663dde1ad7
If a SHM or PHC refclock has a very large offset compensated by the offset option, or ignored with the pps or local option, there is a persistent loss of precision in the calculation of the sample offset using the double format. Rework the code to delay the calculation of the accumulated offset to include the specificed compensation and remaining correction of the system clock, where the calculation can be split to improve the precision. In the pps mode ignore integer seconds competely. The precision of the SOCK refclock is now limited to 1 nanosecond due to the extra double->timespec->double conversion.
136 lines
3.4 KiB
C
136 lines
3.4 KiB
C
/*
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chronyd/chronyc - Programs for keeping computer clocks accurate.
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**********************************************************************
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* Copyright (C) Miroslav Lichvar 2009
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of version 2 of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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**********************************************************************
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=======================================================================
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Unix domain socket refclock driver.
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*/
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#include "config.h"
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#include "sysincl.h"
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#include "refclock.h"
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#include "logging.h"
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#include "util.h"
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#include "sched.h"
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#include "socket.h"
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#define SOCK_MAGIC 0x534f434b
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struct sock_sample {
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/* Time of the measurement (system time) */
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struct timeval tv;
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/* Offset between the true time and the system time (in seconds) */
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double offset;
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/* Non-zero if the sample is from a PPS signal, i.e. another source
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is needed to obtain seconds */
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int pulse;
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/* 0 - normal, 1 - insert leap second, 2 - delete leap second */
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int leap;
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/* Padding, ignored */
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int _pad;
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/* Protocol identifier (0x534f434b) */
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int magic;
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};
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static void read_sample(int sockfd, int event, void *anything)
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{
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struct timespec sys_ts, ref_ts;
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struct sock_sample sample;
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RCL_Instance instance;
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int s;
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instance = (RCL_Instance)anything;
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s = recv(sockfd, &sample, sizeof (sample), 0);
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if (s < 0) {
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DEBUG_LOG("Could not read SOCK sample : %s", strerror(errno));
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return;
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}
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if (s != sizeof (sample)) {
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DEBUG_LOG("Unexpected length of SOCK sample : %d != %ld",
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s, (long)sizeof (sample));
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return;
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}
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if (sample.magic != SOCK_MAGIC) {
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DEBUG_LOG("Unexpected magic number in SOCK sample : %x != %x",
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(unsigned int)sample.magic, (unsigned int)SOCK_MAGIC);
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return;
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}
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UTI_TimevalToTimespec(&sample.tv, &sys_ts);
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UTI_NormaliseTimespec(&sys_ts);
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if (!UTI_IsTimeOffsetSane(&sys_ts, sample.offset))
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return;
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UTI_AddDoubleToTimespec(&sys_ts, sample.offset, &ref_ts);
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if (sample.pulse) {
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RCL_AddPulse(instance, &sys_ts, sample.offset);
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} else {
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RCL_AddSample(instance, &sys_ts, &ref_ts, sample.leap);
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}
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}
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static int sock_initialise(RCL_Instance instance)
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{
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int sockfd;
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char *path;
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RCL_CheckDriverOptions(instance, NULL);
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path = RCL_GetDriverParameter(instance);
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sockfd = SCK_OpenUnixDatagramSocket(NULL, path, 0);
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if (sockfd < 0)
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LOG_FATAL("Could not open socket %s", path);
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RCL_SetDriverData(instance, (void *)(long)sockfd);
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SCH_AddFileHandler(sockfd, SCH_FILE_INPUT, read_sample, instance);
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return 1;
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}
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static void sock_finalise(RCL_Instance instance)
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{
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int sockfd;
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sockfd = (long)RCL_GetDriverData(instance);
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SCH_RemoveFileHandler(sockfd);
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SCK_RemoveSocket(sockfd);
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SCK_CloseSocket(sockfd);
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}
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RefclockDriver RCL_SOCK_driver = {
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sock_initialise,
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sock_finalise,
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NULL
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};
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