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1 /*
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2 * Copyright 2001-2007 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 # include "incls/_precompiled.incl"
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26 # include "incls/_workgroup.cpp.incl"
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27
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28 // Definitions of WorkGang methods.
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29
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30 AbstractWorkGang::AbstractWorkGang(const char* name,
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31 bool are_GC_threads) :
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32 _name(name),
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33 _are_GC_threads(are_GC_threads) {
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34 // Other initialization.
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35 _monitor = new Monitor(/* priority */ Mutex::leaf,
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36 /* name */ "WorkGroup monitor",
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37 /* allow_vm_block */ are_GC_threads);
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38 assert(monitor() != NULL, "Failed to allocate monitor");
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39 _terminate = false;
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40 _task = NULL;
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41 _sequence_number = 0;
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42 _started_workers = 0;
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43 _finished_workers = 0;
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44 }
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45
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46 WorkGang::WorkGang(const char* name,
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47 int workers,
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48 bool are_GC_threads) :
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49 AbstractWorkGang(name, are_GC_threads) {
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50 // Save arguments.
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51 _total_workers = workers;
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52 if (TraceWorkGang) {
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53 tty->print_cr("Constructing work gang %s with %d threads", name, workers);
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54 }
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55 _gang_workers = NEW_C_HEAP_ARRAY(GangWorker*, workers);
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56 assert(gang_workers() != NULL, "Failed to allocate gang workers");
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57 for (int worker = 0; worker < total_workers(); worker += 1) {
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58 GangWorker* new_worker = new GangWorker(this, worker);
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59 assert(new_worker != NULL, "Failed to allocate GangWorker");
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60 _gang_workers[worker] = new_worker;
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61 if (new_worker == NULL || !os::create_thread(new_worker, os::pgc_thread))
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62 vm_exit_out_of_memory(0, "Cannot create worker GC thread. Out of system resources.");
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63 if (!DisableStartThread) {
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64 os::start_thread(new_worker);
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65 }
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66 }
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67 }
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68
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69 AbstractWorkGang::~AbstractWorkGang() {
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70 if (TraceWorkGang) {
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71 tty->print_cr("Destructing work gang %s", name());
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72 }
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73 stop(); // stop all the workers
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74 for (int worker = 0; worker < total_workers(); worker += 1) {
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75 delete gang_worker(worker);
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76 }
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77 delete gang_workers();
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78 delete monitor();
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79 }
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80
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81 GangWorker* AbstractWorkGang::gang_worker(int i) const {
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82 // Array index bounds checking.
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83 GangWorker* result = NULL;
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84 assert(gang_workers() != NULL, "No workers for indexing");
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85 assert(((i >= 0) && (i < total_workers())), "Worker index out of bounds");
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86 result = _gang_workers[i];
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87 assert(result != NULL, "Indexing to null worker");
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88 return result;
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89 }
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90
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91 void WorkGang::run_task(AbstractGangTask* task) {
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92 // This thread is executed by the VM thread which does not block
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93 // on ordinary MutexLocker's.
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94 MutexLockerEx ml(monitor(), Mutex::_no_safepoint_check_flag);
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95 if (TraceWorkGang) {
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96 tty->print_cr("Running work gang %s task %s", name(), task->name());
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97 }
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98 // Tell all the workers to run a task.
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99 assert(task != NULL, "Running a null task");
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100 // Initialize.
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101 _task = task;
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102 _sequence_number += 1;
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103 _started_workers = 0;
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104 _finished_workers = 0;
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105 // Tell the workers to get to work.
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106 monitor()->notify_all();
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107 // Wait for them to be finished
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108 while (finished_workers() < total_workers()) {
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109 if (TraceWorkGang) {
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110 tty->print_cr("Waiting in work gang %s: %d/%d finished sequence %d",
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111 name(), finished_workers(), total_workers(),
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112 _sequence_number);
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113 }
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114 monitor()->wait(/* no_safepoint_check */ true);
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115 }
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116 _task = NULL;
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117 if (TraceWorkGang) {
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118 tty->print_cr("/nFinished work gang %s: %d/%d sequence %d",
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119 name(), finished_workers(), total_workers(),
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120 _sequence_number);
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121 }
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122 }
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123
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124 void AbstractWorkGang::stop() {
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125 // Tell all workers to terminate, then wait for them to become inactive.
