// 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.

#include "node-reserver.h"

#include <stdint.h>
#include <zircon/types.h>

#include <limits>

#include <bitmap/rle-bitmap.h>
#include <blobfs/format.h>

namespace blobfs {

bool NodeReserver::IsNodeReserved(uint32_t node_index) const {
  return reserved_nodes_.Get(node_index, node_index + 1, nullptr);
}

void NodeReserver::Reserve(uint32_t node_index) {
  ZX_DEBUG_ASSERT(!reserved_nodes_.Get(node_index, node_index + 1, nullptr));

  // Mark it as reserved so no one else can allocate it.
  reserved_nodes_.Set(node_index, node_index + 1);
}

void NodeReserver::Unreserve(uint32_t node_index) {
  ZX_DEBUG_ASSERT(reserved_nodes_.Get(node_index, node_index + 1, nullptr));
  zx_status_t status = reserved_nodes_.Clear(node_index, node_index + 1);
  ZX_DEBUG_ASSERT(status == ZX_OK);
}

uint32_t NodeReserver::ReservedNodeCount() const {
  ZX_DEBUG_ASSERT(reserved_nodes_.num_bits() < std::numeric_limits<uint32_t>::max());
  return static_cast<uint32_t>(reserved_nodes_.num_bits());
}

ReservedNode::ReservedNode(NodeReserver* reserver, uint32_t node)
    : reserver_(reserver), node_(node) {
  reserver_->Reserve(node);
}

ReservedNode::ReservedNode(ReservedNode&& o) : reserver_(o.reserver_), node_(o.node_) {
  o.Release();
}

ReservedNode& ReservedNode::operator=(ReservedNode&& o) {
  Reset();
  reserver_ = o.reserver_;
  node_ = o.node_;
  o.Release();
  return *this;
}

ReservedNode::~ReservedNode() { Reset(); }

uint32_t ReservedNode::index() const {
  ZX_DEBUG_ASSERT_MSG(Reserved(), "Accessing unreserved node");
  return node_;
}

void ReservedNode::Reset() {
  if (Reserved()) {
    reserver_->Unreserve(index());
  }
  Release();
}

void ReservedNode::Release() { reserver_ = nullptr; }

bool ReservedNode::Reserved() const { return reserver_ != nullptr; }

}  // namespace blobfs