VBoxServiceTimeSync.cpp@ 47151

Last change on this file since 47151 was 44529, checked in by vboxsync, 12 years ago
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1	/* $Id: VBoxServiceTimeSync.cpp 44529 2013-02-04 15:54:15Z vboxsync $ */
2	/** @file
3	* VBoxService - Guest Additions TimeSync Service.
4	*/
5
6	/*
7	* Copyright (C) 2007-2012 Oracle Corporation
8	*
9	* This file is part of VirtualBox Open Source Edition (OSE), as
10	* available from http://www.virtualbox.org. This file is free software;
11	* you can redistribute it and/or modify it under the terms of the GNU
12	* General Public License (GPL) as published by the Free Software
13	* Foundation, in version 2 as it comes in the "COPYING" file of the
14	* VirtualBox OSE distribution. VirtualBox OSE is distributed in the
15	* hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
16	*/
17
18
19	/** @page pg_vboxservice_timesync The Time Sync Service
20	*
21	* The time sync service plays along with the Time Manager (TM) in the VMM
22	* to keep the guest time accurate using the host machine as reference.
23	* TM will try its best to make sure all timer ticks gets delivered so that
24	* there isn't normally any need to adjust the guest time.
25	*
26	* There are three normal (= acceptable) cases:
27	* -# When the service starts up. This is because ticks and such might
28	* be lost during VM and OS startup. (Need to figure out exactly why!)
29	* -# When the TM is unable to deliver all the ticks and swallows a
30	* backlog of ticks. The threshold for this is configurable with
31	* a default of 60 seconds.
32	* -# The time is adjusted on the host. This can be caused manually by
33	* the user or by some time sync daemon (NTP, LAN server, etc.).
34	*
35	* There are a number of very odd case where adjusting is needed. Here
36	* are some of them:
37	* -# Timer device emulation inaccuracies (like rounding).
38	* -# Inaccuracies in time source VirtualBox uses.
39	* -# The Guest and/or Host OS doesn't perform proper time keeping. This
40	* come about as a result of OS and/or hardware issues.
41	*
42	* The TM is our source for the host time and will make adjustments for
43	* current timer delivery lag. The simplistic approach taken by TM is to
44	* adjust the host time by the current guest timer delivery lag, meaning that
45	* if the guest is behind 1 second with PIT/RTC/++ ticks this should be reflected
46	* in the guest wall time as well.
47	*
48	* Now, there is any amount of trouble we can cause by changing the time.
49	* Most applications probably uses the wall time when they need to measure
50	* things. A walltime that is being juggled about every so often, even if just
51	* a little bit, could occasionally upset these measurements by for instance
52	* yielding negative results.
53	*
54	* This bottom line here is that the time sync service isn't really supposed
55	* to do anything and will try avoid having to do anything when possible.
56	*
57	* The implementation uses the latency it takes to query host time as the
58	* absolute maximum precision to avoid messing up under timer tick catchup
59	* and/or heavy host/guest load. (Rational is that a lot of stuff may happen
60	* on our way back from ring-3 and TM/VMMDev since we're taking the route
61	* thru the inner EM loop with it's force action processing.)
62	*
63	* But this latency has to be measured from our perspective, which means it
64	* could just as easily come out as 0. (OS/2 and Windows guest only updates
65	* the current time when the timer ticks for instance.) The good thing is
66	* that this isn't really a problem since we won't ever do anything unless
67	* the drift is noticeable.
68	*
69	* It now boils down to these three (configuration) factors:
70	* -# g_TimesyncMinAdjust - The minimum drift we will ever bother with.
71	* -# g_TimesyncLatencyFactor - The factor we multiply the latency by to
72	* calculate the dynamic minimum adjust factor.
73	* -# g_TimesyncMaxLatency - When to start discarding the data as utterly
74	* useless and take a rest (someone is too busy to give us good data).
75	* -# g_TimeSyncSetThreshold - The threshold at which we will just set the time
76	* instead of trying to adjust it (milliseconds).
