blob: 9983f936d3147399aca682dcb1c24dccd1b77772 [file] [log] [blame]
// 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 "net/disk_cache/blockfile/sparse_control.h"
#include <stdint.h>
#include "base/bind.h"
#include "base/format_macros.h"
#include "base/location.h"
#include "base/logging.h"
#include "base/macros.h"
#include "base/single_thread_task_runner.h"
#include "base/strings/string_util.h"
#include "base/strings/stringprintf.h"
#include "base/threading/thread_task_runner_handle.h"
#include "base/time/time.h"
#include "net/base/interval.h"
#include "net/base/io_buffer.h"
#include "net/base/net_errors.h"
#include "net/disk_cache/blockfile/backend_impl.h"
#include "net/disk_cache/blockfile/entry_impl.h"
#include "net/disk_cache/blockfile/file.h"
#include "net/disk_cache/net_log_parameters.h"
#include "net/log/net_log.h"
#include "net/log/net_log_event_type.h"
#include "net/log/net_log_with_source.h"
using base::Time;
namespace {
// Stream of the sparse data index.
const int kSparseIndex = 2;
// Stream of the sparse data.
const int kSparseData = 1;
// We can have up to 64k children.
const int kMaxMapSize = 8 * 1024;
// The maximum number of bytes that a child can store.
const int kMaxEntrySize = 0x100000;
// The size of each data block (tracked by the child allocation bitmap).
const int kBlockSize = 1024;
// Returns the name of a child entry given the base_name and signature of the
// parent and the child_id.
// If the entry is called entry_name, child entries will be named something
// like Range_entry_name:XXX:YYY where XXX is the entry signature and YYY is the
// number of the particular child.
std::string GenerateChildName(const std::string& base_name,
int64_t signature,
int64_t child_id) {
return base::StringPrintf("Range_%s:%" PRIx64 ":%" PRIx64, base_name.c_str(),
signature, child_id);
}
// This class deletes the children of a sparse entry.
class ChildrenDeleter
: public base::RefCounted<ChildrenDeleter>,
public disk_cache::FileIOCallback {
public:
ChildrenDeleter(disk_cache::BackendImpl* backend, const std::string& name)
: backend_(backend->GetWeakPtr()), name_(name), signature_(0) {}
void OnFileIOComplete(int bytes_copied) override;
// Two ways of deleting the children: if we have the children map, use Start()
// directly, otherwise pass the data address to ReadData().
void Start(char* buffer, int len);
void ReadData(disk_cache::Addr address, int len);
private:
friend class base::RefCounted<ChildrenDeleter>;
~ChildrenDeleter() override = default;
void DeleteChildren();
base::WeakPtr<disk_cache::BackendImpl> backend_;
std::string name_;
disk_cache::Bitmap children_map_;
int64_t signature_;
std::unique_ptr<char[]> buffer_;
DISALLOW_COPY_AND_ASSIGN(ChildrenDeleter);
};
// This is the callback of the file operation.
void ChildrenDeleter::OnFileIOComplete(int bytes_copied) {
char* buffer = buffer_.release();
Start(buffer, bytes_copied);
}
void ChildrenDeleter::Start(char* buffer, int len) {
buffer_.reset(buffer);
if (len < static_cast<int>(sizeof(disk_cache::SparseData)))
return Release();
// Just copy the information from |buffer|, delete |buffer| and start deleting
// the child entries.
disk_cache::SparseData* data =
reinterpret_cast<disk_cache::SparseData*>(buffer);
signature_ = data->header.signature;
int num_bits = (len - sizeof(disk_cache::SparseHeader)) * 8;
children_map_.Resize(num_bits, false);
children_map_.SetMap(data->bitmap, num_bits / 32);
buffer_.reset();
DeleteChildren();
}
void ChildrenDeleter::ReadData(disk_cache::Addr address, int len) {
DCHECK(address.is_block_file());
if (!backend_.get())
return Release();
disk_cache::File* file(backend_->File(address));
if (!file)
return Release();
size_t file_offset = address.start_block() * address.BlockSize() +
disk_cache::kBlockHeaderSize;
buffer_.reset(new char[len]);
bool completed;
if (!file->Read(buffer_.get(), len, file_offset, this, &completed))
return Release();
if (completed)
OnFileIOComplete(len);
// And wait until OnFileIOComplete gets called.
