--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/memory/metaspace/chunkHeaderPool.hpp Tue Sep 10 09:24:05 2019 +0200
@@ -0,0 +1,140 @@
+/*
+ * Copyright (c) 2019, SAP SE. All rights reserved.
+ * Copyright (c) 2019, Oracle and/or its affiliates. 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_CHUNKHEADERPOOL_HPP
+#define SHARE_MEMORY_METASPACE_CHUNKHEADERPOOL_HPP
+
+#include "memory/metaspace/internStat.hpp"
+#include "memory/metaspace/metachunk.hpp"
+#include "utilities/debug.hpp"
+#include "utilities/globalDefinitions.hpp"
+
+namespace metaspace {
+
+// A simple helper class; A pool of unused chunk headers.
+
+class ChunkHeaderPool {
+
+ static const int slab_capacity = 128;
+
+ struct slab_t {
+ slab_t* next;
+ int top;
+ Metachunk elems [slab_capacity]; // var sized;
+ };
+
+ IntCounter _num_slabs;
+ slab_t* _first_slab;
+ slab_t* _current_slab;
+
+ IntCounter _num_handed_out;
+
+ MetachunkList _freelist;
+
+ const bool _delete_on_destruction;
+
+ void allocate_new_slab();
+
+ static ChunkHeaderPool _chunkHeaderPool;
+
+
+public:
+
+ ChunkHeaderPool(bool delete_on_destruction);
+
+ ~ChunkHeaderPool();
+
+ // Allocates a Metachunk structure. The structure is uninitialized.
+ Metachunk* allocate_chunk_header() {
+
+ Metachunk* c = NULL;
+
+ DEBUG_ONLY(verify(false));
+
+ c = _freelist.remove_first();
+ assert(c == NULL || c->is_dead(), "Not a freelist chunk header?");
+
+ if (c == NULL) {
+
+ if (_current_slab == NULL ||
+ _current_slab->top == slab_capacity) {
+ allocate_new_slab();
+ assert(_current_slab->top < slab_capacity, "Sanity");
+ }
+
+ c = _current_slab->elems + _current_slab->top;
+ _current_slab->top ++;
+
+ }
+
+ _num_handed_out.increment();
+
+ // By contract, the returned structure is uninitialized.
+ // Zap to make this clear.
+ DEBUG_ONLY(c->zap_header(0xBB);)
+
+ return c;
+
+ }
+
+ void return_chunk_header(Metachunk* c) {
+ // We only ever should return free chunks, since returning chunks
+ // happens only on merging and merging only works with free chunks.
+ assert(c != NULL && c->is_free(), "Sanity");
+#ifdef ASSERT
+ // In debug, fill dead header with pattern.
+ c->zap_header(0xCC);
+ c->set_next(NULL);
+ c->set_prev(NULL);
+#endif
+ c->set_dead();
+ _freelist.add(c);
+ _num_handed_out.decrement();
+
+ }
+
+ // Returns number of allocated elements.
+ int used() const { return _num_handed_out.get(); }
+
+ // Returns number of elements in free list.
+ int freelist_size() const { return _freelist.size(); }
+
+ // Returns size of memory used.
+ size_t memory_footprint_words() const;
+
+ DEBUG_ONLY(void verify(bool slow) const;)
+
+ // Returns reference to the one global chunk header pool.
+ static ChunkHeaderPool& pool() { return _chunkHeaderPool; }
+
+};
+
+
+} // namespace metaspace
+
+
+
+
+#endif // SHARE_MEMORY_METASPACE_CHUNKHEADERPOOL_HPP