New VFS API

crates/vfs/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "vfs"
+version = "0.1.0"
+authors = ["rust-analyzer developers"]
+edition = "2018"
+
+[dependencies]
+rustc-hash = "1.0"
+jod-thread = "0.1.0"
+walkdir = "2.3.1"
+globset = "0.4.5"
+crossbeam-channel = "0.4.0"
+
+paths = { path = "../paths" }

crates/vfs/src/file_set.rs

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+//! Partitions a list of files into disjoint subsets.
+//!
+//! Files which do not belong to any explicitly configured `FileSet` belong to
+//! the default `FileSet`.
+use std::{cmp, fmt, iter};
+
+use paths::AbsPathBuf;
+use rustc_hash::FxHashMap;
+
+use crate::{FileId, Vfs, VfsPath};
+
+#[derive(Default, Clone, Eq, PartialEq)]
+pub struct FileSet {
+    files: FxHashMap<VfsPath, FileId>,
+    paths: FxHashMap<FileId, VfsPath>,
+}
+
+impl FileSet {
+    pub fn resolve_path(&self, anchor: FileId, path: &str) -> Option<FileId> {
+        let mut base = self.paths[&anchor].clone();
+        base.pop();
+        let path = base.join(path);
+        let res = self.files.get(&path).copied();
+        res
+    }
+    pub fn insert(&mut self, file_id: FileId, path: VfsPath) {
+        self.files.insert(path.clone(), file_id);
+        self.paths.insert(file_id, path);
+    }
+    pub fn iter(&self) -> impl Iterator<Item = FileId> + '_ {
+        self.paths.keys().copied()
+    }
+}
+
+impl fmt::Debug for FileSet {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("FileSet").field("n_files", &self.files.len()).finish()
+    }
+}
+
+#[derive(Debug)]
+pub struct FileSetConfig {
+    n_file_sets: usize,
+    roots: Vec<(AbsPathBuf, usize)>,
+}
+
+impl FileSetConfig {
+    pub fn builder() -> FileSetConfigBuilder {
+        FileSetConfigBuilder::default()
+    }
+    pub fn partition(&self, vfs: &Vfs) -> Vec<FileSet> {
+        let mut res = vec![FileSet::default(); self.len()];
+        for (file_id, path) in vfs.iter() {
+            let root = self.classify(&path);
+            res[root].insert(file_id, path)
+        }
+        res
+    }
+    fn len(&self) -> usize {
+        self.n_file_sets
+    }
+    fn classify(&self, path: &VfsPath) -> usize {
+        for (root, idx) in self.roots.iter() {
+            if let Some(path) = path.as_path() {
+                if path.starts_with(root) {
+                    return *idx;
+                }
+            }
+        }
+        self.len() - 1
+    }
+}
+
+pub struct FileSetConfigBuilder {
+    roots: Vec<Vec<AbsPathBuf>>,
+}
+
+impl Default for FileSetConfigBuilder {
+    fn default() -> Self {
+        FileSetConfigBuilder { roots: Vec::new() }
+    }
+}
+
+impl FileSetConfigBuilder {
+    pub fn add_file_set(&mut self, roots: Vec<AbsPathBuf>) {
+        self.roots.push(roots)
+    }
+    pub fn build(self) -> FileSetConfig {
+        let n_file_sets = self.roots.len() + 1;
+        let mut roots: Vec<(AbsPathBuf, usize)> = self
+            .roots
+            .into_iter()
+            .enumerate()
+            .flat_map(|(i, paths)| paths.into_iter().zip(iter::repeat(i)))
+            .collect();
+        roots.sort_by_key(|(path, _)| cmp::Reverse(path.to_string_lossy().len()));
+        FileSetConfig { n_file_sets, roots }
+    }
+}

