1 /* 2 * Copyright (C) 2017 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef SRC_TRACING_CORE_TRACE_WRITER_IMPL_H_ 18 #define SRC_TRACING_CORE_TRACE_WRITER_IMPL_H_ 19 20 #include "perfetto/protozero/message_handle.h" 21 #include "perfetto/protozero/scattered_stream_writer.h" 22 #include "perfetto/tracing/core/basic_types.h" 23 #include "perfetto/tracing/core/shared_memory_abi.h" 24 #include "perfetto/tracing/core/trace_writer.h" 25 #include "src/tracing/core/patch_list.h" 26 27 namespace perfetto { 28 29 class SharedMemoryArbiterImpl; 30 31 // See //include/perfetto/tracing/core/trace_writer.h for docs. 32 class TraceWriterImpl : public TraceWriter, 33 public protozero::ScatteredStreamWriter::Delegate { 34 public: 35 // TracePacketHandle is defined in trace_writer.h 36 TraceWriterImpl(SharedMemoryArbiterImpl*, WriterID, BufferID); 37 ~TraceWriterImpl() override; 38 39 // TraceWriter implementation. See documentation in trace_writer.h. 40 TracePacketHandle NewTracePacket() override; 41 void Flush(std::function<void()> callback = {}) override; 42 WriterID writer_id() const override; 43 bool SetFirstChunkId(ChunkID) override; 44 uint64_t written() const override { 45 return protobuf_stream_writer_.written(); 46 } 47 48 void ResetChunkForTesting() { cur_chunk_ = SharedMemoryABI::Chunk(); } 49 50 private: 51 TraceWriterImpl(const TraceWriterImpl&) = delete; 52 TraceWriterImpl& operator=(const TraceWriterImpl&) = delete; 53 54 // ScatteredStreamWriter::Delegate implementation. 55 protozero::ContiguousMemoryRange GetNewBuffer() override; 56 57 // The per-producer arbiter that coordinates access to the shared memory 58 // buffer from several threads. 59 SharedMemoryArbiterImpl* const shmem_arbiter_; 60 61 // ID of the current writer. 62 const WriterID id_; 63 64 // This is just copied back into the chunk header. 65 // See comments in data_source_config.proto for |target_buffer|. 66 const BufferID target_buffer_; 67 68 // Monotonic (% wrapping) sequence id of the chunk. Together with the WriterID 69 // this allows the Service to reconstruct the linear sequence of packets. 70 ChunkID next_chunk_id_ = 0; 71 72 // The chunk we are holding onto (if any). 73 SharedMemoryABI::Chunk cur_chunk_; 74 75 // Passed to protozero message to write directly into |cur_chunk_|. It 76 // keeps track of the write pointer. It calls us back (GetNewBuffer()) when 77 // |cur_chunk_| is filled. 78 protozero::ScatteredStreamWriter protobuf_stream_writer_; 79 80 // The packet returned via NewTracePacket(). Its owned by this class, 81 // TracePacketHandle has just a pointer to it. 82 std::unique_ptr<protos::pbzero::TracePacket> cur_packet_; 83 84 // The start address of |cur_packet_| within |cur_chunk_|. Used to figure out 85 // fragments sizes when a TracePacket write is interrupted by GetNewBuffer(). 86 uint8_t* cur_fragment_start_ = nullptr; 87 88 // true if we received a call to GetNewBuffer() after NewTracePacket(), 89 // false if GetNewBuffer() happened during NewTracePacket() prologue, while 90 // starting the TracePacket header. 91 bool fragmenting_packet_ = false; 92 93 // Set to |true| when the current chunk contains the maximum number of packets 94 // a chunk can contain. When this is |true|, the next packet requires starting 95 // a new chunk. 96 bool reached_max_packets_per_chunk_ = false; 97 98 // When a packet is fragmented across different chunks, the |size_field| of 99 // the outstanding nested protobuf messages is redirected onto Patch entries 100 // in this list at the time the Chunk is returned (because at that point we 101 // have to release the ownership of the current Chunk). This list will be 102 // later sent out-of-band to the tracing service, who will patch the required 103 // chunks, if they are still around. 104 PatchList patch_list_; 105 }; 106 107 } // namespace perfetto 108 109 #endif // SRC_TRACING_CORE_TRACE_WRITER_IMPL_H_ 110