}
void ChildrenDeleter::DeleteChildren() {
int child_id = 0;
if (!children_map_.FindNextSetBit(&child_id) || !backend_.get()) {
// We are done. Just delete this object.
return Release();
}
std::string child_name = GenerateChildName(name_, signature_, child_id);
backend_->SyncDoomEntry(child_name);
children_map_.Set(child_id, false);
// Post a task to delete the next child.
base::ThreadTaskRunnerHandle::Get()->PostTask(
FROM_HERE, base::Bind(&ChildrenDeleter::DeleteChildren, this));
}
// Returns the NetLog event type corresponding to a SparseOperation.
net::NetLogEventType GetSparseEventType(
disk_cache::SparseControl::SparseOperation operation) {
switch (operation) {
case disk_cache::SparseControl::kReadOperation:
return net::NetLogEventType::SPARSE_READ;
case disk_cache::SparseControl::kWriteOperation:
return net::NetLogEventType::SPARSE_WRITE;
case disk_cache::SparseControl::kGetRangeOperation:
return net::NetLogEventType::SPARSE_GET_RANGE;
default:
NOTREACHED();
return net::NetLogEventType::CANCELLED;
}
}
// Logs the end event for |operation| on a child entry. Range operations log
// no events for each child they search through.
void LogChildOperationEnd(const net::NetLogWithSource& net_log,
disk_cache::SparseControl::SparseOperation operation,
int result) {
if (net_log.IsCapturing()) {
net::NetLogEventType event_type;
switch (operation) {
case disk_cache::SparseControl::kReadOperation:
event_type = net::NetLogEventType::SPARSE_READ_CHILD_DATA;
break;
case disk_cache::SparseControl::kWriteOperation:
event_type = net::NetLogEventType::SPARSE_WRITE_CHILD_DATA;
break;
case disk_cache::SparseControl::kGetRangeOperation:
return;
default:
NOTREACHED();
return;
}
net_log.EndEventWithNetErrorCode(event_type, result);
}
}
} // namespace.
namespace disk_cache {
SparseControl::SparseControl(EntryImpl* entry)
: entry_(entry),
child_(NULL),
operation_(kNoOperation),
pending_(false),
finished_(false),
init_(false),
range_found_(false),
abort_(false),
child_map_(child_data_.bitmap, kNumSparseBits, kNumSparseBits / 32),
offset_(0),
buf_len_(0),
child_offset_(0),
child_len_(0),
result_(0) {
memset(&sparse_header_, 0, sizeof(sparse_header_));
memset(&child_data_, 0, sizeof(child_data_));
}
SparseControl::~SparseControl() {
if (child_)
CloseChild();
if (init_)
WriteSparseData();
}
int SparseControl::Init() {
DCHECK(!init_);
// We should not have sparse data for the exposed entry.
if (entry_->GetDataSize(kSparseData))
return net::ERR_CACHE_OPERATION_NOT_SUPPORTED;
// Now see if there is something where we store our data.
int rv = net::OK;
int data_len = entry_->GetDataSize(kSparseIndex);
if (!data_len) {
rv = CreateSparseEntry();
} else {
rv = OpenSparseEntry(data_len);
}
if (rv == net::OK)
init_ = true;
return rv;
}
bool SparseControl::CouldBeSparse() const {
DCHECK(!init_);
if (entry_->GetDataSize(kSparseData))
return false;
// We don't verify the data, just see if it could be there.
return (entry_->GetDataSize(kSparseIndex) != 0);
}
int SparseControl::StartIO(SparseOperation op,
int64_t offset,
net::IOBuffer* buf,
int buf_len,
CompletionOnceCallback callback) {
DCHECK(init_);
// We don't support simultaneous IO for sparse data.
if (operation_ != kNoOperation)
return net::ERR_CACHE_OPERATION_NOT_SUPPORTED;
if (offset < 0 || buf_len < 0)
return net::ERR_INVALID_ARGUMENT;
// We only support up to 64 GB.
if (static_cast<uint64_t>(offset) + static_cast<unsigned int>(buf_len) >=
UINT64_C(0x1000000000)) {
return net::ERR_CACHE_OPERATION_NOT_SUPPORTED;
}
DCHECK(!user_buf_.get());
DCHECK(user_callback_.is_null());
if (!buf && (op == kReadOperation || op == kWriteOperation))
return 0;
// Copy the operation parameters.
