--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/g1/g1StringDedup.cpp Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,214 @@
+/*
+ * Copyright (c) 2014, 2017, 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.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "classfile/javaClasses.inline.hpp"
+#include "gc/g1/g1CollectedHeap.inline.hpp"
+#include "gc/g1/g1GCPhaseTimes.hpp"
+#include "gc/g1/g1StringDedup.hpp"
+#include "gc/g1/g1StringDedupQueue.hpp"
+#include "gc/g1/g1StringDedupStat.hpp"
+#include "gc/g1/g1StringDedupTable.hpp"
+#include "gc/g1/g1StringDedupThread.hpp"
+#include "runtime/atomic.hpp"
+
+bool G1StringDedup::_enabled = false;
+
+void G1StringDedup::initialize() {
+ assert(UseG1GC, "String deduplication only available with G1");
+ if (UseStringDeduplication) {
+ _enabled = true;
+ G1StringDedupQueue::create();
+ G1StringDedupTable::create();
+ G1StringDedupThread::create();
+ }
+}
+
+void G1StringDedup::stop() {
+ assert(is_enabled(), "String deduplication not enabled");
+ G1StringDedupThread::thread()->stop();
+}
+
+bool G1StringDedup::is_candidate_from_mark(oop obj) {
+ if (java_lang_String::is_instance_inlined(obj)) {
+ bool from_young = G1CollectedHeap::heap()->heap_region_containing(obj)->is_young();
+ if (from_young && obj->age() < StringDeduplicationAgeThreshold) {
+ // Candidate found. String is being evacuated from young to old but has not
+ // reached the deduplication age threshold, i.e. has not previously been a
+ // candidate during its life in the young generation.
+ return true;
+ }
+ }
+
+ // Not a candidate
+ return false;
+}
+
+void G1StringDedup::enqueue_from_mark(oop java_string) {
+ assert(is_enabled(), "String deduplication not enabled");
+ if (is_candidate_from_mark(java_string)) {
+ G1StringDedupQueue::push(0 /* worker_id */, java_string);
+ }
+}
+
+bool G1StringDedup::is_candidate_from_evacuation(bool from_young, bool to_young, oop obj) {
+ if (from_young && java_lang_String::is_instance_inlined(obj)) {
+ if (to_young && obj->age() == StringDeduplicationAgeThreshold) {
+ // Candidate found. String is being evacuated from young to young and just
+ // reached the deduplication age threshold.
+ return true;
+ }
+ if (!to_young && obj->age() < StringDeduplicationAgeThreshold) {
+ // Candidate found. String is being evacuated from young to old but has not
+ // reached the deduplication age threshold, i.e. has not previously been a
+ // candidate during its life in the young generation.
+ return true;
+ }
+ }
+
+ // Not a candidate
+ return false;
+}
+
+void G1StringDedup::enqueue_from_evacuation(bool from_young, bool to_young, uint worker_id, oop java_string) {
+ assert(is_enabled(), "String deduplication not enabled");
+ if (is_candidate_from_evacuation(from_young, to_young, java_string)) {
+ G1StringDedupQueue::push(worker_id, java_string);
+ }
+}
+
+void G1StringDedup::deduplicate(oop java_string) {
+ assert(is_enabled(), "String deduplication not enabled");
+ G1StringDedupStat dummy; // Statistics from this path is never used
+ G1StringDedupTable::deduplicate(java_string, dummy);
+}
+
+void G1StringDedup::oops_do(OopClosure* keep_alive) {
+ assert(is_enabled(), "String deduplication not enabled");
+ unlink_or_oops_do(NULL, keep_alive, true /* allow_resize_and_rehash */);
+}
+
+void G1StringDedup::parallel_unlink(G1StringDedupUnlinkOrOopsDoClosure* unlink, uint worker_id) {
+ assert(is_enabled(), "String deduplication not enabled");
+ G1StringDedupQueue::unlink_or_oops_do(unlink);
+ G1StringDedupTable::unlink_or_oops_do(unlink, worker_id);
+}
+
+//
+// Task for parallel unlink_or_oops_do() operation on the deduplication queue
+// and table.
