time_posix.cc 13.1 KB
Newer Older
gejun's avatar
gejun committed
1 2 3 4
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

5
#include "butil/time/time.h"
gejun's avatar
gejun committed
6 7 8 9 10 11 12 13 14 15 16 17

#include <stdint.h>
#include <sys/time.h>
#include <time.h>
#if defined(OS_ANDROID) && !defined(__LP64__)
#include <time64.h>
#endif
#include <unistd.h>

#include <limits>
#include <ostream>

18 19 20 21
#include "butil/basictypes.h"
#include "butil/logging.h"
#include "butil/port.h"
#include "butil/build_config.h"
gejun's avatar
gejun committed
22 23

#if defined(OS_ANDROID)
24
#include "butil/os_compat_android.h"
gejun's avatar
gejun committed
25
#elif defined(OS_NACL)
26
#include "butil/os_compat_nacl.h"
gejun's avatar
gejun committed
27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
#endif

namespace {

#if !defined(OS_MACOSX)
// Define a system-specific SysTime that wraps either to a time_t or
// a time64_t depending on the host system, and associated convertion.
// See crbug.com/162007
#if defined(OS_ANDROID) && !defined(__LP64__)
typedef time64_t SysTime;

SysTime SysTimeFromTimeStruct(struct tm* timestruct, bool is_local) {
  if (is_local)
    return mktime64(timestruct);
  else
    return timegm64(timestruct);
}

void SysTimeToTimeStruct(SysTime t, struct tm* timestruct, bool is_local) {
  if (is_local)
    localtime64_r(&t, timestruct);
  else
    gmtime64_r(&t, timestruct);
}

#else  // OS_ANDROID && !__LP64__
typedef time_t SysTime;

SysTime SysTimeFromTimeStruct(struct tm* timestruct, bool is_local) {
  if (is_local)
    return mktime(timestruct);
  else
    return timegm(timestruct);
}

void SysTimeToTimeStruct(SysTime t, struct tm* timestruct, bool is_local) {
  if (is_local)
    localtime_r(&t, timestruct);
  else
    gmtime_r(&t, timestruct);
}
#endif  // OS_ANDROID

// Helper function to get results from clock_gettime() as TimeTicks object.
// Minimum requirement is MONOTONIC_CLOCK to be supported on the system.
// FreeBSD 6 has CLOCK_MONOTONIC but defines _POSIX_MONOTONIC_CLOCK to -1.
#if (defined(OS_POSIX) &&                                               \
     defined(_POSIX_MONOTONIC_CLOCK) && _POSIX_MONOTONIC_CLOCK >= 0) || \
    defined(OS_BSD) || defined(OS_ANDROID)
76
butil::TimeTicks ClockNow(clockid_t clk_id) {
gejun's avatar
gejun committed
77 78 79 80 81
  uint64_t absolute_micro;

  struct timespec ts;
  if (clock_gettime(clk_id, &ts) != 0) {
    NOTREACHED() << "clock_gettime(" << clk_id << ") failed.";
82
    return butil::TimeTicks();
gejun's avatar
gejun committed
83 84 85
  }

  absolute_micro =
86 87
      (static_cast<int64_t>(ts.tv_sec) * butil::Time::kMicrosecondsPerSecond) +
      (static_cast<int64_t>(ts.tv_nsec) / butil::Time::kNanosecondsPerMicrosecond);
gejun's avatar
gejun committed
88

89
  return butil::TimeTicks::FromInternalValue(absolute_micro);
gejun's avatar
gejun committed
90 91 92 93 94 95 96 97
}
#else  // _POSIX_MONOTONIC_CLOCK
#error No usable tick clock function on this platform.
#endif  // _POSIX_MONOTONIC_CLOCK
#endif  // !defined(OS_MACOSX)

}  // namespace

98
namespace butil {
gejun's avatar
gejun committed
99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385

struct timespec TimeDelta::ToTimeSpec() const {
  int64_t microseconds = InMicroseconds();
  time_t seconds = 0;
  if (microseconds >= Time::kMicrosecondsPerSecond) {
    seconds = InSeconds();
    microseconds -= seconds * Time::kMicrosecondsPerSecond;
  }
  struct timespec result =
      {seconds,
       static_cast<long>(microseconds * Time::kNanosecondsPerMicrosecond)};
  return result;
}

#if !defined(OS_MACOSX)
// The Time routines in this file use standard POSIX routines, or almost-
// standard routines in the case of timegm.  We need to use a Mach-specific
// function for TimeTicks::Now() on Mac OS X.

