1 /* |
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2 * Copyright (c) 2005, 2019, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
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22 * |
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23 */ |
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24 |
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25 #ifndef SHARE_GC_CMS_YIELDINGWORKGROUP_HPP |
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26 #define SHARE_GC_CMS_YIELDINGWORKGROUP_HPP |
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27 |
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28 #include "gc/shared/workgroup.hpp" |
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29 #include "utilities/macros.hpp" |
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30 |
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31 // Forward declarations |
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32 class YieldingFlexibleGangTask; |
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33 class YieldingFlexibleWorkGang; |
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34 |
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35 // Status of tasks |
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36 enum Status { |
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37 INACTIVE, |
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38 ACTIVE, |
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39 YIELDING, |
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40 YIELDED, |
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41 ABORTING, |
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42 ABORTED, |
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43 COMPLETING, |
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44 COMPLETED |
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45 }; |
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46 |
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47 class YieldingWorkData: public StackObj { |
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48 // This would be a struct, but I want accessor methods. |
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49 private: |
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50 AbstractGangTask* _task; |
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51 int _sequence_number; |
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52 public: |
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53 // Constructor and destructor |
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54 YieldingWorkData() : _task(NULL), _sequence_number(0) {} |
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55 ~YieldingWorkData() {} |
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56 |
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57 // Accessors and modifiers |
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58 AbstractGangTask* task() const { return _task; } |
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59 void set_task(AbstractGangTask* value) { _task = value; } |
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60 int sequence_number() const { return _sequence_number; } |
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61 void set_sequence_number(int value) { _sequence_number = value; } |
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62 |
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63 YieldingFlexibleGangTask* yf_task() const { |
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64 return (YieldingFlexibleGangTask*)_task; |
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65 } |
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66 }; |
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67 |
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68 // Class YieldingFlexibleGangWorker: |
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69 // Several instances of this class run in parallel as workers for a gang. |
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70 class YieldingFlexibleGangWorker: public AbstractGangWorker { |
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71 public: |
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72 YieldingFlexibleGangWorker(YieldingFlexibleWorkGang* gang, int id); |
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73 |
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74 public: |
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75 YieldingFlexibleWorkGang* yf_gang() const |
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76 { return (YieldingFlexibleWorkGang*)gang(); } |
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77 |
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78 protected: // Override from parent class |
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79 virtual void loop(); |
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80 }; |
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81 |
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82 class FlexibleGangTask: public AbstractGangTask { |
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83 int _actual_size; // size of gang obtained |
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84 protected: |
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85 int _requested_size; // size of gang requested |
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86 public: |
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87 FlexibleGangTask(const char* name): AbstractGangTask(name), |
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88 _requested_size(0) {} |
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89 |
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90 // The abstract work method. |
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91 // The argument tells you which member of the gang you are. |
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92 virtual void work(uint worker_id) = 0; |
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93 |
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94 int requested_size() const { return _requested_size; } |
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95 int actual_size() const { return _actual_size; } |
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96 |
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97 void set_requested_size(int sz) { _requested_size = sz; } |
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98 void set_actual_size(int sz) { _actual_size = sz; } |
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99 }; |
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100 |
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101 // An abstract task to be worked on by a flexible work gang, |
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102 // and where the workers will periodically yield, usually |
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103 // in response to some condition that is signalled by means |
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104 // that are specific to the task at hand. |
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105 // You subclass this to supply your own work() method. |
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106 // A second feature of this kind of work gang is that |
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107 // it allows for the signalling of certain exceptional |
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108 // conditions that may be encountered during the performance |
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109 // of the task and that may require the task at hand to be |
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110 // `aborted' forthwith. Finally, these gangs are `flexible' |
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111 // in that they can operate at partial capacity with some |
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112 // gang workers waiting on the bench; in other words, the |
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113 // size of the active worker pool can flex (up to an apriori |
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114 // maximum) in response to task requests at certain points. |
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115 // The last part (the flexible part) has not yet been fully |
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116 // fleshed out and is a work in progress. |
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117 class YieldingFlexibleGangTask: public FlexibleGangTask { |
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118 Status _status; |
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119 YieldingFlexibleWorkGang* _gang; |
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120 |
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121 protected: |
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122 // Constructor and desctructor: only construct subclasses. |
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123 YieldingFlexibleGangTask(const char* name): FlexibleGangTask(name), |
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124 _status(INACTIVE), |
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125 _gang(NULL) { } |
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126 |
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127 ~YieldingFlexibleGangTask() { } |
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128 |
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129 friend class YieldingFlexibleWorkGang; |
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130 friend class YieldingFlexibleGangWorker; |
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131 |
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132 void set_status(Status s) { |
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133 _status = s; |
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134 } |
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135 YieldingFlexibleWorkGang* gang() { |
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136 return _gang; |
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137 } |
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138 void set_gang(YieldingFlexibleWorkGang* gang) { |
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139 assert(_gang == NULL || gang == NULL, "Clobber without intermediate reset?"); |
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140 _gang = gang; |
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141 } |
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142 |
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143 public: |
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144 // The abstract work method. |
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145 // The argument tells you which member of the gang you are. |
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146 virtual void work(uint worker_id) = 0; |
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147 |
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148 // Subclasses should call the parent's yield() method |
