| /* |
| * 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/trace_writer_impl.h" |
| |
| #include <string.h> |
| |
| #include <algorithm> |
| #include <type_traits> |
| #include <utility> |
| |
| #include "perfetto/base/logging.h" |
| #include "perfetto/protozero/proto_utils.h" |
| #include "src/tracing/core/shared_memory_arbiter_impl.h" |
| |
| #include "perfetto/trace/trace_packet.pbzero.h" |
| |
| using protozero::proto_utils::kMessageLengthFieldSize; |
| using protozero::proto_utils::WriteRedundantVarInt; |
| using ChunkHeader = perfetto::SharedMemoryABI::ChunkHeader; |
| |
| namespace perfetto { |
| |
| namespace { |
| constexpr size_t kPacketHeaderSize = SharedMemoryABI::kPacketHeaderSize; |
| } // namespace |
| |
| TraceWriterImpl::TraceWriterImpl(SharedMemoryArbiterImpl* shmem_arbiter, |
| WriterID id, |
| BufferID target_buffer) |
| : shmem_arbiter_(shmem_arbiter), |
| id_(id), |
| target_buffer_(target_buffer), |
| protobuf_stream_writer_(this) { |
| // TODO(primiano): we could handle the case of running out of TraceWriterID(s) |
| // more gracefully and always return a no-op TracePacket in NewTracePacket(). |
| PERFETTO_CHECK(id_ != 0); |
| |
| cur_packet_.reset(new protos::pbzero::TracePacket()); |
| cur_packet_->Finalize(); // To avoid the DCHECK in NewTracePacket(). |
| } |
| |
| TraceWriterImpl::~TraceWriterImpl() { |
| if (cur_chunk_.is_valid()) { |
| cur_packet_->Finalize(); |
| Flush(); |
| } |
| shmem_arbiter_->ReleaseWriterID(id_); |
| } |
| |
| void TraceWriterImpl::Flush(std::function<void()> callback) { |
| // Flush() cannot be called in the middle of a TracePacket. |
| PERFETTO_CHECK(cur_packet_->is_finalized()); |
| |
| if (cur_chunk_.is_valid()) { |
| shmem_arbiter_->ReturnCompletedChunk(std::move(cur_chunk_), target_buffer_, |
| &patch_list_); |
| } else { |
| PERFETTO_DCHECK(patch_list_.empty()); |
| } |
| // Always issue the Flush request, even if there is nothing to flush, just |
| // for the sake of getting the callback posted back. |
| shmem_arbiter_->FlushPendingCommitDataRequests(callback); |
| protobuf_stream_writer_.Reset({nullptr, nullptr}); |
| } |
| |
| TraceWriterImpl::TracePacketHandle TraceWriterImpl::NewTracePacket() { |
| // If we hit this, the caller is calling NewTracePacket() without having |
| // finalized the previous packet. |
| PERFETTO_DCHECK(cur_packet_->is_finalized()); |
| |
| fragmenting_packet_ = false; |
| |
| // Reserve space for the size of the message. Note: this call might re-enter |
| // into this class invoking GetNewBuffer() if there isn't enough space or if |
| // this is the very first call to NewTracePacket(). |
| static_assert(kPacketHeaderSize == kMessageLengthFieldSize, |
| "The packet header must match the Message header size"); |
| |
| // It doesn't make sense to begin a packet that is going to fragment |
| // immediately after (8 is just an arbitrary estimation on the minimum size of |
| // a realistic packet). |
| bool chunk_too_full = |
| protobuf_stream_writer_.bytes_available() < kPacketHeaderSize + 8; |
| if (chunk_too_full || reached_max_packets_per_chunk_) { |
| protobuf_stream_writer_.Reset(GetNewBuffer()); |
| } |
| |
| // Send any completed patches to the service to facilitate trace data |
| // recovery by the service. This should only happen when we're completing |
| // the first packet in a chunk which was a continuation from the previous |
| // chunk, i.e. at most once per chunk. |
| if (!patch_list_.empty() && patch_list_.front().is_patched()) { |
| shmem_arbiter_->SendPatches(id_, target_buffer_, &patch_list_); |
| } |
| |
| cur_packet_->Reset(&protobuf_stream_writer_); |
| uint8_t* header = protobuf_stream_writer_.ReserveBytes(kPacketHeaderSize); |
| memset(header, 0, kPacketHeaderSize); |
| cur_packet_->set_size_field(header); |
| uint16_t new_packet_count = cur_chunk_.IncrementPacketCount(); |
| reached_max_packets_per_chunk_ = |
| new_packet_count == ChunkHeader::Packets::kMaxCount; |
| TracePacketHandle handle(cur_packet_.get()); |
| cur_fragment_start_ = protobuf_stream_writer_.write_ptr(); |
| fragmenting_packet_ = true; |
| return handle; |
| } |
| |
| // Called by the Message. We can get here in two cases: |
| // 1. In the middle of writing a Message, |
