src/tracing/core/service_impl.cc

/*
 * Copyright (C) 2017 The Android Open Source Project
 *
 * 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 "src/tracing/core/service_impl.h"

#include <inttypes.h>
#include <string.h>

#include <algorithm>

#include "perfetto/base/logging.h"
#include "perfetto/base/task_runner.h"
#include "perfetto/protozero/proto_utils.h"
#include "perfetto/tracing/core/consumer.h"
#include "perfetto/tracing/core/data_source_config.h"
#include "perfetto/tracing/core/producer.h"
#include "perfetto/tracing/core/shared_memory.h"
#include "perfetto/tracing/core/trace_packet.h"

// General note: this class must assume that Producers are malicious and will
// try to crash / exploit this class. We can trust pointers because they come
// from the IPC layer, but we should never assume that that the producer calls
// come in the right order or their arguments are sane / within bounds.

namespace perfetto {

// TODO add ThreadChecker everywhere.

using protozero::proto_utils::ParseVarInt;

namespace {
constexpr size_t kSystemPageSize = 4096;
constexpr size_t kDefaultShmSize = kSystemPageSize * 16;  // 64 KB.
constexpr size_t kMaxShmSize = kSystemPageSize * 1024;    // 4 MB.
constexpr int kMaxBuffersPerConsumer = 128;
}  // namespace

// static
std::unique_ptr<Service> Service::CreateInstance(
    std::unique_ptr<SharedMemory::Factory> shm_factory,
    base::TaskRunner* task_runner) {
  return std::unique_ptr<Service>(
      new ServiceImpl(std::move(shm_factory), task_runner));
}

ServiceImpl::ServiceImpl(std::unique_ptr<SharedMemory::Factory> shm_factory,
                         base::TaskRunner* task_runner)
    : task_runner_(task_runner),
      shm_factory_(std::move(shm_factory)),
      buffer_ids_(kMaxTraceBufferID),
      weak_ptr_factory_(this) {
  PERFETTO_DCHECK(task_runner_);
}

ServiceImpl::~ServiceImpl() {
  // TODO handle teardown of all Producer.
}

std::unique_ptr<Service::ProducerEndpoint> ServiceImpl::ConnectProducer(
    Producer* producer,
    size_t shared_buffer_size_hint_bytes) {
  const ProducerID id = ++last_producer_id_;
  PERFETTO_DLOG("Producer %" PRIu64 " connected", id);
  size_t shm_size = std::min(shared_buffer_size_hint_bytes, kMaxShmSize);
  if (shm_size % kSystemPageSize || shm_size < kSystemPageSize)
    shm_size = kDefaultShmSize;

  // TODO(primiano): right now Create() will suicide in case of OOM if the mmap
  // fails. We should instead gracefully fail the request and tell the client
  // to go away.
  auto shared_memory = shm_factory_->CreateSharedMemory(shm_size);
  std::unique_ptr<ProducerEndpointImpl> endpoint(new ProducerEndpointImpl(
      id, this, task_runner_, producer, std::move(shared_memory)));
  auto it_and_inserted = producers_.emplace(id, endpoint.get());
  PERFETTO_DCHECK(it_and_inserted.second);
  task_runner_->PostTask(std::bind(&Producer::OnConnect, endpoint->producer_));
  return std::move(endpoint);
}

void ServiceImpl::DisconnectProducer(ProducerID id) {
  PERFETTO_DLOG("Producer %" PRIu64 " disconnected", id);
  PERFETTO_DCHECK(producers_.count(id));
  producers_.erase(id);
}

ServiceImpl::ProducerEndpointImpl* ServiceImpl::GetProducer(
    ProducerID id) const {
  auto it = producers_.find(id);
  if (it == producers_.end())
    return nullptr;
  return it->second;
}

std::unique_ptr<Service::ConsumerEndpoint> ServiceImpl::ConnectConsumer(
    Consumer* consumer) {
  PERFETTO_DLOG("Consumer %p connected", reinterpret_cast<void*>(consumer));
  std::unique_ptr<ConsumerEndpointImpl> endpoint(
      new ConsumerEndpointImpl(this, task_runner_, consumer));
  auto it_and_inserted = consumers_.emplace(endpoint.get());
  PERFETTO_DCHECK(it_and_inserted.second);
  task_runner_->PostTask(std::bind(&Consumer::OnConnect, endpoint->consumer_));
  return std::move(endpoint);
}

void ServiceImpl::DisconnectConsumer(ConsumerEndpointImpl* consumer) {
  PERFETTO_DLOG("Consumer %p disconnected", reinterpret_cast<void*>(consumer));
  PERFETTO_DCHECK(consumers_.count(consumer));

