com.illumon.iris.db.v2.sources

Enum LogicalClock

java.lang.Object

java.lang.Enum<LogicalClock>

com.illumon.iris.db.v2.sources.LogicalClock

All Implemented Interfaces:

Serializable, Comparable<LogicalClock>

public enum LogicalClock
extends Enum<LogicalClock>

A logical update clock that has two states, Updating and Idle.

Each time LogicalClock.startUpdateCycle() is called, the clock transitions to the Updating state and the current value is incremented by one.

When LogicalClock.completeUpdateCycle() is called, the clock transitions back to Idle.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	LogicalClock.State The state component of a logical timestamp.

Enum Constant Summary

Enum Constants

Enum Constant and Description
DEFAULT

Method Summary

Modifier and Type	Method and Description
void	completeUpdateCycle() Increment the current step and set the clock state to idle.
LogicalClock.State	currentState() Get the current clock state.
long	currentStep() Get the current Step of the clock.
long	currentValue() Get the current value of the clock.
void	ensureUpdateCycleCompleted(long updatingCycleValue) After we complete a table refresh, we must ensure that the logical clock is idle.
static LogicalClock.State	getState(long value) Get the LogicalClock.State of the LogicalClock for a particular clock value.
static long	getStep(long value) Get the clock step for the input clock value.
void	resetForUnitTests() Reset the clock to its initial state, in order to ensure that unit tests proceed cleanly.
long	startUpdateCycle() Increment the current value and set the clock state to updating.
static LogicalClock	valueOf(String name) Returns the enum constant of this type with the specified name.
static LogicalClock[]	values() Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

DEFAULT

public static final LogicalClock DEFAULT

Method Detail

values

public static LogicalClock[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (LogicalClock c : LogicalClock.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static LogicalClock valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum type has no constant with the specified name

NullPointerException - if the argument is null

getStep

public static long getStep(long value)

Get the clock step for the input clock value. The step increments one time for each complete start - end cycle.

Parameters:

value - The clock value to get the step for

Returns:

The clock step associated with value

getState

public static LogicalClock.State getState(long value)

Get the LogicalClock.State of the LogicalClock for a particular clock value.

Parameters:

value - The clock value

Returns:

The clock state associated with the input value

currentValue

public final long currentValue()

Get the current value of the clock.

currentStep

public final long currentStep()

Get the current Step of the clock.

See Also:

LogicalClock.getStep(long)

currentState

public final LogicalClock.State currentState()

Get the current clock state.

See Also:

LogicalClock.getState(long)

startUpdateCycle

public final long startUpdateCycle()

Increment the current value and set the clock state to updating.

ImplNote:

The clock must have been idle before this method is called.

completeUpdateCycle

public final void completeUpdateCycle()

Increment the current step and set the clock state to idle.

ImplNote:

The clock must have been updating before this method is called.

ensureUpdateCycleCompleted

public final void ensureUpdateCycleCompleted(long updatingCycleValue)

After we complete a table refresh, we must ensure that the logical clock is idle.

The only valid possibilities are (1) we have completed the cycle, in which case we return; or (2) we have terminated the cycle early and have the same value as at the start of our updating cycle, in which case we complete the cycle.

If our clock is any other value; then it was changed out from under us and we throw an exception.

Parameters:

updatingCycleValue - the clock value at the end of LogicalClock.startUpdateCycle()

resetForUnitTests

@TestUseOnly
public final void resetForUnitTests()

Reset the clock to its initial state, in order to ensure that unit tests proceed cleanly.