Optimize query algorithm

Cargo.lock

@@ -141,6 +141,11 @@ name = "dunce"
 version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "float-ord"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "getrandom"
 version = "0.1.14"
@@ -438,6 +443,7 @@ dependencies = [
  "clap 2.33.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "dirs 2.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "dunce 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "float-ord 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.110 (registry+https://github.com/rust-lang/crates.io-index)",
  "structopt 0.3.14 (registry+https://github.com/rust-lang/crates.io-index)",
  "uuid 0.8.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -463,6 +469,7 @@ dependencies = [
 "checksum dirs 2.0.2 (registry+https://github.com/rust-lang/crates.io-index)" = "13aea89a5c93364a98e9b37b2fa237effbb694d5cfe01c5b70941f7eb087d5e3"
 "checksum dirs-sys 0.3.4 (registry+https://github.com/rust-lang/crates.io-index)" = "afa0b23de8fd801745c471deffa6e12d248f962c9fd4b4c33787b055599bde7b"
 "checksum dunce 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "d0ad6bf6a88548d1126045c413548df1453d9be094a8ab9fd59bf1fdd338da4f"
+"checksum float-ord 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "7bad48618fdb549078c333a7a8528acb57af271d0433bdecd523eb620628364e"
 "checksum getrandom 0.1.14 (registry+https://github.com/rust-lang/crates.io-index)" = "7abc8dd8451921606d809ba32e95b6111925cd2906060d2dcc29c070220503eb"
 "checksum heck 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "20564e78d53d2bb135c343b3f47714a56af2061f1c928fdb541dc7b9fdd94205"
 "checksum hermit-abi 0.1.12 (registry+https://github.com/rust-lang/crates.io-index)" = "61565ff7aaace3525556587bd2dc31d4a07071957be715e63ce7b1eccf51a8f4"

Cargo.toml

@@ -18,6 +18,7 @@ bincode = "1.2.1"
 clap = "2.33.0"
 dirs = "2.0.2"
 dunce = "1.0.0"
+float-ord = "0.2.0"
 serde = { version = "1.0.106", features = ["derive"] }
 structopt = "0.3.12"
 uuid = { version = "0.8.1", features = ["v4"] }

src/db.rs

@@ -4,7 +4,6 @@ use anyhow::{bail, Context, Result};
 use serde::{Deserialize, Serialize};
 use uuid::Uuid;
 
-use std::cmp::Ordering;
 use std::fs::{self, File, OpenOptions};
 use std::io::{self, BufRead, BufReader, Write};
 use std::path::{Path, PathBuf};
@@ -15,9 +14,9 @@ pub use i32 as DBVersion;
 struct DbVersion(u32);
 
 pub struct Db {
+    pub dirs: Vec<Dir>,
+    pub modified: bool,
     data_dir: PathBuf,
-    dirs: Vec<Dir>,
-    modified: bool,
 }
 
 impl Db {
@@ -34,9 +33,9 @@ impl Db {
             Ok(buffer) => buffer,
             Err(e) if e.kind() == io::ErrorKind::NotFound => {
                 return Ok(Db {
-                    data_dir,
-                    modified: false,
                     dirs: Vec::new(),
+                    modified: false,
+                    data_dir,
                 })
             }
             Err(e) => {
@@ -48,9 +47,9 @@ impl Db {
 
         if buffer.is_empty() {
             return Ok(Db {
-                data_dir,
-                modified: false,
                 dirs: Vec::new(),
+                modified: false,
+                data_dir,
             });
         }
 
@@ -87,9 +86,9 @@ impl Db {
         };
 
         Ok(Db {
-            data_dir,
-            modified: false,
             dirs,
+            modified: false,
+            data_dir,
         })
     }
 
