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Fix "Optimized algorithm is not thread safe" #7

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143 changes: 76 additions & 67 deletions Afk.ZoneInfo/TzTimeZone.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@
using System.Diagnostics;
using System.Globalization;
using System.Linq;
using System.Threading;

namespace Afk.ZoneInfo
{
Expand All @@ -15,8 +16,8 @@ namespace Afk.ZoneInfo
/// </remarks>
public sealed class TzTimeZone
{
private List<TzTimeZoneRule> _zoneRules;
private Dictionary<int, List<TzTimeZoneRuleDate>> _zoneDates;
private readonly List<TzTimeZoneRule> _zoneRules = new List<TzTimeZoneRule>();
private TzTimeZoneRuleDate[][][] _zoneDates; // voir ResolveDateChangesForYear

struct ZoneRuleAssociate
{
Expand All @@ -30,8 +31,6 @@ struct ZoneRuleAssociate
/// </summary>
internal TzTimeZone()
{
_zoneRules = new List<TzTimeZoneRule>();
_zoneDates = new Dictionary<int, List<TzTimeZoneRuleDate>>();
}

/// <summary>
Expand Down Expand Up @@ -165,69 +164,85 @@ internal DateTime[] GetDayChangeTime(int year)
/// applicable avant cette date.
/// </summary>
/// <param name="year"></param>
private void UpdateDateChange(int year)
private TzTimeZoneRuleDate[] ResolveDateChangesForYear(int year)
{
lock (_zoneDates)
{
if (!_zoneDates.ContainsKey(year))
{
Dictionary<DateTime, TzTimeZoneRuleDate> dico = new Dictionary<DateTime, TzTimeZoneRuleDate>();
Debug.Assert(year >= 1 && year <= 9999);

// N.B. thread-safe, lock-free; peut occasionnellement calculer la même année deux fois

// 79 blocs de 128 années, couvre 0001-9999 EC
const int blockSize = 128;
const int blockCount = 79;

if (_zoneDates == null)
Interlocked.CompareExchange(ref _zoneDates, new TzTimeZoneRuleDate[blockCount][][], null);

ref var block = ref _zoneDates[year / blockSize];
if (block == null)
Interlocked.CompareExchange(ref block, new TzTimeZoneRuleDate[blockSize][], null);

ref var result = ref block[year % blockSize];
if (result == null)
Interlocked.CompareExchange(ref result, ComputeDateChangesForYear(year), null);

return result;
}

private TzTimeZoneRuleDate[] ComputeDateChangesForYear(int year)
{
Dictionary<DateTime, TzTimeZoneRuleDate> dico = new Dictionary<DateTime, TzTimeZoneRuleDate>();

_zoneDates.Add(year, new List<TzTimeZoneRuleDate>());
for (int index = ZoneRules.Count - 1; index >= 0; index--)
{
TzTimeZoneRule temp = ZoneRules[index];

for (int index = ZoneRules.Count - 1; index >= 0; index--)
if ((temp.StartZone.UtcDate.Year <= year && temp.EndZone.UtcDate.Year >= year) ||
(temp.StartZone.ToLocalTime().Year <= year && temp.EndZone.ToLocalTime().Year >= year))
{
if (TzTimeInfo.Rules.ContainsKey(temp.RuleName))
{
TzTimeZoneRule temp = ZoneRules[index];
List<Rule> rules = TzTimeInfo.Rules[temp.RuleName];

if ((temp.StartZone.UtcDate.Year <= year && temp.EndZone.UtcDate.Year >= year) ||
(temp.StartZone.ToLocalTime().Year <= year && temp.EndZone.ToLocalTime().Year >= year))
foreach (Rule rule in rules)
{
if (TzTimeInfo.Rules.ContainsKey(temp.RuleName))
// On calcule sur trois années pour couvrir les changements d'heure de fin d'année et début d'année
for (int yearRef = year - 1; yearRef <= year + 1; yearRef++)
{
List<Rule> rules = TzTimeInfo.Rules[temp.RuleName];

foreach (Rule rule in rules)
if (rule.LowerYear <= yearRef && rule.HighYear >= yearRef && TzUtilities.IsYearType(yearRef, rule.YearType))
{
// On calcule sur trois années pour couvrir les changements d'heure de fin d'année et début d'année
for (int yearRef = year - 1; yearRef <= year + 1; yearRef++)
// Standard offset applicable à cette règle
TimeSpan stdoff = GetLastSaveOffset(yearRef, rules, rule, temp.StartZone, temp.GmtOffset);
// Date UTC et Local d'application de cette règle
DateTime utc = TzUtilities.GetDateTime(rule, yearRef, temp.GmtOffset, stdoff, DateTimeKind.Utc);
DateTime local = TzUtilities.GetDateTime(rule, yearRef, temp.GmtOffset, stdoff, DateTimeKind.Local);

