--- /dev/null 2020-09-04 12:37:41.765504620 +0200 +++ new/src/hotspot/share/memory/metaspace/msRootChunkArea.hpp 2020-09-04 13:58:05.185451681 +0200 @@ -0,0 +1,207 @@ +/* + * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 2020 SAP SE. All rights reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA + * or visit www.oracle.com if you need additional information or have any + * questions. + * + */ + +#ifndef SHARE_MEMORY_METASPACE_MSROOTCHUNKAREA_HPP +#define SHARE_MEMORY_METASPACE_MSROOTCHUNKAREA_HPP + +#include "memory/allocation.hpp" +#include "memory/metaspace/msChunklevel.hpp" +#include "utilities/debug.hpp" +#include "utilities/globalDefinitions.hpp" + +class outputStream; + +namespace metaspace { + +class Metachunk; +class MetachunkClosure; +class FreeChunkListVector; +class VirtualSpaceNode; + +// RootChunkArea manages a memory area covering a single root chunk. +// +// Such an area may contain a single root chunk, or a number of chunks the +// root chunk was split into. +// +// RootChunkArea contains the functionality to merge and split chunks in +// buddy allocator fashion. +// + +class RootChunkArea { + + // The base address of this area. + // Todo: this may be somewhat superfluous since RootChunkArea only exist in the + // context of a series of chunks, so the address is somewhat implicit. Remove? + const MetaWord* const _base; + + // The first chunk in this area; if this area is maximally + // folded, this is the root chunk covering the whole area size. + Metachunk* _first_chunk; + +public: + + RootChunkArea(const MetaWord* base); + ~RootChunkArea(); + + // Initialize: allocate a root node and a root chunk header; return the + // root chunk header. It will be partly initialized. + // Note: this just allocates a memory-less header; memory itself is allocated inside VirtualSpaceNode. + Metachunk* alloc_root_chunk_header(VirtualSpaceNode* node); + + // Given a chunk c, split it recursively until you get a chunk of the given target_level. + // + // The resulting target chunk resides at the same address as the original chunk. + // The resulting splinters are added to freelists. + // + // Returns pointer to the result chunk; the splitted-off chunks are added as + // free chunks to the freelists. + void split(chunklevel_t target_level, Metachunk* c, FreeChunkListVector* freelists); + + // Given a chunk, attempt to merge it recursively with its neighboring chunks. + // + // If successful (merged at least once), returns address of + // the merged chunk; NULL otherwise. + // + // The merged chunks are removed from the freelists. + // + // !!! Please note that if this method returns a non-NULL value, the + // original chunk will be invalid and should not be accessed anymore! !!! + Metachunk* merge(Metachunk* c, FreeChunkListVector* freelists); + + // Given a chunk c, which must be "in use" and must not be a root chunk, attempt to + // enlarge it in place by claiming its trailing buddy. + // + // This will only work if c is the leader of the buddy pair and the trailing buddy is free. + // + // If successful, the follower chunk will be removed from the freelists, the leader chunk c will + // double in size (level decreased by one). + // + // On success, true is returned, false otherwise. + bool attempt_enlarge_chunk(Metachunk* c, FreeChunkListVector* freelists); + + /// range /// + + const MetaWord* base() const { return _base; } + size_t word_size() const { return chunklevel::MAX_CHUNK_WORD_SIZE; } + const MetaWord* end() const { return _base + word_size(); } + + // Direct access to the first chunk (use with care) + Metachunk* first_chunk() { return _first_chunk; } + const Metachunk* first_chunk() const { return _first_chunk; } + + // Returns true if this root chunk area is completely free: + // In that case, it should only contain one chunk (maximally merged, so a root chunk) + // and it should be free. + bool is_free() const; + + //// Debug stuff //// + +#ifdef ASSERT + void check_pointer(const MetaWord* p) const { + assert(p >= _base && p < _base + word_size(), + "pointer " PTR_FORMAT " oob for this root area [" PTR_FORMAT ".." PTR_FORMAT ")", + p2i(p), p2i(_base), p2i(_base + word_size())); + } + void verify() const; + + // This is a separate operation from verify(). We should be able to call verify() + // from almost anywhere, regardless of state, but verify_area_is_ideally_merged() + // can only be called outside split and merge ops. + void verify_area_is_ideally_merged() const; +#endif // ASSERT + + void print_on(outputStream* st) const; + +}; + +// RootChunkAreaLUT (lookup table) manages a series of contiguous root chunk areas +// in memory (in the context of a VirtualSpaceNode). It allows finding the containing +// root chunk for any given memory address. It allows for easy iteration over all +// root chunks. +// Beyond that it is unexciting. +class RootChunkAreaLUT { + + // Base address of the whole area. + const MetaWord* const _base; + + // Number of root chunk areas. + const int _num; + + // Array of RootChunkArea objects. + RootChunkArea* _arr; + +#ifdef ASSERT + void check_pointer(const MetaWord* p) const { + assert(p >= base() && p < base() + word_size(), "Invalid pointer"); + } +#endif + + // Given an address into this range, return the index into the area array for the + // area this address falls into. + int index_by_address(const MetaWord* p) const { + DEBUG_ONLY(check_pointer(p);) + int idx = (int)((p - base()) / chunklevel::MAX_CHUNK_WORD_SIZE); + assert(idx >= 0 && idx < _num, "Sanity"); + return idx; + } + +public: + + RootChunkAreaLUT(const MetaWord* base, size_t word_size); + ~RootChunkAreaLUT(); + + // Given a memory address into the range this array covers, return the + // corresponding area object. If none existed at this position, create it + // on demand. + RootChunkArea* get_area_by_address(const MetaWord* p) const { + const int idx = index_by_address(p); + RootChunkArea* ra = _arr + idx; + DEBUG_ONLY(ra->check_pointer(p);) + return _arr + idx; + } + + // Access area by its index + int number_of_areas() const { return _num; } + RootChunkArea* get_area_by_index(int index) { assert(index >= 0 && index < _num, "oob"); return _arr + index; } + const RootChunkArea* get_area_by_index(int index) const { assert(index >= 0 && index < _num, "oob"); return _arr + index; } + + /// range /// + + const MetaWord* base() const { return _base; } + size_t word_size() const { return _num * chunklevel::MAX_CHUNK_WORD_SIZE; } + const MetaWord* end() const { return _base + word_size(); } + + // Returns true if all areas in this area table are free (only contain free chunks). + bool is_free() const; + + DEBUG_ONLY(void verify() const;) + + void print_on(outputStream* st) const; + +}; + +} // namespace metaspace + +#endif // SHARE_MEMORY_METASPACE_MSROOTCHUNKAREA_HPP