+//
+class G1StringDedupUnlinkOrOopsDoTask : public AbstractGangTask {
+private:
+ G1StringDedupUnlinkOrOopsDoClosure _cl;
+ G1GCPhaseTimes* _phase_times;
+
+public:
+ G1StringDedupUnlinkOrOopsDoTask(BoolObjectClosure* is_alive,
+ OopClosure* keep_alive,
+ bool allow_resize_and_rehash,
+ G1GCPhaseTimes* phase_times) :
+ AbstractGangTask("G1StringDedupUnlinkOrOopsDoTask"),
+ _cl(is_alive, keep_alive, allow_resize_and_rehash), _phase_times(phase_times) { }
+
+ virtual void work(uint worker_id) {
+ {
+ G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
+ G1StringDedupQueue::unlink_or_oops_do(&_cl);
+ }
+ {
+ G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
+ G1StringDedupTable::unlink_or_oops_do(&_cl, worker_id);
+ }
+ }
+};
+
+void G1StringDedup::unlink_or_oops_do(BoolObjectClosure* is_alive,
+ OopClosure* keep_alive,
+ bool allow_resize_and_rehash,
+ G1GCPhaseTimes* phase_times) {
+ assert(is_enabled(), "String deduplication not enabled");
+
+ G1StringDedupUnlinkOrOopsDoTask task(is_alive, keep_alive, allow_resize_and_rehash, phase_times);
+ G1CollectedHeap* g1h = G1CollectedHeap::heap();
+ g1h->workers()->run_task(&task);
+}
+
+void G1StringDedup::threads_do(ThreadClosure* tc) {
+ assert(is_enabled(), "String deduplication not enabled");
+ tc->do_thread(G1StringDedupThread::thread());
+}
+
+void G1StringDedup::print_worker_threads_on(outputStream* st) {
+ assert(is_enabled(), "String deduplication not enabled");
+ G1StringDedupThread::thread()->print_on(st);
+ st->cr();
+}
+
+void G1StringDedup::verify() {
+ assert(is_enabled(), "String deduplication not enabled");
+ G1StringDedupQueue::verify();
+ G1StringDedupTable::verify();
+}
+
+G1StringDedupUnlinkOrOopsDoClosure::G1StringDedupUnlinkOrOopsDoClosure(BoolObjectClosure* is_alive,
+ OopClosure* keep_alive,
+ bool allow_resize_and_rehash) :
+ _is_alive(is_alive),
+ _keep_alive(keep_alive),
+ _resized_table(NULL),
+ _rehashed_table(NULL),
+ _next_queue(0),
+ _next_bucket(0) {
+ if (allow_resize_and_rehash) {
+ // If both resize and rehash is needed, only do resize. Rehash of
+ // the table will eventually happen if the situation persists.
+ _resized_table = G1StringDedupTable::prepare_resize();
+ if (!is_resizing()) {
+ _rehashed_table = G1StringDedupTable::prepare_rehash();
+ }
+ }
+}
+
+G1StringDedupUnlinkOrOopsDoClosure::~G1StringDedupUnlinkOrOopsDoClosure() {
+ assert(!is_resizing() || !is_rehashing(), "Can not both resize and rehash");
+ if (is_resizing()) {
+ G1StringDedupTable::finish_resize(_resized_table);
+ } else if (is_rehashing()) {
+ G1StringDedupTable::finish_rehash(_rehashed_table);
+ }
+}
+
+// Atomically claims the next available queue for exclusive access by
+// the current thread. Returns the queue number of the claimed queue.
+size_t G1StringDedupUnlinkOrOopsDoClosure::claim_queue() {
+ return (size_t)Atomic::add_ptr(1, &_next_queue) - 1;
+}
+
+// Atomically claims the next available table partition for exclusive
+// access by the current thread. Returns the table bucket number where
+// the claimed partition starts.
+size_t G1StringDedupUnlinkOrOopsDoClosure::claim_table_partition(size_t partition_size) {
+ return (size_t)Atomic::add_ptr(partition_size, &_next_bucket) - partition_size;
+}