operation_ = op;
offset_ = offset;
user_buf_ = buf ? new net::DrainableIOBuffer(buf, buf_len) : NULL;
buf_len_ = buf_len;
user_callback_ = std::move(callback);
result_ = 0;
pending_ = false;
finished_ = false;
abort_ = false;
if (entry_->net_log().IsCapturing()) {
entry_->net_log().BeginEvent(
GetSparseEventType(operation_),
CreateNetLogSparseOperationCallback(offset_, buf_len_));
}
DoChildrenIO();
if (!pending_) {
// Everything was done synchronously.
operation_ = kNoOperation;
user_buf_ = NULL;
user_callback_.Reset();
return result_;
}
return net::ERR_IO_PENDING;
}
int SparseControl::GetAvailableRange(int64_t offset, int len, int64_t* start) {
DCHECK(init_);
// We don't support simultaneous IO for sparse data.
if (operation_ != kNoOperation)
return net::ERR_CACHE_OPERATION_NOT_SUPPORTED;
DCHECK(start);
range_found_ = false;
int result =
StartIO(kGetRangeOperation, offset, NULL, len, CompletionOnceCallback());
if (range_found_) {
*start = offset_;
return result;
}
// This is a failure. We want to return a valid start value in any case.
*start = offset;
return result < 0 ? result : 0; // Don't mask error codes to the caller.
}
void SparseControl::CancelIO() {
if (operation_ == kNoOperation)
return;
abort_ = true;
}
int SparseControl::ReadyToUse(CompletionOnceCallback callback) {
if (!abort_)
return net::OK;
// We'll grab another reference to keep this object alive because we just have
// one extra reference due to the pending IO operation itself, but we'll
// release that one before invoking user_callback_.
entry_->AddRef(); // Balanced in DoAbortCallbacks.
abort_callbacks_.push_back(std::move(callback));
return net::ERR_IO_PENDING;
}
// Static
void SparseControl::DeleteChildren(EntryImpl* entry) {
DCHECK(entry->GetEntryFlags() & PARENT_ENTRY);
int data_len = entry->GetDataSize(kSparseIndex);
if (data_len < static_cast<int>(sizeof(SparseData)) ||
entry->GetDataSize(kSparseData))
return;
int map_len = data_len - sizeof(SparseHeader);
if (map_len > kMaxMapSize || map_len % 4)
return;
char* buffer;
Addr address;
entry->GetData(kSparseIndex, &buffer, &address);
if (!buffer && !address.is_initialized())
return;
entry->net_log().AddEvent(net::NetLogEventType::SPARSE_DELETE_CHILDREN);
DCHECK(entry->backend_.get());
ChildrenDeleter* deleter = new ChildrenDeleter(entry->backend_.get(),
entry->GetKey());
// The object will self destruct when finished.
deleter->AddRef();
if (buffer) {
base::ThreadTaskRunnerHandle::Get()->PostTask(
FROM_HERE,
base::Bind(&ChildrenDeleter::Start, deleter, buffer, data_len));
} else {
base::ThreadTaskRunnerHandle::Get()->PostTask(
FROM_HERE,
base::Bind(&ChildrenDeleter::ReadData, deleter, address, data_len));
}
}
// We are going to start using this entry to store sparse data, so we have to
// initialize our control info.
int SparseControl::CreateSparseEntry() {
if (CHILD_ENTRY & entry_->GetEntryFlags())
return net::ERR_CACHE_OPERATION_NOT_SUPPORTED;
memset(&sparse_header_, 0, sizeof(sparse_header_));
sparse_header_.signature = Time::Now().ToInternalValue();
sparse_header_.magic = kIndexMagic;
sparse_header_.parent_key_len = entry_->GetKey().size();
children_map_.Resize(kNumSparseBits, true);
// Save the header. The bitmap is saved in the destructor.
scoped_refptr<net::IOBuffer> buf(
new net::WrappedIOBuffer(reinterpret_cast<char*>(&sparse_header_)));
int rv = entry_->WriteData(kSparseIndex, 0, buf.get(), sizeof(sparse_header_),
CompletionOnceCallback(), false);
if (rv != sizeof(sparse_header_)) {
DLOG(ERROR) << "Unable to save sparse_header_";
return net::ERR_CACHE_OPERATION_NOT_SUPPORTED;
}
entry_->SetEntryFlags(PARENT_ENTRY);
return net::OK;
}
// We are opening an entry from disk. Make sure that our control data is there.
