// Copyright (c) 2006-2010 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 "net/disk_cache/mem_entry_impl.h"
#include "base/logging.h"
#include "base/stringprintf.h"
#include "net/base/io_buffer.h"
#include "net/base/net_errors.h"
#include "net/disk_cache/mem_backend_impl.h"
#include "net/disk_cache/net_log_parameters.h"
using base::Time;
namespace {
const int kSparseData = 1;
// Maximum size of a sparse entry is 2 to the power of this number.
const int kMaxSparseEntryBits = 12;
// Sparse entry has maximum size of 4KB.
const int kMaxSparseEntrySize = 1 << kMaxSparseEntryBits;
// Convert global offset to child index.
inline int ToChildIndex(int64 offset) {
return static_cast<int>(offset >> kMaxSparseEntryBits);
}
// Convert global offset to offset in child entry.
inline int ToChildOffset(int64 offset) {
return static_cast<int>(offset & (kMaxSparseEntrySize - 1));
}
// Returns a name for a child entry given the base_name of the parent and the
// child_id. This name is only used for logging purposes.
// If the entry is called entry_name, child entries will be named something
// like Range_entry_name:YYY where YYY is the number of the particular child.
std::string GenerateChildName(const std::string& base_name, int child_id) {
return base::StringPrintf("Range_%s:%i", base_name.c_str(), child_id);
}
} // namespace
namespace disk_cache {
MemEntryImpl::MemEntryImpl(MemBackendImpl* backend) {
doomed_ = false;
backend_ = backend;
ref_count_ = 0;
parent_ = NULL;
child_id_ = 0;
child_first_pos_ = 0;
next_ = NULL;
prev_ = NULL;
for (int i = 0; i < NUM_STREAMS; i++)
data_size_[i] = 0;
}
// ------------------------------------------------------------------------
bool MemEntryImpl::CreateEntry(const std::string& key, net::NetLog* net_log) {
net_log_ = net::BoundNetLog::Make(net_log,
net::NetLog::SOURCE_MEMORY_CACHE_ENTRY);
net_log_.BeginEvent(
net::NetLog::TYPE_DISK_CACHE_MEM_ENTRY_IMPL,
make_scoped_refptr(new EntryCreationParameters(key, true)));
key_ = key;
Time current = Time::Now();
last_modified_ = current;
last_used_ = current;
Open();
backend_->ModifyStorageSize(0, static_cast<int32>(key.size()));
return true;
}
void MemEntryImpl::InternalDoom() {
net_log_.AddEvent(net::NetLog::TYPE_ENTRY_DOOM, NULL);
doomed_ = true;
if (!ref_count_) {
if (type() == kParentEntry) {
// If this is a parent entry, we need to doom all the child entries.
if (children_.get()) {
EntryMap children;
children.swap(*children_);
for (EntryMap::iterator i = children.begin();
i != children.end(); ++i) {
// Since a pointer to this object is also saved in the map, avoid
// dooming it.
if (i->second != this)
i->second->Doom();
}
DCHECK(children_->empty());
}
} else {
// If this is a child entry, detach it from the parent.
parent_->DetachChild(child_id_);
}
delete this;
}
}
void MemEntryImpl::Open() {
// Only a parent entry can be opened.
// TODO(hclam): make sure it's correct to not apply the concept of ref
// counting to child entry.
DCHECK(type() == kParentEntry);
ref_count_++;
DCHECK(ref_count_ >= 0);
DCHECK(!doomed_);
}
bool MemEntryImpl::InUse() {
if (type() == kParentEntry) {
return ref_count_ > 0;
} else {
// A child entry is always not in use. The consequence is that a child entry
// can always be evicted while the associated parent entry is currently in
// used (i.e. opened).
return false;
}
}
// ------------------------------------------------------------------------
void MemEntryImpl::Doom() {
if (doomed_)
return;
if (type() == kParentEntry) {
// Perform internal doom from the backend if this is a parent entry.
backend_->InternalDoomEntry(this);
} else {
// Manually detach from the backend and perform internal doom.
backend_->RemoveFromRankingList(this);
InternalDoom();
}
}
void MemEntryImpl::Close() {
// Only a parent entry can be closed.
