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 #include "precompiled.hpp"
25 #include "oops/symbolHandle.hpp"
26 #include "runtime/atomic.hpp"
27 
28 Symbol* volatile TempSymbolCleanupDelayer::_queue[QueueSize] = {};
29 volatile uint TempSymbolCleanupDelayer::_index = 0;
30 
31 // Keep this symbol alive for some time to allow for reuse.
32 // Temp symbols for the same string can often be created in quick succession,
33 // and this queue allows them to be reused instead of churning.
34 void TempSymbolCleanupDelayer::delay_cleanup(Symbol* sym) {
35   assert(sym != nullptr, "precondition");
36   sym->increment_refcount();
37   uint i = Atomic::add(&_index, 1u) % QueueSize;
38   Symbol* old = Atomic::xchg(&_queue[i], sym);
39   Symbol::maybe_decrement_refcount(old);
40 }
41 
42 void TempSymbolCleanupDelayer::drain_queue() {
43   for (uint i = 0; i < QueueSize; i++) {
44     Symbol* sym = Atomic::xchg(&_queue[i], (Symbol*) nullptr);
45     Symbol::maybe_decrement_refcount(sym);
46   }
47 }