/*******************************************************************************
 * Copyright IBM Corp. and others 2017
 *
 * This program and the accompanying materials are made available under
 * the terms of the Eclipse Public License 2.0 which accompanies this
 * distribution and is available at https://www.eclipse.org/legal/epl-2.0/
 * or the Apache License, Version 2.0 which accompanies this distribution
 * and is available at https://www.apache.org/licenses/LICENSE-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License, v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception [1] and GNU General Public
 * License, version 2 with the OpenJDK Assembly Exception [2].
 *
 * [1] https://www.gnu.org/software/classpath/license.html
 * [2] https://openjdk.org/legal/assembly-exception.html
 *
 * SPDX-License-Identifier: EPL-2.0 OR Apache-2.0 OR GPL-2.0-only WITH Classpath-exception-2.0 OR GPL-2.0-only WITH OpenJDK-assembly-exception-1.0
 *******************************************************************************/

#ifndef OMR_DEBUG_SEGMENT_PROVIDER
#define OMR_DEBUG_SEGMENT_PROVIDER

#pragma once

#include <stddef.h>
#include <set>
#include "env/TypedAllocator.hpp"
#include "infra/ReferenceWrapper.hpp"
#include "env/SegmentAllocator.hpp"
#include "env/RawAllocator.hpp"

namespace TR {

/** @class DebugSegmentProvider
 *  @brief The DebugSegmentProvider class provides a facility for verifying the
 *  correctness of compiler scratch memory use.
 *
 *  Using the native facilities available on each platform, a DebugSegmentProvider
 *  provides an alternative allocation mechanism for the TR::MemorySegments used
 *  by the compiler's scratch memory regions.  Instead of releasing virtual address
 *  segments back to the operating system, this implementation instead either
 *  remaps the segment, freeing the underlying physical pages, and changing the
 *  memory protection to trap on any access [preferred], or, if such facilities
 *  are not available, paints the memory segment with a value that should cause
 *  pointer dereferences to be unaligned, and resolve to the high-half of the
 *  virtual address space often reserved for kernel / supervisor use.
 **/
class DebugSegmentProvider : public TR::SegmentAllocator {
public:
    DebugSegmentProvider(size_t defaultSegmentSize, TR::RawAllocator rawAllocator);
    ~DebugSegmentProvider() throw();
    virtual TR::MemorySegment &request(size_t requiredSize);
    virtual void release(TR::MemorySegment &segment) throw();
    virtual size_t bytesAllocated() const throw();
    virtual size_t regionBytesAllocated() const throw();
    virtual size_t systemBytesAllocated() const throw();
    virtual size_t allocationLimit() const throw();
    virtual void setAllocationLimit(size_t);

private:
    TR::RawAllocator _rawAllocator;
    size_t _bytesAllocated;
    typedef TR::typed_allocator<TR::MemorySegment, TR::RawAllocator> SegmentSetAllocator;

    std::set<TR::MemorySegment, std::less<TR::MemorySegment>, SegmentSetAllocator> _segments;
};

} // namespace TR

#endif // OMR_DEBUG_SEGMENT_PROVIDER
