// changeset. pub fn data_for_rev( &self, file_rev: Revision, ) -> Result<FilelogRevisionData, RevlogError> { let data: Vec<u8> = self.revlog.get_rev_data(file_rev)?.into_owned(); Ok(FilelogRevisionData(data.into())) } /// The given node ID is that of the file as found in a filelog, not of a /// changeset. pub fn entry_for_node( &self, file_node: impl Into<NodePrefix>, ) -> Result<FilelogEntry, RevlogError> { let file_rev = self.revlog.rev_from_node(file_node.into())?; self.entry_for_rev(file_rev) } /// The given revision is that of the file as found in a filelog, not of a /// changeset. pub fn entry_for_rev( &self, file_rev: Revision, ) -> Result<FilelogEntry, RevlogError> { Ok(FilelogEntry(self.revlog.get_entry(file_rev)?)) } } fn store_path(hg_path: &HgPath, suffix: &[u8]) -> PathBuf { let encoded_bytes = path_encode(&[b"data/", hg_path.as_bytes(), suffix].concat()); get_path_from_bytes(&encoded_bytes).into() } pub struct FilelogEntry<'a>(RevlogEntry<'a>); impl FilelogEntry<'_> { /// `self.data()` can be expensive, with decompression and delta /// resolution. /// /// *Without* paying this cost, based on revlog index information /// including `RevlogEntry::uncompressed_len`: /// /// * Returns `true` if the length that `self.data().file_data().len()` /// would return is definitely **not equal** to `other_len`. /// * Returns `false` if available information is inconclusive. pub fn file_data_len_not_equal_to(&self, other_len: u64) -> bool { // Relevant code that implement this behavior in Python code: // basefilectx.cmp, filelog.size, storageutil.filerevisioncopied, // revlog.size, revlog.rawsize // Let’s call `file_data_len` what would be returned by // `self.data().file_data().len()`. if self.0.is_cencored() { let file_data_len = 0; return other_len != file_data_len; } if self.0.has_length_affecting_flag_processor() { // We can’t conclude anything about `file_data_len`. return false; } // Revlog revisions (usually) have metadata for the size of // their data after decompression and delta resolution // as would be returned by `Revlog::get_rev_data`. // // For filelogs this is the file’s contents preceded by an optional // metadata block. let uncompressed_len = if let Some(l) = self.0.uncompressed_len() { l as u64 } else { // The field was set to -1, the actual uncompressed len is unknown. // We need to decompress to say more. return false; }; // `uncompressed_len = file_data_len + optional_metadata_len`, // so `file_data_len <= uncompressed_len`. if uncompressed_len < other_len { // Transitively, `file_data_len < other_len`. // So `other_len != file_data_len` definitely. return true; } if uncompressed_len == other_len + 4 { // It’s possible that `file_data_len == other_len` with an empty // metadata block (2 start marker bytes + 2 end marker bytes). // This happens when there wouldn’t otherwise be metadata, but // the first 2 bytes of file data happen to match a start marker // and would be ambiguous. return false; } if !self.0.has_p1() { // There may or may not be copy metadata, so we can’t deduce more // about `file_data_len` without computing file data. return false; } // Filelog ancestry is not meaningful in the way changelog ancestry is. // It only provides hints to delta generation. // p1 and p2 are set to null when making a copy or rename since // contents are likely unrelatedto what might have previously existed // at the destination path. // // Conversely, since here p1 is non-null, there is no copy metadata. // Note that this reasoning may be invalidated in the presence of // merges made by some previous versions of Mercurial that // swapped p1 and p2. See <https://bz.mercurial-scm.org/show_bug.cgi?id=6528> // and `tests/test-issue6528.t`. // // Since copy metadata is currently the only kind of metadata // kept in revlog data of filelogs, // this `FilelogEntry` does not have such metadata: let file_data_len = uncompressed_len; return file_data_len != other_len; } pub fn data(&self) -> Result<FilelogRevisionData, HgError> { Ok(FilelogRevisionData(self.0.data()?.into_owned())) } } /// The data for one revision in a filelog, uncompressed and delta-resolved. pub struct FilelogRevisionData(Vec<u8>); impl FilelogRevisionData { /// Split into metadata and data pub fn split(&self) -> Result<(Option<&[u8]>, &[u8]), HgError> { const DELIMITER: &[u8; 2] = &[b'\x01', b'\n']; if let Some(rest) = self.0.drop_prefix(DELIMITER) { if let Some((metadata, data)) = rest.split_2_by_slice(DELIMITER) { Ok((Some(metadata), data)) } else { Err(HgError::corrupted( "Missing metadata end delimiter in filelog entry", )) } } else { Ok((None, &self.0)) } } /// Returns the file contents at this revision, stripped of any metadata pub fn file_data(&self) -> Result<&[u8], HgError> { let (_metadata, data) = self.split()?; Ok(data) } /// Consume the entry, and convert it into data, discarding any metadata, /// if present. pub fn into_file_data(self) -> Result<Vec<u8>, HgError> { if let (Some(_metadata), data) = self.split()? { Ok(data.to_owned()) } else { Ok(self.0) } } }