// Time -----------------------------------------------------------------------

// Windows uses a Gregorian epoch of 1601.  We need to match this internally
// so that our time representations match across all platforms.  See bug 14734.
//   irb(main):010:0> Time.at(0).getutc()
//   => Thu Jan 01 00:00:00 UTC 1970
//   irb(main):011:0> Time.at(-11644473600).getutc()
//   => Mon Jan 01 00:00:00 UTC 1601
static const int64_t kWindowsEpochDeltaSeconds = GG_INT64_C(11644473600);

// static
const int64_t Time::kWindowsEpochDeltaMicroseconds =
    kWindowsEpochDeltaSeconds * Time::kMicrosecondsPerSecond;

// Some functions in time.cc use time_t directly, so we provide an offset
// to convert from time_t (Unix epoch) and internal (Windows epoch).
// static
const int64_t Time::kTimeTToMicrosecondsOffset = kWindowsEpochDeltaMicroseconds;

// static
Time Time::Now() {
  struct timeval tv;
  struct timezone tz = { 0, 0 };  // UTC
  if (gettimeofday(&tv, &tz) != 0) {
    DCHECK(0) << "Could not determine time of day";
    PLOG(ERROR) << "Call to gettimeofday failed.";
    // Return null instead of uninitialized |tv| value, which contains random
    // garbage data. This may result in the crash seen in crbug.com/147570.
    return Time();
  }
  // Combine seconds and microseconds in a 64-bit field containing microseconds
  // since the epoch.  That's enough for nearly 600 centuries.  Adjust from
  // Unix (1970) to Windows (1601) epoch.
  return Time((tv.tv_sec * kMicrosecondsPerSecond + tv.tv_usec) +
      kWindowsEpochDeltaMicroseconds);
}

// static
Time Time::NowFromSystemTime() {
  // Just use Now() because Now() returns the system time.
  return Now();
}

void Time::Explode(bool is_local, Exploded* exploded) const {
  // Time stores times with microsecond resolution, but Exploded only carries
  // millisecond resolution, so begin by being lossy.  Adjust from Windows
  // epoch (1601) to Unix epoch (1970);
  int64_t microseconds = us_ - kWindowsEpochDeltaMicroseconds;
  // The following values are all rounded towards -infinity.
  int64_t milliseconds;  // Milliseconds since epoch.
  SysTime seconds;  // Seconds since epoch.
  int millisecond;  // Exploded millisecond value (0-999).
  if (microseconds >= 0) {
    // Rounding towards -infinity <=> rounding towards 0, in this case.
    milliseconds = microseconds / kMicrosecondsPerMillisecond;
    seconds = milliseconds / kMillisecondsPerSecond;
    millisecond = milliseconds % kMillisecondsPerSecond;
  } else {
    // Round these *down* (towards -infinity).
    milliseconds = (microseconds - kMicrosecondsPerMillisecond + 1) /
                   kMicrosecondsPerMillisecond;
    seconds = (milliseconds - kMillisecondsPerSecond + 1) /
              kMillisecondsPerSecond;
    // Make this nonnegative (and between 0 and 999 inclusive).
    millisecond = milliseconds % kMillisecondsPerSecond;
    if (millisecond < 0)
      millisecond += kMillisecondsPerSecond;
  }

  struct tm timestruct;
  SysTimeToTimeStruct(seconds, &timestruct, is_local);

  exploded->year         = timestruct.tm_year + 1900;
  exploded->month        = timestruct.tm_mon + 1;
  exploded->day_of_week  = timestruct.tm_wday;
  exploded->day_of_month = timestruct.tm_mday;
  exploded->hour         = timestruct.tm_hour;
  exploded->minute       = timestruct.tm_min;
  exploded->second       = timestruct.tm_sec;
  exploded->millisecond  = millisecond;
}

