blob: e1e67ddbc407550b008f1a78e2de5e414a89559a [file] [log] [blame]
// 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.
// This file describes the structure used to allocate
// from an on-disk bitmap.
#ifndef SRC_STORAGE_MINFS_ALLOCATOR_RESERVATION_H_
#define SRC_STORAGE_MINFS_ALLOCATOR_RESERVATION_H_
#include <lib/fit/function.h>
#include <lib/zx/status.h>
#include <fbl/macros.h>
#include "src/storage/minfs/format.h"
#include "src/storage/minfs/pending_work.h"
#include "src/storage/minfs/superblock.h"
#ifdef __Fuchsia__
#include <fuchsia/minfs/c/fidl.h>
#endif
namespace minfs {
// Forward declaration for a reference to the internal allocator.
class Allocator;
class PendingAllocations;
class PendingDeallocations;
// This class represents a reservation from an Allocator to save a particular number of reserved
// elements for later allocation. Allocation for reserved elements must be done through the
// AllocatorReservation class.
// This class is thread-compatible.
// This class is not assignable, copyable, or moveable.
class AllocatorReservation {
public:
AllocatorReservation(Allocator* allocator);
// Not copyable or movable.
AllocatorReservation(const AllocatorReservation&) = delete;
AllocatorReservation& operator=(const AllocatorReservation&) = delete;
~AllocatorReservation();
// Returns |ZX_OK| when |allocator| reserves |reserved| elements and |this| is successfully
// initialized. Returns an error if not enough elements are available for reservation,
// or there was previous reservation.
zx::status<> Reserve(PendingWork* transaction, size_t reserved);
// Extends reservation by |reserved| number of elements.
// Returns an error if not enough elements are available for reservation.
zx::status<> ExtendReservation(PendingWork* transaction, size_t reserved);
// Allocate a new item in allocator_. Return the index of the newly allocated item.
size_t Allocate();
// Deallocate a new item from allocate_.
void Deallocate(size_t element);
// Unreserve all currently reserved items.
void Cancel();
#ifdef __Fuchsia__
// Swap the element currently allocated at |old_index| for a new index.
// If |old_index| is 0, a new block will still be allocated, but no blocks will be de-allocated.
// The swap will not be persisted until a call to Commit is made.
size_t Swap(size_t old_index);
// size_t GetReserved() const { return reserved_; }
#endif
// Returns the pending allocations. Only Allocator should manipulate it.
PendingAllocations& GetPendingAllocations(Allocator* allocator);
// Returns the pending deallocations. Only Allocator should manipulate it.
PendingDeallocations& GetPendingDeallocations(Allocator* allocator);
std::unique_ptr<PendingDeallocations> TakePendingDeallocations() {
return std::move(deallocations_);
}
// Commit all pending changes, which means all bitmaps are updated (via the transaction). You most
// likely don't need to call this because it is called in Minfs::CommitTransaction.
void Commit(PendingWork* transaction);
size_t GetReserved() const { return reserved_; }
private:
Allocator& allocator_;
size_t reserved_ = 0;
std::unique_ptr<PendingAllocations> allocations_;
std::unique_ptr<PendingDeallocations> deallocations_;
};
} // namespace minfs
#endif // SRC_STORAGE_MINFS_ALLOCATOR_RESERVATION_H_