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src/share/vm/runtime/task.hpp@da862781b584 (annotated)

src/share/vm/runtime/task.hpp

Thu, 21 Nov 2013 12:30:35 -0800

author

kvn

date

Thu, 21 Nov 2013 12:30:35 -0800

changeset 6485

da862781b584

parent 4250

c284cf4781f0

child 6876

710a3c8b516e

permissions

-rw-r--r--

Merge

duke@435	1	/*
mikael@4153	2	* Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.
duke@435	3	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435	4	*
duke@435	5	* This code is free software; you can redistribute it and/or modify it
duke@435	6	* under the terms of the GNU General Public License version 2 only, as
duke@435	7	* published by the Free Software Foundation.
duke@435	8	*
duke@435	9	* This code is distributed in the hope that it will be useful, but WITHOUT
duke@435	10	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435	11	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
duke@435	12	* version 2 for more details (a copy is included in the LICENSE file that
duke@435	13	* accompanied this code).
duke@435	14	*
duke@435	15	* You should have received a copy of the GNU General Public License version
duke@435	16	* 2 along with this work; if not, write to the Free Software Foundation,
duke@435	17	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435	18	*
trims@1907	19	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907	20	* or visit www.oracle.com if you need additional information or have any
trims@1907	21	* questions.
duke@435	22	*
duke@435	23	*/
duke@435	24
stefank@2314	25	#ifndef SHARE_VM_RUNTIME_TASK_HPP
stefank@2314	26	#define SHARE_VM_RUNTIME_TASK_HPP
stefank@2314	27
stefank@2314	28	#include "utilities/top.hpp"
stefank@2314	29
duke@435	30	// A PeriodicTask has the sole purpose of executing its task
duke@435	31	// function with regular intervals.
duke@435	32	// Usage:
duke@435	33	// PeriodicTask pf(10);
duke@435	34	// pf.enroll();
duke@435	35	// ...
duke@435	36	// pf.disenroll();
duke@435	37
zgu@3900	38	class PeriodicTask: public CHeapObj<mtInternal> {
duke@435	39	public:
duke@435	40	// Useful constants.
duke@435	41	// The interval constants are used to ensure the declared interval
duke@435	42	// is appropriate; it must be between min_interval and max_interval,
duke@435	43	// and have a granularity of interval_gran (all in millis).
duke@435	44	enum { max_tasks = 10, // Max number of periodic tasks in system
duke@435	45	interval_gran = 10,
duke@435	46	min_interval = 10,
duke@435	47	max_interval = 10000 };
duke@435	48
duke@435	49	static int num_tasks() { return _num_tasks; }
duke@435	50
duke@435	51	private:
rbackman@4250	52	int _counter;
rbackman@4250	53	const int _interval;
duke@435	54
duke@435	55	static int _num_tasks;
duke@435	56	static PeriodicTask* _tasks[PeriodicTask::max_tasks];
rbackman@4250	57	static void real_time_tick(int delay_time);
duke@435	58
duke@435	59	#ifndef PRODUCT
duke@435	60	static elapsedTimer _timer; // measures time between ticks
duke@435	61	static int _ticks; // total number of ticks
duke@435	62	static int _intervalHistogram[max_interval]; // to check spacing of timer interrupts
duke@435	63	public:
duke@435	64	static void print_intervals();
duke@435	65	#endif
duke@435	66	// Only the WatcherThread can cause us to execute PeriodicTasks
duke@435	67	friend class WatcherThread;
duke@435	68	public:
duke@435	69	PeriodicTask(size_t interval_time); // interval is in milliseconds of elapsed time
duke@435	70	~PeriodicTask();
duke@435	71
duke@435	72	// Make the task active
rbackman@4250	73	// For dynamic enrollment at the time T, the task will execute somewhere
rbackman@4250	74	// between T and T + interval_time.
duke@435	75	void enroll();
duke@435	76
duke@435	77	// Make the task deactive
duke@435	78	void disenroll();
duke@435	79
rbackman@4250	80	void execute_if_pending(int delay_time) {
rbackman@4250	81	// make sure we don't overflow
rbackman@4250	82	jlong tmp = (jlong) _counter + (jlong) delay_time;
rbackman@4250	83
rbackman@4250	84	if (tmp >= (jlong) _interval) {
duke@435	85	_counter = 0;
duke@435	86	task();
rbackman@4250	87	} else {
rbackman@4250	88	_counter += delay_time;
duke@435	89	}
duke@435	90	}
duke@435	91
duke@435	92	// Returns how long (time in milliseconds) before the next time we should
duke@435	93	// execute this task.
rbackman@4250	94	int time_to_next_interval() const {
duke@435	95	assert(_interval > _counter, "task counter greater than interval?");
duke@435	96	return _interval - _counter;
duke@435	97	}
duke@435	98
duke@435	99	// Calculate when the next periodic task will fire.
duke@435	100	// Called by the WatcherThread's run method.
rbackman@4250	101	static int time_to_wait();
duke@435	102
duke@435	103	// The task to perform at each period
duke@435	104	virtual void task() = 0;
duke@435	105	};
stefank@2314	106
stefank@2314	107	#endif // SHARE_VM_RUNTIME_TASK_HPP