// static
Time Time::FromExploded(bool is_local, const Exploded& exploded) {
  struct tm timestruct;
  timestruct.tm_sec    = exploded.second;
  timestruct.tm_min    = exploded.minute;
  timestruct.tm_hour   = exploded.hour;
  timestruct.tm_mday   = exploded.day_of_month;
  timestruct.tm_mon    = exploded.month - 1;
  timestruct.tm_year   = exploded.year - 1900;
  timestruct.tm_wday   = exploded.day_of_week;  // mktime/timegm ignore this
  timestruct.tm_yday   = 0;     // mktime/timegm ignore this
  timestruct.tm_isdst  = -1;    // attempt to figure it out
#if !defined(OS_NACL) && !defined(OS_SOLARIS)
  timestruct.tm_gmtoff = 0;     // not a POSIX field, so mktime/timegm ignore
  timestruct.tm_zone   = NULL;  // not a POSIX field, so mktime/timegm ignore
#endif


  int64_t milliseconds;
  SysTime seconds;

  // Certain exploded dates do not really exist due to daylight saving times,
  // and this causes mktime() to return implementation-defined values when
  // tm_isdst is set to -1. On Android, the function will return -1, while the
  // C libraries of other platforms typically return a liberally-chosen value.
  // Handling this requires the special code below.

  // SysTimeFromTimeStruct() modifies the input structure, save current value.
  struct tm timestruct0 = timestruct;

  seconds = SysTimeFromTimeStruct(&timestruct, is_local);
  if (seconds == -1) {
    // Get the time values with tm_isdst == 0 and 1, then select the closest one
    // to UTC 00:00:00 that isn't -1.
    timestruct = timestruct0;
    timestruct.tm_isdst = 0;
    int64_t seconds_isdst0 = SysTimeFromTimeStruct(&timestruct, is_local);

    timestruct = timestruct0;
    timestruct.tm_isdst = 1;
    int64_t seconds_isdst1 = SysTimeFromTimeStruct(&timestruct, is_local);

    // seconds_isdst0 or seconds_isdst1 can be -1 for some timezones.
    // E.g. "CLST" (Chile Summer Time) returns -1 for 'tm_isdt == 1'.
    if (seconds_isdst0 < 0)
      seconds = seconds_isdst1;
    else if (seconds_isdst1 < 0)
      seconds = seconds_isdst0;
    else
      seconds = std::min(seconds_isdst0, seconds_isdst1);
  }

  // Handle overflow.  Clamping the range to what mktime and timegm might
  // return is the best that can be done here.  It's not ideal, but it's better
  // than failing here or ignoring the overflow case and treating each time
  // overflow as one second prior to the epoch.
  if (seconds == -1 &&
      (exploded.year < 1969 || exploded.year > 1970)) {
    // If exploded.year is 1969 or 1970, take -1 as correct, with the
    // time indicating 1 second prior to the epoch.  (1970 is allowed to handle
    // time zone and DST offsets.)  Otherwise, return the most future or past
    // time representable.  Assumes the time_t epoch is 1970-01-01 00:00:00 UTC.
    //
    // The minimum and maximum representible times that mktime and timegm could
    // return are used here instead of values outside that range to allow for
    // proper round-tripping between exploded and counter-type time
    // representations in the presence of possible truncation to time_t by
    // division and use with other functions that accept time_t.
    //
    // When representing the most distant time in the future, add in an extra
    // 999ms to avoid the time being less than any other possible value that
    // this function can return.

