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src/share/vm/runtime/task.hpp@b20d64f83668 (annotated)

src/share/vm/runtime/task.hpp

Mon, 24 Oct 2011 07:53:17 -0700

author

twisti

date

Mon, 24 Oct 2011 07:53:17 -0700

changeset 3238

b20d64f83668

parent 2314

f95d63e2154a

child 3900

d2a62e0f25eb

permissions

-rw-r--r--

7090904: JSR 292: JRuby junit test crashes in PSScavengeRootsClosure::do_oop
Reviewed-by: kvn, never, jrose

duke@435	1	/*
stefank@2314	2	* Copyright (c) 1997, 2010, 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
duke@435	38	class PeriodicTask: public CHeapObj {
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:
duke@435	52	size_t _counter;
duke@435	53	const size_t _interval;
duke@435	54
duke@435	55	static int _num_tasks;
duke@435	56	static PeriodicTask* _tasks[PeriodicTask::max_tasks];
duke@435	57	static void real_time_tick(size_t 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	// Tells whether is enrolled
duke@435	73	bool is_enrolled() const;
duke@435	74
duke@435	75	// Make the task active
duke@435	76	// NOTE: this may only be called before the WatcherThread has been started
duke@435	77	void enroll();
duke@435	78
duke@435	79	// Make the task deactive
duke@435	80	// NOTE: this may only be called either while the WatcherThread is
duke@435	81	// inactive or by a task from within its task() method. One-shot or
duke@435	82	// several-shot tasks may be implemented this way.
duke@435	83	void disenroll();
duke@435	84
duke@435	85	void execute_if_pending(size_t delay_time) {
duke@435	86	_counter += delay_time;
duke@435	87	if (_counter >= _interval) {
duke@435	88	_counter = 0;
duke@435	89	task();
duke@435	90	}
duke@435	91	}
duke@435	92
duke@435	93	// Returns how long (time in milliseconds) before the next time we should
duke@435	94	// execute this task.
duke@435	95	size_t time_to_next_interval() const {
duke@435	96	assert(_interval > _counter, "task counter greater than interval?");
duke@435	97	return _interval - _counter;
duke@435	98	}
duke@435	99
duke@435	100	// Calculate when the next periodic task will fire.
duke@435	101	// Called by the WatcherThread's run method.
duke@435	102	// This assumes that periodic tasks aren't entering the system
duke@435	103	// dynamically, except for during startup.
duke@435	104	static size_t time_to_wait() {
duke@435	105	if (_num_tasks == 0) {
duke@435	106	// Don't wait any more; shut down the thread since we don't
duke@435	107	// currently support dynamic enrollment.
duke@435	108	return 0;
duke@435	109	}
duke@435	110
duke@435	111	size_t delay = _tasks[0]->time_to_next_interval();
duke@435	112	for (int index = 1; index < _num_tasks; index++) {
duke@435	113	delay = MIN2(delay, _tasks[index]->time_to_next_interval());
duke@435	114	}
duke@435	115	return delay;
duke@435	116	}
duke@435	117
duke@435	118	// The task to perform at each period
duke@435	119	virtual void task() = 0;
duke@435	120	};
stefank@2314	121
stefank@2314	122	#endif // SHARE_VM_RUNTIME_TASK_HPP