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126 MutexLockerEx ml(monitor(), Mutex::_no_safepoint_check_flag);
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127 if (TraceWorkGang) {
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128 tty->print_cr("Stopping work gang %s task %s", name(), task()->name());
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129 }
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130 _task = NULL;
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131 _terminate = true;
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132 monitor()->notify_all();
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133 while (finished_workers() < total_workers()) {
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134 if (TraceWorkGang) {
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135 tty->print_cr("Waiting in work gang %s: %d/%d finished",
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136 name(), finished_workers(), total_workers());
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137 }
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138 monitor()->wait(/* no_safepoint_check */ true);
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139 }
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140 }
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141
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142 void AbstractWorkGang::internal_worker_poll(WorkData* data) const {
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143 assert(monitor()->owned_by_self(), "worker_poll is an internal method");
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144 assert(data != NULL, "worker data is null");
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145 data->set_terminate(terminate());
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146 data->set_task(task());
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147 data->set_sequence_number(sequence_number());
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148 }
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149
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150 void AbstractWorkGang::internal_note_start() {
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151 assert(monitor()->owned_by_self(), "note_finish is an internal method");
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152 _started_workers += 1;
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153 }
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154
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155 void AbstractWorkGang::internal_note_finish() {
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156 assert(monitor()->owned_by_self(), "note_finish is an internal method");
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157 _finished_workers += 1;
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158 }
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159
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160 void AbstractWorkGang::print_worker_threads_on(outputStream* st) const {
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161 uint num_thr = total_workers();
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162 for (uint i = 0; i < num_thr; i++) {
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163 gang_worker(i)->print_on(st);
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164 st->cr();
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165 }
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166 }
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167
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168 void AbstractWorkGang::threads_do(ThreadClosure* tc) const {
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169 assert(tc != NULL, "Null ThreadClosure");
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170 uint num_thr = total_workers();
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171 for (uint i = 0; i < num_thr; i++) {
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172 tc->do_thread(gang_worker(i));
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173 }
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174 }
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175
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176 // GangWorker methods.
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177
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178 GangWorker::GangWorker(AbstractWorkGang* gang, uint id) {
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179 _gang = gang;
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180 set_id(id);
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181 set_name("Gang worker#%d (%s)", id, gang->name());
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182 }
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183
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184 void GangWorker::run() {
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185 initialize();
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186 loop();
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187 }
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188
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189 void GangWorker::initialize() {
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190 this->initialize_thread_local_storage();
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191 assert(_gang != NULL, "No gang to run in");
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192 os::set_priority(this, NearMaxPriority);
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193 if (TraceWorkGang) {
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194 tty->print_cr("Running gang worker for gang %s id %d",
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195 gang()->name(), id());
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196 }
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197 // The VM thread should not execute here because MutexLocker's are used
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198 // as (opposed to MutexLockerEx's).
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199 assert(!Thread::current()->is_VM_thread(), "VM thread should not be part"
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200 " of a work gang");
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201 }
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202
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203 void GangWorker::loop() {
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204 int previous_sequence_number = 0;
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205 Monitor* gang_monitor = gang()->monitor();
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206 for ( ; /* !terminate() */; ) {
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207 WorkData data;
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208 int part; // Initialized below.
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209 {
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210 // Grab the gang mutex.
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211 MutexLocker ml(gang_monitor);
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212 // Wait for something to do.
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213 // Polling outside the while { wait } avoids missed notifies
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214 // in the outer loop.
