Copy owner from previous database file (#364)

CHANGELOG.md

@@ -20,6 +20,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fzf: added `--keep-right` option by default, upgraded minimum version to v0.21.0.
 - Bash: only enable completions on 4.4+.
 - Fzf: bypass `ls` alias in preview window.
+- Retain ownership of database file.
 
 ## [0.8.0] - 2021-12-25
 

Cargo.toml

@@ -23,17 +23,13 @@ bincode = "1.3.1"
 clap = { version = "3.1.0", features = ["derive"] }
 dirs = "4.0.0"
 dunce = "1.0.1"
+fastrand = "1.7.0"
 glob = "0.3.0"
 ordered-float = "2.0.0"
 serde = { version = "1.0.116", features = ["derive"] }
-tempfile = "3.1.0"
-thiserror = "1.0.30"
 
-[target.'cfg(windows)'.dependencies]
-rand = { version = "0.8.4", features = [
-  "getrandom",
-  "small_rng",
-], default-features = false }
+[target.'cfg(unix)'.dependencies]
+nix = "0.23.1"
 
 [build-dependencies]
 clap = { version = "3.1.0", features = ["derive"] }
@@ -44,10 +40,11 @@ clap_complete_fig = "3.1.0"
 assert_cmd = "2.0.0"
 rstest = "0.12.0"
 rstest_reuse = "0.3.0"
+tempfile = "3.1.0"
 
 [features]
 default = []
-nix = []
+nix-dev = []
 
 [profile.release]
 codegen-units = 1

src/cmd/query.rs

@@ -3,10 +3,10 @@ use std::io::{self, Write};
 use anyhow::{Context, Result};
 
 use crate::cmd::{Query, Run};
+use crate::config;
 use crate::db::{Database, DatabaseFile};
 use crate::error::BrokenPipeHandler;
-use crate::fzf::Fzf;
-use crate::{config, util};
+use crate::util::{self, Fzf};
 
 impl Run for Query {
     fn run(&self) -> Result<()> {

src/cmd/remove.rs

@@ -3,9 +3,9 @@ use std::io::{self, Write};
 use anyhow::{bail, Context, Result};
 
 use crate::cmd::{Remove, Run};
+use crate::config;
 use crate::db::DatabaseFile;
-use crate::fzf::Fzf;
-use crate::{config, util};
+use crate::util::{self, Fzf};
 
 impl Run for Remove {
     fn run(&self) -> Result<()> {

src/db/mod.rs

@@ -2,13 +2,14 @@ mod dir;
 mod stream;
 
 use std::fs;
-use std::io::{self, Write};
+use std::io;
 use std::path::{Path, PathBuf};
 
 use anyhow::{Context, Result};
 pub use dir::{Dir, DirList, Epoch, Rank};
 pub use stream::Stream;
-use tempfile::{NamedTempFile, PersistError};
+
+use crate::util;
 
 #[derive(Debug)]
 pub struct Database<'file> {
@@ -24,18 +25,8 @@ impl<'file> Database<'file> {
         }
 
         let buffer = self.dirs.to_bytes()?;
-        let mut file = NamedTempFile::new_in(self.data_dir)
-            .with_context(|| format!("could not create temporary database in: {}", self.data_dir.display()))?;
-
-        // Preallocate enough space on the file, preventing copying later on. This optimization may
-        // fail on some filesystems, but it is safe to ignore it and proceed.
-        let _ = file.as_file().set_len(buffer.len() as _);
-        file.write_all(&buffer)
-            .with_context(|| format!("could not write to temporary database: {}", file.path().display()))?;
-
         let path = db_path(&self.data_dir);
-        persist(file, &path).with_context(|| format!("could not replace database: {}", path.display()))?;
-
+        util::write(&path, &buffer).context("could not write to database")?;
         self.modified = false;
         Ok(())
     }
@@ -120,44 +111,6 @@ impl<'file> Database<'file> {
     }
 }
 
-#[cfg(unix)]
-fn persist<P: AsRef<Path>>(file: NamedTempFile, path: P) -> Result<(), PersistError> {
-    file.persist(path)?;
-    Ok(())
-}
-
-#[cfg(windows)]
-fn persist<P: AsRef<Path>>(mut file: NamedTempFile, path: P) -> Result<(), PersistError> {
-    use std::thread;
-    use std::time::Duration;
-
-    use rand::distributions::{Distribution, Uniform};
-    use rand::rngs::SmallRng;
-    use rand::SeedableRng;
-
-    // File renames on Windows are not atomic and sometimes fail with `PermissionDenied`. This is
-    // extremely unlikely unless it's running in a loop on multiple threads. Nevertheless, we guard
-    // against it by retrying the rename a fixed number of times.
-    const MAX_TRIES: usize = 10;
-    let mut rng = None;
-
-    for _ in 0..MAX_TRIES {
-        match file.persist(&path) {
-            Ok(_) => break,
-            Err(e) if e.error.kind() == io::ErrorKind::PermissionDenied => {
-                let mut rng = rng.get_or_insert_with(SmallRng::from_entropy);
-                let between = Uniform::from(50..150);
-                let duration = Duration::from_millis(between.sample(&mut rng));
-                thread::sleep(duration);
-                file = e.file;
-            }
-            Err(e) => return Err(e),
-        }
-    }
-
-    Ok(())
-}
-
 pub struct DatabaseFile {
     buffer: Vec<u8>,
     data_dir: PathBuf,

src/error.rs

@@ -1,19 +1,20 @@
+use std::fmt::{self, Display, Formatter};
 use std::io;
 
 use anyhow::{bail, Context, Result};
-use thiserror::Error;
-
-#[derive(Debug, Error)]
-#[error("could not find fzf, is it installed?")]
-pub struct FzfNotFound;
 
 /// Custom error type for early exit.
-#[derive(Debug, Error)]
-#[error("")]
+#[derive(Debug)]
 pub struct SilentExit {
     pub code: i32,
 }
 
+impl Display for SilentExit {
+    fn fmt(&self, _: &mut Formatter<'_>) -> fmt::Result {
+        Ok(())
+    }
+}
+
 pub trait BrokenPipeHandler {
     fn pipe_exit(self, device: &str) -> Result<()>;
 }