src/cobalt/h5vcc/h5vcc_crash_log.cc

// Copyright 2017 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "cobalt/h5vcc/h5vcc_crash_log.h"

#include <map>
#include <string>

#include "base/atomicops.h"
#include "base/memory/singleton.h"
#include "base/synchronization/lock.h"

// Unfortunately, the Starboard interface is still experimental and supported
// only on the PS4 for now.
#include "starboard/ps4/core_dump_handler.h"

#include "starboard/system.h"

namespace cobalt {
namespace h5vcc {

// We keep a global mapping of all registered logs.  When a crash occurs, we
// will iterate through the mapping in this dictionary to extract all
// logged entries and write them to the system's crash logger via Starboard.
class CrashLogDictionary {
 public:
  static CrashLogDictionary* GetInstance() {
    return Singleton<CrashLogDictionary,
                     LeakySingletonTraits<CrashLogDictionary> >::get();
  }

  void SetString(const std::string& key, const std::string& value) {
    base::AutoLock lock(mutex_);
    // While the lock prevents contention between other calls to SetString(),
    // the atomics guard against OnCrash(), which doesn't acquire |mutex_|, from
    // accessing the data at the same time.  In the case that OnCrash() is
    // being called, we give up and skip adding the data.
    if (base::subtle::Acquire_CompareAndSwap(&accessing_log_data_, 0, 1) == 0) {
      string_log_map_[key] = value;
      base::subtle::Release_Store(&accessing_log_data_, 0);
    }
  }

 private:
  CrashLogDictionary() : accessing_log_data_(0) {
    SbCoreDumpRegisterHandler(&CoreDumpHandler, this);
  }

  static void CoreDumpHandler(void* context) {
    CrashLogDictionary* crash_log_dictionary =
        static_cast<CrashLogDictionary*>(context);
    crash_log_dictionary->OnCrash();
  }

  void OnCrash() {
    // Check that we're not already updating log data.  If we are, we just
    // give up and skip recording any crash data, but hopefully this is rare.
    if (base::subtle::Acquire_CompareAndSwap(&accessing_log_data_, 0, 1) == 0) {
      for (StringMap::const_iterator iter = string_log_map_.begin();
           iter != string_log_map_.end(); ++iter) {
        SbCoreDumpLogString(iter->first.c_str(), iter->second.c_str());
      }
      base::subtle::Release_Store(&accessing_log_data_, 0);
    }
  }

  friend struct DefaultSingletonTraits<CrashLogDictionary>;

  base::subtle::Atomic32 accessing_log_data_;

  // It is possible for multiple threads to call the H5VCC interface at the
  // same time, and they will all forward to this global singleton, so we
  // use this mutex to protect against concurrent access.
  base::Lock mutex_;

  typedef std::map<std::string, std::string> StringMap;
  // Keeps track of all string values to be logged when a crash occurs.
  StringMap string_log_map_;

  DISALLOW_COPY_AND_ASSIGN(CrashLogDictionary);
};

bool H5vccCrashLog::SetString(const std::string& key,
                              const std::string& value) {
  // Forward the call to a global singleton so that we keep a consistent crash
  // log globally.
  CrashLogDictionary::GetInstance()->SetString(key, value);

  return true;
}

}  // namespace h5vcc
}  // namespace cobalt