Move pthread_tryjoin_np to native code. NFC

src/library_pthread.js

@@ -879,42 +879,14 @@ var LibraryPThread = {
 #endif
   },
 
-  _emscripten_do_pthread_join__deps: ['$cleanupThread', 'pthread_testcancel', 'emscripten_main_thread_process_queued_calls', 'emscripten_futex_wait', 'pthread_self', 'emscripten_main_browser_thread_id',
+  __pthread_join_js__deps: ['$cleanupThread', 'pthread_testcancel', 'emscripten_main_thread_process_queued_calls', 'emscripten_futex_wait', 'pthread_self', 'emscripten_main_browser_thread_id',
 #if ASSERTIONS || IN_TEST_HARNESS || !MINIMAL_RUNTIME || !ALLOW_BLOCKING_ON_MAIN_THREAD
   'emscripten_check_blocking_allowed'
 #endif
   ],
-  _emscripten_do_pthread_join: function(thread, status, block) {
-    if (!thread) {
-      err('pthread_join attempted on a null thread pointer!');
-      return {{{ cDefine('ESRCH') }}};
-    }
-    var self = {{{ makeGetValue('thread', C_STRUCTS.pthread.self, 'i32') }}};
-    if (self !== thread) {
-      err('pthread_join attempted on thread 0x' + thread.toString(16) + ', which does not point to a valid thread, or does not exist anymore!');
-      return {{{ cDefine('ESRCH') }}};
-    }
-    var detach_state = Atomics.load(HEAPU32, (thread + {{{ C_STRUCTS.pthread.detach_state }}}) >> 2);
-    if (detach_state == {{{ cDefine('DT_DETACHED') }}}) {
-      err('Attempted to join thread 0x' + thread.toString(16) + ', which was already detached!');
-      return {{{ cDefine('EINVAL') }}}; // The thread is already detached, can no longer join it!
-    }
-
-    if (detach_state == {{{ cDefine('DT_EXITED') }}}) {
-      err('Attempted to join thread 0x' + thread.toString(16) + ', which was already joined!');
-      return {{{ cDefine('EINVAL') }}};
-    }
-    if (ENVIRONMENT_IS_PTHREAD && _pthread_self() == thread) {
-      err('PThread ' + thread + ' is attempting to join to itself!');
-      return {{{ cDefine('EDEADLK') }}};
-    }
-    else if (!ENVIRONMENT_IS_PTHREAD && _emscripten_main_browser_thread_id() == thread) {
-      err('Main thread ' + thread + ' is attempting to join to itself!');
-      return {{{ cDefine('EDEADLK') }}};
-    }
-
+  __pthread_join_js: function(thread, status, tryjoin) {
 #if ASSERTIONS || IN_TEST_HARNESS || !MINIMAL_RUNTIME || !ALLOW_BLOCKING_ON_MAIN_THREAD
-    if (block) {
+    if (!tryjoin) {
       _emscripten_check_blocking_allowed();
     }
 #endif
@@ -932,9 +904,6 @@ var LibraryPThread = {
         else postMessage({ 'cmd': 'cleanupThread', 'thread': thread });
         return 0;
       }
-      if (!block) {
-        return {{{ cDefine('EBUSY') }}};
-      }
       _pthread_testcancel();
       // In main runtime thread (the thread that initialized the Emscripten C
       // runtime and launched main()), assist pthreads in performing operations
@@ -944,16 +913,6 @@ var LibraryPThread = {
     }
   },
 
-  __pthread_join_js__deps: ['_emscripten_do_pthread_join'],
-  __pthread_join_js: function(thread, status) {
-    return __emscripten_do_pthread_join(thread, status, true);
-  },
-
-  pthread_tryjoin_np__deps: ['_emscripten_do_pthread_join'],
-  pthread_tryjoin_np: function(thread, status) {
-    return __emscripten_do_pthread_join(thread, status, false);
-  },
-
   pthread_kill__deps: ['$killThread', 'emscripten_main_browser_thread_id'],
   pthread_kill: function(thread, signal) {
     if (signal < 0 || signal >= 65/*_NSIG*/) return {{{ cDefine('EINVAL') }}};

system/lib/pthread/pthread_join.c

@@ -8,9 +8,39 @@
 #include "pthread_impl.h"
 #include <pthread.h>
 
-extern int __pthread_join_js(pthread_t thread, void **retval);
-int __pthread_join(pthread_t thread, void **retval) {
-  return __pthread_join_js(thread, retval);
+extern int __pthread_join_js(pthread_t t, void **res, int tryjoin);
+
+static int __pthread_join_internal(pthread_t t, void **res, int tryjoin) {
+  if (t->self != t) {
+    // attempt to join a thread which does not point to a valid thread, or does
+    // not exist anymore.
+    return ESRCH;
+  }
+  // TODO(sbc): IIUC __pthread_join_js currently doesn't handle the case
+  // when the thread becomes detached/joined *during* the join.  This pre-check
+  // can potentially be removed once it does.
+  int state = t->detach_state;
+  if (state == DT_DETACHED || state == DT_EXITED) {
+    // The thread is detached or already joined, and therefore not joinable
+    return EINVAL;
+  }
+  if (t == __pthread_self()) {
+    // thread is attempting to join to itself.
+    return EDEADLK;
+  }
+  return __pthread_join_js(t, res, tryjoin);
+}
+
+int __pthread_join(pthread_t t, void **res) {
+  return __pthread_join_internal(t, res, 0);
 }
+
+// Taken directly from system/lib/libc/musl/src/thread/pthread_join.c
+int __pthread_tryjoin_np(pthread_t t, void **res)
+{
+  return t->detach_state==DT_JOINABLE ? EBUSY : __pthread_join_internal(t, res, 1);
+}
+
 weak_alias(__pthread_join, emscripten_builtin_pthread_join);
+weak_alias(__pthread_tryjoin_np, pthread_tryjoin_np);
 weak_alias(__pthread_join, pthread_join);

tests/other/test_pthread_self_join_detach.c

@@ -4,14 +4,20 @@
 #include <stdio.h>
 #include <string.h>
 
+#ifdef __EMSCRIPTEN__
 #include <emscripten/threading.h>
+#endif
 
 int main() {
   /*
    * When running in PROXY_TO_PTHREAD mode the main thread
    * is already detached
    */
+#ifdef __EMSCRIPTEN__
   int is_detached = !emscripten_is_main_browser_thread();
+#else
+  int is_detached = 0;
+#endif
   pthread_t self = pthread_self();
 
   /*
@@ -20,6 +26,7 @@ int main() {
    * detached
    */
   int ret = pthread_join(self, NULL);
+  printf("pthread_join -> %s\n", strerror(ret));
   if (is_detached) {
     assert(ret == EINVAL);
   } else {
@@ -38,6 +45,10 @@ int main() {
     assert(ret == 0);
   }
 
+  ret = pthread_join(self, NULL);
+  printf("pthread_join -> %s\n", strerror(ret));
+  assert(ret == EINVAL);
+
   puts("passed");
 
   return 0;