DCHECK(type() == kParentEntry);
ref_count_--;
DCHECK(ref_count_ >= 0);
if (!ref_count_ && doomed_)
InternalDoom();
}
std::string MemEntryImpl::GetKey() const {
// A child entry doesn't have key so this method should not be called.
DCHECK(type() == kParentEntry);
return key_;
}
Time MemEntryImpl::GetLastUsed() const {
return last_used_;
}
Time MemEntryImpl::GetLastModified() const {
return last_modified_;
}
int32 MemEntryImpl::GetDataSize(int index) const {
if (index < 0 || index >= NUM_STREAMS)
return 0;
return data_size_[index];
}
int MemEntryImpl::ReadData(int index, int offset, net::IOBuffer* buf,
int buf_len, net::CompletionCallback* completion_callback) {
if (net_log_.IsLoggingAllEvents()) {
net_log_.BeginEvent(
net::NetLog::TYPE_ENTRY_READ_DATA,
make_scoped_refptr(
new ReadWriteDataParameters(index, offset, buf_len, false)));
}
int result = InternalReadData(index, offset, buf, buf_len);
if (net_log_.IsLoggingAllEvents()) {
net_log_.EndEvent(
net::NetLog::TYPE_ENTRY_READ_DATA,
make_scoped_refptr(new ReadWriteCompleteParameters(result)));
}
return result;
}
int MemEntryImpl::WriteData(int index, int offset, net::IOBuffer* buf,
int buf_len, net::CompletionCallback* completion_callback, bool truncate) {
if (net_log_.IsLoggingAllEvents()) {
net_log_.BeginEvent(
net::NetLog::TYPE_ENTRY_WRITE_DATA,
make_scoped_refptr(
new ReadWriteDataParameters(index, offset, buf_len, truncate)));
}
int result = InternalWriteData(index, offset, buf, buf_len, truncate);
if (net_log_.IsLoggingAllEvents()) {
net_log_.EndEvent(
net::NetLog::TYPE_ENTRY_WRITE_DATA,
make_scoped_refptr(new ReadWriteCompleteParameters(result)));
}
return result;
}
int MemEntryImpl::ReadSparseData(int64 offset, net::IOBuffer* buf, int buf_len,
net::CompletionCallback* completion_callback) {
if (net_log_.IsLoggingAllEvents()) {
net_log_.BeginEvent(
net::NetLog::TYPE_SPARSE_READ,
make_scoped_refptr(
new SparseOperationParameters(offset, buf_len)));
}
int result = InternalReadSparseData(offset, buf, buf_len);
if (net_log_.IsLoggingAllEvents())
net_log_.EndEvent(net::NetLog::TYPE_SPARSE_READ, NULL);
return result;
}
int MemEntryImpl::WriteSparseData(int64 offset, net::IOBuffer* buf, int buf_len,
net::CompletionCallback* completion_callback) {
if (net_log_.IsLoggingAllEvents()) {
net_log_.BeginEvent(net::NetLog::TYPE_SPARSE_WRITE,
make_scoped_refptr(
new SparseOperationParameters(offset, buf_len)));
}
int result = InternalWriteSparseData(offset, buf, buf_len);
if (net_log_.IsLoggingAllEvents())
net_log_.EndEvent(net::NetLog::TYPE_SPARSE_WRITE, NULL);
return result;
}
int MemEntryImpl::GetAvailableRange(int64 offset, int len, int64* start,
CompletionCallback* callback) {
if (net_log_.IsLoggingAllEvents()) {
net_log_.BeginEvent(
net::NetLog::TYPE_SPARSE_GET_RANGE,
make_scoped_refptr(
new SparseOperationParameters(offset, len)));
}
int result = GetAvailableRange(offset, len, start);
if (net_log_.IsLoggingAllEvents()) {
net_log_.EndEvent(
net::NetLog::TYPE_SPARSE_GET_RANGE,
make_scoped_refptr(
