Mercurial > hg > graal-compiler
view src/share/vm/gc_implementation/g1/g1StringDedupQueue.hpp @ 18350:23a2faa68470
converted HotSpotForeignCallLinkage to an interface
author | Doug Simon <doug.simon@oracle.com> |
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date | Wed, 12 Nov 2014 14:43:58 +0100 |
parents | 1772223a25a2 |
children |
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/* * Copyright (c) 2014, 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_IMPLEMENTATION_G1_G1STRINGDEDUPQUEUE_HPP #define SHARE_VM_GC_IMPLEMENTATION_G1_G1STRINGDEDUPQUEUE_HPP #include "memory/allocation.hpp" #include "oops/oop.hpp" #include "utilities/stack.hpp" class G1StringDedupUnlinkOrOopsDoClosure; // // The deduplication queue acts as the communication channel between the stop-the-world // mark/evacuation phase and the concurrent deduplication phase. Deduplication candidates // found during mark/evacuation are placed on this queue for later processing in the // deduplication thread. A queue entry is an oop pointing to a String object (as opposed // to entries in the deduplication hashtable which points to character arrays). // // While users of the queue treat it as a single queue, it is implemented as a set of // queues, one queue per GC worker thread, to allow lock-free and cache-friendly enqueue // operations by the GC workers. // // The oops in the queue are treated as weak pointers, meaning the objects they point to // can become unreachable and pruned (cleared) before being popped by the deduplication // thread. // // Pushing to the queue is thread safe (this relies on each thread using a unique worker // id), but only allowed during a safepoint. Popping from the queue is NOT thread safe // and can only be done by the deduplication thread outside a safepoint. // // The StringDedupQueue_lock is only used for blocking and waking up the deduplication // thread in case the queue is empty or becomes non-empty, respectively. This lock does // not otherwise protect the queue content. // class G1StringDedupQueue : public CHeapObj<mtGC> { private: typedef Stack<oop, mtGC> G1StringDedupWorkerQueue; static G1StringDedupQueue* _queue; static const size_t _max_size; static const size_t _max_cache_size; G1StringDedupWorkerQueue* _queues; size_t _nqueues; size_t _cursor; bool _cancel; volatile bool _empty; // Statistics counter, only used for logging. uintx _dropped; G1StringDedupQueue(); ~G1StringDedupQueue(); static void unlink_or_oops_do(G1StringDedupUnlinkOrOopsDoClosure* cl, size_t queue); public: static void create(); // Blocks and waits for the queue to become non-empty. static void wait(); // Wakes up any thread blocked waiting for the queue to become non-empty. static void cancel_wait(); // Pushes a deduplication candidate onto a specific GC worker queue. static void push(uint worker_id, oop java_string); // Pops a deduplication candidate from any queue, returns NULL if // all queues are empty. static oop pop(); static void unlink_or_oops_do(G1StringDedupUnlinkOrOopsDoClosure* cl); static void print_statistics(outputStream* st); static void verify(); }; #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1STRINGDEDUPQUEUE_HPP