| // when |fragmenting_packet_| == true. In this case we want to update the |
| // chunk header with a partial packet and start a new partial packet in the |
| // new chunk. |
| // 2. While calling ReserveBytes() for the packet header in NewTracePacket(). |
| // In this case |fragmenting_packet_| == false and we just want a new chunk |
| // without creating any fragments. |
| protozero::ContiguousMemoryRange TraceWriterImpl::GetNewBuffer() { |
| if (fragmenting_packet_) { |
| uint8_t* const wptr = protobuf_stream_writer_.write_ptr(); |
| PERFETTO_DCHECK(wptr >= cur_fragment_start_); |
| uint32_t partial_size = static_cast<uint32_t>(wptr - cur_fragment_start_); |
| PERFETTO_DCHECK(partial_size < cur_chunk_.size()); |
| |
| // Backfill the packet header with the fragment size. |
| PERFETTO_DCHECK(partial_size > 0); |
| cur_packet_->inc_size_already_written(partial_size); |
| cur_chunk_.SetFlag(ChunkHeader::kLastPacketContinuesOnNextChunk); |
| WriteRedundantVarInt(partial_size, cur_packet_->size_field()); |
| |
| // Descend in the stack of non-finalized nested submessages (if any) and |
| // detour their |size_field| into the |patch_list_|. At this point we have |
| // to release the chunk and they cannot write anymore into that. |
| // TODO(primiano): add tests to cover this logic. |
| bool chunk_needs_patching = false; |
| for (auto* nested_msg = cur_packet_->nested_message(); nested_msg; |
| nested_msg = nested_msg->nested_message()) { |
| uint8_t* const cur_hdr = nested_msg->size_field(); |
| |
| // If this is false the protozero Message has already been instructed to |
| // write, upon Finalize(), its size into the patch list. |
| bool size_field_points_within_chunk = |
| cur_hdr >= cur_chunk_.payload_begin() && |
| cur_hdr + kMessageLengthFieldSize <= cur_chunk_.end(); |
| |
| if (size_field_points_within_chunk) { |
| auto offset = |
| static_cast<uint16_t>(cur_hdr - cur_chunk_.payload_begin()); |
| const ChunkID cur_chunk_id = |
| cur_chunk_.header()->chunk_id.load(std::memory_order_relaxed); |
| Patch* patch = patch_list_.emplace_back(cur_chunk_id, offset); |
| nested_msg->set_size_field(&patch->size_field[0]); |
| chunk_needs_patching = true; |
| } else { |
| #if PERFETTO_DCHECK_IS_ON() |
| // Ensure that the size field of the message points to an element of the |
| // patch list. |
| auto patch_it = std::find_if( |
| patch_list_.begin(), patch_list_.end(), |
| [cur_hdr](const Patch& p) { return &p.size_field[0] == cur_hdr; }); |
| PERFETTO_DCHECK(patch_it != patch_list_.end()); |
| #endif |
| } |
| } // for(nested_msg |
| |
| if (chunk_needs_patching) |
| cur_chunk_.SetFlag(ChunkHeader::kChunkNeedsPatching); |
| } // if(fragmenting_packet) |
| |
| if (cur_chunk_.is_valid()) { |
| // ReturnCompletedChunk will consume the first patched entries from |
| // |patch_list_| and shrink it. |
| shmem_arbiter_->ReturnCompletedChunk(std::move(cur_chunk_), target_buffer_, |
| &patch_list_); |
| } |
| |
| // Start a new chunk. |
| |
| ChunkHeader::Packets packets = {}; |
| if (fragmenting_packet_) { |
| packets.count = 1; |
| packets.flags = ChunkHeader::kFirstPacketContinuesFromPrevChunk; |
| } |
| |
| // The memory order of the stores below doesn't really matter. This |header| |
| // is just a local temporary object. The GetNewChunk() call below will copy it |
| // into the shared buffer with the proper barriers. |
| ChunkHeader header = {}; |
| header.writer_id.store(id_, std::memory_order_relaxed); |
| header.chunk_id.store(next_chunk_id_++, std::memory_order_relaxed); |
| header.packets.store(packets, std::memory_order_relaxed); |
| |
| cur_chunk_ = shmem_arbiter_->GetNewChunk(header); |
| reached_max_packets_per_chunk_ = false; |
| uint8_t* payload_begin = cur_chunk_.payload_begin(); |
| if (fragmenting_packet_) { |
| cur_packet_->set_size_field(payload_begin); |
| memset(payload_begin, 0, kPacketHeaderSize); |
| payload_begin += kPacketHeaderSize; |
| cur_fragment_start_ = payload_begin; |
| } |
| |
| return protozero::ContiguousMemoryRange{payload_begin, cur_chunk_.end()}; |
| } |
| |
| WriterID TraceWriterImpl::writer_id() const { |
| return id_; |
| } |
| |
| // Base class ctor/dtor definition. |
| TraceWriter::TraceWriter() = default; |
| TraceWriter::~TraceWriter() = default; |
| |
| } // namespace perfetto |