77	*/
78
79	/*******************************************************************************
80	* Header Files *
81	*******************************************************************************/
82	#ifdef RT_OS_WINDOWS
83	# include <Windows.h>
84	# include <winbase.h> /** @todo r=bird: Why is this here? Windows.h should include winbase.h... */
85	#else
86	# include <unistd.h>
87	# include <errno.h>
88	# include <time.h>
89	# include <sys/time.h>
90	#endif
91
92	#include <iprt/thread.h>
93	#include <iprt/string.h>
94	#include <iprt/semaphore.h>
95	#include <iprt/time.h>
96	#include <iprt/assert.h>
97	#include <VBox/VBoxGuestLib.h>
98	#include "VBoxServiceInternal.h"
99	#include "VBoxServiceUtils.h"
100
101
102	/*******************************************************************************
103	* Global Variables *
104	*******************************************************************************/
105	/** The timesync interval (milliseconds). */
106	uint32_t g_TimeSyncInterval = 0;
107	/**
108	* @see pg_vboxservice_timesync
109	*
110	* @remark OS/2: There is either a 1 second resolution on the DosSetDateTime
111	* API or a but in the settimeofday implementation. Thus, don't
112	* bother unless there is at least a 1 second drift.
113	*/
114	#ifdef RT_OS_OS2
115	static uint32_t g_TimeSyncMinAdjust = 1000;
116	#else
117	static uint32_t g_TimeSyncMinAdjust = 100;
118	#endif
119	/** @see pg_vboxservice_timesync */
120	static uint32_t g_TimeSyncLatencyFactor = 8;
121	/** @see pg_vboxservice_timesync */
122	static uint32_t g_TimeSyncMaxLatency = 250;
123	/** @see pg_vboxservice_timesync */
124	static uint32_t g_TimeSyncSetThreshold = 20601000;
125	/** Whether the next adjustment should just set the time instead of trying to
126	* adjust it. This is used to implement --timesync-set-start. */
127	static bool volatile g_fTimeSyncSetNext = false;
128	/** Whether to set the time when the VM was restored. */
129	static bool g_fTimeSyncSetOnRestore = true;
130
131	/** Current error count. Used to knowing when to bitch and when not to. */
132	static uint32_t g_cTimeSyncErrors = 0;
133
134	/** The semaphore we're blocking on. */
135	static RTSEMEVENTMULTI g_TimeSyncEvent = NIL_RTSEMEVENTMULTI;
136
137	/** The VM session ID. Changes whenever the VM is restored or reset. */
138	static uint64_t g_idTimeSyncSession;
139
140	#ifdef RT_OS_WINDOWS
141	/** Process token. */
142	static HANDLE g_hTokenProcess = NULL;
143	/** Old token privileges. */
144	static TOKEN_PRIVILEGES g_TkOldPrivileges;
145	/** Backup values for time adjustment. */
146	static DWORD g_dwWinTimeAdjustment;
147	static DWORD g_dwWinTimeIncrement;
148	static BOOL g_bWinTimeAdjustmentDisabled;
149	#endif
150
151
152	/** @copydoc VBOXSERVICE::pfnPreInit */
153	static DECLCALLBACK(int) VBoxServiceTimeSyncPreInit(void)
154	{
155	#ifdef VBOX_WITH_GUEST_PROPS
156	/** @todo Merge this function with VBoxServiceTimeSyncOption() to generalize
157	* the "command line args override guest property values" behavior. */
158
159	/*
160	* Read the service options from the VM's guest properties.
161	* Note that these options can be overridden by the command line options later.
