From b3470de7997f54cf22ebfa3d2e739caa4d4d9691 Mon Sep 17 00:00:00 2001
From: Ajeet D'Souza <98ajeet@gmail.com>
Date: Tue, 17 Mar 2020 13:05:10 +0530
Subject: [PATCH] Remove flock

---
 Cargo.lock | 11 -----------
 Cargo.toml |  1 -
 src/db.rs  | 40 ++++++++++++++--------------------------
 3 files changed, 14 insertions(+), 38 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index b62eb82..696f869 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -134,15 +134,6 @@ dependencies = [
  "serde 1.0.104 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
-[[package]]
-name = "fs2"
-version = "0.4.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "libc 0.2.67 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
 [[package]]
 name = "getrandom"
 version = "0.1.14"
@@ -376,7 +367,6 @@ dependencies = [
  "clap 2.33.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "dirs 2.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "envy 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "fs2 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.104 (registry+https://github.com/rust-lang/crates.io-index)",
  "structopt 0.3.11 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -400,7 +390,6 @@ 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 envy 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)" = "f938a4abd5b75fe3737902dbc2e79ca142cc1526827a9e40b829a086758531a9"
-"checksum fs2 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)" = "9564fc758e15025b46aa6643b1b77d047d1a56a1aea6e01002ac0c7026876213"
 "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 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)" = "1010591b26bbfe835e9faeabeb11866061cc7dcebffd56ad7d0942d0e61aefd8"
diff --git a/Cargo.toml b/Cargo.toml
index a19e022..e92b52f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -18,7 +18,6 @@ bincode = "1.2.1"
 clap = "2.33.0"
 dirs = "2.0.2"
 envy = "0.4.1"
-fs2 = "0.4.3"
 serde = { version = "1.0.104", features = ["derive"] }
 structopt = "0.3.11"
 
diff --git a/src/db.rs b/src/db.rs
index 0e9c4a8..6e5badb 100644
--- a/src/db.rs
+++ b/src/db.rs
@@ -1,17 +1,12 @@
 use crate::dir::Dir;
 use crate::types::{Epoch, Rank};
 use anyhow::{anyhow, bail, Context, Result};
-use fs2::FileExt;
-use std::fs::{self, File, OpenOptions};
+use std::fs::{self, File};
 use std::io::{self, BufRead, BufReader, BufWriter};
 use std::path::{Path, PathBuf};
 
 pub struct DB {
     path: PathBuf,
-    path_tmp: PathBuf,
-
-    file_tmp: File,
-
     dirs: Vec<Dir>,
     modified: bool,
 }
@@ -20,19 +15,6 @@ impl DB {
     pub fn open<P: AsRef<Path>>(path: P) -> Result<DB> {
         let path = path.as_ref().to_path_buf();
 
-        let mut path_tmp = path.clone();
-        path_tmp.set_file_name(".zo.tmp");
-
-        let file_tmp = OpenOptions::new()
-            .write(true)
-            .create(true)
-            .open(&path_tmp)
-            .with_context(|| anyhow!("could not open temporary database file"))?;
-
-        file_tmp
-            .lock_exclusive()
-            .with_context(|| anyhow!("could not lock temporary database file"))?;
-
         let dirs = match File::open(&path) {
             Ok(file) => {
                 let reader = BufReader::new(&file);
@@ -47,8 +29,6 @@ impl DB {
 
         Ok(DB {
             path,
-            path_tmp,
-            file_tmp,
             dirs,
             modified: false,
         })
@@ -56,14 +36,16 @@ impl DB {
 
     pub fn save(&mut self) -> Result<()> {
         if self.modified {
-            self.file_tmp
-                .set_len(0)
-                .with_context(|| "could not truncate temporary database file")?;
+            let path_tmp = self.get_path_tmp();
 
-            let writer = BufWriter::new(&self.file_tmp);
+            let file_tmp = File::create(&path_tmp)
+                .with_context(|| anyhow!("could not open temporary database file"))?;
+
+            let writer = BufWriter::new(&file_tmp);
             bincode::serialize_into(writer, &self.dirs)
                 .with_context(|| anyhow!("could not serialize database"))?;
-            fs::rename(&self.path_tmp, &self.path)
+
+            fs::rename(&path_tmp, &self.path)
                 .with_context(|| anyhow!("could not move temporary database file"))?;
         }
 
@@ -249,6 +231,12 @@ If you wish to merge the two, specify the `--merge` flag."
         Ok(())
     }
 
+    fn get_path_tmp(&self) -> PathBuf {
+        let mut path_tmp = self.path.clone();
+        path_tmp.set_file_name(".zo.tmp");
+        path_tmp
+    }
+
     fn remove_invalid(&mut self) {
         let orig_len = self.dirs.len();
         self.dirs.retain(Dir::is_dir);