int SparseControl::OpenSparseEntry(int data_len) {
if (data_len < static_cast<int>(sizeof(SparseData)))
return net::ERR_CACHE_OPERATION_NOT_SUPPORTED;
if (entry_->GetDataSize(kSparseData))
return net::ERR_CACHE_OPERATION_NOT_SUPPORTED;
if (!(PARENT_ENTRY & entry_->GetEntryFlags()))
return net::ERR_CACHE_OPERATION_NOT_SUPPORTED;
// Dont't go over board with the bitmap. 8 KB gives us offsets up to 64 GB.
int map_len = data_len - sizeof(sparse_header_);
if (map_len > kMaxMapSize || map_len % 4)
return net::ERR_CACHE_OPERATION_NOT_SUPPORTED;
scoped_refptr<net::IOBuffer> buf(
new net::WrappedIOBuffer(reinterpret_cast<char*>(&sparse_header_)));
// Read header.
int rv = entry_->ReadData(kSparseIndex, 0, buf.get(), sizeof(sparse_header_),
CompletionOnceCallback());
if (rv != static_cast<int>(sizeof(sparse_header_)))
return net::ERR_CACHE_READ_FAILURE;
// The real validation should be performed by the caller. This is just to
// double check.
if (sparse_header_.magic != kIndexMagic ||
sparse_header_.parent_key_len !=
static_cast<int>(entry_->GetKey().size()))
return net::ERR_CACHE_OPERATION_NOT_SUPPORTED;
// Read the actual bitmap.
buf = new net::IOBuffer(map_len);
rv = entry_->ReadData(kSparseIndex, sizeof(sparse_header_), buf.get(),
map_len, CompletionOnceCallback());
if (rv != map_len)
return net::ERR_CACHE_READ_FAILURE;
// Grow the bitmap to the current size and copy the bits.
children_map_.Resize(map_len * 8, false);
children_map_.SetMap(reinterpret_cast<uint32_t*>(buf->data()), map_len);
return net::OK;
}
bool SparseControl::OpenChild() {
DCHECK_GE(result_, 0);
std::string key = GenerateChildKey();
if (child_) {
// Keep using the same child or open another one?.
if (key == child_->GetKey())
return true;
CloseChild();
}
// See if we are tracking this child.
if (!ChildPresent())
return ContinueWithoutChild(key);
if (!entry_->backend_.get())
return false;
child_ = entry_->backend_->OpenEntryImpl(key);
if (!child_)
return ContinueWithoutChild(key);
if (!(CHILD_ENTRY & child_->GetEntryFlags()) ||
child_->GetDataSize(kSparseIndex) < static_cast<int>(sizeof(child_data_)))
return KillChildAndContinue(key, false);
scoped_refptr<net::WrappedIOBuffer> buf(
new net::WrappedIOBuffer(reinterpret_cast<char*>(&child_data_)));
// Read signature.
int rv = child_->ReadData(kSparseIndex, 0, buf.get(), sizeof(child_data_),
CompletionOnceCallback());
if (rv != sizeof(child_data_))
return KillChildAndContinue(key, true); // This is a fatal failure.
if (child_data_.header.signature != sparse_header_.signature ||
child_data_.header.magic != kIndexMagic)
return KillChildAndContinue(key, false);
if (child_data_.header.last_block_len < 0 ||
child_data_.header.last_block_len >= kBlockSize) {
// Make sure these values are always within range.
child_data_.header.last_block_len = 0;
child_data_.header.last_block = -1;
}
return true;
}
void SparseControl::CloseChild() {
scoped_refptr<net::WrappedIOBuffer> buf(
new net::WrappedIOBuffer(reinterpret_cast<char*>(&child_data_)));
// Save the allocation bitmap before closing the child entry.
int rv = child_->WriteData(kSparseIndex, 0, buf.get(), sizeof(child_data_),
CompletionOnceCallback(), false);
if (rv != sizeof(child_data_))
DLOG(ERROR) << "Failed to save child data";
child_ = NULL;
}
std::string SparseControl::GenerateChildKey() {
return GenerateChildName(entry_->GetKey(), sparse_header_.signature,
offset_ >> 20);
}
// We are deleting the child because something went wrong.