162	*/
163	uint32_t uGuestPropSvcClientID;
164	int rc = VbglR3GuestPropConnect(&uGuestPropSvcClientID);
165	if (RT_FAILURE(rc))
166	{
167	if (rc == VERR_HGCM_SERVICE_NOT_FOUND) /* Host service is not available. */
168	{
169	VBoxServiceVerbose(0, "VMInfo: Guest property service is not available, skipping\n");
170	rc = VINF_SUCCESS;
171	}
172	else
173	VBoxServiceError("Failed to connect to the guest property service! Error: %Rrc\n", rc);
174	}
175	else
176	{
177	rc = VBoxServiceReadPropUInt32(uGuestPropSvcClientID, "/VirtualBox/GuestAdd/VBoxService/--timesync-interval",
178	&g_TimeSyncInterval, 50, UINT32_MAX - 1);
179	if ( RT_SUCCESS(rc)
180	\|\| rc == VERR_NOT_FOUND)
181	{
182	rc = VBoxServiceReadPropUInt32(uGuestPropSvcClientID, "/VirtualBox/GuestAdd/VBoxService/--timesync-min-adjust",
183	&g_TimeSyncMinAdjust, 0, 3600000);
184	}
185	if ( RT_SUCCESS(rc)
186	\|\| rc == VERR_NOT_FOUND)
187	{
188	rc = VBoxServiceReadPropUInt32(uGuestPropSvcClientID, "/VirtualBox/GuestAdd/VBoxService/--timesync-latency-factor",
189	&g_TimeSyncLatencyFactor, 1, 1024);
190	}
191	if ( RT_SUCCESS(rc)
192	\|\| rc == VERR_NOT_FOUND)
193	{
194	rc = VBoxServiceReadPropUInt32(uGuestPropSvcClientID, "/VirtualBox/GuestAdd/VBoxService/--timesync-max-latency",
195	&g_TimeSyncMaxLatency, 1, 3600000);
196	}
197	if ( RT_SUCCESS(rc)
198	\|\| rc == VERR_NOT_FOUND)
199	{
200	rc = VBoxServiceReadPropUInt32(uGuestPropSvcClientID, "/VirtualBox/GuestAdd/VBoxService/--timesync-set-threshold",
201	&g_TimeSyncSetThreshold, 0, 72460601000 /* a week */);
202	}
203	if ( RT_SUCCESS(rc)
204	\|\| rc == VERR_NOT_FOUND)
205	{
206	char *pszValue;
207	rc = VBoxServiceReadProp(uGuestPropSvcClientID, "/VirtualBox/GuestAdd/VBoxService/--timesync-set-start",
208	&pszValue, NULL /* ppszFlags /, NULL / puTimestamp */);
209	if (RT_SUCCESS(rc))
210	{
211	g_fTimeSyncSetNext = true;
212	RTStrFree(pszValue);
213	}
214	}
215	if ( RT_SUCCESS(rc)
216	\|\| rc == VERR_NOT_FOUND)
217	{
218	uint32_t value;
219	rc = VBoxServiceReadPropUInt32(uGuestPropSvcClientID, "/VirtualBox/GuestAdd/VBoxService/--timesync-set-on-restore",
220	&value, 1, 1);
221	if (RT_SUCCESS(rc))
222	g_fTimeSyncSetOnRestore = !!value;
223	}
224
225	VbglR3GuestPropDisconnect(uGuestPropSvcClientID);
226	}
227
228	if (rc == VERR_NOT_FOUND) /* If a value is not found, don't be sad! */
229	rc = VINF_SUCCESS;
230	return rc;
231	#else
232	/* Nothing to do here yet. */
233	return VINF_SUCCESS;
234	#endif
235	}
236
237
238	/** @copydoc VBOXSERVICE::pfnOption */
239	static DECLCALLBACK(int) VBoxServiceTimeSyncOption(const char ppszShort, int argc, char argv, int *pi)
240	{
241	int rc = -1;
242	uint32_t value;
243	if (ppszShort)
244	/* no short options */;
245	else if (!strcmp(argv[*pi], "--timesync-interval"))
246	rc = VBoxServiceArgUInt32(argc, argv, "", pi,
247	&g_TimeSyncInterval, 50, UINT32_MAX - 1);
248	else if (!strcmp(argv[*pi], "--timesync-min-adjust"))
249	rc = VBoxServiceArgUInt32(argc, argv, "", pi,
250	&g_TimeSyncMinAdjust, 0, 3600000);
251	else if (!strcmp(argv[*pi], "--timesync-latency-factor"))
252	rc = VBoxServiceArgUInt32(argc, argv, "", pi,
253	&g_TimeSyncLatencyFactor, 1, 1024);
254	else if (!strcmp(argv[*pi], "--timesync-max-latency"))
255	rc = VBoxServiceArgUInt32(argc, argv, "", pi,
256	&g_TimeSyncMaxLatency, 1, 3600000);
257	else if (!strcmp(argv[*pi], "--timesync-set-threshold"))
258	rc = VBoxServiceArgUInt32(argc, argv, "", pi,
259	&g_TimeSyncSetThreshold, 0, 72460601000); /* a week */
260	else if (!strcmp(argv[*pi], "--timesync-set-start"))
261	{
262	g_fTimeSyncSetNext = true;
263	rc = VINF_SUCCESS;
264	}
265	else if (!strcmp(argv[*pi], "--timesync-set-on-restore"))
266	{
267	rc = VBoxServiceArgUInt32(argc, argv, "", pi, &value, 1, 1);
268	if (RT_SUCCESS(rc))
269	g_fTimeSyncSetOnRestore = !!value;
270	}
271
272	return rc;
273	}
274
275
276	/** @copydoc VBOXSERVICE::pfnInit */
277	static DECLCALLBACK(int) VBoxServiceTimeSyncInit(void)
278	{
279	/*
280	* If not specified, find the right interval default.
