From c2e6738f6b4dec16d26f23c26a1e5666de12ce99 Mon Sep 17 00:00:00 2001
From: Lynnesbian <lynne@bune.city>
Date: Fri, 24 Sep 2021 23:53:02 +1000
Subject: [PATCH] use Lazy instead of OnceCell for MIMEDB

---
 src/files.rs     |  3 ++-
 src/lib.rs       | 27 +++++----------------------
 src/main.rs      |  4 +---
 src/tests/mod.rs |  3 ---
 4 files changed, 8 insertions(+), 29 deletions(-)

diff --git a/src/files.rs b/src/files.rs
index d4c13a4..2c6cdde 100644
--- a/src/files.rs
+++ b/src/files.rs
@@ -2,6 +2,7 @@ use std::collections::{BTreeSet, HashMap};
 use std::fs::File;
 use std::io;
 use std::io::{Read, Seek, SeekFrom};
+use std::ops::Deref;
 use std::path::Path;
 use std::str::FromStr;
 use std::sync::RwLock;
@@ -96,7 +97,7 @@ pub fn wanted_file(
 pub fn scan_file(entry: &DirEntry, canonical_paths: bool) -> Result<Findings, ScanError> {
 	let path = entry.path();
 	// try to determine mimetype for this entry
-	let result = match mime_type(MIMEDB.get().unwrap(), path) {
+	let result = match mime_type(MIMEDB.deref(), path) {
 		// an error occurred while trying to read the file
 		Err(_) => return Err(ScanError::File(path)),
 		// the file was read successfully, but we were unable to determine its mimetype
diff --git a/src/lib.rs b/src/lib.rs
index 2e81396..2e27eb8 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -9,7 +9,7 @@ pub mod parameters;
 pub mod utils;
 
 use cfg_if::cfg_if;
-use once_cell::sync::OnceCell;
+use once_cell::sync::Lazy;
 
 use crate::findings::Findings;
 use crate::mime_db::MimeDb;
@@ -26,27 +26,10 @@ cfg_if! {
 
 cfg_if! {
 	if #[cfg(any(all(unix, feature = "infer-backend"), all(not(unix), not(feature = "xdg-mime-backend"))))] {
-		/// A [OnceCell] holding an instance of [mime_db::MimeDb].
-		pub static MIMEDB: OnceCell<mime_db::InferDb> = OnceCell::new();
+		/// A [Lazy] holding an instance of [mime_db::MimeDb].
+		pub static MIMEDB: Lazy<mime_db::InferDb> = Lazy::new(|| crate::mime_db::InferDb::init());
 	} else {
-		/// A [OnceCell] holding an instance of [mime_db::MimeDb].
-		pub static MIMEDB: OnceCell<mime_db::XdgDb> = OnceCell::new();
-	}
-}
-
-/// Initialises [`MIMEDB`] with a value dependent on the current backend.
-pub fn init_db() {
-	cfg_if! {
-		if #[cfg(any(all(unix, feature = "infer-backend"), all(not(unix), not(feature = "xdg-mime-backend"))))] {
-			MIMEDB
-				.set(crate::mime_db::InferDb::init())
-				.or(Err("Failed to initialise Infer backend!"))
-				.unwrap();
-		} else {
-			MIMEDB
-				.set(crate::mime_db::XdgDb::init())
-				.or(Err("Failed to initialise XDG Mime backend!"))
-				.unwrap();
-		}
+		/// A [Lazy] holding an instance of [mime_db::MimeDb].
+		pub static MIMEDB: Lazy<mime_db::XdgDb> = Lazy::new(|| crate::mime_db::XdgDb::init());
 	}
 }
diff --git a/src/main.rs b/src/main.rs
index ba53f94..a044c62 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -25,7 +25,7 @@ use fif::files::{scan_directory, scan_from_walkdir};
 use fif::formats::Format;
 use fif::parameters::OutputFormat;
 use fif::utils::{clap_long_version, os_name};
-use fif::{formats, init_db, parameters};
+use fif::{formats, parameters};
 use log::{debug, error, info, trace, warn, Level};
 
 #[cfg(test)]
@@ -58,8 +58,6 @@ fn main() {
 		std::env::consts::ARCH,
 		os_name()
 	);
-	trace!("Initialising mimetype database");
-	init_db();
 
 	debug!("Iterating directory: {:?}", args.dir);
 
diff --git a/src/tests/mod.rs b/src/tests/mod.rs
index 4160a44..5d23395 100644
--- a/src/tests/mod.rs
+++ b/src/tests/mod.rs
@@ -128,9 +128,6 @@ fn simple_directory() {
 	// there should be one file missing: "ignore.fake_ext"
 	assert_eq!(entries.len(), files.len() - 1);
 
-	// initialise global mime DB - this is needed because `scan_from_walkdir` expects it to be present.
-	crate::init_db();
-
 	let results = scan_from_walkdir(&entries, false);
 	let canonical_results = scan_from_walkdir(&entries, true);
 	assert_eq!(results.len(), canonical_results.len());