bool SparseControl::KillChildAndContinue(const std::string& key, bool fatal) {
SetChildBit(false);
child_->DoomImpl();
child_ = NULL;
if (fatal) {
result_ = net::ERR_CACHE_READ_FAILURE;
return false;
}
return ContinueWithoutChild(key);
}
// We were not able to open this child; see what we can do.
bool SparseControl::ContinueWithoutChild(const std::string& key) {
if (kReadOperation == operation_)
return false;
if (kGetRangeOperation == operation_)
return true;
if (!entry_->backend_.get())
return false;
child_ = entry_->backend_->CreateEntryImpl(key);
if (!child_) {
child_ = NULL;
result_ = net::ERR_CACHE_READ_FAILURE;
return false;
}
// Write signature.
InitChildData();
return true;
}
bool SparseControl::ChildPresent() {
int child_bit = static_cast<int>(offset_ >> 20);
if (children_map_.Size() <= child_bit)
return false;
return children_map_.Get(child_bit);
}
void SparseControl::SetChildBit(bool value) {
int child_bit = static_cast<int>(offset_ >> 20);
// We may have to increase the bitmap of child entries.
if (children_map_.Size() <= child_bit)
children_map_.Resize(Bitmap::RequiredArraySize(child_bit + 1) * 32, true);
children_map_.Set(child_bit, value);
}
void SparseControl::WriteSparseData() {
scoped_refptr<net::IOBuffer> buf(new net::WrappedIOBuffer(
reinterpret_cast<const char*>(children_map_.GetMap())));
int len = children_map_.ArraySize() * 4;
int rv = entry_->WriteData(kSparseIndex, sizeof(sparse_header_), buf.get(),
len, CompletionOnceCallback(), false);
if (rv != len) {
DLOG(ERROR) << "Unable to save sparse map";
}
}
bool SparseControl::VerifyRange() {
DCHECK_GE(result_, 0);
child_offset_ = static_cast<int>(offset_) & (kMaxEntrySize - 1);
child_len_ = std::min(buf_len_, kMaxEntrySize - child_offset_);
// We can write to (or get info from) anywhere in this child.
if (operation_ != kReadOperation)
return true;
// Check that there are no holes in this range.
int last_bit = (child_offset_ + child_len_ + 1023) >> 10;
int start = child_offset_ >> 10;
if (child_map_.FindNextBit(&start, last_bit, false)) {
// Something is not here.
DCHECK_GE(child_data_.header.last_block_len, 0);
DCHECK_LT(child_data_.header.last_block_len, kBlockSize);
int partial_block_len = PartialBlockLength(start);
if (start == child_offset_ >> 10) {
// It looks like we don't have anything.
if (partial_block_len <= (child_offset_ & (kBlockSize - 1)))
return false;
}
// We have the first part.
child_len_ = (start << 10) - child_offset_;
if (partial_block_len) {
// We may have a few extra bytes.
child_len_ = std::min(child_len_ + partial_block_len, buf_len_);
}
// There is no need to read more after this one.
buf_len_ = child_len_;
}
return true;
}
void SparseControl::UpdateRange(int result) {
if (result <= 0 || operation_ != kWriteOperation)
return;
DCHECK_GE(child_data_.header.last_block_len, 0);
DCHECK_LT(child_data_.header.last_block_len, kBlockSize);
// Write the bitmap.
int first_bit = child_offset_ >> 10;
int block_offset = child_offset_ & (kBlockSize - 1);
if (block_offset && (child_data_.header.last_block != first_bit ||
child_data_.header.last_block_len < block_offset)) {
// The first block is not completely filled; ignore it.
first_bit++;
}
int last_bit = (child_offset_ + result) >> 10;
block_offset = (child_offset_ + result) & (kBlockSize - 1);
// This condition will hit with the following criteria:
// 1. The first byte doesn't follow the last write.
// 2. The first byte is in the middle of a block.