281	* Then create the event sem to block on.
282	*/
283	if (!g_TimeSyncInterval)
284	g_TimeSyncInterval = g_DefaultInterval * 1000;
285	if (!g_TimeSyncInterval)
286	g_TimeSyncInterval = 10 * 1000;
287
288	VbglR3GetSessionId(&g_idTimeSyncSession);
289	/* The status code is ignored as this information is not available with VBox < 3.2.10. */
290
291	int rc = RTSemEventMultiCreate(&g_TimeSyncEvent);
292	AssertRC(rc);
293	#ifdef RT_OS_WINDOWS
294	if (RT_SUCCESS(rc))
295	{
296	/*
297	* Adjust privileges of this process so we can make system time adjustments.
298	*/
299	if (OpenProcessToken(GetCurrentProcess(), TOKEN_ADJUST_PRIVILEGES \| TOKEN_QUERY, &g_hTokenProcess))
300	{
301	TOKEN_PRIVILEGES tkPriv;
302	RT_ZERO(tkPriv);
303	tkPriv.PrivilegeCount = 1;
304	tkPriv.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED;
305	if (LookupPrivilegeValue(NULL, SE_SYSTEMTIME_NAME, &tkPriv.Privileges[0].Luid))
306	{
307	DWORD cbRet = sizeof(g_TkOldPrivileges);
308	if (AdjustTokenPrivileges(g_hTokenProcess, FALSE, &tkPriv, sizeof(TOKEN_PRIVILEGES), &g_TkOldPrivileges, &cbRet))
309	rc = VINF_SUCCESS;
310	else
311	{
312	DWORD dwErr = GetLastError();
313	rc = RTErrConvertFromWin32(dwErr);
314	VBoxServiceError("VBoxServiceTimeSyncInit: Adjusting token privileges (SE_SYSTEMTIME_NAME) failed with status code %u/%Rrc!\n", dwErr, rc);
315	}
316	}
317	else
318	{
319	DWORD dwErr = GetLastError();
320	rc = RTErrConvertFromWin32(dwErr);
321	VBoxServiceError("VBoxServiceTimeSyncInit: Looking up token privileges (SE_SYSTEMTIME_NAME) failed with status code %u/%Rrc!\n", dwErr, rc);
322	}
323	if (RT_FAILURE(rc))
324	{
325	CloseHandle(g_hTokenProcess);
326	g_hTokenProcess = NULL;
327	}
328	}
329	else
330	{
331	DWORD dwErr = GetLastError();
332	rc = RTErrConvertFromWin32(dwErr);
333	VBoxServiceError("VBoxServiceTimeSyncInit: Opening process token (SE_SYSTEMTIME_NAME) failed with status code %u/%Rrc!\n", dwErr, rc);
334	g_hTokenProcess = NULL;
335	}
336	}
337
338	if (GetSystemTimeAdjustment(&g_dwWinTimeAdjustment, &g_dwWinTimeIncrement, &g_bWinTimeAdjustmentDisabled))
339	VBoxServiceVerbose(3, "VBoxServiceTimeSyncInit: Initially %ld (100ns) units per %ld (100 ns) units interval, disabled=%d\n",
340	g_dwWinTimeAdjustment, g_dwWinTimeIncrement, g_bWinTimeAdjustmentDisabled ? 1 : 0);
341	else
342	{
343	DWORD dwErr = GetLastError();
344	rc = RTErrConvertFromWin32(dwErr);
345	VBoxServiceError("VBoxServiceTimeSyncInit: Could not get time adjustment values! Last error: %ld!\n", dwErr);
346	}
347	#endif /* RT_OS_WINDOWS */
348
349	return rc;
350	}
351
352
353	/**
354	* Try adjust the time using adjtime or similar.
