Count threads at shutdown and warn if not all finished

Cargo.lock

@@ -3210,6 +3210,7 @@ version = "0.0.1"
 dependencies = [
  "backtrace 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "bitflags 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cc 1.0.18 (registry+https://github.com/rust-lang/crates.io-index)",
  "crossbeam-channel 0.2.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "euclid 0.19.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "gdi32-sys 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",

components/config/opts.rs

@@ -226,6 +226,9 @@ pub struct Opts {
 
     /// Print Progressive Web Metrics to console.
     pub print_pwm: bool,
+
+    /// Only shutdown once all theads are finished.
+    pub clean_shutdown: bool,
 }
 
 fn print_usage(app: &str, opts: &Options) {
@@ -600,6 +603,7 @@ pub fn default_opts() -> Opts {
         certificate_path: None,
         unminify_js: false,
         print_pwm: false,
+        clean_shutdown: false,
     }
 }
 
@@ -752,6 +756,11 @@ pub fn from_cmdline_args(args: &[String]) -> ArgumentParsingResult {
         "config directory following xdg spec on linux platform",
         "",
     );
+    opts.optflag(
+        "",
+        "clean-shutdown",
+        "Do not shutdown until all threads have finished (macos only)",
+    );
     opts.optflag("v", "version", "Display servo version information");
     opts.optflag("", "unminify-js", "Unminify Javascript");
     opts.optopt("", "profiler-db-user", "Profiler database user", "");
@@ -1035,6 +1044,7 @@ pub fn from_cmdline_args(args: &[String]) -> ArgumentParsingResult {
         certificate_path: opt_match.opt_str("certificate-path"),
         unminify_js: opt_match.opt_present("unminify-js"),
         print_pwm: opt_match.opt_present("print-pwm"),
+        clean_shutdown: opt_match.opt_present("clean-shutdown"),
     };
 
     set_defaults(opts);

ports/servo/Cargo.toml

@@ -16,6 +16,9 @@ bench = false
 [target.'cfg(windows)'.build-dependencies]
 winres = "0.1"
 
+[target.'cfg(target_os = "macos")'.build-dependencies]
+cc = "1.0"
+
 [package.metadata.winres]
 FileDescription = "Servo"
 LegalCopyright = "© The Servo Project Developers"

ports/servo/build.rs

@@ -2,6 +2,9 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+#[cfg(target_os = "macos")]
+extern crate cc;
+
 #[cfg(windows)]
 extern crate winres;
 
@@ -13,4 +16,10 @@ fn main() {
         res.set_manifest_file("platform/windows/servo.exe.manifest");
         res.compile().unwrap();
     }
+    #[cfg(target_os = "macos")]
+    {
+        cc::Build::new()
+            .file("platform/macos/count_threads.c")
+            .compile("count_threads");
+    }
 }

ports/servo/platform/macos/count_threads.c

@@ -0,0 +1,13 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <mach/mach.h>
+
+int macos_count_running_threads() {
+  task_t task = current_task();
+  thread_act_array_t threads;
+  mach_msg_type_number_t tcnt;
+  task_threads(task, &threads, &tcnt);
+  return tcnt;
+}

ports/servo/platform/macos/mod.rs

@@ -2,7 +2,10 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+use servo::config::opts;
 use std::ptr;
+use std::thread;
+use std::time::Duration;
 
 pub fn deinit() {
     // An unfortunate hack to make sure the linker's dead code stripping doesn't strip our
@@ -10,9 +13,36 @@ pub fn deinit() {
     unsafe {
         ptr::read_volatile(&INFO_PLIST[0]);
     }
+
+    let thread_count = unsafe {
+        macos_count_running_threads()
+    };
+
+    if thread_count != 1 {
+        println!("{} threads are still running after shutdown (bad).", thread_count);
+        if opts::get().clean_shutdown {
+            println!("Waiting until all threads have shutdown");
+            loop {
+                let thread_count = unsafe {
+                    macos_count_running_threads()
+                };
+                if thread_count == 1 {
+                    break;
+                }
+                thread::sleep(Duration::from_millis(1000));
+                println!("{} threads are still running.", thread_count);
+            }
+        }
+    } else {
+        println!("All threads have shutdown (good).");
+    }
 }
 
-#[cfg(target_os = "macos")]
 #[link_section = "__TEXT,__info_plist"]
 #[no_mangle]
 pub static INFO_PLIST: [u8; 619] = *include_bytes!("Info.plist");
+
+#[link(name = "count_threads")]
+extern {
+    fn macos_count_running_threads() -> i32;
+}