// 3. The first byte and the last byte are in the same block.
if (first_bit > last_bit)
return;
if (block_offset && !child_map_.Get(last_bit)) {
// The last block is not completely filled; save it for later.
child_data_.header.last_block = last_bit;
child_data_.header.last_block_len = block_offset;
} else {
child_data_.header.last_block = -1;
}
child_map_.SetRange(first_bit, last_bit, true);
}
int SparseControl::PartialBlockLength(int block_index) const {
if (block_index == child_data_.header.last_block)
return child_data_.header.last_block_len;
// This is really empty.
return 0;
}
void SparseControl::InitChildData() {
child_->SetEntryFlags(CHILD_ENTRY);
memset(&child_data_, 0, sizeof(child_data_));
child_data_.header = sparse_header_;
scoped_refptr<net::WrappedIOBuffer> buf(
new net::WrappedIOBuffer(reinterpret_cast<char*>(&child_data_)));
int rv = child_->WriteData(kSparseIndex, 0, buf.get(), sizeof(child_data_),
CompletionOnceCallback(), false);
if (rv != sizeof(child_data_))
DLOG(ERROR) << "Failed to save child data";
SetChildBit(true);
}
void SparseControl::DoChildrenIO() {
while (DoChildIO()) continue;
// Range operations are finished synchronously, often without setting
// |finished_| to true.
if (kGetRangeOperation == operation_ && entry_->net_log().IsCapturing()) {
entry_->net_log().EndEvent(
net::NetLogEventType::SPARSE_GET_RANGE,
CreateNetLogGetAvailableRangeResultCallback(offset_, result_));
}
if (finished_) {
if (kGetRangeOperation != operation_ && entry_->net_log().IsCapturing()) {
entry_->net_log().EndEvent(GetSparseEventType(operation_));
}
if (pending_)
DoUserCallback(); // Don't touch this object after this point.
}
}
bool SparseControl::DoChildIO() {
finished_ = true;
if (!buf_len_ || result_ < 0)
return false;
if (!OpenChild())
return false;
if (!VerifyRange())
return false;
// We have more work to do. Let's not trigger a callback to the caller.
finished_ = false;
CompletionOnceCallback callback;
if (!user_callback_.is_null()) {
callback = base::BindOnce(&SparseControl::OnChildIOCompleted,
base::Unretained(this));
}
int rv = 0;
switch (operation_) {
case kReadOperation:
if (entry_->net_log().IsCapturing()) {
entry_->net_log().BeginEvent(
net::NetLogEventType::SPARSE_READ_CHILD_DATA,
CreateNetLogSparseReadWriteCallback(child_->net_log().source(),
child_len_));
}
rv = child_->ReadDataImpl(kSparseData, child_offset_, user_buf_.get(),
child_len_, std::move(callback));
break;
case kWriteOperation:
if (entry_->net_log().IsCapturing()) {
entry_->net_log().BeginEvent(
net::NetLogEventType::SPARSE_WRITE_CHILD_DATA,
CreateNetLogSparseReadWriteCallback(child_->net_log().source(),
child_len_));
}
rv = child_->WriteDataImpl(kSparseData, child_offset_, user_buf_.get(),
child_len_, std::move(callback), false);
break;
case kGetRangeOperation:
rv = DoGetAvailableRange();
break;
default:
NOTREACHED();
}
if (rv == net::ERR_IO_PENDING) {
if (!pending_) {
pending_ = true;
// The child will protect himself against closing the entry while IO is in
// progress. However, this entry can still be closed, and that would not
// be a good thing for us, so we increase the refcount until we're
// finished doing sparse stuff.
entry_->AddRef(); // Balanced in DoUserCallback.
}
return false;
}
if (!rv)
return false;
DoChildIOCompleted(rv);
return true;
}
int SparseControl::DoGetAvailableRange() {
if (!child_)
return child_len_; // Move on to the next child.
// Blockfile splits sparse files into multiple child entries, each responsible
// for managing 1MiB of address space. This method is responsible for
// implementing GetAvailableRange within a single child.
//
// Input:
// |child_offset_|, |child_len_|:
// describe range in current child's address space the client requested.
// |offset_| is equivalent to |child_offset_| but in global address space.
//
// For example if this were child [2] and the original call was for
// [0x200005, 0x200007) then |offset_| would be 0x200005, |child_offset_|
// would be 5, and |child_len| would be 2.
//
// Output:
// If nothing found:
// return |child_len_|
//
// If something found:
// |result_| gets the length of the available range.
// |offset_| gets the global address of beginning of the available range.
// |range_found_| get true to signal SparseControl::GetAvailableRange().