  // TODO(primiano) : Check that this is safe (what happens if there are
  // ReadBuffers() calls posted in the meantime? They need to become noop).
  if (consumer->tracing_session_id_)
    FreeBuffers(consumer->tracing_session_id_);  // Will also DisableTracing().
  consumers_.erase(consumer);
}

void ServiceImpl::EnableTracing(ConsumerEndpointImpl* consumer,
                                const TraceConfig& cfg) {
  PERFETTO_DLOG("Enabling tracing for consumer %p",
                reinterpret_cast<void*>(consumer));
  if (consumer->tracing_session_id_) {
    PERFETTO_DLOG(
        "A Consumer is trying to EnableTracing() but another tracing session "
        "is already active (forgot a call to FreeBuffers() ?)");
    // TODO(primiano): make this a bool and return failure to the IPC layer.
    return;
  }

  if (cfg.buffers_size() > kMaxBuffersPerConsumer) {
    PERFETTO_DLOG("Too many buffers configured (%d)", cfg.buffers_size());
    return;  // TODO(primiano): signal failure to the caller.
  }

  const TracingSessionID tsid = ++last_tracing_session_id_;
  TracingSession& ts =
      tracing_sessions_.emplace(tsid, TracingSession(cfg)).first->second;

  PERFETTO_DLOG("Starting tracing session %" PRIu64, tsid);

  // Initialize the log buffers.
  bool did_allocate_all_buffers = true;

  // Allocate the trace buffers. Also create a map to translate a consumer
  // relative index (TraceConfig.DataSourceConfig.target_buffer) into the
  // corresponding BufferID, which is a global ID namespace for the service and
  // all producers.
  ts.buffers_index.reserve(cfg.buffers_size());
  for (int i = 0; i < cfg.buffers_size(); i++) {
    const TraceConfig::BufferConfig& buffer_cfg = cfg.buffers()[i];
    BufferID global_id = buffer_ids_.Allocate();
    if (!global_id) {
      did_allocate_all_buffers = false;  // We ran out of indexes.
      break;
    }
    ts.buffers_index.push_back(global_id);
    auto it_and_inserted = buffers_.emplace(global_id, TraceBuffer());
    PERFETTO_DCHECK(it_and_inserted.second);  // buffers_.count(global_id) == 0.
    TraceBuffer& trace_buffer = it_and_inserted.first->second;
    // TODO(primiano): make TraceBuffer::kBufferPageSize dynamic.
    const size_t buf_size = buffer_cfg.size_kb() * 1024u;
    if (!trace_buffer.Create(buf_size)) {
      did_allocate_all_buffers = false;
      break;
    }
  }

  // This can happen if either:
  // - All the kMaxTraceBufferID slots are taken.
  // - OOM, or, more relistically, we exhausted virtual memory.
  // In any case, free all the previously allocated buffers and abort.
  // TODO: add a test to cover this case, this is quite subtle.
  if (!did_allocate_all_buffers) {
    for (BufferID global_id : ts.buffers_index) {
      buffer_ids_.Free(global_id);
      buffers_.erase(global_id);
    }
    tracing_sessions_.erase(tsid);
    return;  // TODO(primiano): return failure condition?
  }

  consumer->tracing_session_id_ = tsid;

  // Enable the data sources on the producers.
  for (const TraceConfig::DataSource& cfg_data_source : cfg.data_sources()) {
    // Scan all the registered data sources with a matching name.
    auto range = data_sources_.equal_range(cfg_data_source.config().name());
    for (auto it = range.first; it != range.second; it++) {
      const RegisteredDataSource& reg_data_source = it->second;
      ProducerEndpointImpl* producer = GetProducer(reg_data_source.producer_id);
      if (!producer) {
        PERFETTO_DCHECK(false);  // Something in the unregistration is broken.
        continue;
      }
      CreateDataSourceInstanceForProducer(cfg_data_source, producer, &ts);
    }
  }