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215 gang()->internal_worker_poll(&data);
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216 if (TraceWorkGang) {
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217 tty->print("Polled outside for work in gang %s worker %d",
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218 gang()->name(), id());
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219 tty->print(" terminate: %s",
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220 data.terminate() ? "true" : "false");
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221 tty->print(" sequence: %d (prev: %d)",
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222 data.sequence_number(), previous_sequence_number);
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223 if (data.task() != NULL) {
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224 tty->print(" task: %s", data.task()->name());
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225 } else {
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226 tty->print(" task: NULL");
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227 }
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228 tty->cr();
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229 }
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230 for ( ; /* break or return */; ) {
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231 // Terminate if requested.
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232 if (data.terminate()) {
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233 gang()->internal_note_finish();
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234 gang_monitor->notify_all();
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235 return;
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236 }
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237 // Check for new work.
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238 if ((data.task() != NULL) &&
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239 (data.sequence_number() != previous_sequence_number)) {
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240 gang()->internal_note_start();
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241 gang_monitor->notify_all();
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242 part = gang()->started_workers() - 1;
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243 break;
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244 }
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245 // Nothing to do.
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246 gang_monitor->wait(/* no_safepoint_check */ true);
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247 gang()->internal_worker_poll(&data);
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248 if (TraceWorkGang) {
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249 tty->print("Polled inside for work in gang %s worker %d",
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250 gang()->name(), id());
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251 tty->print(" terminate: %s",
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252 data.terminate() ? "true" : "false");
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253 tty->print(" sequence: %d (prev: %d)",
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254 data.sequence_number(), previous_sequence_number);
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255 if (data.task() != NULL) {
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256 tty->print(" task: %s", data.task()->name());
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257 } else {
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258 tty->print(" task: NULL");
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259 }
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260 tty->cr();
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261 }
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262 }
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263 // Drop gang mutex.
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264 }
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265 if (TraceWorkGang) {
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266 tty->print("Work for work gang %s id %d task %s part %d",
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267 gang()->name(), id(), data.task()->name(), part);
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268 }
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269 assert(data.task() != NULL, "Got null task");
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270 data.task()->work(part);
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271 {
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272 if (TraceWorkGang) {
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273 tty->print("Finish for work gang %s id %d task %s part %d",
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274 gang()->name(), id(), data.task()->name(), part);
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275 }
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276 // Grab the gang mutex.
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277 MutexLocker ml(gang_monitor);
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278 gang()->internal_note_finish();
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279 // Tell the gang you are done.
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280 gang_monitor->notify_all();
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281 // Drop the gang mutex.
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282 }
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283 previous_sequence_number = data.sequence_number();
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284 }
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285 }
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286
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287 bool GangWorker::is_GC_task_thread() const {
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288 return gang()->are_GC_threads();
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289 }
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290
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291 void GangWorker::print_on(outputStream* st) const {
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292 st->print("\"%s\" ", name());
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293 Thread::print_on(st);
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294 st->cr();
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295 }
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296
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297 // Printing methods
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298
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299 const char* AbstractWorkGang::name() const {
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300 return _name;
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301 }
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302
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303 #ifndef PRODUCT
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304
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305 const char* AbstractGangTask::name() const {
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306 return _name;
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307 }
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308
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309 #endif /* PRODUCT */
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310
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311 // *** WorkGangBarrierSync
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312
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313 WorkGangBarrierSync::WorkGangBarrierSync()
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314 : _monitor(Mutex::safepoint, "work gang barrier sync", true),
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315 _n_workers(0), _n_completed(0) {
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316 }
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317
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318 WorkGangBarrierSync::WorkGangBarrierSync(int n_workers, const char* name)
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319 : _monitor(Mutex::safepoint, name, true),
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320 _n_workers(n_workers), _n_completed(0) {
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321 }
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322
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323 void WorkGangBarrierSync::set_n_workers(int n_workers) {
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324 _n_workers = n_workers;
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325 _n_completed = 0;
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326 }
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327
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328 void WorkGangBarrierSync::enter() {
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329 MutexLockerEx x(monitor(), Mutex::_no_safepoint_check_flag);
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330 inc_completed();
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331 if (n_completed() == n_workers()) {
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332 monitor()->notify_all();
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333 }
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334 else {
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335 while (n_completed() != n_workers()) {
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336 monitor()->wait(/* no_safepoint_check */ true);
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337 }
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338 }
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339 }
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340
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341 // SubTasksDone functions.
