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cache all appcontext switches #2227

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merged 6 commits into from
Nov 21, 2023
Merged

cache all appcontext switches #2227

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62273ed
cache all appcontext switches
Wraith2 Nov 17, 2023
a8a0ec3
use atomically updated byte enum instead of Nullable<bool>
Wraith2 Nov 18, 2023
fd62694
fix tests and add note about reflection
Wraith2 Nov 18, 2023
b776663
fix tests and add note about reflection
Wraith2 Nov 18, 2023
ec730e0
fix typo
Wraith2 Nov 18, 2023
f1243c0
more typos. note, do not code at 2am.
Wraith2 Nov 18, 2023
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42 changes: 36 additions & 6 deletions src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/LocalAppContextSwitches.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,8 +15,8 @@ internal static partial class LocalAppContextSwitches

private static bool? s_legacyRowVersionNullBehavior;
private static bool? s_suppressInsecureTLSWarning;
private static bool s_makeReadAsyncBlocking;
private static bool s_useMinimumLoginTimeout;
private static bool? s_makeReadAsyncBlocking;
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bool? is a structure with two fields. It is not updated atomically. The lock-free reads and writes below have race conditions.

If you want the reads to be lock-free, you can either:

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Thanks. I've updated all the variables to use the tristate enum pattern.

private static bool? s_useMinimumLoginTimeout;

#if !NETFRAMEWORK
static LocalAppContextSwitches()
Expand All @@ -36,7 +36,7 @@ static LocalAppContextSwitches()

#if NETFRAMEWORK
internal const string DisableTNIRByDefaultString = @"Switch.Microsoft.Data.SqlClient.DisableTNIRByDefaultInConnectionString";
private static bool s_disableTNIRByDefault;
private static bool? s_disableTNIRByDefault;

/// <summary>
/// Transparent Network IP Resolution (TNIR) is a revision of the existing MultiSubnetFailover feature.
Expand All @@ -54,7 +54,17 @@ static LocalAppContextSwitches()
/// This app context switch defaults to 'false'.
/// </summary>
public static bool DisableTNIRByDefault
=> AppContext.TryGetSwitch(DisableTNIRByDefaultString, out s_disableTNIRByDefault) && s_disableTNIRByDefault;
{
get
{
if (s_disableTNIRByDefault is null)
{
bool result = AppContext.TryGetSwitch(DisableTNIRByDefaultString, out bool returnedValue) && returnedValue;
s_disableTNIRByDefault = result;
}
return s_disableTNIRByDefault.Value;
}
}
#endif

/// <summary>
Expand Down Expand Up @@ -101,14 +111,34 @@ public static bool LegacyRowVersionNullBehavior
/// This app context switch defaults to 'false'.
/// </summary>
public static bool MakeReadAsyncBlocking
=> AppContext.TryGetSwitch(MakeReadAsyncBlockingString, out s_makeReadAsyncBlocking) && s_makeReadAsyncBlocking;
{
get
{
if (s_makeReadAsyncBlocking is null)
{
bool result = AppContext.TryGetSwitch(MakeReadAsyncBlockingString, out bool returnedValue) && returnedValue;
s_makeReadAsyncBlocking = result;
}
return s_makeReadAsyncBlocking.Value;
}
}

/// <summary>
/// Specifies minimum login timeout to be set to 1 second instead of 0 seconds,
/// to prevent a login attempt from waiting indefinitely.
/// This app context switch defaults to 'true'.
/// </summary>
public static bool UseMinimumLoginTimeout
=> !AppContext.TryGetSwitch(UseMinimumLoginTimeoutString, out s_useMinimumLoginTimeout) || s_useMinimumLoginTimeout;
{
get
{
if (s_useMinimumLoginTimeout is null)
{
bool result = AppContext.TryGetSwitch(UseMinimumLoginTimeoutString, out bool returnedValue) && returnedValue;
s_useMinimumLoginTimeout = result;
}
return s_useMinimumLoginTimeout.Value;
}
}
}
}
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