mirror of
https://github.com/fish-shell/fish-shell.git
synced 2024-12-23 00:43:39 +08:00
405 lines
15 KiB
Rust
405 lines
15 KiB
Rust
//! The classes responsible for autoloading functions and completions.
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use crate::common::{escape, ScopeGuard};
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use crate::env::Environment;
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use crate::io::IoChain;
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use crate::parser::Parser;
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#[cfg(test)]
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use crate::tests::prelude::*;
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use crate::wchar::{wstr, WString, L};
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use crate::wutil::{file_id_for_path, FileId, INVALID_FILE_ID};
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use lru::LruCache;
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use std::collections::{HashMap, HashSet};
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use std::num::NonZeroUsize;
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use std::time;
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/// autoload_t is a class that knows how to autoload .fish files from a list of directories. This
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/// is used by autoloading functions and completions. It maintains a file cache, which is
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/// responsible for potentially cached accesses of files, and then a list of files that have
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/// actually been autoloaded. A client may request a file to autoload given a command name, and may
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/// be returned a path which it is expected to source.
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/// autoload_t does not have any internal locks; it is the responsibility of the caller to lock
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/// it.
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#[derive(Default)]
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pub struct Autoload {
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/// The environment variable whose paths we observe.
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env_var_name: &'static wstr,
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/// A map from command to the files we have autoloaded.
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autoloaded_files: HashMap<WString, FileId>,
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/// The list of commands that we are currently autoloading.
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current_autoloading: HashSet<WString>,
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/// The autoload cache.
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/// This is a unique_ptr because want to change it if the value of our environment variable
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/// changes. This is never null (but it may be a cache with no paths).
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cache: Box<AutoloadFileCache>,
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}
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impl Autoload {
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/// Construct an autoloader that loads from the paths given by \p env_var_name.
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pub fn new(env_var_name: &'static wstr) -> Self {
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Self {
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env_var_name,
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..Default::default()
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}
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}
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/// Given a command, get a path to autoload.
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/// For example, if the environment variable is 'fish_function_path' and the command is 'foo',
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/// this will look for a file 'foo.fish' in one of the directories given by fish_function_path.
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/// If there is no such file, OR if the file has been previously resolved and is now unchanged,
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/// this will return none. But if the file is either new or changed, this will return the path.
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/// After returning a path, the command is marked in-progress until the caller calls
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/// mark_autoload_finished() with the same command. Note this does not actually execute any
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/// code; it is the caller's responsibility to load the file.
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pub fn resolve_command(&mut self, cmd: &wstr, env: &dyn Environment) -> Option<WString> {
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if let Some(var) = env.get(self.env_var_name) {
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self.resolve_command_impl(cmd, var.as_list())
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} else {
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self.resolve_command_impl(cmd, &[])
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}
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}
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/// Helper to actually perform an autoload.
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/// This is a static function because it executes fish script, and so must be called without
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/// holding any particular locks.
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pub fn perform_autoload(path: &wstr, parser: &Parser) {
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// We do the useful part of what exec_subshell does ourselves
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// - we source the file.
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// We don't create a buffer or check ifs or create a read_limit
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let script_source = L!("source ").to_owned() + &escape(path)[..];
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let prev_statuses = parser.get_last_statuses();
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let _put_back = ScopeGuard::new((), |()| parser.set_last_statuses(prev_statuses));
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parser.eval(&script_source, &IoChain::new());
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}
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/// Mark that a command previously returned from path_to_autoload is finished autoloading.
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pub fn mark_autoload_finished(&mut self, cmd: &wstr) {
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let removed = self.current_autoloading.remove(cmd);
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assert!(removed, "cmd was not being autoloaded");
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}
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/// \return whether a command is currently being autoloaded.
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pub fn autoload_in_progress(&self, cmd: &wstr) -> bool {
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self.current_autoloading.contains(cmd)
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}
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/// \return whether a command could potentially be autoloaded.
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/// This does not actually mark the command as being autoloaded.
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pub fn can_autoload(&mut self, cmd: &wstr) -> bool {
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self.cache.check(cmd, true /* allow stale */).is_some()
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}
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/// \return whether autoloading has been attempted for a command.
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pub fn has_attempted_autoload(&self, cmd: &wstr) -> bool {
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self.cache.is_cached(cmd)
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}
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/// \return the names of all commands that have been autoloaded. Note this includes "in-flight"
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/// commands.
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pub fn get_autoloaded_commands(&self) -> Vec<WString> {
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let mut result = Vec::with_capacity(self.autoloaded_files.len());
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for k in self.autoloaded_files.keys() {
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result.push(k.to_owned());
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}
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// Sort the output to make it easier to test.
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result.sort();
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result
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}
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/// Mark that all autoloaded files have been forgotten.
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/// Future calls to path_to_autoload() will return previously-returned paths.
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pub fn clear(&mut self) {
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// Note there is no reason to invalidate the cache here.
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self.autoloaded_files.clear();
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}
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/// Invalidate any underlying cache.
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/// This is exposed for testing.
