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Diffstat (limited to 'sntp/libevent/evutil_time.c')
| -rw-r--r-- | sntp/libevent/evutil_time.c | 488 |
1 files changed, 488 insertions, 0 deletions
diff --git a/sntp/libevent/evutil_time.c b/sntp/libevent/evutil_time.c new file mode 100644 index 0000000..e433043 --- /dev/null +++ b/sntp/libevent/evutil_time.c @@ -0,0 +1,488 @@ +/* + * Copyright (c) 2007-2012 Niels Provos and Nick Mathewson + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. The name of the author may not be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#include "event2/event-config.h" +#include "evconfig-private.h" + +#ifdef _WIN32 +#include <winsock2.h> +#define WIN32_LEAN_AND_MEAN +#include <windows.h> +#undef WIN32_LEAN_AND_MEAN +#endif + +#include <sys/types.h> +#ifdef EVENT__HAVE_STDLIB_H +#include <stdlib.h> +#endif +#include <errno.h> +#include <limits.h> +#ifndef EVENT__HAVE_GETTIMEOFDAY +#include <sys/timeb.h> +#endif +#if !defined(EVENT__HAVE_NANOSLEEP) && !defined(EVENT_HAVE_USLEEP) && \ + !defined(_WIN32) +#include <sys/select.h> +#endif +#include <time.h> +#include <sys/stat.h> +#include <string.h> + +#include "event2/util.h" +#include "util-internal.h" +#include "log-internal.h" + +#ifndef EVENT__HAVE_GETTIMEOFDAY +/* No gettimeofday; this must be windows. */ +int +evutil_gettimeofday(struct timeval *tv, struct timezone *tz) +{ +#ifdef _MSC_VER +#define U64_LITERAL(n) n##ui64 +#else +#define U64_LITERAL(n) n##llu +#endif + + /* Conversion logic taken from Tor, which in turn took it + * from Perl. GetSystemTimeAsFileTime returns its value as + * an unaligned (!) 64-bit value containing the number of + * 100-nanosecond intervals since 1 January 1601 UTC. */ +#define EPOCH_BIAS U64_LITERAL(116444736000000000) +#define UNITS_PER_SEC U64_LITERAL(10000000) +#define USEC_PER_SEC U64_LITERAL(1000000) +#define UNITS_PER_USEC U64_LITERAL(10) + union { + FILETIME ft_ft; + ev_uint64_t ft_64; + } ft; + + if (tv == NULL) + return -1; + + GetSystemTimeAsFileTime(&ft.ft_ft); + + if (EVUTIL_UNLIKELY(ft.ft_64 < EPOCH_BIAS)) { + /* Time before the unix epoch. */ + return -1; + } + ft.ft_64 -= EPOCH_BIAS; + tv->tv_sec = (long) (ft.ft_64 / UNITS_PER_SEC); + tv->tv_usec = (long) ((ft.ft_64 / UNITS_PER_USEC) % USEC_PER_SEC); + return 0; +} +#endif + +#define MAX_SECONDS_IN_MSEC_LONG \ + (((LONG_MAX) - 999) / 1000) + +long +evutil_tv_to_msec_(const struct timeval *tv) +{ + if (tv->tv_usec > 1000000 || tv->tv_sec > MAX_SECONDS_IN_MSEC_LONG) + return -1; + + return (tv->tv_sec * 1000) + ((tv->tv_usec + 999) / 1000); +} + +/* + Replacement for usleep on platforms that don't have one. Not guaranteed to + be any more finegrained than 1 msec. + */ +void +evutil_usleep_(const struct timeval *tv) +{ + if (!tv) + return; +#if defined(_WIN32) + { + long msec = evutil_tv_to_msec_(tv); + Sleep((DWORD)msec); + } +#elif defined(EVENT__HAVE_NANOSLEEP) + { + struct timespec ts; + ts.tv_sec = tv->tv_sec; + ts.tv_nsec = tv->tv_usec*1000; + nanosleep(&ts, NULL); + } +#elif defined(EVENT__HAVE_USLEEP) + /* Some systems don't like to usleep more than 999999 usec */ + sleep(tv->tv_sec); + usleep(tv->tv_usec); +#else + select(0, NULL, NULL, NULL, tv); +#endif +} + +/* + This function assumes it's called repeatedly with a + not-actually-so-monotonic time source whose outputs are in 'tv'. It + implements a trivial ratcheting mechanism so that the values never go + backwards. + */ +static void +adjust_monotonic_time(struct evutil_monotonic_timer *base, + struct timeval *tv) +{ + evutil_timeradd(tv, &base->adjust_monotonic_clock, tv); + + if (evutil_timercmp(tv, &base->last_time, <)) { + /* Guess it wasn't monotonic after all. */ + struct timeval adjust; + evutil_timersub(&base->last_time, tv, &adjust); + evutil_timeradd(&adjust, &base->adjust_monotonic_clock, + &base->adjust_monotonic_clock); + *tv = base->last_time; + } + base->last_time = *tv; +} + +#if defined(HAVE_POSIX_MONOTONIC) +/* ===== + The POSIX clock_gettime() interface provides a few ways to get at a + monotonic clock. CLOCK_MONOTONIC is most widely supported. Linux also + provides a CLOCK_MONOTONIC_COARSE with accuracy of about 1-4 msec. + + On all platforms I'm aware of, CLOCK_MONOTONIC really is monotonic. + Platforms don't agree about whether it should jump on a sleep/resume. + */ + +int +evutil_configure_monotonic_time_(struct evutil_monotonic_timer *base, + int flags) +{ + /* CLOCK_MONOTONIC exists on FreeBSD, Linux, and Solaris. You need to + * check for it at runtime, because some older kernel versions won't + * have it working. */ +#ifdef CLOCK_MONOTONIC_COARSE + const int precise = flags & EV_MONOT_PRECISE; +#endif + const int fallback = flags & EV_MONOT_FALLBACK; + struct timespec ts; + +#ifdef CLOCK_MONOTONIC_COARSE + if (CLOCK_MONOTONIC_COARSE < 0) { + /* Technically speaking, nothing keeps CLOCK_* from being + * negative (as far as I know). This check and the one below + * make sure that it's safe for us to use -1 as an "unset" + * value. */ + event_errx(1,"I didn't expect CLOCK_MONOTONIC_COARSE to be < 0"); + } + if (! precise && ! fallback) { + if (clock_gettime(CLOCK_MONOTONIC_COARSE, &ts) == 0) { + base->monotonic_clock = CLOCK_MONOTONIC_COARSE; + return 0; + } + } +#endif + if (!fallback && clock_gettime(CLOCK_MONOTONIC, &ts) == 0) { + base->monotonic_clock = CLOCK_MONOTONIC; + return 0; + } + + if (CLOCK_MONOTONIC < 0) { + event_errx(1,"I didn't expect CLOCK_MONOTONIC to be < 0"); + } + + base->monotonic_clock = -1; + return 0; +} + +int +evutil_gettime_monotonic_(struct evutil_monotonic_timer *base, + struct timeval *tp) +{ + struct timespec ts; + + if (base->monotonic_clock < 0) { + if (evutil_gettimeofday(tp, NULL) < 0) + return -1; + adjust_monotonic_time(base, tp); + return 0; + } + + if (clock_gettime(base->monotonic_clock, &ts) == -1) + return -1; + tp->tv_sec = ts.tv_sec; + tp->tv_usec = ts.tv_nsec / 1000; + + return 0; +} +#endif + +#if defined(HAVE_MACH_MONOTONIC) +/* ====== + Apple is a little late to the POSIX party. And why not? Instead of + clock_gettime(), they provide mach_absolute_time(). Its units are not + fixed; we need to use mach_timebase_info() to get the right functions to + convert its units into nanoseconds. + + To all appearances, mach_absolute_time() seems to be honest-to-goodness + monotonic. Whether it stops during sleep or not is unspecified in + principle, and dependent on CPU architecture in practice. + */ + +int +evutil_configure_monotonic_time_(struct evutil_monotonic_timer *base, + int flags) +{ + const int fallback = flags & EV_MONOT_FALLBACK; + struct mach_timebase_info mi; + memset(base, 0, sizeof(*base)); + /* OSX has mach_absolute_time() */ + if (!fallback && + mach_timebase_info(&mi) == 0 && + mach_absolute_time() != 0) { + /* mach_timebase_info tells us how to convert + * mach_absolute_time() into nanoseconds, but we + * want to use microseconds instead. */ + mi.denom *= 1000; + memcpy(&base->mach_timebase_units, &mi, sizeof(mi)); + } else { + base->mach_timebase_units.numer = 0; + } + return 0; +} + +int +evutil_gettime_monotonic_(struct evutil_monotonic_timer *base, + struct timeval *tp) +{ + ev_uint64_t abstime, usec; + if (base->mach_timebase_units.numer == 0) { + if (evutil_gettimeofday(tp, NULL) < 0) + return -1; + adjust_monotonic_time(base, tp); + return 0; + } + + abstime = mach_absolute_time(); + usec = (abstime * base->mach_timebase_units.numer) + / (base->mach_timebase_units.denom); + tp->tv_sec = usec / 1000000; + tp->tv_usec = usec % 1000000; + + return 0; +} +#endif + +#if defined(HAVE_WIN32_MONOTONIC) +/* ===== + Turn we now to Windows. Want monontonic time on Windows? + + Windows has QueryPerformanceCounter(), which gives time most high- + resolution time. It's a pity it's not so monotonic in practice; it's + also got some fun bugs, especially: with older Windowses, under + virtualizations, with funny hardware, on multiprocessor systems, and so + on. PEP418 [1] has a nice roundup of the issues here. + + There's GetTickCount64() on Vista and later, which gives a number of 1-msec + ticks since startup. The accuracy here might be as bad as 10-20 msec, I + hear. There's an undocumented function (NtSetTimerResolution) that + allegedly increases the accuracy. Good luck! + + There's also GetTickCount(), which is only 32 bits, but seems to be + supported on pre-Vista versions of Windows. Apparently, you can coax + another 14 bits out of it, giving you 2231 years before rollover. + + The less said about timeGetTime() the better. + + "We don't care. We don't have to. We're the Phone Company." + -- Lily Tomlin, SNL + + Our strategy, if precise timers are turned off, is to just use the best + GetTickCount equivalent available. If we've been asked for precise timing, + then we mostly[2] assume that GetTickCount is monotonic, and correct + GetPerformanceCounter to approximate it. + + [1] http://www.python.org/dev/peps/pep-0418 + [2] Of course, we feed the Windows stuff into adjust_monotonic_time() + anyway, just in case it isn't. + + */ +/* + Parts of our logic in the win32 timer code here are closely based on + BitTorrent's libUTP library. That code is subject to the following + license: + + Copyright (c) 2010 BitTorrent, Inc. + + Permission is hereby granted, free of charge, to any person obtaining a + copy of this software and associated documentation files (the + "Software"), to deal in the Software without restriction, including + without limitation the rights to use, copy, modify, merge, publish, + distribute, sublicense, and/or sell copies of the Software, and to + permit persons to whom the Software is furnished to do so, subject to + the following conditions: + + The above copyright notice and this permission notice shall be included + in all copies or substantial portions of the Software. + + THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS + OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF + MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND + NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE + LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION + OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION + WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. +*/ + +static ev_uint64_t +evutil_GetTickCount_(struct evutil_monotonic_timer *base) +{ + if (base->GetTickCount64_fn) { + /* Let's just use GetTickCount64 if we can. */ + return base->GetTickCount64_fn(); + } else if (base->GetTickCount_fn) { + /* Greg Hazel assures me that this works, that BitTorrent has + * done it for years, and this it won't turn around and + * bite us. He says they found it on some game programmers' + * forum some time around 2007. + */ + ev_uint64_t v = base->GetTickCount_fn(); + return (DWORD)v | ((v >> 18) & 0xFFFFFFFF00000000); + } else { + /* Here's