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content / browser / indexed_db / file_stream_reader_to_data_pipe.cc [blame]
// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "content/browser/indexed_db/file_stream_reader_to_data_pipe.h"
#include <optional>
#include "base/functional/bind.h"
#include "base/memory/scoped_refptr.h"
#include "mojo/public/cpp/system/simple_watcher.h"
#include "net/base/net_errors.h"
#include "services/network/public/cpp/net_adapters.h"
namespace content::indexed_db {
namespace {
// This class owns itself and deletes itself after `completion_callback_` is
// run.
// TODO(estade): rename this class and this file.
class FileStreamReaderToDataPipe {
public:
FileStreamReaderToDataPipe(const base::FilePath& file_path,
uint64_t offset,
uint64_t read_length,
mojo::ScopedDataPipeProducerHandle dest,
base::OnceCallback<void(int)> completion_callback);
~FileStreamReaderToDataPipe();
void Start();
private:
void ReadMore();
void OnDataPipeWritable(MojoResult result);
void OnDataPipeClosed(MojoResult result);
void OnComplete(int result);
base::File file_;
mojo::ScopedDataPipeProducerHandle dest_;
base::OnceCallback<void(int)> completion_callback_;
uint64_t transferred_bytes_ = 0;
uint64_t offset_;
uint64_t read_length_;
scoped_refptr<network::NetToMojoPendingBuffer> pending_write_;
// Optional so that its construction can be deferred.
std::optional<mojo::SimpleWatcher> writable_handle_watcher_;
};
FileStreamReaderToDataPipe::FileStreamReaderToDataPipe(
const base::FilePath& file_path,
uint64_t offset,
uint64_t read_length,
mojo::ScopedDataPipeProducerHandle dest,
base::OnceCallback<void(int)> completion_callback)
: dest_(std::move(dest)),
completion_callback_(std::move(completion_callback)),
offset_(offset),
read_length_(read_length) {
DCHECK(!writable_handle_watcher_.has_value());
writable_handle_watcher_.emplace(FROM_HERE,
mojo::SimpleWatcher::ArmingPolicy::MANUAL);
writable_handle_watcher_->Watch(
dest_.get(), MOJO_HANDLE_SIGNAL_WRITABLE,
base::BindRepeating(&FileStreamReaderToDataPipe::OnDataPipeWritable,
base::Unretained(this)));
file_.Initialize(file_path, base::File::FLAG_OPEN | base::File::FLAG_READ);
}
FileStreamReaderToDataPipe::~FileStreamReaderToDataPipe() = default;
void FileStreamReaderToDataPipe::Start() {
if (file_.IsValid()) {
ReadMore();
} else {
OnComplete(net::FileErrorToNetError(file_.error_details()));
}
}
void FileStreamReaderToDataPipe::ReadMore() {
// This loop shouldn't block the thread for *too* long as the mojo pipe has a
// capacity of 2MB (i.e. `BeginWrite()` will return MOJO_RESULT_SHOULD_WAIT at
// some point when reading in a very large file).
while (true) {
DCHECK(!pending_write_);
MojoResult mojo_result =
network::NetToMojoPendingBuffer::BeginWrite(&dest_, &pending_write_);
switch (mojo_result) {
case MOJO_RESULT_OK:
break;
case MOJO_RESULT_SHOULD_WAIT:
// The pipe is full. We need to wait for it to have more space.
writable_handle_watcher_->ArmOrNotify();
return;
case MOJO_RESULT_FAILED_PRECONDITION:
// The data pipe consumer handle has been closed.
OnComplete(net::ERR_ABORTED);
return;
default:
// The body stream is in a bad state. Bail out.
OnComplete(net::ERR_UNEXPECTED);
return;
}
size_t read_bytes = base::checked_cast<size_t>(
std::min(static_cast<uint64_t>(pending_write_->size()),
read_length_ - transferred_bytes_));
base::span<uint8_t> buffer =
base::as_writable_bytes(base::make_span(*pending_write_))
.first(read_bytes);
std::optional<size_t> result =
file_.Read(offset_ + transferred_bytes_, buffer);
if (!result || !*result) {
// Error or EOF.
dest_ = pending_write_->Complete(0);
OnComplete(net::ERR_FAILED);
return;
}
dest_ = pending_write_->Complete(*result);
transferred_bytes_ += *result;
if (transferred_bytes_ >= read_length_) {
OnComplete(net::OK);
return;
}
pending_write_ = nullptr;
}
}
void FileStreamReaderToDataPipe::OnDataPipeWritable(MojoResult result) {
if (result == MOJO_RESULT_FAILED_PRECONDITION) {
OnComplete(net::ERR_ABORTED);
return;
}
DCHECK_EQ(result, MOJO_RESULT_OK) << result;
ReadMore();
}
void FileStreamReaderToDataPipe::OnComplete(int result) {
// Resets the watchers, pipes and the exchange handler, so that
// we will never be called back.
writable_handle_watcher_->Cancel();
pending_write_ = nullptr;
dest_.reset();
std::move(completion_callback_).Run(result);
delete this;
}
} // namespace
void OpenFileAndReadIntoPipe(
const base::FilePath& file_path,
uint64_t offset,
uint64_t read_length,
mojo::ScopedDataPipeProducerHandle dest,
base::OnceCallback<void(int)> completion_callback) {
(new FileStreamReaderToDataPipe(file_path, offset, read_length,
std::move(dest),
std::move(completion_callback)))
->Start();
}
} // namespace content::indexed_db