stormpot

Interface SlotInfo<T extends Poolable>

public interface SlotInfo<T extends Poolable>

An informative little interface, used by Expiration instances to determine if a slot has expired or is still invalid for claiming.

Author:

Chris Vest <mr.chrisvest@gmail.com>

Method Summary

Methods

Modifier and Type	Method and Description
long	getAgeMillis() Get the approximate number of milliseconds that have transpired since the object was allocated.
long	getClaimCount() Get the number of times the object has been claimed since it was allocated.
T	getPoolable() Get the Poolable object represented by this SlotInfo instance.
long	getStamp() Get the stamp value that has been set on this SlotInfo, or 0 if none has been set since the Poolable was allocated.
int	randomInt() Produce a random int number.
void	setStamp(long stamp) Set the stamp value on this SlotInfo.

Method Detail

getAgeMillis

long getAgeMillis()

Get the approximate number of milliseconds that have transpired since the object was allocated.

Returns:

The age of the object in milliseconds.

getClaimCount

long getClaimCount()

Get the number of times the object has been claimed since it was allocated.

Returns:

The objects claim count.

getPoolable

T getPoolable()

Get the Poolable object represented by this SlotInfo instance.

Warning

Do not release() Poolables from within an Expiration — doing so is a user error, and the behaviour of the pool in such a situation is unspecified and implementation specific. This means that dead-locks and infinite loops are possible outcomes as well.

Warning

Also note that accessing the Poolable through this method, from your Expiration implementation, is a potentially concurrent access. This means that you need to take thread-safety issues into consideration - especially if you intend on manipulating the Poolable. In particular, you might be racing with other threads that are checking if this Poolable is expired or not, and they might even have claimed the Poolable and put it to use, by the time it is returned from this method.

Returns:

The Poolable being examined for validity. Never null.

randomInt

int randomInt()

Produce a random int number. This is useful for introducing spread, if the Expiration would otherwise have a tendency to cluster expirations close together in time, thereby causing the pool to suddenly have very few objects because of mass expirations.

Putting this method on SlotInfo might seem weird at first, but it allows the implementation to have very little contention. This is important on Java versions that don’t have ThreadLocalRandom.

Returns:

A pseudo-random 32 bit integer.

getStamp

long getStamp()

Get the stamp value that has been set on this SlotInfo, or 0 if none has been set since the Poolable was allocated.

Apart from the zero-value, the actual meaning of this value is completely up to the Expiration that sets it.

Returns:

The current stamp value.

setStamp

void setStamp(long stamp)

Set the stamp value on this SlotInfo.

This method is only thread-safe to call from within the scope of the Expiration.hasExpired(SlotInfo) method.

The stamp value is 0 by default, if it has not been set after the Poolable has been allocated. Its meaning is otherwise up to the particular Expiration that might use it.

Parameters:

stamp - The new stamp value.