new GetAvailableRangeResultParameters(*start, result)));
}
return result;
}
bool MemEntryImpl::CouldBeSparse() const {
DCHECK_EQ(kParentEntry, type());
return (children_.get() != NULL);
}
int MemEntryImpl::ReadyForSparseIO(
net::CompletionCallback* completion_callback) {
return net::OK;
}
// ------------------------------------------------------------------------
MemEntryImpl::~MemEntryImpl() {
for (int i = 0; i < NUM_STREAMS; i++)
backend_->ModifyStorageSize(data_size_[i], 0);
backend_->ModifyStorageSize(static_cast<int32>(key_.size()), 0);
net_log_.EndEvent(net::NetLog::TYPE_DISK_CACHE_MEM_ENTRY_IMPL, NULL);
}
int MemEntryImpl::InternalReadData(int index, int offset, net::IOBuffer* buf,
int buf_len) {
DCHECK(type() == kParentEntry || index == kSparseData);
if (index < 0 || index >= NUM_STREAMS)
return net::ERR_INVALID_ARGUMENT;
int entry_size = GetDataSize(index);
if (offset >= entry_size || offset < 0 || !buf_len)
return 0;
if (buf_len < 0)
return net::ERR_INVALID_ARGUMENT;
if (offset + buf_len > entry_size)
buf_len = entry_size - offset;
UpdateRank(false);
memcpy(buf->data(), &(data_[index])[offset], buf_len);
return buf_len;
}
int MemEntryImpl::InternalWriteData(int index, int offset, net::IOBuffer* buf,
int buf_len, bool truncate) {
DCHECK(type() == kParentEntry || index == kSparseData);
if (index < 0 || index >= NUM_STREAMS)
return net::ERR_INVALID_ARGUMENT;
if (offset < 0 || buf_len < 0)
return net::ERR_INVALID_ARGUMENT;
int max_file_size = backend_->MaxFileSize();
// offset of buf_len could be negative numbers.
if (offset > max_file_size || buf_len > max_file_size ||
offset + buf_len > max_file_size) {
return net::ERR_FAILED;
}
// Read the size at this point.
int entry_size = GetDataSize(index);
PrepareTarget(index, offset, buf_len);
if (entry_size < offset + buf_len) {
backend_->ModifyStorageSize(entry_size, offset + buf_len);
data_size_[index] = offset + buf_len;
} else if (truncate) {
if (entry_size > offset + buf_len) {
backend_->ModifyStorageSize(entry_size, offset + buf_len);
data_size_[index] = offset + buf_len;
}
}
UpdateRank(true);
if (!buf_len)
return 0;
memcpy(&(data_[index])[offset], buf->data(), buf_len);
return buf_len;
}
int MemEntryImpl::InternalReadSparseData(int64 offset, net::IOBuffer* buf,
int buf_len) {
DCHECK(type() == kParentEntry);
if (!InitSparseInfo())
return net::ERR_CACHE_OPERATION_NOT_SUPPORTED;
if (offset < 0 || buf_len < 0)
return net::ERR_INVALID_ARGUMENT;
// We will keep using this buffer and adjust the offset in this buffer.
scoped_refptr<net::DrainableIOBuffer> io_buf(
new net::DrainableIOBuffer(buf, buf_len));
// Iterate until we have read enough.
while (io_buf->BytesRemaining()) {
MemEntryImpl* child = OpenChild(offset + io_buf->BytesConsumed(), false);
// No child present for that offset.
if (!child)
break;
// We then need to prepare the child offset and len.
int child_offset = ToChildOffset(offset + io_buf->BytesConsumed());
// If we are trying to read from a position that the child entry has no data
// we should stop.
