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// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#pragma once
#ifndef __Fuchsia__
#error Fuchsia-only Header
#include <utility>
#include <blobfs/transaction-manager.h>
#include <fbl/vector.h>
#include <lib/zx/vmo.h>
namespace blobfs {
struct WriteRequest {
zx_handle_t vmo;
size_t vmo_offset;
size_t dev_offset;
size_t length;
// A transaction consisting of enqueued VMOs to be written
// out to disk at specified locations.
class WriteTxn {
explicit WriteTxn(TransactionManager* transaction_manager)
: transaction_manager_(transaction_manager), vmoid_(VMOID_INVALID), block_count_(0) {}
virtual ~WriteTxn();
// Identifies that |nblocks| blocks of data starting at |relative_block| within the |vmo|
// should be written out to |absolute_block| on disk at a later point in time.
void Enqueue(const zx::vmo& vmo, uint64_t relative_block, uint64_t absolute_block,
uint64_t nblocks);
fbl::Vector<WriteRequest>& Requests() { return requests_; }
// Returns the first block at which this WriteTxn exists within its VMO buffer.
// Requires all requests within the transaction to have been copied to a single buffer.
size_t BlkStart() const;
// Returns the total number of blocks in all requests within the WriteTxn. This number is
// calculated at call time, unless the WriteTxn has already been fully buffered, at which point
// the final |block_count_| is set. This is then returned for all subsequent calls to BlkCount.
size_t BlkCount() const;
bool IsBuffered() const {
return vmoid_ != VMOID_INVALID;
// Sets the source buffer for the WriteTxn to |vmoid|.
void SetBuffer(vmoid_t vmoid);
// Checks if the WriteTxn vmoid_ matches |vmoid|.
bool CheckBuffer(vmoid_t vmoid) const {
return vmoid_ == vmoid;
// Resets the transaction's state.
void Reset() {
// Activates the transaction.
zx_status_t Flush();
TransactionManager* transaction_manager_;
vmoid_t vmoid_;
fbl::Vector<WriteRequest> requests_;
size_t block_count_;
} // namespace blobfs