Reland of Improve linearized pdf load/show time.

pdf/chunk_stream.cc

Index: pdf/chunk_stream.cc
diff --git a/pdf/chunk_stream.cc b/pdf/chunk_stream.cc
deleted file mode 100644
index adb3cb6edaf5c90a8015930f2378f291791ff94c..0000000000000000000000000000000000000000
--- a/pdf/chunk_stream.cc
+++ /dev/null
@@ -1,175 +0,0 @@
-// Copyright (c) 2010 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "pdf/chunk_stream.h"
-
-#include <stddef.h>
-#include <string.h>
-
-#define __STDC_LIMIT_MACROS
-#ifdef _WIN32
-#include <limits.h>
-#else
-#include <stdint.h>
-#endif
-
-#include <algorithm>
-
-namespace chrome_pdf {
-
-ChunkStream::ChunkStream() : stream_size_(0) {
-}
-
-ChunkStream::~ChunkStream() {
-}
-
-void ChunkStream::Clear() {
-  chunks_.clear();
-  data_.clear();
-  stream_size_ = 0;
-}
-
-void ChunkStream::Preallocate(size_t stream_size) {
-  data_.reserve(stream_size);
-  stream_size_ = stream_size;
-}
-
-size_t ChunkStream::GetSize() const {
-  return data_.size();
-}
-
-bool ChunkStream::WriteData(size_t offset, void* buffer, size_t size) {
-  if (SIZE_MAX - size < offset)
-    return false;
-
-  if (data_.size() < offset + size)
-    data_.resize(offset + size);
-
-  memcpy(&data_[offset], buffer, size);
-
-  if (chunks_.empty()) {
-    chunks_[offset] = size;
-    return true;
-  }
-
-  std::map<size_t, size_t>::iterator start = chunks_.upper_bound(offset);
-  if (start != chunks_.begin())
-    --start;  // start now points to the key equal or lower than offset.
-  if (start->first + start->second < offset)
-    ++start;  // start element is entirely before current chunk, skip it.
-
-  std::map<size_t, size_t>::iterator end = chunks_.upper_bound(offset + size);
-  if (start == end) {  // No chunks to merge.
-    chunks_[offset] = size;
-    return true;
-  }
-
-  --end;
-
-  size_t new_offset = std::min<size_t>(start->first, offset);
-  size_t new_size =
-      std::max<size_t>(end->first + end->second, offset + size) - new_offset;
-
-  chunks_.erase(start, ++end);
-
-  chunks_[new_offset] = new_size;
-
-  return true;
-}
-
-bool ChunkStream::ReadData(size_t offset, size_t size, void* buffer) const {
-  if (!IsRangeAvailable(offset, size))
-    return false;
-
-  memcpy(buffer, &data_[offset], size);
-  return true;
-}
-
-bool ChunkStream::GetMissedRanges(
-    size_t offset, size_t size,
-    std::vector<std::pair<size_t, size_t> >* ranges) const {
-  if (IsRangeAvailable(offset, size))
-    return false;
-
-  ranges->clear();
-  if (chunks_.empty()) {
-    ranges->push_back(std::pair<size_t, size_t>(offset, size));
-    return true;
-  }
-
-  std::map<size_t, size_t>::const_iterator start = chunks_.upper_bound(offset);
-  if (start != chunks_.begin())
-    --start;  // start now points to the key equal or lower than offset.
-  if (start->first + start->second < offset)
-    ++start;  // start element is entirely before current chunk, skip it.
-
-  std::map<size_t, size_t>::const_iterator end =
-      chunks_.upper_bound(offset + size);
-  if (start == end) {  // No data in the current range available.
-    ranges->push_back(std::pair<size_t, size_t>(offset, size));
-    return true;
-  }
-
-  size_t cur_offset = offset;
-  std::map<size_t, size_t>::const_iterator it;
-  for (it = start; it != end; ++it) {
-    if (cur_offset < it->first) {
-      size_t new_size = it->first - cur_offset;
-      ranges->push_back(std::pair<size_t, size_t>(cur_offset, new_size));
-      cur_offset = it->first + it->second;
-    } else if (cur_offset < it->first + it->second) {
-      cur_offset = it->first + it->second;
-    }
-  }
-
-  // Add last chunk.
-  if (cur_offset < offset + size)
-    ranges->push_back(std::pair<size_t, size_t>(cur_offset,
-        offset + size - cur_offset));
-
-  return true;
-}
-
-bool ChunkStream::IsRangeAvailable(size_t offset, size_t size) const {
-  if (chunks_.empty())
-    return false;
-
-  if (SIZE_MAX - size < offset)
-    return false;
-
-  std::map<size_t, size_t>::const_iterator it = chunks_.upper_bound(offset);
-  if (it == chunks_.begin())
-    return false;  // No chunks includes offset byte.
-
-  --it;  // Now it starts equal or before offset.
-  return (it->first + it->second) >= (offset + size);
-}
-
-size_t ChunkStream::GetFirstMissingByte() const {
-  if (chunks_.empty())
-    return 0;
-  std::map<size_t, size_t>::const_iterator begin = chunks_.begin();
-  return begin->first > 0 ? 0 : begin->second;
-}
-
-size_t ChunkStream::GetFirstMissingByteInInterval(size_t offset) const {
-  if (chunks_.empty())
-    return 0;
-  std::map<size_t, size_t>::const_iterator it = chunks_.upper_bound(offset);
-  if (it == chunks_.begin())
-    return 0;
-  --it;
-  return it->first + it->second;
-}
-
-size_t ChunkStream::GetLastMissingByteInInterval(size_t offset) const {
-  if (chunks_.empty())
-    return stream_size_ - 1;
-  std::map<size_t, size_t>::const_iterator it = chunks_.upper_bound(offset);
-  if (it == chunks_.end())
-    return stream_size_ - 1;
-  return it->first - 1;
-}
-
-}  // namespace chrome_pdf