1 /*
 2  * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
 3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 4  *
 5  * This code is free software; you can redistribute it and/or modify it
 6  * under the terms of the GNU General Public License version 2 only, as
 7  * published by the Free Software Foundation.
 8  *
 9  * This code is distributed in the hope that it will be useful, but WITHOUT
10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12  * version 2 for more details (a copy is included in the LICENSE file that
13  * accompanied this code).
14  *
15  * You should have received a copy of the GNU General Public License version
16  * 2 along with this work; if not, write to the Free Software Foundation,
17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18  *
19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20  * or visit www.oracle.com if you need additional information or have any
21  * questions.
22  *
23  */
24 
25 #include "precompiled.hpp"
26 
27 #include "gc/shenandoah/shenandoahHeapRegionClosures.hpp"
28 #include "gc/shenandoah/shenandoahMarkingContext.hpp"
29 #include "gc/shenandoah/shenandoahSharedVariables.hpp"
30 
31 ShenandoahSynchronizePinnedRegionStates::ShenandoahSynchronizePinnedRegionStates() :
32   _lock(ShenandoahHeap::heap()->lock()) { }
33 
34 void ShenandoahSynchronizePinnedRegionStates::heap_region_do(ShenandoahHeapRegion* r) {
35   // Drop "pinned" state from regions that no longer have a pinned count. Put
36   // regions with a pinned count into the "pinned" state.
37   if (r->is_active()) {
38     synchronize_pin_count(r);
39   }
40 }
41 
42 void ShenandoahSynchronizePinnedRegionStates::synchronize_pin_count(ShenandoahHeapRegion* r) {
43   if (r->is_pinned()) {
44     if (r->pin_count() == 0) {
45       ShenandoahHeapLocker locker(_lock);
46       r->make_unpinned();
47     }
48   } else {
49     if (r->pin_count() > 0) {
50       ShenandoahHeapLocker locker(_lock);
51       r->make_pinned();
52     }
53   }
54 }
55 
56 ShenandoahFinalMarkUpdateRegionStateClosure::ShenandoahFinalMarkUpdateRegionStateClosure(ShenandoahMarkingContext *ctx) :
57         _ctx(ctx) { }
58 
59 void ShenandoahFinalMarkUpdateRegionStateClosure::heap_region_do(ShenandoahHeapRegion* r) {
60   if (r->is_active()) {
61     if (_ctx != nullptr) {
62       // _ctx may be null when this closure is used to sync only the pin status
63       // update the watermark of old regions. For old regions we cannot reset
64       // the TAMS because we rely on that to keep promoted objects alive after
65       // old marking is complete.
66 
67       // All allocations past TAMS are implicitly live, adjust the region data.
68       // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
69       HeapWord *tams = _ctx->top_at_mark_start(r);
70       HeapWord *top = r->top();
71       if (top > tams) {
72         r->increase_live_data_alloc_words(pointer_delta(top, tams));
73       }
74     }
75 
76     // We are about to select the collection set, make sure it knows about
77     // current pinning status. Also, this allows trashing more regions that
78     // now have their pinning status dropped.
79     _pins.synchronize_pin_count(r);
80 
81     // Remember limit for updating refs. It's guaranteed that we get no
82     // from-space-refs written from here on.
83     r->set_update_watermark_at_safepoint(r->top());
84   } else {
85     assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
86     assert(_ctx == nullptr || _ctx->top_at_mark_start(r) == r->top(),
87            "Region " SIZE_FORMAT " should have correct TAMS", r->index());
88   }
89 }