355	*
356	* @returns true on success, false on failure.
357	*
358	* @param pDrift The time adjustment.
359	*/
360	static bool VBoxServiceTimeSyncAdjust(PCRTTIMESPEC pDrift)
361	{
362	#ifdef RT_OS_WINDOWS
363	/** @todo r=bird: NT4 doesn't have GetSystemTimeAdjustment according to MSDN. */
364	/** @todo r=bird: g_hTokenProcess cannot be NULL here.
365	* VBoxServiceTimeSyncInit will fail and the service will not be
366	* started with it being NULL. VBoxServiceTimeSyncInit OTOH will NOT
367	* be called until the service thread has terminated. If anything
368	* else is the case, there is buggy code somewhere.*/
369	if (g_hTokenProcess == NULL) /* Is the token already closed when shutting down? */
370	return false;
371
372	DWORD dwWinTimeAdjustment, dwWinNewTimeAdjustment, dwWinTimeIncrement;
373	BOOL fWinTimeAdjustmentDisabled;
374	if (GetSystemTimeAdjustment(&dwWinTimeAdjustment, &dwWinTimeIncrement, &fWinTimeAdjustmentDisabled))
375	{
376	DWORD dwDiffMax = g_dwWinTimeAdjustment * 0.50;
377	DWORD dwDiffNew = dwWinTimeAdjustment * 0.10;
378
379	if (RTTimeSpecGetMilli(pDrift) > 0)
380	{
381	dwWinNewTimeAdjustment = dwWinTimeAdjustment + dwDiffNew;
382	if (dwWinNewTimeAdjustment > (g_dwWinTimeAdjustment + dwDiffMax))
383	{
384	dwWinNewTimeAdjustment = g_dwWinTimeAdjustment + dwDiffMax;
385	dwDiffNew = dwDiffMax;
386	}
387	}
388	else
389	{
390	dwWinNewTimeAdjustment = dwWinTimeAdjustment - dwDiffNew;
391	if (dwWinNewTimeAdjustment < (g_dwWinTimeAdjustment - dwDiffMax))
392	{
393	dwWinNewTimeAdjustment = g_dwWinTimeAdjustment - dwDiffMax;
394	dwDiffNew = dwDiffMax;
395	}
396	}
397
398	VBoxServiceVerbose(3, "VBoxServiceTimeSyncAdjust: Drift=%lldms\n", RTTimeSpecGetMilli(pDrift));
399	VBoxServiceVerbose(3, "VBoxServiceTimeSyncAdjust: OrgTA=%ld, CurTA=%ld, NewTA=%ld, DiffNew=%ld, DiffMax=%ld\n",
400	g_dwWinTimeAdjustment, dwWinTimeAdjustment, dwWinNewTimeAdjustment, dwDiffNew, dwDiffMax);
401	if (SetSystemTimeAdjustment(dwWinNewTimeAdjustment, FALSE /* Periodic adjustments enabled. */))
402	{
403	g_cTimeSyncErrors = 0;
404	return true;
405	}
406
407	if (g_cTimeSyncErrors++ < 10)
408	VBoxServiceError("VBoxServiceTimeSyncAdjust: SetSystemTimeAdjustment failed, error=%u\n", GetLastError());
409	}
410	else if (g_cTimeSyncErrors++ < 10)
411	VBoxServiceError("VBoxServiceTimeSyncAdjust: GetSystemTimeAdjustment failed, error=%ld\n", GetLastError());
412
413	#elif defined(RT_OS_OS2) \|\| defined(RT_OS_HAIKU)
414	/* No API for doing gradual time adjustments. */
415
416	#else /* PORTME */
417	/*
418	* Try use adjtime(), most unix-like systems have this.
