importers/proto/packet_sequence_state.h

/*
 * Copyright (C) 2019 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.
 */

#ifndef SRC_TRACE_PROCESSOR_IMPORTERS_PROTO_PACKET_SEQUENCE_STATE_H_
#define SRC_TRACE_PROCESSOR_IMPORTERS_PROTO_PACKET_SEQUENCE_STATE_H_

#include <stdint.h>

#include <unordered_map>
#include <vector>

#include "perfetto/base/compiler.h"
#include "perfetto/protozero/proto_decoder.h"
#include "src/trace_processor/stack_profile_tracker.h"
#include "src/trace_processor/storage/trace_storage.h"
#include "src/trace_processor/trace_blob_view.h"
#include "src/trace_processor/trace_processor_context.h"

#include "protos/perfetto/trace/trace_packet_defaults.pbzero.h"
#include "protos/perfetto/trace/track_event/track_event.pbzero.h"

namespace perfetto {
namespace trace_processor {

#if PERFETTO_DCHECK_IS_ON()
// When called from GetOrCreateDecoder(), should include the stringified name of
// the MessageType.
#define PERFETTO_TYPE_IDENTIFIER PERFETTO_DEBUG_FUNCTION_IDENTIFIER()
#else  // PERFETTO_DCHECK_IS_ON()
#define PERFETTO_TYPE_IDENTIFIER nullptr
#endif  // PERFETTO_DCHECK_IS_ON()

// Entry in an interning index, refers to the interned message.
class InternedMessageView {
 public:
  InternedMessageView(TraceBlobView msg) : message_(std::move(msg)) {}

  InternedMessageView(InternedMessageView&&) = default;
  InternedMessageView& operator=(InternedMessageView&&) = default;

  // Allow copy by cloning the TraceBlobView. This is required for
  // UpdateTracePacketDefaults().
  InternedMessageView(const InternedMessageView& view)
      : message_(view.message_.slice(0, view.message_.length())) {}
  InternedMessageView& operator=(const InternedMessageView& view) {
    this->message_ = view.message_.slice(0, view.message_.length());
    this->decoder_ = nullptr;
    this->decoder_type_ = nullptr;
    this->submessages_.clear();
    return *this;
  }

  // Lazily initializes and returns the decoder object for the message. The
  // decoder is stored in the InternedMessageView to avoid having to parse the
  // message multiple times.
  template <typename MessageType>
  typename MessageType::Decoder* GetOrCreateDecoder() {
    if (!decoder_) {
      // Lazy init the decoder and save it away, so that we don't have to
      // reparse the message every time we access the interning entry.
      decoder_ = std::unique_ptr<void, std::function<void(void*)>>(
          new typename MessageType::Decoder(message_.data(), message_.length()),
          [](void* obj) {
            delete reinterpret_cast<typename MessageType::Decoder*>(obj);
          });
      decoder_type_ = PERFETTO_TYPE_IDENTIFIER;
    }
    // Verify that the type of the decoder didn't change.
    if (PERFETTO_TYPE_IDENTIFIER &&
        strcmp(decoder_type_,
               // GCC complains if this arg can be null.
               PERFETTO_TYPE_IDENTIFIER ? PERFETTO_TYPE_IDENTIFIER : "") != 0) {
      PERFETTO_FATAL(
          "Interning entry accessed under different types! previous type: "
          "%s. new type: %s.",
          decoder_type_, PERFETTO_DEBUG_FUNCTION_IDENTIFIER());
    }
    return reinterpret_cast<typename MessageType::Decoder*>(decoder_.get());
  }

  // Lookup a submessage of the interned message, which is then itself stored
  // as InternedMessageView, so that we only need to parse it once. Returns
  // nullptr if the field isn't set.
  // TODO(eseckler): Support repeated fields.
  template <typename MessageType, uint32_t FieldId>
  InternedMessageView* GetOrCreateSubmessageView() {
    auto it = submessages_.find(FieldId);
    if (it != submessages_.end())
      return it->second.get();
    auto* decoder = GetOrCreateDecoder<MessageType>();
    // Calls the at() template method on the decoder.
    auto field = decoder->template at<FieldId>().as_bytes();
    if (!field.data)
      return nullptr;
    const size_t offset = message_.offset_of(field.data);
    TraceBlobView submessage = message_.slice(offset, field.size);
    InternedMessageView* submessage_view =
        new InternedMessageView(std::move(submessage));
    submessages_.emplace_hint(
        it, FieldId, std::unique_ptr<InternedMessageView>(submessage_view));
    return submessage_view;
  }

  const TraceBlobView& message() { return message_; }

 private:
  using SubMessageViewMap =
      std::unordered_map<uint32_t /*field_id*/,
                         std::unique_ptr<InternedMessageView>>;

  TraceBlobView message_;