// Contient les dates de la règle avec le décalage gmt et standard applicable AVANT cette date
TzTimeZoneRuleDate ruleDate = new TzTimeZoneRuleDate(utc, local, temp.GmtOffset, stdoff);
if (ruleDate > temp.StartZone && ruleDate <= temp.EndZone)
{
if (rule.LowerYear <= yearRef && rule.HighYear >= yearRef && TzUtilities.IsYearType(yearRef, rule.YearType))
{
// Standard offset applicable à cette règle
TimeSpan stdoff = GetLastSaveOffset(yearRef, rules, rule, temp.StartZone, temp.GmtOffset);
// Date UTC et Local d'application de cette règle
DateTime utc = TzUtilities.GetDateTime(rule, yearRef, temp.GmtOffset, stdoff, DateTimeKind.Utc);
DateTime local = TzUtilities.GetDateTime(rule, yearRef, temp.GmtOffset, stdoff, DateTimeKind.Local);

// Contient les dates de la règle avec le décalage gmt et standard applicable AVANT cette date
TzTimeZoneRuleDate ruleDate = new TzTimeZoneRuleDate(utc, local, temp.GmtOffset, stdoff);
if (ruleDate > temp.StartZone && ruleDate <= temp.EndZone)
{
if (!dico.ContainsKey(ruleDate.UtcDate))
dico.Add(ruleDate.UtcDate, ruleDate);
}
}
if (!dico.ContainsKey(ruleDate.UtcDate))
dico.Add(ruleDate.UtcDate, ruleDate);
}
}
}
}
}
}
}

// On ajoute les changements induits par les date until de zone
for (int index = ZoneRules.Count - 1; index >= 0; index--)
{
TzTimeZoneRule temp = ZoneRules[index];

if (temp.EndZone.UtcDate.Year == year || temp.EndZone.ToLocalTime().Year == year)
{
if (!dico.ContainsKey(temp.EndZone.UtcDate))
dico.Add(temp.EndZone.UtcDate, temp.EndZone);
}
}
// On ajoute les changements induits par les date until de zone
for (int index = ZoneRules.Count - 1; index >= 0; index--)
{
TzTimeZoneRule temp = ZoneRules[index];

_zoneDates[year].AddRange(dico.Values.OrderBy(e => e.UtcDate));
if (temp.EndZone.UtcDate.Year == year || temp.EndZone.ToLocalTime().Year == year)
{
if (!dico.ContainsKey(temp.EndZone.UtcDate))
dico.Add(temp.EndZone.UtcDate, temp.EndZone);
}
}

return dico.Values.OrderBy(e => e.UtcDate).ToArray();
}

/// <summary>
Expand All @@ -242,18 +257,15 @@ public DateTime ToLocalTime(DateTime datetime, bool optimize = false)

if (datetime.Kind == DateTimeKind.Local) return datetime;

Debug.Assert(datetime.Kind == DateTimeKind.Utc);

if (optimize)
{
UpdateDateChange(datetime.Year);
List<TzTimeZoneRuleDate> knownDate = _zoneDates[datetime.Year];
if (knownDate.Any())
var knownDate = ResolveDateChangesForYear(datetime.Year);
foreach (var elt in knownDate)
{
foreach (var elt in knownDate)
{
if ((datetime < elt.UtcDate && datetime.Kind == DateTimeKind.Utc) ||
(datetime < elt.ToLocalTime() && datetime.Kind == DateTimeKind.Local))
return TzUtilities.GetDateTime(datetime, elt.GmtOffset, elt.StandardOffset, DateTimeKind.Local);
}
if (datetime < elt.UtcDate)
return TzUtilities.GetDateTime(datetime, elt.GmtOffset, elt.StandardOffset, DateTimeKind.Local);
}
}

Expand All @@ -278,6 +290,8 @@ public DateTime ToUniversalTime(DateTime datetime, bool optimize = false)

if (datetime.Kind == DateTimeKind.Utc) return datetime;

Debug.Assert(datetime.Kind == DateTimeKind.Local);

// Check that local date is cover by zone
if (!ZoneRules.Any(z => datetime >= z.StartZone.ToLocalTime() && datetime < z.EndZone.ToLocalTime()))
{
Expand All @@ -286,16 +300,11 @@ public DateTime ToUniversalTime(DateTime datetime, bool optimize = false)

if (optimize)
{
UpdateDateChange(datetime.Year);
List<TzTimeZoneRuleDate> knownDate = _zoneDates[datetime.Year];
if (knownDate.Any())
var knownDate = ResolveDateChangesForYear(datetime.Year);
foreach (var elt in knownDate)
{
foreach (var elt in knownDate)
{
if ((datetime.Kind == DateTimeKind.Utc && datetime < elt.UtcDate) ||
(datetime.Kind == DateTimeKind.Local && datetime < elt.ToLocalTime()))
return TzUtilities.GetDateTime(datetime, elt.GmtOffset, elt.StandardOffset, DateTimeKind.Utc);
}
if (datetime < elt.ToLocalTime())
return TzUtilities.GetDateTime(datetime, elt.GmtOffset, elt.StandardOffset, DateTimeKind.Utc);
}
}

Expand Down