13ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch// Copyright 2012 the V8 project authors. All rights reserved. 2b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch// Use of this source code is governed by a BSD-style license that can be 3b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch// found in the LICENSE file. 43ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 53ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch#ifndef V8_DATE_H_ 63ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch#define V8_DATE_H_ 73ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 8b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch#include "src/allocation.h" 9b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch#include "src/base/platform/platform.h" 10b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch#include "src/globals.h" 113ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 123ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 133ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdochnamespace v8 { 143ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdochnamespace internal { 153ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 163ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdochclass DateCache { 173ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch public: 183ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch static const int kMsPerMin = 60 * 1000; 193ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch static const int kSecPerDay = 24 * 60 * 60; 203ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch static const int64_t kMsPerDay = kSecPerDay * 1000; 213ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 223ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // The largest time that can be passed to OS date-time library functions. 233ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch static const int kMaxEpochTimeInSec = kMaxInt; 243ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch static const int64_t kMaxEpochTimeInMs = 253ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch static_cast<int64_t>(kMaxInt) * 1000; 263ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 273ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // The largest time that can be stored in JSDate. 283ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch static const int64_t kMaxTimeInMs = 293ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch static_cast<int64_t>(864000000) * 10000000; 303ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 313ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // Conservative upper bound on time that can be stored in JSDate 323ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // before UTC conversion. 333ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch static const int64_t kMaxTimeBeforeUTCInMs = 343ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch kMaxTimeInMs + 10 * kMsPerDay; 353ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 363ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // Sentinel that denotes an invalid local offset. 373ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch static const int kInvalidLocalOffsetInMs = kMaxInt; 383ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // Sentinel that denotes an invalid cache stamp. 393ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // It is an invariant of DateCache that cache stamp is non-negative. 403ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch static const int kInvalidStamp = -1; 413ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 42b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch DateCache() : stamp_(0), tz_cache_(base::OS::CreateTimezoneCache()) { 433ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch ResetDateCache(); 443ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch } 453ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 46b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch virtual ~DateCache() { 47b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch base::OS::DisposeTimezoneCache(tz_cache_); 48b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch tz_cache_ = NULL; 49b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch } 503ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 513ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 523ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // Clears cached timezone information and increments the cache stamp. 533ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch void ResetDateCache(); 543ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 553ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 563ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // Computes floor(time_ms / kMsPerDay). 573ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch static int DaysFromTime(int64_t time_ms) { 583ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch if (time_ms < 0) time_ms -= (kMsPerDay - 1); 593ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch return static_cast<int>(time_ms / kMsPerDay); 603ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch } 613ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 623ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 633ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // Computes modulo(time_ms, kMsPerDay) given that 643ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // days = floor(time_ms / kMsPerDay). 653ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch static int TimeInDay(int64_t time_ms, int days) { 663ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch return static_cast<int>(time_ms - days * kMsPerDay); 673ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch } 683ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 693ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 703ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // Given the number of days since the epoch, computes the weekday. 713ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // ECMA 262 - 15.9.1.6. 723ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch int Weekday(int days) { 733ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch int result = (days + 4) % 7; 743ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch return result >= 0 ? result : result + 7; 753ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch } 763ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 773ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 783ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch bool IsLeap(int year) { 793ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch return year % 4 == 0 && (year % 100 != 0 || year % 400 == 0); 803ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch } 813ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 823ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 833ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // ECMA 262 - 15.9.1.7. 843ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch int LocalOffsetInMs() { 853ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch if (local_offset_ms_ == kInvalidLocalOffsetInMs) { 863ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch local_offset_ms_ = GetLocalOffsetFromOS(); 873ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch } 883ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch return local_offset_ms_; 893ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch } 903ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 913ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 923ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch const char* LocalTimezone(int64_t time_ms) { 933ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch if (time_ms < 0 || time_ms > kMaxEpochTimeInMs) { 943ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch time_ms = EquivalentTime(time_ms); 953ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch } 96b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch return base::OS::LocalTimezone(static_cast<double>(time_ms), tz_cache_); 973ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch } 983ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 993ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // ECMA 262 - 15.9.5.26 1003ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch int TimezoneOffset(int64_t time_ms) { 1013ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch int64_t local_ms = ToLocal(time_ms); 