Pepper: Narrow locking at ld subprocess start.

Currently, subprocess_mu_ is held the entire time the ld subprocess is
starting. This blocks a larger refactor that I'd like to make as part of nexe
loading.

I'd like to change ServiceRuntime::LoadModule() to be asynchronous to simplify
threading behavior on the plugin side when loading nexe modules. However, this
requires that many methods are made asynchronous, including
Plugin::LoadHelperNaClModule().

PnaclTranslateThread will need to use a pattern similar to WaitForSelLdrStart()
to resume execution on a background thread. However, I don't like the idea of
introducing another mutex and condvar to deal with while holding
subprocess_mu_.

This change narrows the time that subprocess_mu_ is held to make that refactor
possible. This follows a similar change made for the llc subprocess.

BUG=333950
R=bbudge@chromium.org

Review URL: https://codereview.chromium.org/308193004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@274557 0039d316-1c4b-4281-b951-d872f2087c98

ppapi/native_client/src/trusted/plugin/pnacl_translate_thread.cc

@@ -339,29 +339,38 @@ bool PnaclTranslateThread::RunLdSubprocess() {
 
   nacl::DescWrapper* ld_out_file = nexe_file_->write_wrapper();
   pp::Core* core = pp::Module::Get()->core();
+  int64_t ld_start_time = NaClGetTimeOfDayMicroseconds();
+  PP_FileHandle ld_file_handle = resources_->TakeLdFileHandle();
+  // On success, ownership of ld_file_handle is transferred.
+  nacl::scoped_ptr<NaClSubprocess> ld_subprocess(
+      plugin_->LoadHelperNaClModule(resources_->GetLlcUrl(),
+                                    ld_file_handle,
+                                    &error_info));
+  if (ld_subprocess.get() == NULL) {
+    if (ld_file_handle != PP_kInvalidFileHandle)
+      CloseFileHandle(ld_file_handle);
+    TranslateFailed(PP_NACL_ERROR_PNACL_LD_SETUP,
+                    "Link process could not be created: " +
+                    error_info.message());
+    return false;
+  }
+  core->CallOnMainThread(0,
+                         coordinator_->GetUMATimeCallback(
+                             "NaCl.Perf.PNaClLoadTime.LoadLinker",
+                             NaClGetTimeOfDayMicroseconds() - ld_start_time),
+                         PP_OK);
+
   {
-    // Create LD process
     nacl::MutexLocker ml(&subprocess_mu_);
-    int64_t ld_start_time = NaClGetTimeOfDayMicroseconds();
-    PP_FileHandle ld_file_handle = resources_->TakeLdFileHandle();
-
-    // On success, ownership of ld_file_handle is transferred.
-    ld_subprocess_.reset(plugin_->LoadHelperNaClModule(
-        resources_->GetLdUrl(), ld_file_handle, &error_info));
-    if (ld_subprocess_ == NULL) {
-      if (ld_file_handle != PP_kInvalidFileHandle)
-        CloseFileHandle(ld_file_handle);
-      TranslateFailed(PP_NACL_ERROR_PNACL_LD_SETUP,
-                      "Link process could not be created: " +
-                      error_info.message());
+    // If we received a call to AbortSubprocesses() before we had a chance to
+    // set llc_subprocess_, shut down and clean up the subprocess started here.
+    if (subprocesses_aborted_) {
+      ld_subprocess->service_runtime()->Shutdown();
       return false;
     }
+    DCHECK(ld_subprocess_.get() == NULL);
+    ld_subprocess_.swap(ld_subprocess);
     ld_subprocess_active_ = true;
-    core->CallOnMainThread(0,
-                           coordinator_->GetUMATimeCallback(
-                               "NaCl.Perf.PNaClLoadTime.LoadLinker",
-                               NaClGetTimeOfDayMicroseconds() - ld_start_time),
-                           PP_OK);
   }
 
   int64_t link_start_time = NaClGetTimeOfDayMicroseconds();