Add installer::SetupSingleton.

chrome/installer/setup/setup_singleton.cc

Index: chrome/installer/setup/setup_singleton.cc
diff --git a/chrome/installer/setup/setup_singleton.cc b/chrome/installer/setup/setup_singleton.cc
new file mode 100644
index 0000000000000000000000000000000000000000..f6c02431a6ce7a8279505368b7b121381404a7d0
--- /dev/null
+++ b/chrome/installer/setup/setup_singleton.cc
@@ -0,0 +1,113 @@
+// Copyright 2016 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 "chrome/installer/setup/setup_singleton.h"
+
+#include "base/files/file_path.h"
+#include "base/logging.h"
+#include "base/numerics/safe_conversions.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/time/time.h"
+#include "chrome/installer/util/installation_state.h"
+#include "chrome/installer/util/installer_state.h"
+
+namespace installer {
+
+std::unique_ptr<SetupSingleton> SetupSingleton::Acquire(
+    const base::CommandLine& command_line,
+    const MasterPreferences& master_preferences,
+    InstallerState* installer_state,
+    InstallationState* original_state) {
+  DCHECK(installer_state);
+  DCHECK(original_state);
+
+  const base::string16 sync_primitive_name_suffix(
+      base::SizeTToString16(std::hash<base::FilePath::StringType>()(
+          installer_state->target_path().value())));
+
+  std::unique_ptr<SetupSingleton> setup_singleton(
+      new SetupSingleton(sync_primitive_name_suffix));
+
+  // This mutex is acquired before signaling |exit_event_| and released after
+  // acquiring |setup_mutex_|. It ensures that a single thread signals
+  // |exit_event_| and waits for |setup_mutex_| to be released at a time.
+  base::win::ScopedHandle exit_event_mutex(::CreateMutex(
+      nullptr, FALSE,
+      (L"Global\\ChromeSetupExitEventMutex_" + sync_primitive_name_suffix)
+          .c_str()));
+  DCHECK(exit_event_mutex.IsValid());
+
+  // Signal |exit_event_|. This causes any call to Wait() on a SetupSingleton

[grt (UTC plus 2), 2016/09/01 12:05:39]

this comment applies to line 48, no? please move it down there.

[fdoray, 2016/09/01 15:45:22]

Done.

+  // bound to the same Chrome installation as |setup_singleton| to return
+  // immediately.
+  std::unique_ptr<ScopedHoldMutex> scoped_hold_exit_event_mutex(

[grt (UTC plus 2), 2016/09/01 12:05:39]

rather than using a unique_ptr that you release() below, how about putting this
in its own block?
    {
      ScopedHoldMutex scoped_hold_exit_event_mutex;
      if (!scoped_hold_exit_event_mutex.Acquire(...))
        return nullptr;
       ...
    }

[fdoray, 2016/09/01 15:45:22]

Done.

+      new ScopedHoldMutex);
+  if (!scoped_hold_exit_event_mutex->Acquire(exit_event_mutex.Get()))
+    return nullptr;
+  setup_singleton->exit_event_.Signal();
+
+  // Acquire |setup_mutex_|.
+  if (!setup_singleton->scoped_hold_setup_mutex_.Acquire(
+          setup_singleton->setup_mutex_.Get())) {
+    return nullptr;
+  }
+  setup_singleton->exit_event_.Reset();
+  scoped_hold_exit_event_mutex.reset(nullptr);
+
+  // Update |installer_state| and |original_state|.

[grt (UTC plus 2), 2016/09/01 12:05:39]

nit: swap these in the comment so that they match the order in the code.

[fdoray, 2016/09/01 15:45:23]

Done.

+  original_state->Initialize();
+  installer_state->Initialize(command_line, master_preferences,
+                              *original_state);
+
+  return setup_singleton;
+}
+
+SetupSingleton::~SetupSingleton() {
+  ::ReleaseMutex(setup_mutex_.Get());

[grt (UTC plus 2), 2016/09/01 12:05:39]

remove this? doesn't scoped_hold_setup_mutex_ auto-release?

[fdoray, 2016/09/01 15:45:23]

Done.

+}
+
+bool SetupSingleton::Wait(const base::TimeDelta& max_time) {
+  const bool exit_event_signaled = exit_event_.TimedWait(max_time);
+  return exit_event_signaled;
+}
+
+SetupSingleton::ScopedHoldMutex::ScopedHoldMutex() = default;
+
+SetupSingleton::ScopedHoldMutex::~ScopedHoldMutex() {
+  if (mutex_ != INVALID_HANDLE_VALUE)
+    ::ReleaseMutex(mutex_);
+}
+
+bool SetupSingleton::ScopedHoldMutex::Acquire(HANDLE mutex) {
+  DCHECK_NE(INVALID_HANDLE_VALUE, mutex);
+  DCHECK_EQ(INVALID_HANDLE_VALUE, mutex_);
+
+  const DWORD wait_return_value = ::WaitForSingleObject(
+      mutex, base::saturated_cast<DWORD>(

[grt (UTC plus 2), 2016/09/01 12:05:39]

since you control the input, i think a static_cast is fine here. saturated_cast
is better for cases where the input is from an untrusted source.

[fdoray, 2016/09/01 15:45:23]

Done.

+                 base::TimeDelta::FromSeconds(30).InMilliseconds()));
+  if (wait_return_value == WAIT_ABANDONED ||
+      wait_return_value == WAIT_OBJECT_0) {
+    mutex_ = mutex;
+    return true;
+  }
+
+  DCHECK_EQ(static_cast<DWORD>(WAIT_TIMEOUT), wait_return_value);

[grt (UTC plus 2), 2016/09/01 12:05:39]

if you change this this to:
  DPCHECK(wait_return_value != WAIT_FAILED);
then the logging magic will include a friendly string for the last-error code.

[fdoray, 2016/09/01 15:45:23]

Done.

+  return false;
+}
+
+SetupSingleton::SetupSingleton(const base::string16& sync_primitive_name_suffix)
+    : setup_mutex_(::CreateMutex(
+          nullptr,
+          FALSE,
+          (L"Global\\ChromeSetupMutex_" + sync_primitive_name_suffix).c_str())),
+      exit_event_(base::win::ScopedHandle(::CreateEvent(
+          nullptr,
+          TRUE,
+          FALSE,
+          (L"Global\\ChromeSetupExitEvent_" + sync_primitive_name_suffix)
+              .c_str()))) {
+  DCHECK(setup_mutex_.IsValid());
+}
+
+}  // namespace installer