419	*/
420	struct timeval tv;
421	RTTimeSpecGetTimeval(pDrift, &tv);
422	if (adjtime(&tv, NULL) == 0)
423	{
424	if (g_cVerbosity >= 1)
425	VBoxServiceVerbose(1, "VBoxServiceTimeSyncAdjust: adjtime by %RDtimespec\n", pDrift);
426	g_cTimeSyncErrors = 0;
427	return true;
428	}
429	#endif
430
431	/* failed */
432	return false;
433	}
434
435
436	/**
437	* Cancels any pending time adjustment.
438	*
439	* Called when we've caught up and before calls to VBoxServiceTimeSyncSet.
440	*/
441	static void VBoxServiceTimeSyncCancelAdjust(void)
442	{
443	#ifdef RT_OS_WINDOWS
444	/** @todo r=bird: g_hTokenProcess cannot be NULL here. See argumentation in
445	* VBoxServiceTimeSyncAdjust. */
446	if (g_hTokenProcess == NULL) /* No process token (anymore)? */
447	return;
448	if (SetSystemTimeAdjustment(0, TRUE /* Periodic adjustments disabled. */))
449	VBoxServiceVerbose(3, "VBoxServiceTimeSyncCancelAdjust: Windows Time Adjustment is now disabled.\n");
450	else if (g_cTimeSyncErrors++ < 10)
451	VBoxServiceError("VBoxServiceTimeSyncCancelAdjust: SetSystemTimeAdjustment(,disable) failed, error=%u\n", GetLastError());
452	#endif /* !RT_OS_WINDOWS */
453	}
454
455
456	/**
457	* Try adjust the time using adjtime or similar.
458	*
459	* @returns true on success, false on failure.
460	*
461	* @param pDrift The time adjustment.
462	*/
463	static void VBoxServiceTimeSyncSet(PCRTTIMESPEC pDrift)
464	{
465	/*
466	* Query the current time, adjust it by adding the drift and set it.
467	*/
468	RTTIMESPEC NewGuestTime;
469	int rc = RTTimeSet(RTTimeSpecAdd(RTTimeNow(&NewGuestTime), pDrift));
470	if (RT_SUCCESS(rc))
471	{
472	/* Succeeded - reset the error count and log the change. */
473	g_cTimeSyncErrors = 0;
474
475	if (g_cVerbosity >= 1)
476	{
477	char sz[64];
478	RTTIME Time;
479	VBoxServiceVerbose(1, "time set to %s\n",
480	RTTimeToString(RTTimeExplode(&Time, &NewGuestTime), sz, sizeof(sz)));
481	#ifdef DEBUG
482	RTTIMESPEC Tmp;
483	if (g_cVerbosity >= 3)
484	VBoxServiceVerbose(3, " now %s\n",
485	RTTimeToString(RTTimeExplode(&Time, RTTimeNow(&Tmp)), sz, sizeof(sz)));
486	#endif
487	}
488	}
489	else if (g_cTimeSyncErrors++ < 10)
490	VBoxServiceError("VBoxServiceTimeSyncSet: RTTimeSet(%RDtimespec) failed: %Rrc\n", &NewGuestTime, rc);
491	}
492
493
494	/** @copydoc VBOXSERVICE::pfnWorker */
495	DECLCALLBACK(int) VBoxServiceTimeSyncWorker(bool volatile *pfShutdown)
496	{
497	RTTIME Time;
498	char sz[64];
499	int rc = VINF_SUCCESS;
500
501	/*
502	* Tell the control thread that it can continue spawning services.
503	*/
504	RTThreadUserSignal(RTThreadSelf());
505
506	/*
507	* The Work Loop.
508	*/
509	for (;;)
510	{
511	/*
512	* Try get a reliable time reading.
