1 /* 2 * Copyright (C) 2020 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 #include "src/trace_processor/tp_metatrace.h" 18 19 namespace perfetto { 20 namespace trace_processor { 21 namespace metatrace { 22 23 bool g_enabled = false; 24 Enable()25void Enable() { 26 g_enabled = true; 27 } 28 DisableAndReadBuffer(std::function<void (Record *)> fn)29void DisableAndReadBuffer(std::function<void(Record*)> fn) { 30 g_enabled = false; 31 if (!fn) 32 return; 33 RingBuffer::GetInstance()->ReadAll(fn); 34 } 35 RingBuffer()36RingBuffer::RingBuffer() { 37 static_assert((kCapacity & (kCapacity - 1)) == 0, 38 "Capacity should be a power of 2"); 39 } 40 ReadAll(std::function<void (Record *)> fn)41void RingBuffer::ReadAll(std::function<void(Record*)> fn) { 42 // Mark as reading so we don't get reentrancy in obtaining new 43 // trace events. 44 is_reading_ = true; 45 46 uint64_t start = (write_idx_ - start_idx_) < kCapacity 47 ? start_idx_ 48 : write_idx_ - kCapacity; 49 uint64_t end = write_idx_; 50 51 // Increment the write index by kCapacity + 1. This ensures that if 52 // ScopedEntry is destoryed in |fn| below, we won't get overwrites 53 // while reading the buffer. 54 // This works because of the logic in ~ScopedEntry and 55 // RingBuffer::HasOverwritten which ensures that we don't overwrite entries 56 // more than kCapcity elements in the past. 57 write_idx_ += kCapacity + 1; 58 59 for (uint64_t i = start; i < end; ++i) { 60 Record* record = At(i); 61 62 // If the slice was unfinished for some reason, don't emit it. 63 if (record->duration_ns != 0) { 64 fn(record); 65 } 66 } 67 68 // Ensure that the start pointer is updated to the write pointer. 69 start_idx_ = write_idx_; 70 71 // Remove the reading marker. 72 is_reading_ = false; 73 } 74 75 } // namespace metatrace 76 } // namespace trace_processor 77 } // namespace perfetto 78