1023ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch return static_cast<int>((time_ms - local_ms) / kMsPerMin); 1033ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch } 1043ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 1053ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // ECMA 262 - 15.9.1.9 106b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // LocalTime(t) = t + LocalTZA + DaylightSavingTA(t) 1073ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch int64_t ToLocal(int64_t time_ms) { 1083ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch return time_ms + LocalOffsetInMs() + DaylightSavingsOffsetInMs(time_ms); 1093ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch } 1103ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 1113ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // ECMA 262 - 15.9.1.9 112b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // UTC(t) = t - LocalTZA - DaylightSavingTA(t - LocalTZA) 1133ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch int64_t ToUTC(int64_t time_ms) { 114b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // We need to compute UTC time that corresponds to the given local time. 115b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // Literally following spec here leads to incorrect time computation at 116b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // the points were we transition to and from DST. 117b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // 118b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // The following shows that using DST for (t - LocalTZA - hour) produces 119b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // correct conversion. 120b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // 121b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // Consider transition to DST at local time L1. 122b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // Let L0 = L1 - hour, L2 = L1 + hour, 123b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // U1 = UTC time that corresponds to L1, 124b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // U0 = U1 - hour. 125b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // Transitioning to DST moves local clock one hour forward L1 => L2, so 126b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // U0 = UTC time that corresponds to L0 = L0 - LocalTZA, 127b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // U1 = UTC time that corresponds to L1 = L1 - LocalTZA, 128b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // U1 = UTC time that corresponds to L2 = L2 - LocalTZA - hour. 129b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // Note that DST(U0 - hour) = 0, DST(U0) = 0, DST(U1) = 1. 130b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // U0 = L0 - LocalTZA - DST(L0 - LocalTZA - hour), 131b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // U1 = L1 - LocalTZA - DST(L1 - LocalTZA - hour), 132b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // U1 = L2 - LocalTZA - DST(L2 - LocalTZA - hour). 133b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // 134b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // Consider transition from DST at local time L1. 135b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // Let L0 = L1 - hour, 136b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // U1 = UTC time that corresponds to L1, 137b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // U0 = U1 - hour, U2 = U1 + hour. 138b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // Transitioning from DST moves local clock one hour back L1 => L0, so 139b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // U0 = UTC time that corresponds to L0 (before transition) 140b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // = L0 - LocalTZA - hour. 141b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // U1 = UTC time that corresponds to L0 (after transition) 142b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // = L0 - LocalTZA = L1 - LocalTZA - hour 143b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // U2 = UTC time that corresponds to L1 = L1 - LocalTZA. 144b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // Note that DST(U0) = 1, DST(U1) = 0, DST(U2) = 0. 145b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // U0 = L0 - LocalTZA - DST(L0 - LocalTZA - hour) = L0 - LocalTZA - DST(U0). 146b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // U2 = L1 - LocalTZA - DST(L1 - LocalTZA - hour) = L1 - LocalTZA - DST(U1). 147b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // It is impossible to get U1 from local time. 148b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 149b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch const int kMsPerHour = 3600 * 1000; 1503ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch time_ms -= LocalOffsetInMs(); 151b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch return time_ms - DaylightSavingsOffsetInMs(time_ms - kMsPerHour); 1523ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch } 1533ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 1543ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 1553ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // Computes a time equivalent to the given time according 1563ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // to ECMA 262 - 15.9.1.9. 1573ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // The issue here is that some library calls don't work right for dates 1583ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // that cannot be represented using a non-negative signed 32 bit integer 1593ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // (measured in whole seconds based on the 1970 epoch). 1603ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // We solve this by mapping the time to a year with same leap-year-ness 1613ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // and same starting day for the year. The ECMAscript specification says 1623ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // we must do this, but for compatibility with other browsers, we use 1633ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // the actual year if it is in the range 1970..2037 1643ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch int64_t EquivalentTime(int64_t time_ms) { 1653ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch int days = DaysFromTime(time_ms); 1663ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch int time_within_day_ms = static_cast<int>(time_ms - days * kMsPerDay); 1673ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch int year, month, day; 1683ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch YearMonthDayFromDays(days, &year, &month, &day); 1693ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch int new_days = DaysFromYearMonth(EquivalentYear(year), month) + day - 1; 1703ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch return static_cast<int64_t>(new_days) * kMsPerDay + time_within_day_ms; 1713ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch } 1723ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 1733ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // Returns an equivalent year in the range [2008-2035] matching 1743ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // - leap year, 1753ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // - week day of first day. 1763ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // ECMA 262 - 15.9.1.9. 1773ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch int EquivalentYear(int year) { 1783ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch int week_day = Weekday(DaysFromYearMonth(year, 0)); 1793ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch int recent_year = (IsLeap(year) ? 1956 : 1967) + (week_day * 12) % 28; 1803ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // Find the year in the range 2008..2037 that is equivalent mod 28. 1813ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // Add 3*28 to give a positive argument to the modulus operator. 