xref: /aosp_15_r20/external/perfetto/src/tracing/core/trace_writer_for_testing.h (revision 6dbdd20afdafa5e3ca9b8809fa73465d530080dc)
1 /*
2  * Copyright (C) 2018 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 #ifndef SRC_TRACING_CORE_TRACE_WRITER_FOR_TESTING_H_
17 #define SRC_TRACING_CORE_TRACE_WRITER_FOR_TESTING_H_
18 
19 #include <vector>
20 
21 #include "perfetto/ext/tracing/core/trace_writer.h"
22 #include "perfetto/protozero/message_handle.h"
23 #include "perfetto/protozero/root_message.h"
24 #include "perfetto/protozero/scattered_heap_buffer.h"
25 #include "protos/perfetto/trace/trace_packet.gen.h"
26 
27 namespace perfetto {
28 
29 // A specialization of TraceWriter for testing which writes into memory
30 // allocated by the ScatteredHeapBuffer.
31 // See //include/perfetto/ext/tracing/core/trace_writer.h for docs.
32 class TraceWriterForTesting : public TraceWriter {
33  public:
34   TraceWriterForTesting();
35   ~TraceWriterForTesting() override;
36 
37   // TraceWriter implementation. See documentation in trace_writer.h.
38   // TracePacketHandle is defined in trace_writer.h
39   TracePacketHandle NewTracePacket() override;
40   void FinishTracePacket() override;
41   void Flush(std::function<void()> callback = {}) override;
42 
43   std::vector<protos::gen::TracePacket> GetAllTracePackets();
44   protos::gen::TracePacket GetOnlyTracePacket();
45 
46   WriterID writer_id() const override;
47   uint64_t written() const override;
48 
49  private:
50   TraceWriterForTesting(const TraceWriterForTesting&) = delete;
51   TraceWriterForTesting& operator=(const TraceWriterForTesting&) = delete;
52 
53   protozero::ScatteredHeapBuffer delegate_;
54   protozero::ScatteredStreamWriter stream_;
55 
56   // The packet returned via NewTracePacket(). Its owned by this class,
57   // TracePacketHandle has just a pointer to it.
58   //
59   // The caller of NewTracePacket can use TakeStreamWriter() and use the stream
60   // writer directly: in that case:
61   // * cur_packet_->size() is not up to date. Only the stream writer has the
62   //   correct information.
63   // * cur_packet_->nested_message() is always nullptr.
64   // * cur_packet_->size_field() is still used to track the start of the current
65   //   packet.
66   std::unique_ptr<protozero::RootMessage<protos::pbzero::TracePacket>>
67       cur_packet_;
68 
69   size_t cur_packet_written_start_ = 0;
70 };
71 
72 }  // namespace perfetto
73 
74 #endif  // SRC_TRACING_CORE_TRACE_WRITER_FOR_TESTING_H_
75