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#include "perfetto/protozero/scattered_stream_writer.h"
18
19#include <algorithm>
20
21#include "perfetto/base/logging.h"
22
23namespace protozero {
24
25ScatteredStreamWriter::Delegate::~Delegate() {}
26
27ScatteredStreamWriter::ScatteredStreamWriter(Delegate* delegate)
28    : delegate_(delegate),
29      cur_range_({nullptr, nullptr}),
30      write_ptr_(nullptr) {}
31
32ScatteredStreamWriter::~ScatteredStreamWriter() {}
33
34void ScatteredStreamWriter::Reset(ContiguousMemoryRange range) {
35  cur_range_ = range;
36  write_ptr_ = range.begin;
37  PERFETTO_DCHECK(!write_ptr_ || write_ptr_ < cur_range_.end);
38}
39
40void ScatteredStreamWriter::Extend() {
41  Reset(delegate_->GetNewBuffer());
42}
43
44void ScatteredStreamWriter::WriteBytesSlowPath(const uint8_t* src,
45                                               size_t size) {
46  size_t bytes_left = size;
47  while (bytes_left > 0) {
48    if (write_ptr_ >= cur_range_.end)
49      Extend();
50    const size_t burst_size = std::min(bytes_available(), bytes_left);
51    WriteBytesUnsafe(src, burst_size);
52    bytes_left -= burst_size;
53    src += burst_size;
54  }
55}
56
57// TODO(primiano): perf optimization: I suspect that at the end this will always
58// be called with |size| == 4, in which case we might just hardcode it.
59uint8_t* ScatteredStreamWriter::ReserveBytes(size_t size) {
60  if (write_ptr_ + size > cur_range_.end) {
61    // Assume the reservations are always < Delegate::GetNewBuffer().size(),
62    // so that one single call to Extend() will definitely give enough headroom.
63    Extend();
64    PERFETTO_DCHECK(write_ptr_ + size <= cur_range_.end);
65  }
66  uint8_t* begin = write_ptr_;
67  write_ptr_ += size;
68#if PERFETTO_DCHECK_IS_ON()
69  memset(begin, 0, size);
70#endif
71  return begin;
72}
73
74}  // namespace protozero
75