crates/vfs/src/lib.rs

@@ -0,0 +1,138 @@
+//! # Virtual File System
+//!
+//! VFS stores all files read by rust-analyzer. Reading file contents from VFS
+//! always returns the same contents, unless VFS was explicitly modified with
+//! `set_file_contents`. All changes to VFS are logged, and can be retrieved via
+//! `take_changes` method. The pack of changes is then pushed to `salsa` and
+//! triggers incremental recomputation.
+//!
+//! Files in VFS are identified with `FileId`s -- interned paths. The notion of
+//! the path, `VfsPath` is somewhat abstract: at the moment, it is represented
+//! as an `std::path::PathBuf` internally, but this is an implementation detail.
+//!
+//! VFS doesn't do IO or file watching itself. For that, see the `loader`
+//! module. `loader::Handle` is an object-safe trait which abstracts both file
+//! loading and file watching. `Handle` is dynamically configured with a set of
+//! directory entries which should be scanned and watched. `Handle` then
+//! asynchronously pushes file changes. Directory entries are configured in
+//! free-form via list of globs, it's up to the `Handle` to interpret the globs
+//! in any specific way.
+//!
+//! A simple `WalkdirLoaderHandle` is provided, which doesn't implement watching
+//! and just scans the directory using walkdir.
+//!
+//! VFS stores a flat list of files. `FileSet` can partition this list of files
+//! into disjoint sets of files. Traversal-like operations (including getting
+//! the neighbor file by the relative path) are handled by the `FileSet`.
+//! `FileSet`s are also pushed to salsa and cause it to re-check `mod foo;`
+//! declarations when files are created or deleted.
+//!
+//! `file_set::FileSet` and `loader::Entry` play similar, but different roles.
+//! Both specify the "set of paths/files", one is geared towards file watching,
+//! the other towards salsa changes. In particular, single `file_set::FileSet`
+//! may correspond to several `loader::Entry`. For example, a crate from
+//! crates.io which uses code generation would have two `Entries` -- for sources
+//! in `~/.cargo`, and for generated code in `./target/debug/build`. It will
+//! have a single `FileSet` which unions the two sources.
+mod vfs_path;
+mod path_interner;
+pub mod file_set;
+pub mod loader;
+pub mod walkdir_loader;
+
+use std::{fmt, mem};
+
+use crate::path_interner::PathInterner;
+
+pub use crate::vfs_path::VfsPath;
+pub use paths::{AbsPath, AbsPathBuf};
+
+#[derive(Copy, Clone, Debug, Ord, PartialOrd, Eq, PartialEq, Hash)]
+pub struct FileId(pub u32);
+
+#[derive(Default)]
+pub struct Vfs {
+    interner: PathInterner,
+    data: Vec<Option<Vec<u8>>>,
+    changes: Vec<ChangedFile>,
+}
+
+pub struct ChangedFile {
+    pub file_id: FileId,
+    pub change_kind: ChangeKind,
+}
+
+impl ChangedFile {
+    pub fn exists(&self) -> bool {
+        self.change_kind != ChangeKind::Delete
+    }
+    pub fn is_created_or_deleted(&self) -> bool {
+        matches!(self.change_kind, ChangeKind::Create | ChangeKind::Delete)
+    }
+}
+
+#[derive(Eq, PartialEq)]
+pub enum ChangeKind {
+    Create,
+    Modify,
+    Delete,
+}
+
+impl Vfs {
+    pub fn file_id(&self, path: &VfsPath) -> Option<FileId> {
+        self.interner.get(path).filter(|&it| self.get(it).is_some())
+    }
+    pub fn file_path(&self, file_id: FileId) -> VfsPath {
+        self.interner.lookup(file_id).clone()
+    }
+    pub fn file_contents(&self, file_id: FileId) -> &[u8] {
+        self.get(file_id).as_deref().unwrap()
+    }
+    pub fn iter(&self) -> impl Iterator<Item = (FileId, VfsPath)> + '_ {
+        (0..self.data.len())
+            .map(|it| FileId(it as u32))
+            .filter(move |&file_id| self.get(file_id).is_some())
+            .map(move |file_id| {
+                let path = self.interner.lookup(file_id).clone();
+                (file_id, path)
+            })
+    }
+    pub fn set_file_contents(&mut self, path: VfsPath, contents: Option<Vec<u8>>) {
+        let file_id = self.alloc_file_id(path);
+        let change_kind = match (&self.get(file_id), &contents) {
+            (None, None) => return,
+            (None, Some(_)) => ChangeKind::Create,
+            (Some(_), None) => ChangeKind::Delete,
+            (Some(old), Some(new)) if old == new => return,
+            (Some(_), Some(_)) => ChangeKind::Modify,
+        };
+
+        *self.get_mut(file_id) = contents;
+        self.changes.push(ChangedFile { file_id, change_kind })
+    }
+    pub fn has_changes(&self) -> bool {
+        !self.changes.is_empty()
+    }
+    pub fn take_changes(&mut self) -> Vec<ChangedFile> {
+        mem::take(&mut self.changes)
+    }
+    fn alloc_file_id(&mut self, path: VfsPath) -> FileId {
+        let file_id = self.interner.intern(path);
+        let idx = file_id.0 as usize;
+        let len = self.data.len().max(idx + 1);
+        self.data.resize_with(len, || None);
+        file_id
+    }
+    fn get(&self, file_id: FileId) -> &Option<Vec<u8>> {
+        &self.data[file_id.0 as usize]
+    }
+    fn get_mut(&mut self, file_id: FileId) -> &mut Option<Vec<u8>> {
+        &mut self.data[file_id.0 as usize]
+    }
+}
+
+impl fmt::Debug for Vfs {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("Vfs").field("n_files", &self.data.len()).finish()
+    }
+}

