mojo: kill app_thread before unloading main app library and add tests

mojo/shell/in_process_dynamic_service_runner.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "mojo/shell/in_process_dynamic_service_runner.h"
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop_proxy.h"
-#include "base/scoped_native_library.h"
 #include "mojo/public/platform/native/system_thunks.h"
 
 namespace mojo {
 namespace shell {
 
 InProcessDynamicServiceRunner::InProcessDynamicServiceRunner(
     Context* context)
     : keep_alive_(context),
       thread_(this, "app_thread") {
 }
@@ skipping 23 matching lines @@
   DCHECK(!thread_.HasBeenStarted());
   thread_.Start();
 }
 
 void InProcessDynamicServiceRunner::Run() {
   DVLOG(2) << "Loading/running Mojo app in process from library: "
            << app_path_.value();
 
   do {
     base::NativeLibraryLoadError error;
-    base::ScopedNativeLibrary app_library(
-        base::LoadNativeLibrary(app_path_, &error));
-    if (!app_library.is_valid()) {
+    app_library_.Reset(base::LoadNativeLibrary(app_path_, &error));
+    if (!app_library_.is_valid()) {
       LOG(ERROR) << "Failed to load app library (error: " << error.ToString()
                  << ")";
       break;
     }
 
     MojoSetSystemThunksFn mojo_set_system_thunks_fn =
-        reinterpret_cast<MojoSetSystemThunksFn>(app_library.GetFunctionPointer(
+        reinterpret_cast<MojoSetSystemThunksFn>(app_library_.GetFunctionPointer(
             "MojoSetSystemThunks"));
     if (mojo_set_system_thunks_fn) {
       MojoSystemThunks system_thunks = MojoMakeSystemThunks();
       size_t expected_size = mojo_set_system_thunks_fn(&system_thunks);
       if (expected_size > sizeof(MojoSystemThunks)) {
         LOG(ERROR)
             << "Invalid app library: expected MojoSystemThunks size: "
             << expected_size;
         break;
       }
     } else {
       // In the component build, Mojo Apps link against mojo_system_impl.
 #if !defined(COMPONENT_BUILD)
       // Strictly speaking this is not required, but it's very unusual to have
       // an app that doesn't require the basic system library.
       LOG(WARNING) << "MojoSetSystemThunks not found in app library";
 #endif
     }
 
     typedef MojoResult (*MojoMainFunction)(MojoHandle);
     MojoMainFunction main_function = reinterpret_cast<MojoMainFunction>(
-        app_library.GetFunctionPointer("MojoMain"));
+        app_library_.GetFunctionPointer("MojoMain"));
     if (!main_function) {
       LOG(ERROR) << "Entrypoint MojoMain not found";
       break;
     }
 
     // |MojoMain()| takes ownership of the service handle.
     MojoResult result = main_function(service_handle_.release().value());
     if (result < MOJO_RESULT_OK)
       LOG(ERROR) << "MojoMain returned an error: " << result;
+ // TODO(tim): Remove this ugly hack.

[darin (slow to review), 2014/07/19 21:18:00]

nit: can you explain what this ugly hack is achieving? it is not obvious.

[tim (not reviewing), 2014/07/19 21:59:42]

Sorry about that. What was happening was:

What's happening here is
* chromium-based apps like network_service have their own copy of base
* binding the shell_handle in MojoMains spins up a HandleWatcher
thread which registers some TLS data
* the destructor for that data points to a function in copy 2 of base::
* the app finishes up
* dlclose() the DSO (bye bye copy 2 of base)
* thread exits, kaboom

For shared library builds this was actually working because the pointer to the
static base:: function is still mapped. For static builds, it's gone.  If we do
*not* Reset the library here and let the thread terminate first, all is good.

I called it an "ugly hack" because of the #ifdef COMPONENT_BUILD... but as
discussed offline perhaps this is what we should do in all cases. I can see if I
can clean things up with that in mind.

+#if defined(COMPONENT_BUILD)
+    app_library_.Reset(base::NativeLibrary());
+#endif
   } while (false);
 
   bool success = app_completed_callback_runner_.Run();
   app_completed_callback_runner_.Reset();
   LOG_IF(ERROR, !success) << "Failed post run app_completed_callback";
 }
 
 }  // namespace shell
 }  // namespace mojo