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Fix time zone cache so it is not initialized when the snapshot is built.

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Review URL: http://codereview.chromium.org/1576002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4326 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
whesse@chromium.org 2010-03-30 14:29:32 +00:00
parent c51c67d9c0
commit 22025291da
1 changed files with 28 additions and 5 deletions
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33
src/date.js
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@ -121,9 +121,16 @@ function EquivalentTime(t) {
}
// Because computing the DST offset is a pretty expensive operation
// we keep a cache of last computed offset along with a time interval
// local_time_offset is initialized when the DST_offset_cache is missed.
// It must not be used until after a call to DaylightSavingsOffset().
// In this way, only one check, for a DST cache miss, is needed.
var local_time_offset;
// Because computing the DST offset is an expensive operation,
// we keep a cache of the last computed DST offset along with a time interval
// where we know the cache is valid.
// When the cache is valid, local_time_offset is also valid.
var DST_offset_cache = {
// Cached DST offset.
offset: 0,
@ -149,6 +156,11 @@ function DaylightSavingsOffset(t) {
// If the time fits in the cached interval, return the cached offset.
if (t <= end) return cache.offset;
// If the cache misses, the local_time_offset may not be initialized.
if (IS_UNDEFINED(local_time_offset)) {
local_time_offset = %DateLocalTimeOffset();
}
// Compute a possible new interval end.
var new_end = end + cache.increment;
@ -185,6 +197,10 @@ function DaylightSavingsOffset(t) {
}
}
// If the cache misses, the local_time_offset may not be initialized.
if (IS_UNDEFINED(local_time_offset)) {
local_time_offset = %DateLocalTimeOffset();
}
// Compute the DST offset for the time and shrink the cache interval
// to only contain the time. This allows fast repeated DST offset
// computations for the same time.
@ -215,11 +231,11 @@ function WeekDay(time) {
return Modulo(DAY(time) + 4, 7);
}
var local_time_offset = %DateLocalTimeOffset();
function LocalTime(time) {
if (NUMBER_IS_NAN(time)) return time;
return time + local_time_offset + DaylightSavingsOffset(time);
// DaylightSavingsOffset called before local_time_offset used.
return time + DaylightSavingsOffset(time) + local_time_offset;
}
function LocalTimeNoCheck(time) {
@ -228,6 +244,8 @@ function LocalTimeNoCheck(time) {
}
// Inline the DST offset cache checks for speed.
// The cache is hit, or DaylightSavingsOffset is called,
// before local_time_offset is used.
var cache = DST_offset_cache;
if (cache.start <= time && time <= cache.end) {
var dst_offset = cache.offset;
@ -240,6 +258,11 @@ function LocalTimeNoCheck(time) {
function UTC(time) {
if (NUMBER_IS_NAN(time)) return time;
// local_time_offset is needed before the call to DaylightSavingsOffset,
// so it may be uninitialized.
if (IS_UNDEFINED(local_time_offset)) {
local_time_offset = %DateLocalTimeOffset();
}
var tmp = time - local_time_offset;
return tmp - DaylightSavingsOffset(tmp);
}
@ -566,7 +589,7 @@ function TimeString(time) {
function LocalTimezoneString(time) {
var timezoneOffset =
(local_time_offset + DaylightSavingsOffset(time)) / msPerMinute;
(DaylightSavingsOffset(time) + local_time_offset) / msPerMinute;
var sign = (timezoneOffset >= 0) ? 1 : -1;
var hours = FLOOR((sign * timezoneOffset)/60);
var min = FLOOR((sign * timezoneOffset)%60);