Bug 1638927 - Replace `lazy_static` with `once_cell` in XULStore. r=froydnj

TSan returns false positives for `lazy_static`. While we could
blocklist it, `once_cell` has equivalent functionality, but with a more
modern API, so let's use it instead.

Depends on D75864

Differential Revision: https://phabricator.services.mozilla.com/D76342

Cargo.lock

@@ -5790,13 +5790,13 @@ dependencies = [
  "crossbeam-utils 0.6.5",
  "cstr",
  "failure",
- "lazy_static",
  "libc",
  "lmdb-rkv",
  "log",
  "moz_task",
  "nserror",
  "nsstring",
+ "once_cell",
  "rkv 0.10.4",
  "serde_json",
  "tempfile",

toolkit/components/xulstore/Cargo.toml

@@ -7,13 +7,13 @@ license = "MPL-2.0"
 [dependencies]
 crossbeam-utils = "0.6.3"
 cstr = "0.1"
-lazy_static = "1.0"
 libc = "0.2"
 lmdb-rkv = "0.14"
 log = "0.4"
 moz_task = { path = "../../../xpcom/rust/moz_task" }
 nsstring = { path = "../../../xpcom/rust/nsstring" }
 nserror = { path = "../../../xpcom/rust/nserror" }
+once_cell = "1"
 rkv = "0.10.2"
 serde_json = "1"
 tempfile = "3"

toolkit/components/xulstore/src/lib.rs

@@ -7,8 +7,6 @@ extern crate crossbeam_utils;
 extern crate cstr;
 #[macro_use]
 extern crate failure;
-#[macro_use]
-extern crate lazy_static;
 extern crate libc;
 extern crate lmdb;
 #[macro_use]
@@ -16,6 +14,7 @@ extern crate log;
 extern crate moz_task;
 extern crate nserror;
 extern crate nsstring;
+extern crate once_cell;
 extern crate rkv;
 extern crate serde_json;
 extern crate tempfile;

toolkit/components/xulstore/src/persist.rs

@@ -22,29 +22,29 @@ use crossbeam_utils::atomic::AtomicCell;
 use lmdb::Error as LmdbError;
 use moz_task::{dispatch_background_task_with_options, DispatchOptions, Task, TaskRunnable};
 use nserror::nsresult;
+use once_cell::sync::Lazy;
 use rkv::{StoreError as RkvStoreError, Value};
 use std::{collections::HashMap, sync::Mutex, thread::sleep, time::Duration};
 use xpcom::RefPtr;
 
-lazy_static! {
-    /// A map of key/value pairs to persist.  Values are Options so we can
-    /// use the same structure for both puts and deletes, with a `None` value
-    /// identifying a key that should be deleted from the database.
-    ///
-    /// This is a map rather than a sequence in order to merge consecutive
-    /// changes to the same key, i.e. when a consumer sets *foo* to `bar`
-    /// and then sets it again to `baz` before we persist the first change.
-    ///
-    /// In that case, there's no point in setting *foo* to `bar` before we set
-    /// it to `baz`, and the map ensures we only ever persist the latest value
-    /// for any given key.
-    static ref CHANGES: Mutex<Option<HashMap<String, Option<String>>>> = { Mutex::new(None) };
+/// A map of key/value pairs to persist.  Values are Options so we can
+/// use the same structure for both puts and deletes, with a `None` value
+/// identifying a key that should be deleted from the database.
+///
+/// This is a map rather than a sequence in order to merge consecutive
+/// changes to the same key, i.e. when a consumer sets *foo* to `bar`
+/// and then sets it again to `baz` before we persist the first change.
+///
+/// In that case, there's no point in setting *foo* to `bar` before we set
+/// it to `baz`, and the map ensures we only ever persist the latest value
+/// for any given key.
+static CHANGES: Lazy<Mutex<Option<HashMap<String, Option<String>>>>> =
+    Lazy::new(|| Mutex::new(None));
 
-    /// A Mutex that prevents two PersistTasks from running at the same time,
-    /// since each task opens the database, and we need to ensure there is only
-    /// one open database handle for the database at any given time.
-    static ref PERSIST: Mutex<()> = { Mutex::new(()) };
-}
+/// A Mutex that prevents two PersistTasks from running at the same time,
+/// since each task opens the database, and we need to ensure there is only
+/// one open database handle for the database at any given time.
+static PERSIST: Lazy<Mutex<()>> = Lazy::new(|| Mutex::new(()));
 
 /// Synchronously persists changes recorded in memory to disk. Typically
 /// called from a background thread, however this can be called from the main

toolkit/components/xulstore/src/statics.rs

@@ -10,6 +10,7 @@ use crate::{
 use lmdb::Error as LmdbError;
 use moz_task::is_main_thread;
 use nsstring::nsString;
+use once_cell::sync::Lazy;
 use rkv::{migrate::Migrator, Rkv, SingleStore, StoreError, StoreOptions, Value};
 use std::{
     collections::BTreeMap,
@@ -34,14 +35,13 @@ impl Database {
     }
 }
 
-lazy_static! {
-    static ref PROFILE_DIR: Mutex<Option<PathBuf>> = {
-        observe_profile_change();
-        Mutex::new(get_profile_dir().ok())
-    };
-    pub(crate) static ref DATA_CACHE: Mutex<Option<XULStoreCache>> =
-        { Mutex::new(cache_data().ok()) };
-}
+static PROFILE_DIR: Lazy<Mutex<Option<PathBuf>>> = Lazy::new(|| {
+    observe_profile_change();
+    Mutex::new(get_profile_dir().ok())
+});
+
+pub(crate) static DATA_CACHE: Lazy<Mutex<Option<XULStoreCache>>> =
+    Lazy::new(|| Mutex::new(cache_data().ok()));
 
 pub(crate) fn get_database() -> XULStoreResult<Database> {
     let xulstore_dir = get_xulstore_dir()?;