@@ -271,27 +270,6 @@ impl Db {
         Ok(())
     }
 
-    pub fn query(&mut self, keywords: &[String], now: Epoch) -> Option<&Dir> {
-        let (idx, dir, _) = self
-            .dirs
-            .iter()
-            .enumerate()
-            .filter(|(_, dir)| dir.is_match(&keywords))
-            .map(|(idx, dir)| (idx, dir, dir.get_frecency(now)))
-            .max_by(|(_, _, frecency1), (_, _, frecency2)| {
-                frecency1.partial_cmp(frecency2).unwrap_or(Ordering::Equal)
-            })?;
-
-        if dir.is_dir() {
-            // FIXME: change this to Some(dir) once the MIR borrow checker comes to stable Rust
-            Some(&self.dirs[idx])
-        } else {
-            self.dirs.swap_remove(idx);
-            self.modified = true;
-            self.query(keywords, now)
-        }
-    }
-
     pub fn query_many<'a>(&'a mut self, keywords: &'a [String]) -> impl Iterator<Item = &'a Dir> {
         self.query_all()
             .iter()
@@ -300,7 +278,7 @@ impl Db {
 
     pub fn query_all(&mut self) -> &[Dir] {
         let orig_len = self.dirs.len();
-        self.dirs.retain(Dir::is_dir);
+        self.dirs.retain(Dir::is_valid);
 
         if orig_len != self.dirs.len() {
             self.modified = true;

src/dir.rs

@@ -13,8 +13,8 @@ pub struct Dir {
 }
 
 impl Dir {
-    pub fn is_dir(&self) -> bool {
+    pub fn is_valid(&self) -> bool {
-        self.path.is_dir()
+        self.rank.is_finite() && self.rank >= 1.0 && self.path.is_dir()
     }
 
     #[cfg(unix)]

src/subcommand/query.rs

@@ -1,6 +1,8 @@
+use crate::db::Db;
 use crate::util;
 
 use anyhow::{bail, Result};
+use float_ord::FloatOrd;
 use structopt::StructOpt;
 
 use std::io::{self, Write};
@@ -19,7 +21,8 @@ impl Query {
         let path_opt = if self.interactive {
             self.query_interactive()?
         } else {
-            self.query()?
+            let mut db = util::get_db()?;
+            self.query(&mut db)?
         };
 
         match path_opt {
@@ -35,7 +38,8 @@ impl Query {
         Ok(())
     }
 
-    fn query(&self) -> Result<Option<Vec<u8>>> {
+    fn query(&self, db: &mut Db) -> Result<Option<Vec<u8>>> {
+        // if the input is already a valid path, simply return it
         if let [path] = self.keywords.as_slice() {
             if Path::new(path).is_dir() {
                 return Ok(Some(path.as_bytes().to_vec()));
@@ -50,14 +54,28 @@ impl Query {
             .map(|keyword| keyword.to_lowercase())
             .collect::<Vec<_>>();
 
-        let path_opt = util::get_db()?.query(&keywords, now).map(|dir| {
+        db.dirs
-            // `path_to_bytes` is guaranteed to succeed here since
+            .sort_unstable_by_key(|dir| FloatOrd(dir.get_frecency(now)));
-            // the path has already been queried successfully
-            let path_bytes = util::path_to_bytes(&dir.path).unwrap();
-            path_bytes.to_vec()
-        });
 
-        Ok(path_opt)
+        // Iterating in reverse order ensures that the directory indices do not
+        // change as we remove them.
+        for idx in (0..db.dirs.len()).rev() {
+            let dir = &db.dirs[idx];
+            if !dir.is_match(&keywords) {
+                continue;
+            }
+
+            if !dir.is_valid() {
+                db.dirs.swap_remove(idx);
+                db.modified = true;
+                continue;
+            }
+
+            let path = util::path_to_bytes(&dir.path)?.to_vec();
+            return Ok(Some(path));
+        }
+
+        Ok(None)
     }
 
     fn query_interactive(&self) -> Result<Option<Vec<u8>>> {