Improve exit logic. NFC

- Don't call `exitRuntime()` when `ENVIRONMENT_IS_PTHREAD` is true.
- Remove the early return from `exitRuntime()`.
- Rework if/else statements in `$exitJS()`.

Author: kleisauke

src/library.js

@@ -68,28 +68,29 @@ mergeInto(LibraryManager.library, {
 #endif // ASSERTIONS && !EXIT_RUNTIME
 
 #if USE_PTHREADS
-    if (!implicit) {
-      if (ENVIRONMENT_IS_PTHREAD) {
+    if (ENVIRONMENT_IS_PTHREAD) {
+#if ASSERTIONS
+      assert(!implicit, "exit should never be called implicitly in a pthread");
+#endif
 #if PTHREADS_DEBUG
-        err('Pthread 0x' + _pthread_self().toString(16) + ' called exit(), posting exitOnMainThread.');
-#endif
-        // When running in a pthread we propagate the exit back to the main thread
-        // where it can decide if the whole process should be shut down or not.
-        // The pthread may have decided not to exit its own runtime, for example
-        // because it runs a main loop, but that doesn't affect the main thread.
-        exitOnMainThread(status);
-        throw 'unwind';
-      } else {
+      err('Pthread 0x' + _pthread_self().toString(16) + ' called exit(), posting exitOnMainThread.');
+#endif
+      // When running in a pthread we propagate the exit back to the main thread
+      // where it can decide if the whole process should be shut down or not.
+      // The pthread may have decided not to exit its own runtime, for example
+      // because it runs a main loop, but that doesn't affect the main thread.
+      exitOnMainThread(status);
+      throw 'unwind';
 #if PTHREADS_DEBUG
+    } else if (!implicit) {
 #if EXIT_RUNTIME
-        err('main thread called exit: keepRuntimeAlive=' + keepRuntimeAlive() + ' (counter=' + runtimeKeepaliveCounter + ')');
+      err('main thread called exit: keepRuntimeAlive=' + keepRuntimeAlive() + ' (counter=' + runtimeKeepaliveCounter + ')');
 #else
-        err('main thread called exit: keepRuntimeAlive=' + keepRuntimeAlive());
-#endif
-#endif
-      }
+      err('main thread called exit: keepRuntimeAlive=' + keepRuntimeAlive());
+#endif // EXIT_RUNTIME
+#endif // PTHREADS_DEBUG
     }
-#endif
+#endif // USE_PTHREADS
 
 #if EXIT_RUNTIME
     if (!keepRuntimeAlive()) {
@@ -100,10 +101,10 @@ mergeInto(LibraryManager.library, {
 #if ASSERTIONS
     // if exit() was called explicitly, warn the user if the runtime isn't actually being shut down
     if (keepRuntimeAlive() && !implicit) {
-#if !EXIT_RUNTIME
-      var msg = 'program exited (with status: ' + status + '), but EXIT_RUNTIME is not set, so halting execution but not exiting the runtime or preventing further async execution (build with EXIT_RUNTIME=1, if you want a true shutdown)';
-#else
+#if EXIT_RUNTIME
       var msg = 'program exited (with status: ' + status + '), but keepRuntimeAlive() is set (counter=' + runtimeKeepaliveCounter + ') due to an async operation, so halting execution but not exiting the runtime or preventing further async execution (you can use emscripten_force_exit, if you want to force a true shutdown)';
+#else
+      var msg = 'program exited (with status: ' + status + '), but EXIT_RUNTIME is not set, so halting execution but not exiting the runtime or preventing further async execution (build with EXIT_RUNTIME=1, if you want a true shutdown)';
 #endif // EXIT_RUNTIME
 #if MODULARIZE
       readyPromiseReject(msg);

src/preamble.js

@@ -295,9 +295,6 @@ function exitRuntime() {
 #if STACK_OVERFLOW_CHECK
   checkStackCookie();
 #endif
-#if USE_PTHREADS
-  if (ENVIRONMENT_IS_PTHREAD) return; // PThreads reuse the runtime from the main thread.
-#endif
 #if !STANDALONE_WASM
   ___funcs_on_exit(); // Native atexit() functions
 #endif

src/worker.js

@@ -266,7 +266,7 @@ self.onmessage = (e) => {
           }
 #if ASSERTIONS
         } else {
-          // else e == 'unwind', and we should fall through here and keep the pthread alive for asynchronous events.
+          // else ex == 'unwind', and we should fall through here and keep the pthread alive for asynchronous events.
           err('Pthread 0x' + Module['_pthread_self']().toString(16) + ' completed its main entry point with an `unwind`, keeping the worker alive for asynchronous operation.');
 #endif
         }