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// Copyright (c) 2012 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 "base/logging.h"
#include "net/disk_cache/flash/format.h"
#include "net/disk_cache/flash/segment.h"
#include "net/disk_cache/flash/storage.h"
namespace disk_cache {
Segment::Segment(int32 index, bool read_only, Storage* storage)
: read_only_(read_only),
init_(false),
storage_(storage),
offset_(index * kFlashSegmentSize),
summary_offset_(offset_ + kFlashSegmentSize - kFlashSummarySize),
write_offset_(offset_) {
DCHECK(storage);
DCHECK(storage->size() % kFlashSegmentSize == 0);
}
Segment::~Segment() {
DCHECK(!init_ || read_only_);
}
bool Segment::Init() {
if (init_)
return false;
if (offset_ < 0 || offset_ + kFlashSegmentSize > storage_->size())
return false;
if (!read_only_) {
init_ = true;
return true;
}
int32 summary[kFlashMaxEntryCount + 1];
if (!storage_->Read(summary, kFlashSummarySize, summary_offset_))
return false;
size_t entry_count = summary[0];
DCHECK_LE(entry_count, kFlashMaxEntryCount);
std::vector<int32> tmp(summary + 1, summary + 1 + entry_count);
header_offsets_.swap(tmp);
init_ = true;
return true;
}
bool Segment::WriteData(const void* buffer, int32 size, int32* offset) {
DCHECK(init_ && !read_only_);
DCHECK(CanHold(size));
if (!storage_->Write(buffer, size, write_offset_))
return false;
if (offset)
*offset = write_offset_;
write_offset_ += size;
return true;
}
bool Segment::WriteHeader(const void* header, int32 size, int32* offset) {
int32 my_offset;
if (!WriteData(header, size, &my_offset))
return false;
if (offset)
*offset = my_offset;
header_offsets_.push_back(my_offset);
return true;
}
bool Segment::ReadData(void* buffer, int32 size, int32 offset) const {
DCHECK(offset >= offset_ && offset + size <= offset_ + kFlashSegmentSize);
return storage_->Read(buffer, size, offset);
}
bool Segment::Close() {
DCHECK(init_);
if (read_only_)
return true;
DCHECK(header_offsets_.size() <= kFlashMaxEntryCount);
int32 summary[kFlashMaxEntryCount + 1];
summary[0] = header_offsets_.size();
std::copy(header_offsets_.begin(), header_offsets_.end(), summary + 1);
if (!storage_->Write(summary, kFlashSummarySize, summary_offset_))
return false;
read_only_ = true;
return true;
}
bool Segment::CanHold(int32 size) const {
return header_offsets_.size() < kFlashMaxEntryCount &&
write_offset_ + size <= summary_offset_;
}
} // namespace disk_cache
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