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//------------------------------------------------------------------------------
// <copyright file="TimeoutTimer.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//
// Class used to manage timeouts in complex system operations.
//
// <owner current="true" primary="true">Microsoft</owner>
// <owner current="true" primary="false">Microsoft</owner>
//------------------------------------------------------------------------------
namespace System.Data.ProviderBase
{
using System;
using System.Data.Common;
using System.Diagnostics;
// Purpose:
// Manages determining and tracking timeouts
//
// Intended use:
// Call StartXXXXTimeout() to get a timer with the given expiration point
// Get remaining time in appropriate format to pass to subsystem timeouts
// Check for timeout via IsExpired for checks in managed code.
// Simply abandon to GC when done.
internal class TimeoutTimer
{
//-------------------
// Fields
//-------------------
private long _timerExpire;
private bool _isInfiniteTimeout;
//-------------------
// Timeout-setting methods
//-------------------
// Get a new timer that will expire in the given number of seconds
// For input, a value of zero seconds indicates infinite timeout
internal static TimeoutTimer StartSecondsTimeout(int seconds)
{
//--------------------
// Preconditions: None (seconds must conform to SetTimeoutSeconds requirements)
//--------------------
// Method body
var timeout = new TimeoutTimer();
timeout.SetTimeoutSeconds(seconds);
//---------------------
// Postconditions
Debug.Assert(timeout != null); // Need a valid timeouttimer if no error
return timeout;
}
// Get a new timer that will expire in the given number of milliseconds
// No current need to support infinite milliseconds timeout
internal static TimeoutTimer StartMillisecondsTimeout(long milliseconds)
{
//--------------------
// Preconditions
Debug.Assert(0 <= milliseconds);
//--------------------
// Method body
var timeout = new TimeoutTimer();
timeout._timerExpire = checked(ADP.TimerCurrent() + (milliseconds * TimeSpan.TicksPerMillisecond));
timeout._isInfiniteTimeout = false;
//---------------------
// Postconditions
Debug.Assert(timeout != null); // Need a valid timeouttimer if no error
return timeout;
}
//-------------------
// Methods for changing timeout
//-------------------
internal void SetTimeoutSeconds(int seconds)
{
//--------------------
// Preconditions
Debug.Assert(0 <= seconds || InfiniteTimeout == seconds); // no need to support negative seconds at present
//--------------------
// Method body
if (InfiniteTimeout == seconds)
{
_isInfiniteTimeout = true;
}
else
{
// Stash current time + timeout
_timerExpire = checked(ADP.TimerCurrent() + ADP.TimerFromSeconds(seconds));
_isInfiniteTimeout = false;
}
//---------------------
// Postconditions:None
}
//-------------------
// Timeout info properties
//-------------------
// Indicator for infinite timeout when starting a timer
internal static readonly long InfiniteTimeout = 0;
// Is this timer in an expired state?
internal bool IsExpired
{
get
{
return !IsInfinite && ADP.TimerHasExpired(_timerExpire);
}
}
// is this an infinite-timeout timer?
internal bool IsInfinite
{
get
{
return _isInfiniteTimeout;
}
}
// Special accessor for TimerExpire for use when thunking to legacy timeout methods.
internal long LegacyTimerExpire
{
get
{
return (_isInfiniteTimeout) ? Int64.MaxValue : _timerExpire;
}
}
// Returns milliseconds remaining trimmed to zero for none remaining
// and long.MaxValue for infinite
// This method should be prefered for internal calculations that are not
// yet common enough to code into the TimeoutTimer class itself.
internal long MillisecondsRemaining
{
get
{
//-------------------
// Preconditions: None
//-------------------
// Method Body
long milliseconds;
if (_isInfiniteTimeout)
{
milliseconds = long.MaxValue;
}
else
{
milliseconds = ADP.TimerRemainingMilliseconds(_timerExpire);
if (0 > milliseconds)
{
milliseconds = 0;
}
}
//--------------------
// Postconditions
Debug.Assert(0<=milliseconds); // This property guarantees no negative return values
return milliseconds;
}
}
}
}
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