crates/vfs/src/loader.rs

@@ -0,0 +1,69 @@
+//! Object safe interface for file watching and reading.
+use std::fmt;
+
+use paths::AbsPathBuf;
+
+pub enum Entry {
+    Files(Vec<AbsPathBuf>),
+    Directory { path: AbsPathBuf, globs: Vec<String> },
+}
+
+pub struct Config {
+    pub load: Vec<Entry>,
+    pub watch: Vec<usize>,
+}
+
+pub enum Message {
+    DidSwitchConfig { n_entries: usize },
+    DidLoadAllEntries,
+    Loaded { files: Vec<(AbsPathBuf, Option<Vec<u8>>)> },
+}
+
+pub type Sender = Box<dyn Fn(Message) + Send>;
+
+pub trait Handle: fmt::Debug {
+    fn spawn(sender: Sender) -> Self
+    where
+        Self: Sized;
+    fn set_config(&mut self, config: Config);
+    fn invalidate(&mut self, path: AbsPathBuf);
+    fn load_sync(&mut self, path: &AbsPathBuf) -> Option<Vec<u8>>;
+}
+
+impl Entry {
+    pub fn rs_files_recursively(base: AbsPathBuf) -> Entry {
+        Entry::Directory { path: base, globs: globs(&["*.rs"]) }
+    }
+    pub fn local_cargo_package(base: AbsPathBuf) -> Entry {
+        Entry::Directory { path: base, globs: globs(&["*.rs", "!/target/"]) }
+    }
+    pub fn cargo_package_dependency(base: AbsPathBuf) -> Entry {
+        Entry::Directory {
+            path: base,
+            globs: globs(&["*.rs", "!/tests/", "!/examples/", "!/benches/"]),
+        }
+    }
+}
+
+fn globs(globs: &[&str]) -> Vec<String> {
+    globs.iter().map(|it| it.to_string()).collect()
+}
+
+impl fmt::Debug for Message {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Message::Loaded { files } => {
+                f.debug_struct("Loaded").field("n_files", &files.len()).finish()
+            }
+            Message::DidSwitchConfig { n_entries } => {
+                f.debug_struct("DidSwitchConfig").field("n_entries", n_entries).finish()
+            }
+            Message::DidLoadAllEntries => f.debug_struct("DidLoadAllEntries").finish(),
+        }
+    }
+}
+
+#[test]
+fn handle_is_object_safe() {
+    fn _assert(_: &dyn Handle) {}
+}

crates/vfs/src/path_interner.rs

@@ -0,0 +1,31 @@
+//! Maps paths to compact integer ids. We don't care about clearings paths which
+//! no longer exist -- the assumption is total size of paths we ever look at is
+//! not too big.
+use rustc_hash::FxHashMap;
+
+use crate::{FileId, VfsPath};
+
+#[derive(Default)]
+pub(crate) struct PathInterner {
+    map: FxHashMap<VfsPath, FileId>,
+    vec: Vec<VfsPath>,
+}
+
+impl PathInterner {
+    pub(crate) fn get(&self, path: &VfsPath) -> Option<FileId> {
+        self.map.get(path).copied()
+    }
+    pub(crate) fn intern(&mut self, path: VfsPath) -> FileId {
+        if let Some(id) = self.get(&path) {
+            return id;
+        }
+        let id = FileId(self.vec.len() as u32);
+        self.map.insert(path.clone(), id);
+        self.vec.push(path);
+        id
+    }
+
+    pub(crate) fn lookup(&self, id: FileId) -> &VfsPath {
+        &self.vec[id.0 as usize]
+    }
+}