513	*/
514	int cTries = 3;
515	do
516	{
517	/* query it. */
518	RTTIMESPEC GuestNow0, GuestNow, HostNow;
519	RTTimeNow(&GuestNow0);
520	int rc2 = VbglR3GetHostTime(&HostNow);
521	if (RT_FAILURE(rc2))
522	{
523	if (g_cTimeSyncErrors++ < 10)
524	VBoxServiceError("VBoxServiceTimeSyncWorker: VbglR3GetHostTime failed; rc2=%Rrc\n", rc2);
525	break;
526	}
527	RTTimeNow(&GuestNow);
528
529	/* calc latency and check if it's ok. */
530	RTTIMESPEC GuestElapsed = GuestNow;
531	RTTimeSpecSub(&GuestElapsed, &GuestNow0);
532	if ((uint32_t)RTTimeSpecGetMilli(&GuestElapsed) < g_TimeSyncMaxLatency)
533	{
534	/*
535	* Set the time once after we were restored.
536	* (Of course only if the drift is bigger than MinAdjust)
537	*/
538	uint32_t TimeSyncSetThreshold = g_TimeSyncSetThreshold;
539	if (g_fTimeSyncSetOnRestore)
540	{
541	uint64_t idNewSession = g_idTimeSyncSession;
542	VbglR3GetSessionId(&idNewSession);
543	if (idNewSession != g_idTimeSyncSession)
544	{
545	VBoxServiceVerbose(3, "VBoxServiceTimeSyncWorker: The VM session ID changed, forcing resync.\n");
546	TimeSyncSetThreshold = 0;
547	g_idTimeSyncSession = idNewSession;
548	}
549	}
550
551	/*
552	* Calculate the adjustment threshold and the current drift.
553	*/
554	uint32_t MinAdjust = RTTimeSpecGetMilli(&GuestElapsed) * g_TimeSyncLatencyFactor;
555	if (MinAdjust < g_TimeSyncMinAdjust)
556	MinAdjust = g_TimeSyncMinAdjust;
557
558	RTTIMESPEC Drift = HostNow;
559	RTTimeSpecSub(&Drift, &GuestNow);
560	if (RTTimeSpecGetMilli(&Drift) < 0)
561	MinAdjust += g_TimeSyncMinAdjust; /* extra buffer against moving time backwards. */
562
563	RTTIMESPEC AbsDrift = Drift;
564	RTTimeSpecAbsolute(&AbsDrift);
565	if (g_cVerbosity >= 3)
566	{
567	VBoxServiceVerbose(3, "VBoxServiceTimeSyncWorker: Host: %s (MinAdjust: %RU32 ms)\n",
568	RTTimeToString(RTTimeExplode(&Time, &HostNow), sz, sizeof(sz)), MinAdjust);
569	VBoxServiceVerbose(3, "VBoxServiceTimeSyncWorker: Guest: - %s => %RDtimespec drift\n",
570	RTTimeToString(RTTimeExplode(&Time, &GuestNow), sz, sizeof(sz)),
571	&Drift);
572	}
573
574	uint32_t AbsDriftMilli = RTTimeSpecGetMilli(&AbsDrift);
575	if (AbsDriftMilli > MinAdjust)
576	{
577	/*
578	* Ok, the drift is above the threshold.
579	*
580	* Try a gradual adjustment first, if that fails or the drift is
581	* too big, fall back on just setting the time.
582	*/
583
584	if ( AbsDriftMilli > TimeSyncSetThreshold
585	\|\| g_fTimeSyncSetNext
586	\|\| !VBoxServiceTimeSyncAdjust(&Drift))
587	{
588	VBoxServiceTimeSyncCancelAdjust();
589	VBoxServiceTimeSyncSet(&Drift);
590	}
591	}
592	else
593	VBoxServiceTimeSyncCancelAdjust();
594	break;
595	}
596	VBoxServiceVerbose(3, "VBoxServiceTimeSyncWorker: %RDtimespec: latency too high (%RDtimespec) sleeping 1s\n", GuestElapsed);
597	RTThreadSleep(1000);
598	} while (--cTries > 0);
599
600	/* Clear the set-next/set-start flag. */
601	g_fTimeSyncSetNext = false;
602
603	/*
604	* Block for a while.
605	*
606	* The event semaphore takes care of ignoring interruptions and it
607	* allows us to implement service wakeup later.