// return 0 to exit loop.
net::Interval<int> to_find(child_offset_, child_offset_ + child_len_);
// Within each child, valid portions are mostly tracked via the |child_map_|
// bitmap which marks which 1KiB 'blocks' have valid data. Scan the bitmap
// for the first contiguous range of set bits that's relevant to the range
// [child_offset_, child_offset_ + len)
int first_bit = child_offset_ >> 10;
int last_bit = (child_offset_ + child_len_ + kBlockSize - 1) >> 10;
int found = first_bit;
int bits_found = child_map_.FindBits(&found, last_bit, true);
net::Interval<int> bitmap_range(found * kBlockSize,
found * kBlockSize + bits_found * kBlockSize);
// Bits on the bitmap should only be set when the corresponding block was
// fully written (it's really being used). If a block is partially used, it
// has to start with valid data, the length of the valid data is saved in
// |header.last_block_len| and the block number saved in |header.last_block|.
// This is updated after every write; with |header.last_block| set to -1
// if no sub-KiB range is being tracked.
net::Interval<int> last_write_range;
if (child_data_.header.last_block >= 0) {
last_write_range =
net::Interval<int>(child_data_.header.last_block * kBlockSize,
child_data_.header.last_block * kBlockSize +
child_data_.header.last_block_len);
}
// Often |last_write_range| is contiguously after |bitmap_range|, but not
// always. See if they can be combined.
if (!last_write_range.Empty() && !bitmap_range.Empty() &&
bitmap_range.max() == last_write_range.min()) {
bitmap_range.SetMax(last_write_range.max());
last_write_range.Clear();
}
// Do any of them have anything relevant?
bitmap_range.IntersectWith(to_find);
last_write_range.IntersectWith(to_find);
// Now return the earliest non-empty interval, if any.
net::Interval<int> result_range = bitmap_range;
if (bitmap_range.Empty() || (!last_write_range.Empty() &&
last_write_range.min() < bitmap_range.min()))
result_range = last_write_range;
if (result_range.Empty()) {
// Nothing found, so we just skip over this child.
return child_len_;
}
// Package up our results.
range_found_ = true;
offset_ += result_range.min() - child_offset_;
result_ = result_range.max() - result_range.min();
return 0;
}
void SparseControl::DoChildIOCompleted(int result) {
LogChildOperationEnd(entry_->net_log(), operation_, result);
if (result < 0) {
// We fail the whole operation if we encounter an error.
result_ = result;
return;
}
UpdateRange(result);
result_ += result;
offset_ += result;
buf_len_ -= result;
// We'll be reusing the user provided buffer for the next chunk.
if (buf_len_ && user_buf_.get())
user_buf_->DidConsume(result);
}
void SparseControl::OnChildIOCompleted(int result) {
DCHECK_NE(net::ERR_IO_PENDING, result);
DoChildIOCompleted(result);
if (abort_) {
// We'll return the current result of the operation, which may be less than
// the bytes to read or write, but the user cancelled the operation.
abort_ = false;
if (entry_->net_log().IsCapturing()) {
entry_->net_log().AddEvent(net::NetLogEventType::CANCELLED);
entry_->net_log().EndEvent(GetSparseEventType(operation_));
}
// We have an indirect reference to this object for every callback so if
// there is only one callback, we may delete this object before reaching
// DoAbortCallbacks.
bool has_abort_callbacks = !abort_callbacks_.empty();
DoUserCallback();
if (has_abort_callbacks)
DoAbortCallbacks();
return;
}
// We are running a callback from the message loop. It's time to restart what
// we were doing before.
DoChildrenIO();
}
void SparseControl::DoUserCallback() {
DCHECK(!user_callback_.is_null());
CompletionOnceCallback cb = std::move(user_callback_);
user_buf_ = NULL;
pending_ = false;
operation_ = kNoOperation;
int rv = result_;
entry_->Release(); // Don't touch object after this line.
std::move(cb).Run(rv);
}
void SparseControl::DoAbortCallbacks() {
std::vector<CompletionOnceCallback> abort_callbacks;
abort_callbacks.swap(abort_callbacks_);
for (CompletionOnceCallback& callback : abort_callbacks) {
// Releasing all references to entry_ may result in the destruction of this
// object so we should not be touching it after the last Release().
entry_->Release();
std::move(callback).Run(net::OK);
}
}
} // namespace disk_cache