  // Trigger delayed task if the trace is time limited.
  if (cfg.duration_ms()) {
    auto weak_this = weak_ptr_factory_.GetWeakPtr();
    task_runner_->PostDelayedTask(
        [weak_this, tsid] {
          if (weak_this)
            weak_this->DisableTracing(tsid);
        },
        cfg.duration_ms());
  }
}

// DisableTracing just stops the data sources but doesn't free up any buffer.
// This is to allow the consumer to freeze the buffers (by stopping the trace)
// and then drain the buffers. The actual teardown of the TracingSession happens
// in FreeBuffers().
void ServiceImpl::DisableTracing(TracingSessionID tsid) {
  PERFETTO_DLOG("Disabling tracing session %" PRIu64, tsid);
  TracingSession* tracing_session = GetTracingSession(tsid);
  if (!tracing_session) {
    // Can happen if the consumer calls this before EnableTracing() or after
    // FreeBuffers().
    PERFETTO_DLOG("Couldn't find tracing session %" PRIu64, tsid);
    return;
  }
  for (const auto& data_source_inst : tracing_session->data_source_instances) {
    const ProducerID producer_id = data_source_inst.first;
    const DataSourceInstanceID ds_inst_id = data_source_inst.second;
    ProducerEndpointImpl* producer = GetProducer(producer_id);
    if (!producer)
      continue;  // This could legitimately happen if a Producer disconnects.
    producer->producer_->TearDownDataSourceInstance(ds_inst_id);
  }
  tracing_session->data_source_instances.clear();

  // Deliberately NOT removing the session from |tracing_session_|, it's still
  // needed to call ReadBuffers(). FreeBuffers() will erase() the session.
}

void ServiceImpl::ReadBuffers(TracingSessionID tsid,
                              ConsumerEndpointImpl* consumer) {
  PERFETTO_DLOG("Reading buffers for session %" PRIu64, tsid);
  TracingSession* tracing_session = GetTracingSession(tsid);
  if (!tracing_session) {
    PERFETTO_DLOG(
        "Consumer invoked ReadBuffers() but no tracing session is active");
    return;  // TODO(primiano): signal failure?
  }
  // TODO(primiano): Most of this code is temporary and we should find a better
  // solution to bookkeep the log buffer (e.g., an allocator-like freelist)
  // rather than leveraging the SharedMemoryABI (which is intended only for the
  // Producer <> Service SMB and not for the TraceBuffer itself).
  auto weak_consumer = consumer->GetWeakPtr();
  for (size_t buf_idx = 0; buf_idx < tracing_session->num_buffers();
       buf_idx++) {
    auto tbuf_iter = buffers_.find(tracing_session->buffers_index[buf_idx]);
    if (tbuf_iter == buffers_.end()) {
      PERFETTO_DCHECK(false);
      continue;
    }
    TraceBuffer& tbuf = tbuf_iter->second;
    SharedMemoryABI& abi = *tbuf.abi;
    for (size_t i = 0; i < tbuf.num_pages(); i++) {
      const size_t page_idx = (i + tbuf.cur_page) % tbuf.num_pages();
      if (abi.is_page_free(page_idx))
        continue;
      uint32_t layout = abi.page_layout_dbg(page_idx);
      size_t num_chunks = abi.GetNumChunksForLayout(layout);
      for (size_t chunk_idx = 0; chunk_idx < num_chunks; chunk_idx++) {
        if (abi.GetChunkState(page_idx, chunk_idx) ==
            SharedMemoryABI::kChunkFree) {
          continue;
        }
        auto chunk = abi.GetChunkUnchecked(page_idx, layout, chunk_idx);
        uint16_t num_packets;
        uint8_t flags;
        std::tie(num_packets, flags) = chunk.GetPacketCountAndFlags();
        const uint8_t* ptr = chunk.payload_begin();

        // shared_ptr is really a workardound for the fact that is not possible
        // to std::move() move-only types in labmdas until C++17.
        std::shared_ptr<std::vector<TracePacket>> packets(
            new std::vector<TracePacket>());
        packets->reserve(num_packets);

        for (size_t pack_idx = 0; pack_idx < num_packets; pack_idx++) {
          uint64_t pack_size = 0;
          ptr = ParseVarInt(ptr, chunk.end(), &pack_size);
          // TODO stitching, look at the flags.
          bool skip = (pack_idx == 0 &&
                       flags & SharedMemoryABI::ChunkHeader::
                                   kFirstPacketContinuesFromPrevChunk) ||
                      (pack_idx == num_packets - 1 &&
                       flags & SharedMemoryABI::ChunkHeader::
                                   kLastPacketContinuesOnNextChunk);