608	*/
609	if (*pfShutdown)
610	break;
611	int rc2 = RTSemEventMultiWait(g_TimeSyncEvent, g_TimeSyncInterval);
612	if (*pfShutdown)
613	break;
614	if (rc2 != VERR_TIMEOUT && RT_FAILURE(rc2))
615	{
616	VBoxServiceError("VBoxServiceTimeSyncWorker: RTSemEventMultiWait failed; rc2=%Rrc\n", rc2);
617	rc = rc2;
618	break;
619	}
620	}
621
622	VBoxServiceTimeSyncCancelAdjust();
623	RTSemEventMultiDestroy(g_TimeSyncEvent);
624	g_TimeSyncEvent = NIL_RTSEMEVENTMULTI;
625	return rc;
626	}
627
628
629	/** @copydoc VBOXSERVICE::pfnStop */
630	static DECLCALLBACK(void) VBoxServiceTimeSyncStop(void)
631	{
632	RTSemEventMultiSignal(g_TimeSyncEvent);
633	}
634
635
636	/** @copydoc VBOXSERVICE::pfnTerm */
637	static DECLCALLBACK(void) VBoxServiceTimeSyncTerm(void)
638	{
639	#ifdef RT_OS_WINDOWS
640	/*
641	* Restore the SE_SYSTEMTIME_NAME token privileges (if init succeeded).
642	*/
643	if (g_hTokenProcess)
644	{
645	if (!AdjustTokenPrivileges(g_hTokenProcess, FALSE, &g_TkOldPrivileges, sizeof(TOKEN_PRIVILEGES), NULL, NULL))
646	{
647	DWORD dwErr = GetLastError();
648	VBoxServiceError("VBoxServiceTimeSyncTerm: Restoring token privileges (SE_SYSTEMTIME_NAME) failed with code %u!\n", dwErr);
649	}
650	CloseHandle(g_hTokenProcess);
651	g_hTokenProcess = NULL;
652	}
653	#endif /* !RT_OS_WINDOWS */
654
655	if (g_TimeSyncEvent != NIL_RTSEMEVENTMULTI)
656	{
657	RTSemEventMultiDestroy(g_TimeSyncEvent);
658	g_TimeSyncEvent = NIL_RTSEMEVENTMULTI;
659	}
660	}
661
662
663	/**
664	* The 'timesync' service description.
665	*/
666	VBOXSERVICE g_TimeSync =
667	{
668	/* pszName. */
669	"timesync",
670	/* pszDescription. */
671	"Time synchronization",
672	/* pszUsage. */
673	" [--timesync-interval <ms>] [--timesync-min-adjust <ms>]\n"
674	" [--timesync-latency-factor <x>] [--timesync-max-latency <ms>]\n"
675	" [--timesync-set-threshold <ms>] [--timesync-set-start]\n"
676	" [--timesync-set-on-restore 0\|1]"
677	,
678	/* pszOptions. */
679	" --timesync-interval Specifies the interval at which to synchronize the\n"
680	" time with the host. The default is 10000 ms.\n"
681	" --timesync-min-adjust The minimum absolute drift value measured in\n"
682	" milliseconds to make adjustments for.\n"
683	" The default is 1000 ms on OS/2 and 100 ms elsewhere.\n"
684	" --timesync-latency-factor\n"
685	" The factor to multiply the time query latency with\n"
686	" to calculate the dynamic minimum adjust time.\n"
687	" The default is 8 times.\n"
688	" --timesync-max-latency The max host timer query latency to accept.\n"
689	" The default is 250 ms.\n"
690	" --timesync-set-threshold\n"
691	" The absolute drift threshold, given as milliseconds,\n"
692	" where to start setting the time instead of trying to\n"
693	" adjust it. The default is 20 min.\n"
694	" --timesync-set-start Set the time when starting the time sync service.\n"
695	" --timesync-set-on-restore 0\|1\n"
696	" Immediately set the time when the VM was restored.\n"
697	" 1 = set (default), 0 = don't set.\n"
698	,
699	/* methods */
700	VBoxServiceTimeSyncPreInit,
701	VBoxServiceTimeSyncOption,
702	VBoxServiceTimeSyncInit,
703	VBoxServiceTimeSyncWorker,
704	VBoxServiceTimeSyncStop,
705	VBoxServiceTimeSyncTerm
706	};
707

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source: vbox/trunk/src/VBox/Additions/common/VBoxService/VBoxServiceTimeSync.cpp@ 47151

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