Class SafeClock

SafeClock maintains a "safe" time in milliseconds.

Inheritance

object

SafeClock

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: Tangosol.Util

Assembly: Coherence.dll

Syntax

public class SafeClock

Remarks

This clock guarantees that the time never "goes back". More specifically, when queried twice on the same thread, the second query will never return a value that is less then the value returned by the first.

If we detect the system clock moving backward, an attempt will be made to gradually compensate the safe clock (by slowing it down), so in the long run the safe time is the same as the system time.

The SafeClock supports the concept of "clock jitter", which is a small time interval that the system clock could fluctuate by without a corresponding passage of wall time.

Constructors

SafeClock(long)

Create a new SafeClock with the default maximum expected jitter.

Declaration

public SafeClock(long ldtUnsafe)

Parameters

Type	Name	Description
long	ldtUnsafe	The current unsafe time

SafeClock(long, long)

Create a new SafeClock with the specified jitter threshold.

Declaration

public SafeClock(long ldtUnsafe, long lJitter)

Parameters

Type	Name	Description
long	ldtUnsafe	The current unsafe time
long	lJitter	The maximum expected jitter in the underlying system clock

Fields

DEFAULT_JITTER_THRESHOLD

The default jitter threshold.

Declaration

public static readonly long DEFAULT_JITTER_THRESHOLD

Field Value

Type	Description
long

m_lJitter

The maximum expected jitter exposed by the underlying unsafe clock.

Declaration

protected readonly long m_lJitter

Field Value

Type	Description
long

m_ldtLastSafe

The last known safe time value.

Declaration

protected long m_ldtLastSafe

Field Value

Type	Description
long

m_ldtLastUnsafe

The last recorded unsafe time value.

Declaration

protected long m_ldtLastUnsafe

Field Value

Type	Description
long

Methods

GetLastSafeTimeMillis()

Returns the last "safe" time as computed by a previous call to the GetSafeTimeMillis method. Note: Since the underlying field is non-volatile, the returned value is only guaranteed to be no less than the last value returned by GetSafeTimeMillis() call on the same thread.

Declaration

public long GetLastSafeTimeMillis()

Returns

Type	Description
long	The last "safe" time in milliseconds.

GetSafeTimeMillis(long)

Returns a "safe" current time in milliseconds.

Declaration

public long GetSafeTimeMillis(long ldtUnsafe)

Parameters

Type	Name	Description
long	ldtUnsafe	The current unsafe time

Returns

Type	Description
long	The difference, measured in milliseconds, between the corrected current time and midnight, January 1, 0001.

UpdateSafeTimeMillis(long)

Updates and returns a "safe" current time in milliseconds based on the "unsafe" time.

Declaration

protected long UpdateSafeTimeMillis(long ldtUnsafe)

Parameters

Type	Name	Description
long	ldtUnsafe	The unsafe current time in milliseconds.

Returns

Type	Description
long	The corrected safe time.