  // Stores the decoder for the message_, so that the message does not have to
  // be re-decoded every time the interned message is looked up. Lazily
  // initialized in GetOrCreateDecoder(). Since we don't know the type of the
  // decoder until GetOrCreateDecoder() is called, we store the decoder as a
  // void* unique_pointer with a destructor function that's supplied in
  // GetOrCreateDecoder() when the decoder is created.
  std::unique_ptr<void, std::function<void(void*)>> decoder_;

  // Type identifier for the decoder. Only valid in debug builds and on
  // supported platforms. Used to verify that GetOrCreateDecoder() is always
  // called with the same template argument.
  const char* decoder_type_ = nullptr;

  // Views of submessages of the interned message. Submessages are lazily
  // added by GetOrCreateSubmessageView(). By storing submessages and their
  // decoders, we avoid having to decode submessages multiple times if they
  // looked up often.
  SubMessageViewMap submessages_;
};

using InternedMessageMap =
    std::unordered_map<uint64_t /*iid*/, InternedMessageView>;
using InternedFieldMap =
    std::unordered_map<uint32_t /*field_id*/, InternedMessageMap>;

class PacketSequenceState;

class PacketSequenceStateGeneration {
 public:
  // Returns |nullptr| if the message with the given |iid| was not found (also
  // records a stat in this case).
  template <uint32_t FieldId, typename MessageType>
  typename MessageType::Decoder* LookupInternedMessage(uint64_t iid);

  // Returns |nullptr| if no defaults were set.
  InternedMessageView* GetTracePacketDefaultsView() {
    if (!trace_packet_defaults_)
      return nullptr;
    return &trace_packet_defaults_.value();
  }

  // Returns |nullptr| if no defaults were set.
  protos::pbzero::TracePacketDefaults::Decoder* GetTracePacketDefaults() {
    InternedMessageView* view = GetTracePacketDefaultsView();
    if (!view)
      return nullptr;
    return view->GetOrCreateDecoder<protos::pbzero::TracePacketDefaults>();
  }

  // Returns |nullptr| if no TrackEventDefaults were set.
  protos::pbzero::TrackEventDefaults::Decoder* GetTrackEventDefaults() {
    auto* packet_defaults_view = GetTracePacketDefaultsView();
    if (packet_defaults_view) {
      auto* track_event_defaults_view =
          packet_defaults_view
              ->GetOrCreateSubmessageView<protos::pbzero::TracePacketDefaults,
                                          protos::pbzero::TracePacketDefaults::
                                              kTrackEventDefaultsFieldNumber>();
      if (track_event_defaults_view) {
        return track_event_defaults_view
            ->GetOrCreateDecoder<protos::pbzero::TrackEventDefaults>();
      }
    }
    return nullptr;
  }

  PacketSequenceState* state() const { return state_; }

 private:
  friend class PacketSequenceState;

  PacketSequenceStateGeneration(PacketSequenceState* state,
                                size_t generation_index)
      : state_(state), generation_index_(generation_index) {}

  PacketSequenceStateGeneration(PacketSequenceState* state,
                                size_t generation_index,
                                InternedFieldMap interned_data,
                                TraceBlobView defaults)
      : state_(state),
        generation_index_(generation_index),
        interned_data_(interned_data),
        trace_packet_defaults_(InternedMessageView(std::move(defaults))) {}

  void InternMessage(uint32_t field_id, TraceBlobView message);

  void SetTracePacketDefaults(TraceBlobView defaults) {
    // Defaults should only be set once per generation.
    PERFETTO_DCHECK(!trace_packet_defaults_);
    trace_packet_defaults_ = InternedMessageView(std::move(defaults));
  }

  PacketSequenceState* state_;
  size_t generation_index_;
  InternedFieldMap interned_data_;
  base::Optional<InternedMessageView> trace_packet_defaults_;
};

class PacketSequenceState {
 public:
  PacketSequenceState(TraceProcessorContext* context)
      : context_(context), stack_profile_tracker_(context) {
    generations_.emplace_back(
        new PacketSequenceStateGeneration(this, generations_.size()));
  }

  int64_t IncrementAndGetTrackEventTimeNs(int64_t delta_ns) {
    PERFETTO_DCHECK(track_event_timestamps_valid());
    track_event_timestamp_ns_ += delta_ns;
    return track_event_timestamp_ns_;
  }

  int64_t IncrementAndGetTrackEventThreadTimeNs(int64_t delta_ns) {
    PERFETTO_DCHECK(track_event_timestamps_valid());
    track_event_thread_timestamp_ns_ += delta_ns;
    return track_event_thread_timestamp_ns_;
  }

  int64_t IncrementAndGetTrackEventThreadInstructionCount(int64_t delta) {
    PERFETTO_DCHECK(track_event_timestamps_valid());
    track_event_thread_instruction_count_ += delta;
    return track_event_thread_instruction_count_;
  }

