Use base::Thread instead of single-threaded SequencedWorkerPool in TestLauncher.

base/test/launcher/test_launcher.cc

 // Copyright 2013 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 "base/test/launcher/test_launcher.h"
 
 #include <memory>
 
 #include "base/at_exit.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/environment.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/files/scoped_file.h"
 #include "base/format_macros.h"
 #include "base/hash.h"
 #include "base/lazy_instance.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/macros.h"
+#include "base/memory/ptr_util.h"
 #include "base/message_loop/message_loop.h"
 #include "base/process/kill.h"
 #include "base/process/launch.h"
 #include "base/run_loop.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/pattern.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringize_macros.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/test/gtest_util.h"
 #include "base/test/launcher/test_launcher_tracer.h"
 #include "base/test/launcher/test_results_tracker.h"
 #include "base/test/sequenced_worker_pool_owner.h"
 #include "base/test/test_switches.h"
 #include "base/test/test_timeouts.h"
+#include "base/threading/thread.h"
 #include "base/threading/thread_checker.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/time/time.h"
 #include "build/build_config.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 #if defined(OS_POSIX)
 #include <fcntl.h>
 #endif
 
@@ skipping 516 matching lines @@
 
   // Record the exact command line used to launch the child.
   CommandLine new_command_line(
       PrepareCommandLineForGTest(command_line, wrapper));
 
   // When running in parallel mode we need to redirect stdio to avoid mixed-up
   // output. We also always redirect on the bots to get the test output into
   // JSON summary.
   bool redirect_stdio = (parallel_jobs_ > 1) || BotModeEnabled();
 
-  worker_pool_owner_->pool()->PostWorkerTask(
+  GetTaskRunner()->PostTask(
       FROM_HERE,
       Bind(&DoLaunchChildTestProcess, new_command_line, timeout, options,
            redirect_stdio, RetainedRef(ThreadTaskRunnerHandle::Get()),
            Bind(&TestLauncher::OnLaunchTestProcessFinished, Unretained(this),
                 completed_callback),
            launched_callback));
 }
 
 void TestLauncher::OnTestFinished(const TestResult& result) {
   ++test_finished_count_;
@@ skipping 207 matching lines @@
   } else if (!command_line->HasSwitch(kGTestFilterFlag) || BotModeEnabled()) {
     // Retry failures 3 times by default if we are running all of the tests or
     // in bot mode.
     retry_limit_ = 3;
   }
 
   if (command_line->HasSwitch(switches::kTestLauncherForceRunBrokenTests))
     force_run_broken_tests_ = true;
 
   if (command_line->HasSwitch(switches::kTestLauncherJobs)) {
-    int jobs = -1;
-    if (!StringToInt(command_line->GetSwitchValueASCII(
+    size_t jobs = 0U;
+    if (!StringToSizeT(command_line->GetSwitchValueASCII(
                          switches::kTestLauncherJobs), &jobs) ||
-        jobs < 0) {
+        !jobs) {
       LOG(ERROR) << "Invalid value for " << switches::kTestLauncherJobs;
       return false;
     }
 
     parallel_jobs_ = jobs;
   } else if (command_line->HasSwitch(kGTestFilterFlag) && !BotModeEnabled()) {
     // Do not run jobs in parallel by default if we are running a subset of
     // the tests and if bot mode is off.
-    parallel_jobs_ = 1;
+    parallel_jobs_ = 1U;
   }
 
   fprintf(stdout, "Using %" PRIuS " parallel jobs.\n", parallel_jobs_);
   fflush(stdout);
-  worker_pool_owner_.reset(
-      new SequencedWorkerPoolOwner(parallel_jobs_, "test_launcher"));
+  if (parallel_jobs_ > 1U) {
+    worker_pool_owner_ = MakeUnique<SequencedWorkerPoolOwner>(
+        parallel_jobs_, "test_launcher");
+  } else {
+    worker_thread_ = MakeUnique<Thread>("test_launcher");
+    worker_thread_->Start();
+  }
 
   if (command_line->HasSwitch(switches::kTestLauncherFilterFile) &&
       command_line->HasSwitch(kGTestFilterFlag)) {
     LOG(ERROR) << "Only one of --test-launcher-filter-file and --gtest_filter "
                << "at a time is allowed.";
     return false;
   }
 
   if (command_line->HasSwitch(switches::kTestLauncherFilterFile)) {
     base::FilePath filter_file_path = base::MakeAbsoluteFilePath(
@@ skipping 273 matching lines @@
     fprintf(stdout, "\t%s\n", i->second.GetCommandLineString().c_str());
 #endif
   }
 
   fflush(stdout);
 
   // Arm the timer again - otherwise it would fire only once.
   watchdog_timer_.Reset();
 }
 
+scoped_refptr<TaskRunner> TestLauncher::GetTaskRunner() {
+  if (worker_pool_owner_) {
+    DCHECK(!worker_thread_);

[danakj, 2016/09/16 17:52:48]

nit: how about instead at the top of this method:

DCHECK_NE(!!worker_pool_owner_, !!worker_thread_);

[gab, 2016/09/16 18:09:29]

Nice trick :-), done.

+    return worker_pool_owner_->pool();
+  }
+  DCHECK(worker_thread_);
+  DCHECK(worker_thread_->IsRunning());
+  return worker_thread_->task_runner();
+}
+
 std::string GetTestOutputSnippet(const TestResult& result,
                                  const std::string& full_output) {
   size_t run_pos = full_output.find(std::string("[ RUN      ] ") +
                                     result.full_name);
   if (run_pos == std::string::npos)
     return std::string();
 
   size_t end_pos = full_output.find(std::string("[  FAILED  ] ") +
                                     result.full_name,
                                     run_pos);
@@ skipping 12 matching lines @@
   }
 
   std::string snippet(full_output.substr(run_pos));
   if (end_pos != std::string::npos)
     snippet = full_output.substr(run_pos, end_pos - run_pos);
 
   return snippet;
 }
 
 }  // namespace base