// Copyright 2015 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/trace_event/memory_dump_manager.h"

#include <algorithm>

#include "base/atomic_sequence_num.h"
#include "base/compiler_specific.h"
#include "base/trace_event/memory_dump_provider.h"
#include "base/trace_event/process_memory_dump.h"
#include "base/trace_event/trace_event_argument.h"

namespace base {
namespace trace_event {

namespace {

MemoryDumpManager* g_instance_for_testing = nullptr;
const int kTraceEventNumArgs = 1;
const char* kTraceEventArgNames[] = {"dumps"};
const unsigned char kTraceEventArgTypes[] = {TRACE_VALUE_TYPE_CONVERTABLE};
StaticAtomicSequenceNumber g_next_guid;

const char* DumpPointTypeToString(const DumpPointType& dump_point_type) {
  switch (dump_point_type) {
    case DumpPointType::TASK_BEGIN:
      return "TASK_BEGIN";
    case DumpPointType::TASK_END:
      return "TASK_END";
    case DumpPointType::PERIODIC_INTERVAL:
      return "PERIODIC_INTERVAL";
    case DumpPointType::EXPLICITLY_TRIGGERED:
      return "EXPLICITLY_TRIGGERED";
  }
  NOTREACHED();
  return "UNKNOWN";
}

}  // namespace

// TODO(primiano): this should be smarter and should do something similar to
// trace event synthetic delays.
const char MemoryDumpManager::kTraceCategory[] =
    TRACE_DISABLED_BY_DEFAULT("memory-dumps");

// static
MemoryDumpManager* MemoryDumpManager::GetInstance() {
  if (g_instance_for_testing)
    return g_instance_for_testing;

  return Singleton<MemoryDumpManager,
                   LeakySingletonTraits<MemoryDumpManager>>::get();
}

// static
void MemoryDumpManager::SetInstanceForTesting(MemoryDumpManager* instance) {
  g_instance_for_testing = instance;
}

MemoryDumpManager::MemoryDumpManager()
    : dump_provider_currently_active_(nullptr), memory_tracing_enabled_(0) {
}

MemoryDumpManager::~MemoryDumpManager() {
  base::trace_event::TraceLog::GetInstance()->RemoveEnabledStateObserver(this);
}

void MemoryDumpManager::Initialize() {
  TRACE_EVENT0(kTraceCategory, "init");  // Add to trace-viewer category list.
  trace_event::TraceLog::GetInstance()->AddEnabledStateObserver(this);
}

void MemoryDumpManager::RegisterDumpProvider(MemoryDumpProvider* mdp) {
  AutoLock lock(lock_);
  if (std::find(dump_providers_registered_.begin(),
                dump_providers_registered_.end(),
                mdp) != dump_providers_registered_.end()) {
    return;
  }
  dump_providers_registered_.push_back(mdp);
}

void MemoryDumpManager::UnregisterDumpProvider(MemoryDumpProvider* mdp) {
  AutoLock lock(lock_);

  // Remove from the registered providers list.
  auto it = std::find(dump_providers_registered_.begin(),
                      dump_providers_registered_.end(), mdp);
  if (it != dump_providers_registered_.end())
    dump_providers_registered_.erase(it);

  // Remove from the enabled providers list. This is to deal with the case that
  // UnregisterDumpProvider is called while the trace is enabled.
  it = std::find(dump_providers_enabled_.begin(), dump_providers_enabled_.end(),
                 mdp);
  if (it != dump_providers_enabled_.end())
    dump_providers_enabled_.erase(it);
}

void MemoryDumpManager::RequestDumpPoint(DumpPointType dump_point_type) {
  // TODO(primiano): this will have more logic to coordinate dump points across
  // multiple processes via IPC. See crbug.com/462930.

  // Bail out immediately if tracing is not enabled at all.
  if (!UNLIKELY(subtle::NoBarrier_Load(&memory_tracing_enabled_)))
    return;

  // TODO(primiano): Make guid actually unique (cross-process) by hashing it
  // with the PID. See crbug.com/462931 for details.
  const uint64 guid = g_next_guid.GetNext();
  CreateLocalDumpPoint(dump_point_type, guid);
}

void MemoryDumpManager::BroadcastDumpRequest() {
  NOTREACHED();  // TODO(primiano): implement IPC synchronization.
}

// Creates a dump point for the current process and appends it to the trace.
void MemoryDumpManager::CreateLocalDumpPoint(DumpPointType dump_point_type,
                                             uint64 guid) {
  bool did_any_provider_dump = false;
  scoped_ptr<ProcessMemoryDump> pmd(new ProcessMemoryDump());

  // Serialize dump point generation so that memory dump providers don't have to
  // deal with thread safety.
  {
    AutoLock lock(lock_);
    for (auto it = dump_providers_enabled_.begin();
         it != dump_providers_enabled_.end();) {
      dump_provider_currently_active_ = *it;
      if (dump_provider_currently_active_->DumpInto(pmd.get())) {
        did_any_provider_dump = true;
        ++it;
      } else {
        LOG(ERROR) << "The memory dumper "
                   << dump_provider_currently_active_->GetFriendlyName()
                   << " failed, possibly due to sandboxing (crbug.com/461788), "
                      "disabling it for current process. Try restarting chrome "
                      "with the --no-sandbox switch.";
        it = dump_providers_enabled_.erase(it);
      }
      dump_provider_currently_active_ = nullptr;
    }
  }

  // Don't create a dump point if all the dumpers failed.
  if (!did_any_provider_dump)
    return;

  scoped_refptr<ConvertableToTraceFormat> event_value(new TracedValue());
  pmd->AsValueInto(static_cast<TracedValue*>(event_value.get()));
  const char* const event_name = DumpPointTypeToString(dump_point_type);

  TRACE_EVENT_API_ADD_TRACE_EVENT(
      TRACE_EVENT_PHASE_MEMORY_DUMP,
      TraceLog::GetCategoryGroupEnabled(kTraceCategory), event_name, guid,
      kTraceEventNumArgs, kTraceEventArgNames, kTraceEventArgTypes,
      NULL /* arg_values */, &event_value, TRACE_EVENT_FLAG_HAS_ID);
}

void MemoryDumpManager::OnTraceLogEnabled() {
  // TODO(primiano): at this point we query  TraceLog::GetCurrentCategoryFilter
  // to figure out (and cache) which dumpers should be enabled or not.
  // For the moment piggy back everything on the generic "memory" category.
  bool enabled;
  TRACE_EVENT_CATEGORY_GROUP_ENABLED(kTraceCategory, &enabled);

  AutoLock lock(lock_);
  if (enabled) {
    dump_providers_enabled_.assign(dump_providers_registered_.begin(),
                                   dump_providers_registered_.end());
  } else {
    dump_providers_enabled_.clear();
  }
  subtle::NoBarrier_Store(&memory_tracing_enabled_, 1);
}

void MemoryDumpManager::OnTraceLogDisabled() {
  AutoLock lock(lock_);
  dump_providers_enabled_.clear();
  subtle::NoBarrier_Store(&memory_tracing_enabled_, 0);
}

}  // namespace trace_event
}  // namespace base