          PERFETTO_DLOG("  #%-3zu len:%" PRIu64 " skip: %d\n", pack_idx,
                        pack_size, skip);
          if (ptr > chunk.end() - pack_size) {
            PERFETTO_DLOG("out of bounds!\n");
            break;
          }
          if (!skip) {
            packets->emplace_back();
            packets->back().AddChunk(Chunk(ptr, pack_size));
          }
          ptr += pack_size;
        }  // for(packet)
        task_runner_->PostTask([weak_consumer, packets]() {
          if (weak_consumer)
            weak_consumer->consumer_->OnTraceData(std::move(*packets),
                                                  true /*has_more*/);
        });
      }  // for(chunk)
    }    // for(page_idx)
  }      // for(buffer_id)
  task_runner_->PostTask([weak_consumer]() {
    if (weak_consumer)
      weak_consumer->consumer_->OnTraceData(std::vector<TracePacket>(),
                                            false /*has_more*/);
  });
}

void ServiceImpl::FreeBuffers(TracingSessionID tsid) {
  PERFETTO_DLOG("Freeing buffers for session %" PRIu64, tsid);
  TracingSession* tracing_session = GetTracingSession(tsid);
  if (!tracing_session) {
    PERFETTO_DLOG(
        "Consumer invoked FreeBuffers() but no tracing session is active");
    return;  // TODO(primiano): signal failure?
  }
  DisableTracing(tsid);
  for (BufferID buffer_id : tracing_session->buffers_index) {
    buffer_ids_.Free(buffer_id);
    PERFETTO_DCHECK(buffers_.count(buffer_id) == 1);
    buffers_.erase(buffer_id);
  }
  tracing_sessions_.erase(tsid);
}

void ServiceImpl::RegisterDataSource(ProducerID producer_id,
                                     DataSourceID ds_id,
                                     const DataSourceDescriptor& desc) {
  PERFETTO_DLOG("Producer %" PRIu64
                " registered data source \"%s\", ID: %" PRIu64,
                producer_id, desc.name().c_str(), ds_id);

  PERFETTO_DCHECK(!desc.name().empty());
  data_sources_.emplace(desc.name(),
                        RegisteredDataSource{producer_id, ds_id, desc});

  // If there are existing tracing sessions, we need to check if the new
  // data source is enabled by any of them.
  if (tracing_sessions_.empty())
    return;

  ProducerEndpointImpl* producer = GetProducer(producer_id);
  if (!producer) {
    PERFETTO_DCHECK(false);
    return;
  }

  for (auto& iter : tracing_sessions_) {
    TracingSession& tracing_session = iter.second;
    for (const TraceConfig::DataSource& cfg_data_source :
         tracing_session.config.data_sources()) {
      if (cfg_data_source.config().name() == desc.name())
        CreateDataSourceInstanceForProducer(cfg_data_source, producer,
                                            &tracing_session);
    }
  }
}

void ServiceImpl::CreateDataSourceInstanceForProducer(
    const TraceConfig::DataSource& cfg_data_source,
    ProducerEndpointImpl* producer,
    TracingSession* tracing_session) {
  // TODO(primiano): match against |producer_name_filter| and add tests
  // for registration ordering (data sources vs consumers).

  // Create a copy of the DataSourceConfig specified in the trace config. This
  // will be passed to the producer after translating the |target_buffer| id.
  // The |target_buffer| parameter passed by the consumer in the trace config is
  // relative to the buffers declared in the same trace config. This has to be
  // translated to the global BufferID before passing it to the producers, which
  // don't know anything about tracing sessions and consumers.

