// 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 {

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

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* MemoryDumpTypeToString(const MemoryDumpType& dump_type) {
  switch (dump_type) {
    case MemoryDumpType::TASK_BEGIN:
      return "TASK_BEGIN";
    case MemoryDumpType::TASK_END:
      return "TASK_END";
    case MemoryDumpType::PERIODIC_INTERVAL:
      return "PERIODIC_INTERVAL";
    case MemoryDumpType::EXPLICITLY_TRIGGERED:
      return "EXPLICITLY_TRIGGERED";
  }
  NOTREACHED();
  return "UNKNOWN";
}

// Internal class used to hold details about ProcessMemoryDump requests for the
// current process.
// TODO(primiano): In the upcoming CLs, ProcessMemoryDump will become async.
// and this class will be used to convey more details across PostTask()s.
class ProcessMemoryDumpHolder
    : public RefCountedThreadSafe<ProcessMemoryDumpHolder> {
 public:
  ProcessMemoryDumpHolder(MemoryDumpRequestArgs req_args)
      : req_args(req_args) {}

  ProcessMemoryDump process_memory_dump;
  const MemoryDumpRequestArgs req_args;

 private:
  friend class RefCountedThreadSafe<ProcessMemoryDumpHolder>;
  virtual ~ProcessMemoryDumpHolder() {}
  DISALLOW_COPY_AND_ASSIGN(ProcessMemoryDumpHolder);
};

void FinalizeDumpAndAddToTrace(
    const scoped_refptr<ProcessMemoryDumpHolder>& pmd_holder) {
  scoped_refptr<ConvertableToTraceFormat> event_value(new TracedValue());
  pmd_holder->process_memory_dump.AsValueInto(
      static_cast<TracedValue*>(event_value.get()));
  const char* const event_name =
      MemoryDumpTypeToString(pmd_holder->req_args.dump_type);

  TRACE_EVENT_API_ADD_TRACE_EVENT(
      TRACE_EVENT_PHASE_MEMORY_DUMP,
      TraceLog::GetCategoryGroupEnabled(kTraceCategory), event_name,
      pmd_holder->req_args.dump_guid, kTraceEventNumArgs, kTraceEventArgNames,
      kTraceEventArgTypes, nullptr /* arg_values */, &event_value,
      TRACE_EVENT_FLAG_HAS_ID);
}

}  // namespace

// static
const char* const MemoryDumpManager::kTraceCategoryForTesting = kTraceCategory;

// 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),
      delegate_(nullptr),
      memory_tracing_enabled_(0) {
  g_next_guid.GetNext();  // Make sure that first guid is not zero.
}

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::SetDelegate(MemoryDumpManagerDelegate* delegate) {
  AutoLock lock(lock_);
  DCHECK_EQ(static_cast<MemoryDumpManagerDelegate*>(nullptr), delegate_);
  delegate_ = delegate;
}

void MemoryDumpManager::RegisterDumpProvider(MemoryDumpProvider* mdp) {
  AutoLock lock(lock_);
  dump_providers_registered_.insert(mdp);
}

void MemoryDumpManager::UnregisterDumpProvider(MemoryDumpProvider* mdp) {
  AutoLock lock(lock_);
  // Remove from the enabled providers list. This is to deal with the case that
  // UnregisterDumpProvider is called while the trace is enabled.
  dump_providers_enabled_.erase(mdp);
  dump_providers_registered_.erase(mdp);
}

void MemoryDumpManager::RequestGlobalDump(
    MemoryDumpType dump_type,
    const MemoryDumpCallback& callback) {
  // Bail out immediately if tracing is not enabled at all.
  if (!UNLIKELY(subtle::NoBarrier_Load(&memory_tracing_enabled_)))
    return;

  const uint64 guid =
      TraceLog::GetInstance()->MangleEventId(g_next_guid.GetNext());

  // The delegate_ is supposed to be thread safe, immutable and long lived.
  // No need to keep the lock after we ensure that a delegate has been set.
  MemoryDumpManagerDelegate* delegate;
  {
    AutoLock lock(lock_);
    delegate = delegate_;
  }

  if (delegate) {
    // The delegate is in charge to coordinate the request among all the
    // processes and call the CreateLocalDumpPoint on the local process.
    MemoryDumpRequestArgs args = {guid, dump_type};
    delegate->RequestGlobalMemoryDump(args, callback);
  } else if (!callback.is_null()) {
    callback.Run(guid, false /* success */);
  }
}

void MemoryDumpManager::RequestGlobalDump(MemoryDumpType dump_type) {
  RequestGlobalDump(dump_type, MemoryDumpCallback());
}

// Creates a memory dump for the current process and appends it to the trace.
void MemoryDumpManager::CreateProcessDump(const MemoryDumpRequestArgs& args) {
  scoped_refptr<ProcessMemoryDumpHolder> pmd_holder(
      new ProcessMemoryDumpHolder(args));
  ProcessMemoryDump* pmd = &pmd_holder->process_memory_dump;
  bool did_any_provider_dump = false;

  // Serialize dump generation so that memory dump providers don't have to deal
  // with thread safety.
  {
    AutoLock lock(lock_);
    for (auto dump_provider_iter = dump_providers_enabled_.begin();
         dump_provider_iter != dump_providers_enabled_.end();) {
      // InvokeDumpProviderLocked will remove the MDP from the set if it fails.
      MemoryDumpProvider* mdp = *dump_provider_iter;
      ++dump_provider_iter;
      // Invoke the dump provider synchronously.
      did_any_provider_dump |= InvokeDumpProviderLocked(mdp, pmd);
    }
  }  // AutoLock

  // If at least one synchronous provider did dump, add the dump to the trace.
  if (did_any_provider_dump)
    FinalizeDumpAndAddToTrace(pmd_holder);
}

// Invokes the MemoryDumpProvider.DumpInto(), taking care of the failsafe logic
// which disables the dumper when failing (crbug.com/461788). The caller must
// hold the |lock_| when invoking this.
bool MemoryDumpManager::InvokeDumpProviderLocked(MemoryDumpProvider* mdp,
                                                 ProcessMemoryDump* pmd) {
  lock_.AssertAcquired();
  dump_provider_currently_active_ = mdp;
  bool dump_successful = mdp->DumpInto(pmd);
  dump_provider_currently_active_ = nullptr;
  if (!dump_successful) {
    LOG(ERROR) << "The memory dumper " << mdp->GetFriendlyName()
               << " failed, possibly due to sandboxing (crbug.com/461788), "
                  "disabling it for current process. Try restarting chrome "
                  "with the --no-sandbox switch.";
    dump_providers_enabled_.erase(mdp);
  }
  return dump_successful;
}

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_ = dump_providers_registered_;
  } 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