1 /* 2 * Copyright (C) 2022 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/util/streaming_line_reader.h" 18 19 #include "perfetto/base/logging.h" 20 #include "perfetto/ext/base/utils.h" 21 22 namespace perfetto { 23 namespace trace_processor { 24 namespace util { 25 StreamingLineReader(LinesCallback cb)26StreamingLineReader::StreamingLineReader(LinesCallback cb) 27 : lines_callback_(std::move(cb)) {} 28 StreamingLineReader::~StreamingLineReader() = default; 29 BeginWrite(size_t write_buf_size)30char* StreamingLineReader::BeginWrite(size_t write_buf_size) { 31 PERFETTO_DCHECK(size_before_write_ == 0); 32 size_before_write_ = buf_.size(); 33 buf_.resize(size_before_write_ + write_buf_size); 34 return &buf_[size_before_write_]; 35 } 36 EndWrite(size_t size_written)37void StreamingLineReader::EndWrite(size_t size_written) { 38 PERFETTO_DCHECK(size_before_write_ + size_written <= buf_.size()); 39 buf_.resize(size_before_write_ + size_written); 40 size_before_write_ = 0; 41 42 size_t consumed = Tokenize(base::StringView(buf_.data(), buf_.size())); 43 PERFETTO_DCHECK(consumed <= buf_.size()); 44 45 // Unless we got very lucky, the last line in the chunk just written will be 46 // incomplete. Move it to the beginning of the buffer so it gets glued 47 // together on the next {Begin,End}Write() call. 48 buf_.erase(buf_.begin(), buf_.begin() + static_cast<ssize_t>(consumed)); 49 } 50 Tokenize(base::StringView input)51size_t StreamingLineReader::Tokenize(base::StringView input) { 52 size_t chars_consumed = 0; 53 const char* line_start = input.data(); 54 std::vector<base::StringView> lines; 55 lines.reserve(1000); // An educated guess to avoid silly expansions. 56 for (const char* c = input.data(); c < input.end(); ++c) { 57 if (*c != '\n') 58 continue; 59 lines.emplace_back(line_start, static_cast<size_t>(c - line_start)); 60 line_start = c + 1; 61 chars_consumed = static_cast<size_t>(c + 1 - input.data()); 62 } // for(c : input) 63 64 PERFETTO_DCHECK(lines.empty() ^ (chars_consumed != 0)); 65 if (!lines.empty()) 66 lines_callback_(lines); 67 return chars_consumed; 68 } 69 70 } // namespace util 71 } // namespace trace_processor 72 } // namespace perfetto 73