Bug 1802503 - Rust: Implement a rust dispatcher connected to GCD

.circleci/config.yml

@@ -83,6 +83,34 @@ commands:
             glean_parser coverage --allow-reserved -c glean_coverage.txt -f codecovio -o codecov.json glean-core/metrics.yaml
             bin/codecov.sh -X yaml -f codecov.json
 
+  test-rust-native-dispatcher:
+    steps:
+      - run:
+          name: Install required dependencies
+          command: |
+            sudo apt update
+            sudo apt install -y cmake ninja-build clang
+      - run:
+          name: Install libdispatch
+          command: |
+            cd ~
+            git clone https://github.com/apple/swift-corelibs-libdispatch
+            cd swift-corelibs-libdispatch
+            mkdir build && cd build
+            cmake -G Ninja \
+              -DCMAKE_C_COMPILER=clang \
+              -DCMAKE_CXX_COMPILER=clang++ \
+              -DCMAKE_BUILD_WITH_INSTALL_RPATH=On \
+              ..
+            ninja
+            sudo ninja install
+
+      - run:
+          name: Run Rust tests with native dispatcher
+          command: |
+            export LD_LIBRARY_PATH=/usr/local/lib
+            cargo test --verbose --jobs 6 --features native-dispatcher -- --nocapture
+
   install-rustup:
     steps:
       - run:
@@ -324,6 +352,7 @@ jobs:
     resource_class: "medium+"
     steps:
       - test-rust
+      - test-rust-native-dispatcher
 
   Rust tests - beta:
     docker:
@@ -528,6 +557,7 @@ jobs:
       - restore_cache:
           keys:
             - v2-cargo-cache-{{arch}}-{{checksum "buildtype.txt"}}-{{checksum "Cargo.lock"}}
+
       - run:
           name: Run iOS build
           command: bash bin/run-ios-build.sh

glean-core/Cargo.toml

@@ -46,13 +46,17 @@ uniffi_macros = "0.22.0"
 time = "0.1.40"
 remove_dir_all = "0.5.3"
 env_logger = { version = "0.9.0", default-features = false, optional = true }
+dispatch = { version = "0.2.0", optional = true }
 
 [target.'cfg(target_os = "android")'.dependencies]
 android_logger = { version = "0.11.0", default-features = false }
 
 [target.'cfg(target_os = "ios")'.dependencies]
 oslog = { version = "0.1.0", default-features = false, features = ["logger"] }
 
+[target.'cfg(any(target_os = "ios"))'.dependencies]
+dispatch = "0.2.0"
+
 [dev-dependencies]
 env_logger = { version = "0.9.0", default-features = false, features = ["termcolor", "atty", "humantime"] }
 tempfile = "3.1.0"
@@ -67,3 +71,5 @@ uniffi_build = { version = "0.22.0", features = ["builtin-bindgen"] }
 preinit_million_queue = []
 # Enable `env_logger`. Only works on non-Android non-iOS targets.
 enable_env_logger = ["env_logger"]
+# Use libdispatch, default on iOS
+native-dispatcher = ["dispatch"]

glean-core/rlb/Cargo.toml

@@ -46,3 +46,4 @@ flate2 = "1.0.19"
 
 [features]
 preinit_million_queue = ["glean-core/preinit_million_queue"]
+native-dispatcher = ["glean-core/native-dispatcher"]

glean-core/src/dispatcher/global.rs

@@ -2,10 +2,12 @@
 // License, v. 2.0. If a copy of the MPL was not distributed with this
 // file, You can obtain one at https://mozilla.org/MPL/2.0/.
 
-use once_cell::sync::Lazy;
 use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::Arc;
 use std::sync::RwLock;
 
+use once_cell::sync::Lazy;
+
 use super::{DispatchError, DispatchGuard, Dispatcher};
 
 #[cfg(feature = "preinit_million_queue")]
@@ -26,7 +28,7 @@ pub fn is_test_mode() -> bool {
 ///
 /// A dispatcher is cheap to create, so we create one on every access instead of caching it.
 /// This avoids troubles for tests where the global dispatcher _can_ change.
-fn guard() -> DispatchGuard {
+fn guard() -> Arc<DispatchGuard> {
     GLOBAL_DISPATCHER
         .read()
         .unwrap()
@@ -89,11 +91,7 @@ fn join_dispatcher_thread() -> Result<(), DispatchError> {
     let mut lock = GLOBAL_DISPATCHER.write().unwrap();
     let dispatcher = lock.as_mut().expect("Global dispatcher has gone missing");
 
-    if let Some(worker) = dispatcher.worker.take() {
-        return worker.join().map_err(|_| DispatchError::WorkerPanic);
-    }
-
-    Ok(())
+    dispatcher.join()
 }
 
 /// Kill the blocked dispatcher without processing the queue.