zircon/system/ulib/blobfs/include/blobfs/unbuffered-operations-builder.h

// Copyright 2019 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
#endif

#include <utility>

#include <blobfs/operation.h>
#include <fbl/macros.h>
#include <fbl/vector.h>
#include <lib/zx/vmo.h>
#include <zircon/assert.h>
#include <zircon/device/block.h>

namespace blobfs {

// A builder which helps clients collect and coalesce UnbufferedOperations which target the same
// in-memory / on-disk structures.
//
// This class is thread-compatible.
class UnbufferedOperationsBuilder {
public:
    UnbufferedOperationsBuilder() : block_count_(0) {}
    UnbufferedOperationsBuilder(const UnbufferedOperationsBuilder&) = delete;
    UnbufferedOperationsBuilder& operator=(const UnbufferedOperationsBuilder&) = delete;
    UnbufferedOperationsBuilder(UnbufferedOperationsBuilder&&) = default;
    UnbufferedOperationsBuilder& operator=(UnbufferedOperationsBuilder&&) = default;
    ~UnbufferedOperationsBuilder();

    // Returns the total number of blocks in all requests.
    uint64_t BlockCount() const { return block_count_; }

    // Adds a UnbufferedOperation to the list of requests.
    //
    // Empty requests are dropped.
    void Add(const UnbufferedOperation& operation);

    // Removes the vector of requests, and returns them to the caller.
    // This resets the |UnbufferedOperationsBuilder| object.
    fbl::Vector<UnbufferedOperation> TakeOperations();

private:
    fbl::Vector<UnbufferedOperation> operations_;
    uint64_t block_count_;
};

// Sums the |length| of all requests.
uint64_t BlockCount(const fbl::Vector<UnbufferedOperation>& requests);

} // namespace blobfs