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342
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343 SubTasksDone::SubTasksDone(int n) :
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344 _n_tasks(n), _n_threads(1), _tasks(NULL) {
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345 _tasks = NEW_C_HEAP_ARRAY(jint, n);
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346 guarantee(_tasks != NULL, "alloc failure");
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347 clear();
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348 }
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349
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350 bool SubTasksDone::valid() {
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351 return _tasks != NULL;
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352 }
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353
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354 void SubTasksDone::set_par_threads(int t) {
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355 #ifdef ASSERT
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356 assert(_claimed == 0 || _threads_completed == _n_threads,
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357 "should not be called while tasks are being processed!");
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358 #endif
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359 _n_threads = (t == 0 ? 1 : t);
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360 }
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361
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362 void SubTasksDone::clear() {
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363 for (int i = 0; i < _n_tasks; i++) {
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364 _tasks[i] = 0;
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365 }
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366 _threads_completed = 0;
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367 #ifdef ASSERT
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368 _claimed = 0;
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369 #endif
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370 }
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371
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372 bool SubTasksDone::is_task_claimed(int t) {
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373 assert(0 <= t && t < _n_tasks, "bad task id.");
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374 jint old = _tasks[t];
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375 if (old == 0) {
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376 old = Atomic::cmpxchg(1, &_tasks[t], 0);
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377 }
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378 assert(_tasks[t] == 1, "What else?");
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379 bool res = old != 0;
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380 #ifdef ASSERT
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381 if (!res) {
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382 assert(_claimed < _n_tasks, "Too many tasks claimed; missing clear?");
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383 Atomic::inc(&_claimed);
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384 }
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385 #endif
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386 return res;
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387 }
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388
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389 void SubTasksDone::all_tasks_completed() {
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390 jint observed = _threads_completed;
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391 jint old;
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392 do {
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393 old = observed;
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394 observed = Atomic::cmpxchg(old+1, &_threads_completed, old);
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395 } while (observed != old);
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396 // If this was the last thread checking in, clear the tasks.
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397 if (observed+1 == _n_threads) clear();
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398 }
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399
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400
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401 SubTasksDone::~SubTasksDone() {
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402 if (_tasks != NULL) FREE_C_HEAP_ARRAY(jint, _tasks);
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403 }
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404
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405 // *** SequentialSubTasksDone
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406
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407 void SequentialSubTasksDone::clear() {
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408 _n_tasks = _n_claimed = 0;
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409 _n_threads = _n_completed = 0;
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410 }
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411
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412 bool SequentialSubTasksDone::valid() {
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413 return _n_threads > 0;
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414 }
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415
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416 bool SequentialSubTasksDone::is_task_claimed(int& t) {
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417 jint* n_claimed_ptr = &_n_claimed;
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418 t = *n_claimed_ptr;
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419 while (t < _n_tasks) {
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420 jint res = Atomic::cmpxchg(t+1, n_claimed_ptr, t);
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421 if (res == t) {
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422 return false;
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423 }
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424 t = *n_claimed_ptr;
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425 }
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426 return true;
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427 }
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428
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429 bool SequentialSubTasksDone::all_tasks_completed() {
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430 jint* n_completed_ptr = &_n_completed;
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431 jint complete = *n_completed_ptr;
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432 while (true) {
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433 jint res = Atomic::cmpxchg(complete+1, n_completed_ptr, complete);
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434 if (res == complete) {
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435 break;
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436 }
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437 complete = res;
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438 }
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439 if (complete+1 == _n_threads) {
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440 clear();
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441 return true;
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442 }
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443 return false;
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444 }
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