if (child_offset < child->child_first_pos_)
break;
if (net_log_.IsLoggingAllEvents()) {
net_log_.BeginEvent(
net::NetLog::TYPE_SPARSE_READ_CHILD_DATA,
make_scoped_refptr(new SparseReadWriteParameters(
child->net_log().source(),
io_buf->BytesRemaining())));
}
int ret = child->ReadData(kSparseData, child_offset, io_buf,
io_buf->BytesRemaining(), NULL);
if (net_log_.IsLoggingAllEvents()) {
net_log_.EndEventWithNetErrorCode(
net::NetLog::TYPE_SPARSE_READ_CHILD_DATA, ret);
}
// If we encounter an error in one entry, return immediately.
if (ret < 0)
return ret;
else if (ret == 0)
break;
// Increment the counter by number of bytes read in the child entry.
io_buf->DidConsume(ret);
}
UpdateRank(false);
return io_buf->BytesConsumed();
}
int MemEntryImpl::InternalWriteSparseData(int64 offset, net::IOBuffer* buf,
int buf_len) {
DCHECK(type() == kParentEntry);
if (!InitSparseInfo())
return net::ERR_CACHE_OPERATION_NOT_SUPPORTED;
if (offset < 0 || buf_len < 0)
return net::ERR_INVALID_ARGUMENT;
scoped_refptr<net::DrainableIOBuffer> io_buf(
new net::DrainableIOBuffer(buf, buf_len));
// This loop walks through child entries continuously starting from |offset|
// and writes blocks of data (of maximum size kMaxSparseEntrySize) into each
// child entry until all |buf_len| bytes are written. The write operation can
// start in the middle of an entry.
while (io_buf->BytesRemaining()) {
MemEntryImpl* child = OpenChild(offset + io_buf->BytesConsumed(), true);
int child_offset = ToChildOffset(offset + io_buf->BytesConsumed());
// Find the right amount to write, this evaluates the remaining bytes to
// write and remaining capacity of this child entry.
int write_len = std::min(static_cast<int>(io_buf->BytesRemaining()),
kMaxSparseEntrySize - child_offset);
// Keep a record of the last byte position (exclusive) in the child.
int data_size = child->GetDataSize(kSparseData);
if (net_log_.IsLoggingAllEvents()) {
net_log_.BeginEvent(
net::NetLog::TYPE_SPARSE_WRITE_CHILD_DATA,
make_scoped_refptr(new SparseReadWriteParameters(
child->net_log().source(),
write_len)));
}
// Always writes to the child entry. This operation may overwrite data
// previously written.
// TODO(hclam): if there is data in the entry and this write is not
// continuous we may want to discard this write.
int ret = child->WriteData(kSparseData, child_offset, io_buf, write_len,
NULL, true);
if (net_log_.IsLoggingAllEvents()) {
net_log_.EndEventWithNetErrorCode(
net::NetLog::TYPE_SPARSE_WRITE_CHILD_DATA, ret);
}
if (ret < 0)
return ret;
else if (ret == 0)
break;
// Keep a record of the first byte position in the child if the write was
// not aligned nor continuous. This is to enable witting to the middle
// of an entry and still keep track of data off the aligned edge.
if (data_size != child_offset)
child->child_first_pos_ = child_offset;
// Adjust the offset in the IO buffer.
io_buf->DidConsume(ret);
}
UpdateRank(true);
return io_buf->BytesConsumed();
}
int MemEntryImpl::GetAvailableRange(int64 offset, int len, int64* start) {
DCHECK(type() == kParentEntry);
DCHECK(start);
if (!InitSparseInfo())
return net::ERR_CACHE_OPERATION_NOT_SUPPORTED;
if (offset < 0 || len < 0 || !start)
return net::ERR_INVALID_ARGUMENT;
MemEntryImpl* current_child = NULL;
// Find the first child and record the number of empty bytes.
int empty = FindNextChild(offset, len, ¤t_child);
if (current_child) {
*start = offset + empty;
len -= empty;
// Counts the number of continuous bytes.
int continuous = 0;
// This loop scan for continuous bytes.
while (len && current_child) {
// Number of bytes available in this child.