  DataSourceConfig ds_config = cfg_data_source.config();  // Deliberate copy.
  auto relative_buffer_id = ds_config.target_buffer();
  if (relative_buffer_id >= tracing_session->num_buffers()) {
    PERFETTO_LOG(
        "The TraceConfig for DataSource %s specified a traget_buffer out of "
        "bound (%d). Skipping it.",
        ds_config.name().c_str(), relative_buffer_id);
    return;
  }
  BufferID global_id = tracing_session->buffers_index[relative_buffer_id];
  PERFETTO_DCHECK(global_id);
  ds_config.set_target_buffer(global_id);

  DataSourceInstanceID inst_id = ++last_data_source_instance_id_;
  tracing_session->data_source_instances.emplace(producer->id_, inst_id);
  PERFETTO_DLOG("Starting data source %s with target buffer %" PRIu16,
                ds_config.name().c_str(), global_id);
  producer->producer_->CreateDataSourceInstance(inst_id, ds_config);
}

void ServiceImpl::CopyProducerPageIntoLogBuffer(ProducerID producer_id,
                                                BufferID target_buffer_id,
                                                const uint8_t* src,
                                                size_t size) {
  // TODO right now the page_size in the SMB and the trace_buffers_ can
  // mismatch. Remove the ability to decide the page size on the Producer.

  auto buf_iter = buffers_.find(target_buffer_id);
  if (buf_iter == buffers_.end()) {
    PERFETTO_DLOG("Could not find target buffer %u for producer %" PRIu64,
                  target_buffer_id, producer_id);
    return;
  }
  TraceBuffer& buf = buf_iter->second;

  // TODO(primiano): we should have a set<BufferID> |allowed_target_buffers| in
  // ProducerEndpointImpl to perform ACL checks and prevent that the Producer
  // passes a |target_buffer| which is valid, but that we never asked it to use.
  // Essentially we want to prevent a malicious producer to inject data into a
  // log buffer that has nothing to do with it.

  PERFETTO_DCHECK(size == kBufferPageSize);
  uint8_t* dst = buf.get_next_page();

  // TODO(primiano): use sendfile(). Requires to make the tbuf itself
  // a file descriptor (just use SharedMemory without sharing it).
  PERFETTO_DLOG(
      "Copying page %p from producer %" PRIu64 " into buffer %" PRIu16,
      reinterpret_cast<const void*>(src), producer_id, target_buffer_id);
  memcpy(dst, src, size);
}

ServiceImpl::TracingSession* ServiceImpl::GetTracingSession(
    TracingSessionID tsid) {
  auto it = tsid ? tracing_sessions_.find(tsid) : tracing_sessions_.end();
  if (it == tracing_sessions_.end())
    return nullptr;
  return &it->second;
}

////////////////////////////////////////////////////////////////////////////////
// ServiceImpl::ConsumerEndpointImpl implementation
////////////////////////////////////////////////////////////////////////////////

ServiceImpl::ConsumerEndpointImpl::ConsumerEndpointImpl(ServiceImpl* service,
                                                        base::TaskRunner*,
                                                        Consumer* consumer)
    : service_(service), consumer_(consumer), weak_ptr_factory_(this) {}

ServiceImpl::ConsumerEndpointImpl::~ConsumerEndpointImpl() {
  consumer_->OnDisconnect();
  service_->DisconnectConsumer(this);
}

void ServiceImpl::ConsumerEndpointImpl::EnableTracing(const TraceConfig& cfg) {
  service_->EnableTracing(this, cfg);
}

void ServiceImpl::ConsumerEndpointImpl::DisableTracing() {
  if (tracing_session_id_) {
    service_->DisableTracing(tracing_session_id_);
  } else {
    PERFETTO_LOG("Consumer called DisableTracing() but tracing was not active");
  }
}

void ServiceImpl::ConsumerEndpointImpl::ReadBuffers() {
  if (tracing_session_id_) {
    service_->ReadBuffers(tracing_session_id_, this);
  } else {
    PERFETTO_LOG("Consumer called ReadBuffers() but tracing was not active");
  }
}

void ServiceImpl::ConsumerEndpointImpl::FreeBuffers() {
  if (tracing_session_id_) {
    service_->FreeBuffers(tracing_session_id_);
  } else {
    PERFETTO_LOG("Consumer called FreeBuffers() but tracing was not active");
  }
}

base::WeakPtr<ServiceImpl::ConsumerEndpointImpl>
ServiceImpl::ConsumerEndpointImpl::GetWeakPtr() {
  return weak_ptr_factory_.GetWeakPtr();
}

////////////////////////////////////////////////////////////////////////////////
// ServiceImpl::ProducerEndpointImpl implementation
////////////////////////////////////////////////////////////////////////////////