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#[cfg(test)]
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fn invalidate_cache(&mut self) {
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self.cache = Box::new(AutoloadFileCache::with_dirs(self.cache.dirs().to_owned()));
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}
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/// Like resolve_autoload(), but accepts the paths directly.
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/// This is exposed for testing.
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fn resolve_command_impl(&mut self, cmd: &wstr, paths: &[WString]) -> Option<WString> {
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// Are we currently in the process of autoloading this?
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if self.current_autoloading.contains(cmd) {
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return None;
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}
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// Check to see if our paths have changed. If so, replace our cache.
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// Note we don't have to modify autoloadable_files_. We'll naturally detect if those have
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// changed when we query the cache.
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if paths != self.cache.dirs() {
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self.cache = Box::new(AutoloadFileCache::with_dirs(paths.to_owned()));
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}
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// Do we have an entry to load?
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let file = self.cache.check(cmd, false)?;
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// Is this file the same as what we previously autoloaded?
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if let Some(loaded_file) = self.autoloaded_files.get(cmd) {
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if *loaded_file == file.file_id {
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// The file has been autoloaded and is unchanged.
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return None;
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}
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}
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// We're going to (tell our caller to) autoload this command.
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self.current_autoloading.insert(cmd.to_owned());
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self.autoloaded_files.insert(cmd.to_owned(), file.file_id);
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Some(file.path)
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}
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}
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/// The time before we'll recheck an autoloaded file.
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const AUTOLOAD_STALENESS_INTERVALL: u64 = 15;
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/// Represents a file that we might want to autoload.
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#[derive(Clone)]
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struct AutoloadableFile {
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/// The path to the file.
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path: WString,
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/// The metadata for the file.
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file_id: FileId,
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}
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// A timestamp is a monotonic point in time.
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type Timestamp = time::Instant;
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type MissesLruCache = LruCache<WString, Timestamp>;
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struct KnownFile {
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file: AutoloadableFile,
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last_checked: Timestamp,
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}
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/// Class representing a cache of files that may be autoloaded.
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/// This is responsible for performing cached accesses to a set of paths.
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struct AutoloadFileCache {
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/// The directories from which to load.
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dirs: Vec<WString>,
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/// Our LRU cache of checks that were misses.
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/// The key is the command, the value is the time of the check.
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misses_cache: MissesLruCache,
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/// The set of files that we have returned to the caller, along with the time of the check.
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/// The key is the command (not the path).
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known_files: HashMap<WString, KnownFile>,
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}
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impl Default for AutoloadFileCache {
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fn default() -> Self {
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Self::new()
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}
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}
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impl AutoloadFileCache {
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/// Initialize with a set of directories.
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fn with_dirs(dirs: Vec<WString>) -> Self {
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Self {
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dirs,
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misses_cache: MissesLruCache::new(NonZeroUsize::new(1024).unwrap()),
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known_files: HashMap::new(),
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}
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}
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/// Initialize with empty directories.
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fn new() -> Self {
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Self::with_dirs(vec![])
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}
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/// \return the directories.
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fn dirs(&self) -> &[WString] {
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&self.dirs
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}
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/// Check if a command \p cmd can be loaded.
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/// If \p allow_stale is true, allow stale entries; otherwise discard them.
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/// This returns an autoloadable file, or none() if there is no such file.
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fn check(&mut self, cmd: &wstr, allow_stale: bool) -> Option<AutoloadableFile> {
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// Check hits.
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if let Some(value) = self.known_files.get(cmd) {
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if allow_stale || Self::is_fresh(value.last_checked, Self::current_timestamp()) {
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// Re-use this cached hit.
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return Some(value.file.clone());
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}
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// The file is stale, remove it.
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self.known_files.remove(cmd);
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}
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// Check misses.
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if let Some(miss) = self.misses_cache.get(cmd) {
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if allow_stale || Self::is_fresh(*miss, Self::current_timestamp()) {
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// Re-use this cached miss.
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return None;
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}
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// The miss is stale, remove it.
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self.misses_cache.pop(cmd);
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}
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// We couldn't satisfy this request from the cache. Hit the disk.
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let file = self.locate_file(cmd);
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if let Some(file) = file.as_ref() {
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let old_value = self.known_files.insert(
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cmd.to_owned(),
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KnownFile {
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file: file.clone(),
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last_checked: Self::current_timestamp(),
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},
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);
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assert!(
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old_value.is_none(),
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"Known files cache should not have contained this cmd"
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);
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} else {
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let old_value = self
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.misses_cache
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.put(cmd.to_owned(), Self::current_timestamp());
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assert!(
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old_value.is_none(),
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"Misses cache should not have contained this cmd",
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);
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}
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file
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}
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/// \return true if a command is cached (either as a hit or miss).
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fn is_cached(&self, cmd: &wstr) -> bool {
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self.known_files.contains_key(cmd) || self.misses_cache.contains(cmd)
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}
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/// \return the current timestamp.
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fn current_timestamp() -> Timestamp {
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Timestamp::now()
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}
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/// \return whether a timestamp is fresh enough to use.