  // Intern a message into the current generation.
  void InternMessage(uint32_t field_id, TraceBlobView message) {
    generations_.back()->InternMessage(field_id, std::move(message));
  }

  // Set the trace packet defaults for the current generation. If the current
  // generation already has defaults set, starts a new generation without
  // invalidating other incremental state (such as interned data).
  void UpdateTracePacketDefaults(TraceBlobView defaults) {
    if (!generations_.back()->GetTracePacketDefaultsView()) {
      generations_.back()->SetTracePacketDefaults(std::move(defaults));
      return;
    }

    // The new defaults should only apply to subsequent messages on the
    // sequence. Add a new generation with the updated defaults but the
    // current generation's interned data state.
    generations_.emplace_back(new PacketSequenceStateGeneration(
        this, generations_.size(), generations_.back()->interned_data_,
        std::move(defaults)));
  }

  void SetThreadDescriptor(int32_t pid,
                           int32_t tid,
                           int64_t timestamp_ns,
                           int64_t thread_timestamp_ns,
                           int64_t thread_instruction_count) {
    track_event_timestamps_valid_ = true;
    pid_and_tid_valid_ = true;
    pid_ = pid;
    tid_ = tid;
    track_event_timestamp_ns_ = timestamp_ns;
    track_event_thread_timestamp_ns_ = thread_timestamp_ns;
    track_event_thread_instruction_count_ = thread_instruction_count;
  }

  void OnPacketLoss() {
    packet_loss_ = true;
    track_event_timestamps_valid_ = false;
  }

  // Starts a new generation with clean-slate incremental state and defaults.
  void OnIncrementalStateCleared() {
    packet_loss_ = false;
    generations_.emplace_back(
        new PacketSequenceStateGeneration(this, generations_.size()));
  }

  bool IsIncrementalStateValid() const { return !packet_loss_; }

  StackProfileTracker& stack_profile_tracker() {
    return stack_profile_tracker_;
  }

  // Returns a pointer to the current generation.
  PacketSequenceStateGeneration* current_generation() const {
    return generations_.back().get();
  }

  bool track_event_timestamps_valid() const {
    return track_event_timestamps_valid_;
  }

  bool pid_and_tid_valid() const { return pid_and_tid_valid_; }

  int32_t pid() const { return pid_; }
  int32_t tid() const { return tid_; }

  TraceProcessorContext* context() const { return context_; }

 private:
  // TODO(eseckler): Reference count the generations so that we can get rid of
  // past generations once all packets referring to them have been parsed.
  using GenerationList =
      std::vector<std::unique_ptr<PacketSequenceStateGeneration>>;

  TraceProcessorContext* context_;

  // If true, incremental state on the sequence is considered invalid until we
  // see the next packet with incremental_state_cleared. We assume that we
  // missed some packets at the beginning of the trace.
  bool packet_loss_ = true;

  // We can only consider TrackEvent delta timestamps to be correct after we
  // have observed a thread descriptor (since the last packet loss).
  bool track_event_timestamps_valid_ = false;

  // |pid_| and |tid_| are only valid after we parsed at least one
  // ThreadDescriptor packet on the sequence.
  bool pid_and_tid_valid_ = false;

  // Process/thread ID of the packet sequence set by a ThreadDescriptor
  // packet. Used as default values for TrackEvents that don't specify a
  // pid/tid override. Only valid after |pid_and_tid_valid_| is set to true.
  int32_t pid_ = 0;
  int32_t tid_ = 0;

  // Current wall/thread timestamps/counters used as reference for the next
  // TrackEvent delta timestamp.
  int64_t track_event_timestamp_ns_ = 0;
  int64_t track_event_thread_timestamp_ns_ = 0;
  int64_t track_event_thread_instruction_count_ = 0;

  GenerationList generations_;
  StackProfileTracker stack_profile_tracker_;
};

template <uint32_t FieldId, typename MessageType>
typename MessageType::Decoder*
PacketSequenceStateGeneration::LookupInternedMessage(uint64_t iid) {
  auto field_it = interned_data_.find(FieldId);
  if (field_it != interned_data_.end()) {
    auto* message_map = &field_it->second;
    auto it = message_map->find(iid);
    if (it != message_map->end()) {
      return it->second.GetOrCreateDecoder<MessageType>();
    }
  }
  state_->context()->storage->IncrementStats(
      stats::interned_data_tokenizer_errors);
  PERFETTO_DLOG("Could not find interning entry for field ID %" PRIu32
                ", generation %zu, and IID %" PRIu64,
                FieldId, generation_index_, iid);
  return nullptr;
}

}  // namespace trace_processor
}  // namespace perfetto

#endif  // SRC_TRACE_PROCESSOR_IMPORTERS_PROTO_PACKET_SEQUENCE_STATE_H_