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1 /*
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2 * Copyright 2005 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
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26 // Forward declarations
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27 class YieldingFlexibleWorkGang;
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28
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29 // Status of tasks
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30 enum Status {
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31 INACTIVE,
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32 ACTIVE,
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33 YIELDING,
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34 YIELDED,
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35 ABORTING,
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36 ABORTED,
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37 COMPLETING,
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38 COMPLETED
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39 };
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40
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41 // Class YieldingFlexibleGangWorker:
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42 // Several instances of this class run in parallel as workers for a gang.
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43 class YieldingFlexibleGangWorker: public GangWorker {
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44 public:
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45 // Ctor
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46 YieldingFlexibleGangWorker(AbstractWorkGang* gang, int id) :
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47 GangWorker(gang, id) { }
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48
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49 public:
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50 YieldingFlexibleWorkGang* yf_gang() const
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51 { return (YieldingFlexibleWorkGang*)gang(); }
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52
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53 protected: // Override from parent class
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54 virtual void loop();
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55 };
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56
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57 // An abstract task to be worked on by a flexible work gang,
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58 // and where the workers will periodically yield, usually
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59 // in response to some condition that is signalled by means
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60 // that are specific to the task at hand.
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61 // You subclass this to supply your own work() method.
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62 // A second feature of this kind of work gang is that
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63 // it allows for the signalling of certain exceptional
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64 // conditions that may be encountered during the performance
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65 // of the task and that may require the task at hand to be
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66 // `aborted' forthwith. Finally, these gangs are `flexible'
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67 // in that they can operate at partial capacity with some
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68 // gang workers waiting on the bench; in other words, the
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69 // size of the active worker pool can flex (up to an apriori
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70 // maximum) in response to task requests at certain points.
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71 // The last part (the flexible part) has not yet been fully
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72 // fleshed out and is a work in progress.
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73 class YieldingFlexibleGangTask: public AbstractGangTask {
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74 Status _status;
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75 YieldingFlexibleWorkGang* _gang;
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76 int _actual_size; // size of gang obtained
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77
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78 protected:
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79 int _requested_size; // size of gang requested
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80
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81 // Constructor and desctructor: only construct subclasses.
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82 YieldingFlexibleGangTask(const char* name): AbstractGangTask(name),
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83 _status(INACTIVE),
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84 _gang(NULL),
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85 _requested_size(0) { }
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86
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87 virtual ~YieldingFlexibleGangTask() { }
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88
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89 friend class YieldingFlexibleWorkGang;
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90 friend class YieldingFlexibleGangWorker;
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91 NOT_PRODUCT(virtual bool is_YieldingFlexibleGang_task() const {
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92 return true;
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93 })
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94
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95 void set_status(Status s) {
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96 _status = s;
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97 }
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98 YieldingFlexibleWorkGang* gang() {
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99 return _gang;
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100 }
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101 void set_gang(YieldingFlexibleWorkGang* gang) {
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102 assert(_gang == NULL || gang == NULL, "Clobber without intermediate reset?");
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103 _gang = gang;
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104 }
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105
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106 public:
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107 // The abstract work method.
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108 // The argument tells you which member of the gang you are.
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109 virtual void work(int i) = 0;
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110
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111 // Subclasses should call the parent's yield() method
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112 // after having done any work specific to the subclass.
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113 virtual void yield();
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114
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115 // An abstract method supplied by
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116 // a concrete sub-class which is used by the coordinator
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117 // to do any "central yielding" work.
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118 virtual void coordinator_yield() = 0;
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119
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120 // Subclasses should call the parent's abort() method
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121 // after having done any work specific to the sunbclass.
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122 virtual void abort();
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123
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124 Status status() const { return _status; }
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125 bool yielded() const { return _status == YIELDED; }
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126 bool completed() const { return _status == COMPLETED; }
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127 bool aborted() const { return _status == ABORTED; }
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128 bool active() const { return _status == ACTIVE; }
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129
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130 int requested_size() const { return _requested_size; }
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131 int actual_size() const { return _actual_size; }
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132
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133 void set_requested_size(int sz) { _requested_size = sz; }
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134 void set_actual_size(int sz) { _actual_size = sz; }
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135 };
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136
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137 // Class YieldingWorkGang: A subclass of WorkGang.
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138 // In particular, a YieldingWorkGang is made up of
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139 // YieldingGangWorkers, and provides infrastructure
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140 // supporting yielding to the "GangOverseer",
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141 // being the thread that orchestrates the WorkGang via run_task().
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142 class YieldingFlexibleWorkGang: public AbstractWorkGang {
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143 // Here's the public interface to this class.
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144 public:
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145 // Constructor and destructor.
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342
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146 YieldingFlexibleWorkGang(const char* name, int workers,
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147 bool are_GC_task_threads);
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0
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148
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149 YieldingFlexibleGangTask* yielding_task() const {
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150 assert(task() == NULL || task()->is_YieldingFlexibleGang_task(),
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151 "Incorrect cast");
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152 return (YieldingFlexibleGangTask*)task();
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153 }
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154 // Run a task; returns when the task is done, or the workers yield,
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155 // or the task is aborted, or the work gang is terminated via stop().
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156 // A task that has been yielded can be continued via this same interface
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157 // by using the same task repeatedly as the argument to the call.
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158 // It is expected that the YieldingFlexibleGangTask carries the appropriate
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159 // continuation information used by workers to continue the task
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160 // from its last yield point. Thus, a completed task will return
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161 // immediately with no actual work having been done by the workers.
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162 void run_task(AbstractGangTask* task) {
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163 guarantee(false, "Use start_task instead");
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164 }
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165 void start_task(YieldingFlexibleGangTask* new_task);
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166 void continue_task(YieldingFlexibleGangTask* gang_task);
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167
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168 // Abort a currently running task, if any; returns when all the workers
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169 // have stopped working on the current task and have returned to their
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170 // waiting stations.
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171 void abort_task();
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172
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173 // Yield: workers wait at their current working stations
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174 // until signalled to proceed by the overseer.
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175 void yield();
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176
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177 // Abort: workers are expected to return to their waiting
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178 // stations, whence they are ready for the next task dispatched
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179 // by the overseer.
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180 void abort();
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181
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182 private:
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183 // The currently active workers in this gang.
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184 // This is a number that is dynamically adjusted by
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185 // the run_task() method at each subsequent invocation,
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186 // using data in the YieldingFlexibleGangTask.
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187 int _active_workers;
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188 int _yielded_workers;
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189 void wait_for_gang();
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190
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191 public:
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192 // Accessors for fields
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193 int active_workers() const {
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194 return _active_workers;
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195 }
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196
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197 int yielded_workers() const {
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198 return _yielded_workers;
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199 }
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200
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201 private:
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202 friend class YieldingFlexibleGangWorker;
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203 void reset(); // NYI
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204 };
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