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fn is_fresh(then: Timestamp, now: Timestamp) -> bool {
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let seconds = now.duration_since(then).as_secs();
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seconds < AUTOLOAD_STALENESS_INTERVALL
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}
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/// Attempt to find an autoloadable file by searching our path list for a given command.
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/// \return the file, or none() if none.
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fn locate_file(&self, cmd: &wstr) -> Option<AutoloadableFile> {
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// If the command is empty or starts with NULL (i.e. is empty as a path)
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// we'd try to source the *directory*, which exists.
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// So instead ignore these here.
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if cmd.is_empty() {
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return None;
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}
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if cmd.as_char_slice()[0] == '\0' {
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return None;
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}
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// Re-use the storage for path.
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let mut path;
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for dir in self.dirs() {
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// Construct the path as dir/cmd.fish
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path = dir.to_owned();
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path.push('/');
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path.push_utfstr(cmd);
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path.push_str(".fish");
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let file_id = file_id_for_path(&path);
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if file_id != INVALID_FILE_ID {
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// Found it.
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return Some(AutoloadableFile { path, file_id });
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}
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}
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None
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}
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}
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#[test]
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#[serial]
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fn test_autoload() {
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test_init();
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use crate::common::{charptr2wcstring, wcs2zstring};
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use crate::fds::wopen_cloexec;
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use crate::wutil::sprintf;
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use nix::fcntl::OFlag;
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macro_rules! run {
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( $fmt:expr $(, $arg:expr )* $(,)? ) => {
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let cmd = wcs2zstring(&sprintf!($fmt $(, $arg)*));
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let status = unsafe { libc::system(cmd.as_ptr()) };
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assert!(status == 0);
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};
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}
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fn touch_file(path: &wstr) {
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use nix::sys::stat::Mode;
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use std::io::Write;
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let mut file = wopen_cloexec(
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path,
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OFlag::O_RDWR | OFlag::O_CREAT,
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Mode::from_bits_truncate(0o666),
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)
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.unwrap();
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file.write_all(b"Hello").unwrap();
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}
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let mut t1 = "/tmp/fish_test_autoload.XXXXXX\0".as_bytes().to_vec();
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let p1 = charptr2wcstring(unsafe { libc::mkdtemp(t1.as_mut_ptr().cast()) });
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let mut t2 = "/tmp/fish_test_autoload.XXXXXX\0".as_bytes().to_vec();
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let p2 = charptr2wcstring(unsafe { libc::mkdtemp(t2.as_mut_ptr().cast()) });
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let paths = &[p1.clone(), p2.clone()];
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let mut autoload = Autoload::new(L!("test_var"));
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assert!(autoload.resolve_command_impl(L!("file1"), paths).is_none());
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assert!(autoload
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.resolve_command_impl(L!("nothing"), paths)
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.is_none());
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assert!(autoload.get_autoloaded_commands().is_empty());
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run!("touch %ls/file1.fish", p1);
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run!("touch %ls/file2.fish", p2);
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autoload.invalidate_cache();
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assert!(!autoload.autoload_in_progress(L!("file1")));
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assert!(autoload.resolve_command_impl(L!("file1"), paths).is_some());
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assert!(autoload.resolve_command_impl(L!("file1"), paths).is_none());
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assert!(autoload.autoload_in_progress(L!("file1")));
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assert!(autoload.get_autoloaded_commands() == vec![L!("file1")]);
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autoload.mark_autoload_finished(L!("file1"));
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assert!(!autoload.autoload_in_progress(L!("file1")));
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assert!(autoload.get_autoloaded_commands() == vec![L!("file1")]);
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assert!(autoload.resolve_command_impl(L!("file1"), paths).is_none());
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assert!(autoload
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.resolve_command_impl(L!("nothing"), paths)
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.is_none());
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assert!(autoload.resolve_command_impl(L!("file2"), paths).is_some());
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assert!(autoload.resolve_command_impl(L!("file2"), paths).is_none());
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autoload.mark_autoload_finished(L!("file2"));
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assert!(autoload.resolve_command_impl(L!("file2"), paths).is_none());
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assert!((autoload.get_autoloaded_commands() == vec![L!("file1"), L!("file2")]));
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autoload.clear();
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assert!(autoload.resolve_command_impl(L!("file1"), paths).is_some());
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autoload.mark_autoload_finished(L!("file1"));
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assert!(autoload.resolve_command_impl(L!("file1"), paths).is_none());
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assert!(autoload
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.resolve_command_impl(L!("nothing"), paths)
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.is_none());
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assert!(autoload.resolve_command_impl(L!("file2"), paths).is_some());
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assert!(autoload.resolve_command_impl(L!("file2"), paths).is_none());
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autoload.mark_autoload_finished(L!("file2"));
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assert!(autoload.resolve_command_impl(L!("file1"), paths).is_none());
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touch_file(&sprintf!("%ls/file1.fish", p1));
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autoload.invalidate_cache();
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assert!(autoload.resolve_command_impl(L!("file1"), paths).is_some());
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autoload.mark_autoload_finished(L!("file1"));
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run!(L!("rm -Rf %ls"), p1);
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run!(L!("rm -Rf %ls"), p2);
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}
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