--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc/g1/collectionSetChooser.hpp Wed May 13 15:16:06 2015 +0200
@@ -0,0 +1,196 @@
+/*
+ * Copyright (c) 2001, 2015, 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_VM_GC_G1_COLLECTIONSETCHOOSER_HPP
+#define SHARE_VM_GC_G1_COLLECTIONSETCHOOSER_HPP
+
+#include "gc/g1/heapRegion.hpp"
+#include "utilities/growableArray.hpp"
+
+class CollectionSetChooser: public CHeapObj<mtGC> {
+
+ GrowableArray<HeapRegion*> _regions;
+
+ // Unfortunately, GrowableArray uses ints for length and indexes. To
+ // avoid excessive casting in the rest of the class the following
+ // wrapper methods are provided that use uints.
+
+ uint regions_length() { return (uint) _regions.length(); }
+ HeapRegion* regions_at(uint i) { return _regions.at((int) i); }
+ void regions_at_put(uint i, HeapRegion* hr) {
+ _regions.at_put((int) i, hr);
+ }
+ void regions_at_put_grow(uint i, HeapRegion* hr) {
+ _regions.at_put_grow((int) i, hr);
+ }
+ void regions_trunc_to(uint i) { _regions.trunc_to((uint) i); }
+
+ // The index of the next candidate old region to be considered for
+ // addition to the CSet.
+ uint _curr_index;
+
+ // The number of candidate old regions added to the CSet chooser.
+ // Note: this is not updated when removing a region using
+ // remove_and_move_to_next() below.
+ uint _length;
+
+ // Keeps track of the start of the next array chunk to be claimed by
+ // parallel GC workers.
+ uint _first_par_unreserved_idx;
+
+ // If a region has more live bytes than this threshold, it will not
+ // be added to the CSet chooser and will not be a candidate for
+ // collection.
+ size_t _region_live_threshold_bytes;
+
+ // The sum of reclaimable bytes over all the regions in the CSet chooser.
+ size_t _remaining_reclaimable_bytes;
+
+public:
+
+ // Return the current candidate region to be considered for
+ // collection without removing it from the CSet chooser.
+ HeapRegion* peek() {
+ HeapRegion* res = NULL;
+ if (_curr_index < _length) {
+ res = regions_at(_curr_index);
+ assert(res != NULL,
+ err_msg("Unexpected NULL hr in _regions at index %u",
+ _curr_index));
+ }
+ return res;
+ }
+
+ // Remove the given region from the CSet chooser and move to the
+ // next one. The given region should be the current candidate region
+ // in the CSet chooser.
+ void remove_and_move_to_next(HeapRegion* hr) {
+ assert(hr != NULL, "pre-condition");
+ assert(_curr_index < _length, "pre-condition");
+ assert(regions_at(_curr_index) == hr, "pre-condition");
+ regions_at_put(_curr_index, NULL);
+ assert(hr->reclaimable_bytes() <= _remaining_reclaimable_bytes,
+ err_msg("remaining reclaimable bytes inconsistent "
+ "from region: "SIZE_FORMAT" remaining: "SIZE_FORMAT,
+ hr->reclaimable_bytes(), _remaining_reclaimable_bytes));
+ _remaining_reclaimable_bytes -= hr->reclaimable_bytes();
+ _curr_index += 1;
+ }
+
+ CollectionSetChooser();
+
+ void sort_regions();
+
+ // Determine whether to add the given region to the CSet chooser or
+ // not. Currently, we skip humongous regions (we never add them to
+ // the CSet, we only reclaim them during cleanup) and regions whose
+ // live bytes are over the threshold.
+ bool should_add(HeapRegion* hr) {
+ assert(hr->is_marked(), "pre-condition");
+ assert(!hr->is_young(), "should never consider young regions");
+ return !hr->is_humongous() &&
+ hr->live_bytes() < _region_live_threshold_bytes;
+ }
+
+ // Returns the number candidate old regions added
+ uint length() { return _length; }
+
+ // Serial version.
+ void add_region(HeapRegion *hr);
+
+ // Must be called before calls to claim_array_chunk().
+ // n_regions is the number of regions, chunk_size the chunk size.
+ void prepare_for_par_region_addition(uint n_regions, uint chunk_size);
+ // Returns the first index in a contiguous chunk of chunk_size indexes
+ // that the calling thread has reserved. These must be set by the
+ // calling thread using set_region() (to NULL if necessary).
+ uint claim_array_chunk(uint chunk_size);
+ // Set the marked array entry at index to hr. Careful to claim the index
+ // first if in parallel.
+ void set_region(uint index, HeapRegion* hr);
+ // Atomically increment the number of added regions by region_num
+ // and the amount of reclaimable bytes by reclaimable_bytes.
+ void update_totals(uint region_num, size_t reclaimable_bytes);
+
+ void clear();
+
+ // Return the number of candidate regions that remain to be collected.
+ uint remaining_regions() { return _length - _curr_index; }
+
+ // Determine whether the CSet chooser has more candidate regions or not.
+ bool is_empty() { return remaining_regions() == 0; }
+
+ // Return the reclaimable bytes that remain to be collected on
+ // all the candidate regions in the CSet chooser.
+ size_t remaining_reclaimable_bytes() { return _remaining_reclaimable_bytes; }
+
+ // Returns true if the used portion of "_regions" is properly
+ // sorted, otherwise asserts false.
+ void verify() PRODUCT_RETURN;
+};
+
+class CSetChooserParUpdater : public StackObj {
+private:
+ CollectionSetChooser* _chooser;
+ bool _parallel;
+ uint _chunk_size;
+ uint _cur_chunk_idx;
+ uint _cur_chunk_end;
+ uint _regions_added;
+ size_t _reclaimable_bytes_added;
+
+public:
+ CSetChooserParUpdater(CollectionSetChooser* chooser,
+ bool parallel, uint chunk_size) :
+ _chooser(chooser), _parallel(parallel), _chunk_size(chunk_size),
+ _cur_chunk_idx(0), _cur_chunk_end(0),
+ _regions_added(0), _reclaimable_bytes_added(0) { }
+
+ ~CSetChooserParUpdater() {
+ if (_parallel && _regions_added > 0) {
+ _chooser->update_totals(_regions_added, _reclaimable_bytes_added);
+ }
+ }
+
+ void add_region(HeapRegion* hr) {
+ if (_parallel) {
+ if (_cur_chunk_idx == _cur_chunk_end) {
+ _cur_chunk_idx = _chooser->claim_array_chunk(_chunk_size);
+ _cur_chunk_end = _cur_chunk_idx + _chunk_size;
+ }
+ assert(_cur_chunk_idx < _cur_chunk_end, "invariant");
+ _chooser->set_region(_cur_chunk_idx, hr);
+ _cur_chunk_idx += 1;
+ } else {
+ _chooser->add_region(hr);
+ }
+ _regions_added += 1;
+ _reclaimable_bytes_added += hr->reclaimable_bytes();
+ }
+
+ bool should_add(HeapRegion* hr) { return _chooser->should_add(hr); }
+};
+
+#endif // SHARE_VM_GC_G1_COLLECTIONSETCHOOSER_HPP
+