ServiceImpl::ProducerEndpointImpl::ProducerEndpointImpl(
    ProducerID id,
    ServiceImpl* service,
    base::TaskRunner* task_runner,
    Producer* producer,
    std::unique_ptr<SharedMemory> shared_memory)
    : id_(id),
      service_(service),
      task_runner_(task_runner),
      producer_(std::move(producer)),
      shared_memory_(std::move(shared_memory)),
      shmem_abi_(reinterpret_cast<uint8_t*>(shared_memory_->start()),
                 shared_memory_->size(),
                 kSystemPageSize) {
  // TODO(primiano): make the page-size for the SHM dynamic and find a way to
  // communicate that to the Producer (add a field to the
  // InitializeConnectionResponse IPC).
}

ServiceImpl::ProducerEndpointImpl::~ProducerEndpointImpl() {
  producer_->OnDisconnect();
  service_->DisconnectProducer(id_);
}

void ServiceImpl::ProducerEndpointImpl::RegisterDataSource(
    const DataSourceDescriptor& desc,
    RegisterDataSourceCallback callback) {
  DataSourceID ds_id = ++last_data_source_id_;
  if (!desc.name().empty()) {
    service_->RegisterDataSource(id_, ds_id, desc);
  } else {
    PERFETTO_DLOG("Received RegisterDataSource() with empty name");
    ds_id = 0;
  }
  task_runner_->PostTask(std::bind(std::move(callback), ds_id));
}

void ServiceImpl::ProducerEndpointImpl::UnregisterDataSource(
    DataSourceID dsid) {
  PERFETTO_CHECK(dsid);
  // TODO(primiano): implement the bookkeeping logic.
}

void ServiceImpl::ProducerEndpointImpl::NotifySharedMemoryUpdate(
    const std::vector<uint32_t>& changed_pages) {
  for (uint32_t page_idx : changed_pages) {
    if (page_idx >= shmem_abi_.num_pages())
      continue;  // Very likely a malicious producer playing dirty.

    if (!shmem_abi_.is_page_complete(page_idx))
      continue;
    if (!shmem_abi_.TryAcquireAllChunksForReading(page_idx))
      continue;

    // TODO: we should start collecting individual chunks from non fully
    // complete pages after a while.

    service_->CopyProducerPageIntoLogBuffer(
        id_, shmem_abi_.get_target_buffer(page_idx),
        shmem_abi_.page_start(page_idx), shmem_abi_.page_size());

    shmem_abi_.ReleaseAllChunksAsFree(page_idx);
  }
}

SharedMemory* ServiceImpl::ProducerEndpointImpl::shared_memory() const {
  return shared_memory_.get();
}

std::unique_ptr<TraceWriter>
ServiceImpl::ProducerEndpointImpl::CreateTraceWriter(BufferID) {
  // TODO(primiano): not implemented yet.
  // This code path is hit only in in-process configuration, where tracing
  // Service and Producer are hosted in the same process. It's a use case we
  // want to support, but not too interesting right now.
  PERFETTO_CHECK(false);
}

////////////////////////////////////////////////////////////////////////////////
// ServiceImpl::TraceBuffer implementation
////////////////////////////////////////////////////////////////////////////////

ServiceImpl::TraceBuffer::TraceBuffer() = default;

bool ServiceImpl::TraceBuffer::Create(size_t sz) {
  data = base::PageAllocator::AllocateMayFail(sz);
  if (!data) {
    PERFETTO_ELOG("Trace buffer allocation failed (size: %zu, page_size: %zu)",
                  sz, kBufferPageSize);
    return false;
  }
  size = sz;
  abi.reset(new SharedMemoryABI(get_page(0), size, kBufferPageSize));
  return true;
}

ServiceImpl::TraceBuffer::~TraceBuffer() = default;
ServiceImpl::TraceBuffer::TraceBuffer(ServiceImpl::TraceBuffer&&) noexcept =
    default;
ServiceImpl::TraceBuffer& ServiceImpl::TraceBuffer::operator=(
    ServiceImpl::TraceBuffer&&) = default;

////////////////////////////////////////////////////////////////////////////////
// ServiceImpl::TracingSession implementation
////////////////////////////////////////////////////////////////////////////////

ServiceImpl::TracingSession::TracingSession(const TraceConfig& new_config)
    : config(new_config) {}

}  // namespace perfetto