the fallback implementation. We have to use + * GetTickCount() with its given signature, so we only get + * 32 bits worth of milliseconds, which will roll ove every + * 49 days or so. */ + DWORD ticks = GetTickCount(); + if (ticks < base->last_tick_count) { + base->adjust_tick_count += ((ev_uint64_t)1) << 32; + } + base->last_tick_count = ticks; + return ticks + base->adjust_tick_count; + } +} + +int +evutil_configure_monotonic_time_(struct evutil_monotonic_timer *base, + int flags) +{ + const int precise = flags & EV_MONOT_PRECISE; + const int fallback = flags & EV_MONOT_FALLBACK; + HANDLE h; + memset(base, 0, sizeof(*base)); + + h = evutil_load_windows_system_library_(TEXT("kernel32.dll")); + if (h != NULL && !fallback) { + base->GetTickCount64_fn = (ev_GetTickCount_func)GetProcAddress(h, "GetTickCount64"); + base->GetTickCount_fn = (ev_GetTickCount_func)GetProcAddress(h, "GetTickCount"); + } + + base->first_tick = base->last_tick_count = evutil_GetTickCount_(base); + if (precise && !fallback) { + LARGE_INTEGER freq; + if (QueryPerformanceFrequency(&freq)) { + LARGE_INTEGER counter; + QueryPerformanceCounter(&counter); + base->first_counter = counter.QuadPart; + base->usec_per_count = 1.0e6 / freq.QuadPart; + base->use_performance_counter = 1; + } + } + + return 0; +} + +static inline ev_int64_t +abs64(ev_int64_t i) +{ + return i < 0 ? -i : i; +} + + +int +evutil_gettime_monotonic_(struct evutil_monotonic_timer *base, + struct timeval *tp) +{ + ev_uint64_t ticks = evutil_GetTickCount_(base); + if (base->use_performance_counter) { + /* Here's a trick we took from BitTorrent's libutp, at Greg + * Hazel's recommendation. We use QueryPerformanceCounter for + * our high-resolution timer, but use GetTickCount*() to keep + * it sane, and adjust_monotonic_time() to keep it monotonic. + */ + LARGE_INTEGER counter; + ev_int64_t counter_elapsed, counter_usec_elapsed, ticks_elapsed; + QueryPerformanceCounter(&counter); + counter_elapsed = (ev_int64_t) + (counter.QuadPart - base->first_counter); + ticks_elapsed = ticks - base->first_tick; + /* TODO: This may upset VC6. If you need this to work with + * VC6, please supply an appropriate patch. */ + counter_usec_elapsed = (ev_int64_t) + (counter_elapsed * base->usec_per_count); + + if (abs64(ticks_elapsed*1000 - counter_usec_elapsed) > 1000000) { + /* It appears that the QueryPerformanceCounter() + * result is more than 1 second away from + * GetTickCount() result. Let's adjust it to be as + * accurate as we can; adjust_monotnonic_time() below + * will keep it monotonic. */ + counter_usec_elapsed = ticks_elapsed * 1000; + base->first_counter = (ev_uint64_t) (counter.QuadPart - counter_usec_elapsed / base->usec_per_count); + } + tp->tv_sec = (time_t) (counter_usec_elapsed / 1000000); + tp->tv_usec = counter_usec_elapsed % 1000000; + + } else { + /* We're just using GetTickCount(). */ + tp->tv_sec = (time_t) (ticks / 1000); + tp->tv_usec = (ticks % 1000) * 1000; + } + adjust_monotonic_time(base, tp); + + return 0; +} +#endif + +#if defined(HAVE_FALLBACK_MONOTONIC) +/* ===== + And if none of the other options work, let's just use gettimeofday(), and + ratchet it forward so that it acts like a monotonic timer, whether it + wants to or not. + */ + +int +evutil_configure_monotonic_time_(struct evutil_monotonic_timer *base, + int precise) +{ + memset(base, 0, sizeof(*base)); + return 0; +} + +int +evutil_gettime_monotonic_(struct evutil_monotonic_timer *base, + struct timeval *tp) +{ + if (evutil_gettimeofday(tp, NULL) < 0) + return -1; + adjust_monotonic_time(base, tp); + return 0; + +} +#endif |