Thu, 04 Sep 2014 16:53:27 -0700
8057531: refactor gc argument processing code slightly
Reviewed-by: mgerdin, tschatzl, jmasa
1 /*
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25 #ifndef SHARE_VM_RUNTIME_TASK_HPP
26 #define SHARE_VM_RUNTIME_TASK_HPP
28 #include "utilities/top.hpp"
30 // A PeriodicTask has the sole purpose of executing its task
31 // function with regular intervals.
32 // Usage:
33 // PeriodicTask pf(10);
34 // pf.enroll();
35 // ...
36 // pf.disenroll();
38 class PeriodicTask: public CHeapObj<mtInternal> {
39 public:
40 // Useful constants.
41 // The interval constants are used to ensure the declared interval
42 // is appropriate; it must be between min_interval and max_interval,
43 // and have a granularity of interval_gran (all in millis).
44 enum { max_tasks = 10, // Max number of periodic tasks in system
45 interval_gran = 10,
46 min_interval = 10,
47 max_interval = 10000 };
49 static int num_tasks() { return _num_tasks; }
51 private:
52 int _counter;
53 const int _interval;
55 static int _num_tasks;
56 static PeriodicTask* _tasks[PeriodicTask::max_tasks];
57 static void real_time_tick(int delay_time);
59 #ifndef PRODUCT
60 static elapsedTimer _timer; // measures time between ticks
61 static int _ticks; // total number of ticks
62 static int _intervalHistogram[max_interval]; // to check spacing of timer interrupts
63 public:
64 static void print_intervals();
65 #endif
66 // Only the WatcherThread can cause us to execute PeriodicTasks
67 friend class WatcherThread;
68 public:
69 PeriodicTask(size_t interval_time); // interval is in milliseconds of elapsed time
70 ~PeriodicTask();
72 // Make the task active
73 // For dynamic enrollment at the time T, the task will execute somewhere
74 // between T and T + interval_time.
75 void enroll();
77 // Make the task deactive
78 void disenroll();
80 void execute_if_pending(int delay_time) {
81 // make sure we don't overflow
82 jlong tmp = (jlong) _counter + (jlong) delay_time;
84 if (tmp >= (jlong) _interval) {
85 _counter = 0;
86 task();
87 } else {
88 _counter += delay_time;
89 }
90 }
92 // Returns how long (time in milliseconds) before the next time we should
93 // execute this task.
94 int time_to_next_interval() const {
95 assert(_interval > _counter, "task counter greater than interval?");
96 return _interval - _counter;
97 }
99 // Calculate when the next periodic task will fire.
100 // Called by the WatcherThread's run method.
101 static int time_to_wait();
103 // The task to perform at each period
104 virtual void task() = 0;
105 };
107 #endif // SHARE_VM_RUNTIME_TASK_HPP