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149 // after having done any work specific to the subclass. |
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150 virtual void yield(); |
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151 |
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152 // An abstract method supplied by |
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153 // a concrete sub-class which is used by the coordinator |
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154 // to do any "central yielding" work. |
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155 virtual void coordinator_yield() = 0; |
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156 |
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157 // Subclasses should call the parent's abort() method |
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158 // after having done any work specific to the sunbclass. |
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159 virtual void abort(); |
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160 |
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161 Status status() const { return _status; } |
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162 bool yielding() const { return _status == YIELDING; } |
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163 bool yielded() const { return _status == YIELDED; } |
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164 bool completed() const { return _status == COMPLETED; } |
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165 bool aborted() const { return _status == ABORTED; } |
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166 bool active() const { return _status == ACTIVE; } |
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167 |
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168 // This method configures the task for proper termination. |
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169 // Some tasks do not have any requirements on termination |
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170 // and may inherit this method that does nothing. Some |
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171 // tasks do some coordination on termination and override |
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172 // this method to implement that coordination. |
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173 virtual void set_for_termination(uint active_workers) {} |
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174 }; |
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175 // Class YieldingWorkGang: A subclass of WorkGang. |
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176 // In particular, a YieldingWorkGang is made up of |
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177 // YieldingGangWorkers, and provides infrastructure |
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178 // supporting yielding to the "GangOverseer", |
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179 // being the thread that orchestrates the WorkGang via run_task(). |
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180 class YieldingFlexibleWorkGang: public AbstractWorkGang { |
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181 // Here's the public interface to this class. |
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182 public: |
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183 // Constructor and destructor. |
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184 YieldingFlexibleWorkGang(const char* name, uint workers, |
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185 bool are_GC_task_threads); |
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186 |
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187 YieldingFlexibleGangTask* yielding_task() const { |
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188 return task(); |
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189 } |
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190 // Allocate a worker and return a pointer to it. |
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191 AbstractGangWorker* allocate_worker(uint which); |
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192 |
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193 // Run a task; returns when the task is done, or the workers yield, |
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194 // or the task is aborted. |
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195 // A task that has been yielded can be continued via this same interface |
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196 // by using the same task repeatedly as the argument to the call. |
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197 // It is expected that the YieldingFlexibleGangTask carries the appropriate |
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198 // continuation information used by workers to continue the task |
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199 // from its last yield point. Thus, a completed task will return |
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200 // immediately with no actual work having been done by the workers. |
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201 void run_task(AbstractGangTask* task) { |
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202 guarantee(false, "Use start_task instead"); |
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203 } |
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204 void start_task(YieldingFlexibleGangTask* new_task); |
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205 void continue_task(YieldingFlexibleGangTask* gang_task); |
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206 |
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207 // Abort a currently running task, if any; returns when all the workers |
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208 // have stopped working on the current task and have returned to their |
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209 // waiting stations. |
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210 void abort_task(); |
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211 |
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212 // Yield: workers wait at their current working stations |
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213 // until signalled to proceed by the overseer. |
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214 void yield(); |
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215 |
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216 // Abort: workers are expected to return to their waiting |
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217 // stations, whence they are ready for the next task dispatched |
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218 // by the overseer. |
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219 void abort(); |
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220 |
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221 private: |
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222 uint _yielded_workers; |
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223 void wait_for_gang(); |
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224 |
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225 public: |
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226 // Accessors for fields |
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227 uint yielded_workers() const { |
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228 return _yielded_workers; |
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229 } |
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230 |
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231 private: |
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232 friend class YieldingFlexibleGangWorker; |
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233 void reset(); // NYI |
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234 |
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235 |
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236 // The monitor which protects these data, |
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237 // and notifies of changes in it. |
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238 Monitor* _monitor; |
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239 // Accessors for fields |
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240 Monitor* monitor() const { |
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241 return _monitor; |
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242 } |
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243 |
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244 // The number of started workers. |
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245 uint _started_workers; |
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246 // The number of finished workers. |
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247 uint _finished_workers; |
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248 |
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249 uint started_workers() const { |
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250 return _started_workers; |
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251 } |
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252 uint finished_workers() const { |
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253 return _finished_workers; |
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254 } |
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255 |
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256 // A sequence number for the current task. |
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257 int _sequence_number; |
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258 int sequence_number() const { |
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259 return _sequence_number; |
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260 } |
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261 |
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262 YieldingFlexibleGangTask* _task; |
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263 YieldingFlexibleGangTask* task() const { |
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264 return _task; |
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265 } |
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266 |
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267 void internal_worker_poll(YieldingWorkData* data) const; |
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268 void internal_note_start(); |
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269 void internal_note_finish(); |
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270 }; |
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271 |
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272 #endif // SHARE_GC_CMS_YIELDINGWORKGROUP_HPP |
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