    // On Android, SysTime is int64_t, special care must be taken to avoid
    // overflows.
    const int64_t min_seconds = (sizeof(SysTime) < sizeof(int64_t))
                                  ? std::numeric_limits<SysTime>::min()
                                  : std::numeric_limits<int32_t>::min();
    const int64_t max_seconds = (sizeof(SysTime) < sizeof(int64_t))
                                  ? std::numeric_limits<SysTime>::max()
                                  : std::numeric_limits<int32_t>::max();
    if (exploded.year < 1969) {
      milliseconds = min_seconds * kMillisecondsPerSecond;
    } else {
      milliseconds = max_seconds * kMillisecondsPerSecond;
      milliseconds += (kMillisecondsPerSecond - 1);
    }
  } else {
    milliseconds = seconds * kMillisecondsPerSecond + exploded.millisecond;
  }

  // Adjust from Unix (1970) to Windows (1601) epoch.
  return Time((milliseconds * kMicrosecondsPerMillisecond) +
      kWindowsEpochDeltaMicroseconds);
}

// TimeTicks ------------------------------------------------------------------
// static
TimeTicks TimeTicks::Now() {
  return ClockNow(CLOCK_MONOTONIC);
}

// static
TimeTicks TimeTicks::HighResNow() {
  return Now();
}

// static
bool TimeTicks::IsHighResNowFastAndReliable() {
  return true;
}

// static
TimeTicks TimeTicks::ThreadNow() {
#if (defined(_POSIX_THREAD_CPUTIME) && (_POSIX_THREAD_CPUTIME >= 0)) || \
    defined(OS_ANDROID)
  return ClockNow(CLOCK_THREAD_CPUTIME_ID);
#else
  NOTREACHED();
  return TimeTicks();
#endif
}

// Use the Chrome OS specific system-wide clock.
#if defined(OS_CHROMEOS)
// static
TimeTicks TimeTicks::NowFromSystemTraceTime() {
  uint64_t absolute_micro;

  struct timespec ts;
  if (clock_gettime(kClockSystemTrace, &ts) != 0) {
    // NB: fall-back for a chrome os build running on linux
    return HighResNow();
  }

  absolute_micro =
      (static_cast<int64_t>(ts.tv_sec) * Time::kMicrosecondsPerSecond) +
      (static_cast<int64_t>(ts.tv_nsec) / Time::kNanosecondsPerMicrosecond);

  return TimeTicks(absolute_micro);
}

#else  // !defined(OS_CHROMEOS)

// static
TimeTicks TimeTicks::NowFromSystemTraceTime() {
  return HighResNow();
}

#endif  // defined(OS_CHROMEOS)

#endif  // !OS_MACOSX

// static
Time Time::FromTimeVal(struct timeval t) {
  DCHECK_LT(t.tv_usec, static_cast<int>(Time::kMicrosecondsPerSecond));
  DCHECK_GE(t.tv_usec, 0);
  if (t.tv_usec == 0 && t.tv_sec == 0)
    return Time();
  if (t.tv_usec == static_cast<suseconds_t>(Time::kMicrosecondsPerSecond) - 1 &&
      t.tv_sec == std::numeric_limits<time_t>::max())
    return Max();
  return Time(
      (static_cast<int64_t>(t.tv_sec) * Time::kMicrosecondsPerSecond) +
      t.tv_usec +
      kTimeTToMicrosecondsOffset);
}

struct timeval Time::ToTimeVal() const {
  struct timeval result;
  if (is_null()) {
    result.tv_sec = 0;
    result.tv_usec = 0;
    return result;
  }
  if (is_max()) {
    result.tv_sec = std::numeric_limits<time_t>::max();
    result.tv_usec = static_cast<suseconds_t>(Time::kMicrosecondsPerSecond) - 1;
    return result;
  }
  int64_t us = us_ - kTimeTToMicrosecondsOffset;
  result.tv_sec = us / Time::kMicrosecondsPerSecond;
  result.tv_usec = us % Time::kMicrosecondsPerSecond;
  return result;
}

386
}  // namespace butil