1 /*
   2  * Copyright (c) 2017, 2019, Oracle and/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 "gc/z/zNMethodTableEntry.hpp"
  26 #include "gc/z/zNMethodTableIteration.hpp"
  27 #include "memory/iterator.hpp"
  28 #include "runtime/atomic.hpp"
  29 #include "utilities/debug.hpp"
  30 #include "utilities/globalDefinitions.hpp"
  31 
  32 ZNMethodTableIteration::ZNMethodTableIteration() :
  33     _table(NULL),
  34     _size(0),
  35     _claimed(0) {}
  36 
  37 bool ZNMethodTableIteration::in_progress() const {
  38   return _table != NULL;
  39 }
  40 
  41 void ZNMethodTableIteration::nmethods_do_begin(ZNMethodTableEntry* table, size_t size) {
  42   assert(!in_progress(), "precondition");
  43 
  44   _table = table;
  45   _size = size;
  46   _claimed = 0;
  47 }
  48 
  49 void ZNMethodTableIteration::nmethods_do_end() {
  50   assert(_claimed >= _size, "Failed to claim all table entries");
  51 
  52   // Finish iteration
  53   _table = NULL;
  54 }
  55 
  56 void ZNMethodTableIteration::nmethods_do(NMethodClosure* cl) {
  57   for (;;) {
  58     // Claim table partition. Each partition is currently sized to span
  59     // two cache lines. This number is just a guess, but seems to work well.
  60     const size_t partition_size = (ZCacheLineSize * 2) / sizeof(ZNMethodTableEntry);
  61     const size_t partition_start = MIN2(Atomic::add(partition_size, &_claimed) - partition_size, _size);
  62     const size_t partition_end = MIN2(partition_start + partition_size, _size);
  63     if (partition_start == partition_end) {
  64       // End of table
  65       break;
  66     }
  67 
  68     // Process table partition
  69     for (size_t i = partition_start; i < partition_end; i++) {
  70       const ZNMethodTableEntry entry = _table[i];
  71       if (entry.registered()) {
  72         cl->do_nmethod(entry.method());
  73       }
  74     }
  75   }
  76 }