1823ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch return 2008 + (recent_year + 3 * 28 - 2008) % 28; 1833ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch } 1843ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 1853ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // Given the number of days since the epoch, computes 1863ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // the corresponding year, month, and day. 1873ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch void YearMonthDayFromDays(int days, int* year, int* month, int* day); 1883ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 1893ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // Computes the number of days since the epoch for 1903ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // the first day of the given month in the given year. 1913ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch int DaysFromYearMonth(int year, int month); 1923ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 1933ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // Cache stamp is used for invalidating caches in JSDate. 1943ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // We increment the stamp each time when the timezone information changes. 1953ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // JSDate objects perform stamp check and invalidate their caches if 1963ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // their saved stamp is not equal to the current stamp. 1973ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch Smi* stamp() { return stamp_; } 1983ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch void* stamp_address() { return &stamp_; } 1993ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 2003ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // These functions are virtual so that we can override them when testing. 2013ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch virtual int GetDaylightSavingsOffsetFromOS(int64_t time_sec) { 2023ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch double time_ms = static_cast<double>(time_sec * 1000); 203b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch return static_cast<int>( 204b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch base::OS::DaylightSavingsOffset(time_ms, tz_cache_)); 2053ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch } 2063ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 2073ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch virtual int GetLocalOffsetFromOS() { 208b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch double offset = base::OS::LocalTimeOffset(tz_cache_); 209b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch DCHECK(offset < kInvalidLocalOffsetInMs); 2103ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch return static_cast<int>(offset); 2113ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch } 2123ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 2133ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch private: 2143ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // The implementation relies on the fact that no time zones have 2153ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // more than one daylight savings offset change per 19 days. 2163ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // In Egypt in 2010 they decided to suspend DST during Ramadan. This 2173ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // led to a short interval where DST is in effect from September 10 to 2183ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // September 30. 2193ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch static const int kDefaultDSTDeltaInSec = 19 * kSecPerDay; 2203ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 2213ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // Size of the Daylight Savings Time cache. 2223ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch static const int kDSTSize = 32; 2233ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 2243ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // Daylight Savings Time segment stores a segment of time where 2253ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // daylight savings offset does not change. 2263ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch struct DST { 2273ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch int start_sec; 2283ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch int end_sec; 2293ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch int offset_ms; 2303ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch int last_used; 2313ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch }; 2323ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 2333ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // Computes the daylight savings offset for the given time. 2343ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // ECMA 262 - 15.9.1.8 2353ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch int DaylightSavingsOffsetInMs(int64_t time_ms); 2363ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 2373ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // Sets the before_ and the after_ segments from the DST cache such that 2383ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // the before_ segment starts earlier than the given time and 2393ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // the after_ segment start later than the given time. 2403ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // Both segments might be invalid. 2413ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // The last_used counters of the before_ and after_ are updated. 2423ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch void ProbeDST(int time_sec); 2433ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 2443ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // Finds the least recently used segment from the DST cache that is not 2453ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // equal to the given 'skip' segment. 2463ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch DST* LeastRecentlyUsedDST(DST* skip); 2473ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 2483ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // Extends the after_ segment with the given point or resets it 2493ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // if it starts later than the given time + kDefaultDSTDeltaInSec. 2503ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch inline void ExtendTheAfterSegment(int time_sec, int offset_ms); 2513ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 2523ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // Makes the given segment invalid. 2533ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch inline void ClearSegment(DST* segment); 2543ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 2553ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch bool InvalidSegment(DST* segment) { 2563ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch return segment->start_sec > segment->end_sec; 2573ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch } 2583ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 2593ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch Smi* stamp_; 2603ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 2613ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // Daylight Saving Time cache. 2623ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch DST dst_[kDSTSize]; 2633ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch int dst_usage_counter_; 2643ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch DST* before_; 2653ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch DST* after_; 2663ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 2673ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch int local_offset_ms_; 2683ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 2693ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch // Year/Month/Day cache. 2703ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch bool ymd_valid_; 2713ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch int ymd_days_; 2723ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch int ymd_year_; 2733ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch int ymd_month_; 2743ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch int ymd_day_; 275b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 276b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch base::TimezoneCache* tz_cache_; 2773ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch}; 2783ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 2793ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch} } // namespace v8::internal 2803ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch 2813ef787dbeca8a5fb1086949cda830dccee07bfbdBen Murdoch#endif 282