int data_size = current_child->GetDataSize(kSparseData) -
ToChildOffset(*start + continuous);
if (data_size > len)
data_size = len;
// We have found more continuous bytes so increment the count. Also
// decrement the length we should scan.
continuous += data_size;
len -= data_size;
// If the next child is discontinuous, break the loop.
if (FindNextChild(*start + continuous, len, ¤t_child))
break;
}
return continuous;
}
*start = offset;
return 0;
}
void MemEntryImpl::PrepareTarget(int index, int offset, int buf_len) {
int entry_size = GetDataSize(index);
if (entry_size >= offset + buf_len)
return; // Not growing the stored data.
if (static_cast<int>(data_[index].size()) < offset + buf_len)
data_[index].resize(offset + buf_len);
if (offset <= entry_size)
return; // There is no "hole" on the stored data.
// Cleanup the hole not written by the user. The point is to avoid returning
// random stuff later on.
memset(&(data_[index])[entry_size], 0, offset - entry_size);
}
void MemEntryImpl::UpdateRank(bool modified) {
Time current = Time::Now();
last_used_ = current;
if (modified)
last_modified_ = current;
if (!doomed_)
backend_->UpdateRank(this);
}
bool MemEntryImpl::InitSparseInfo() {
DCHECK(type() == kParentEntry);
if (!children_.get()) {
// If we already have some data in sparse stream but we are being
// initialized as a sparse entry, we should fail.
if (GetDataSize(kSparseData))
return false;
children_.reset(new EntryMap());
// The parent entry stores data for the first block, so save this object to
// index 0.
(*children_)[0] = this;
}
return true;
}
bool MemEntryImpl::InitChildEntry(MemEntryImpl* parent, int child_id,
net::NetLog* net_log) {
DCHECK(!parent_);
DCHECK(!child_id_);
net_log_ = net::BoundNetLog::Make(net_log,
net::NetLog::SOURCE_MEMORY_CACHE_ENTRY);
net_log_.BeginEvent(
net::NetLog::TYPE_DISK_CACHE_MEM_ENTRY_IMPL,
make_scoped_refptr(new EntryCreationParameters(
GenerateChildName(parent->key(), child_id_),
true)));
parent_ = parent;
child_id_ = child_id;
Time current = Time::Now();
last_modified_ = current;
last_used_ = current;
// Insert this to the backend's ranking list.
backend_->InsertIntoRankingList(this);
return true;
}
MemEntryImpl* MemEntryImpl::OpenChild(int64 offset, bool create) {
DCHECK(type() == kParentEntry);
int index = ToChildIndex(offset);
EntryMap::iterator i = children_->find(index);
if (i != children_->end()) {
return i->second;
} else if (create) {
MemEntryImpl* child = new MemEntryImpl(backend_);
child->InitChildEntry(this, index, net_log_.net_log());
(*children_)[index] = child;
return child;
}
return NULL;
}
int MemEntryImpl::FindNextChild(int64 offset, int len, MemEntryImpl** child) {
DCHECK(child);
*child = NULL;
int scanned_len = 0;
// This loop tries to find the first existing child.
while (scanned_len < len) {
// This points to the current offset in the child.
int current_child_offset = ToChildOffset(offset + scanned_len);
MemEntryImpl* current_child = OpenChild(offset + scanned_len, false);
if (current_child) {
int child_first_pos = current_child->child_first_pos_;
// This points to the first byte that we should be reading from, we need
// to take care of the filled region and the current offset in the child.
int first_pos = std::max(current_child_offset, child_first_pos);
// If the first byte position we should read from doesn't exceed the
// filled region, we have found the first child.
if (first_pos < current_child->GetDataSize(kSparseData)) {
*child = current_child;
// We need to advance the scanned length.
scanned_len += first_pos - current_child_offset;
break;
}
}
scanned_len += kMaxSparseEntrySize - current_child_offset;
}
return scanned_len;
}
void MemEntryImpl::DetachChild(int child_id) {
children_->erase(child_id);
}
} // namespace disk_cache