com.trivago.triava.tcache

Class AccessTimeObjectHolder<V>

java.lang.Object

com.trivago.triava.tcache.AccessTimeObjectHolder<V>

Type Parameters:

V - The value type

All Implemented Interfaces:

TCacheHolder<V>, Serializable

public final class AccessTimeObjectHolder<V>
extends Object
implements TCacheHolder<V>

Represents a Cache entry with associated metadata. This cache entry is valid as long as data != null

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
AccessTimeObjectHolder(V value, CacheWriteMode writeMode) Construct a holder.
AccessTimeObjectHolder(V value, long maxIdleTimeMillis, long maxCacheTimeSecs, CacheWriteMode writeMode)

Method Summary

Modifier and Type	Method and Description
V	get() Returns the value, that this holder holds.
long	getCreationTime() Returns the creation time of this holder, given in ms since EPOCH.
long	getExpirationTime() Returns the expiration time, given in ms since EPOCH.
long	getLastAccessTime() Returns the last access time, given in MILLISECONDS since EPOCH
int	getUseCount() Returns the number of times this holder was accessed.
void	incrementUseCount()
boolean	isInvalid() Returns whether this holder is valid.
static boolean	isValid(AccessTimeObjectHolder<?> holder) Returns whether the holder is valid.
V	peek() Returns the value, that this holder holds.
protected boolean	release() Releases all references to objects that this holder holds.
void	setExpireUntil(int maxDelay, TimeUnit timeUnit, Random random) |-------------- maxCacheTimeMillis --------------| | | |--- newMaxCacheTimeMillis ---| | | | | -|---------|-------------------|------------------|------------------------------------- time | | | | | now now + delayMillis | | = expirationOnNewExpireUntil | | | inputDate + baseTimeMillis = creationTime creationTime + maxCacheTime
void	setMaxIdleTime(int idleTime, TimeUnit timeUnit)
String	toString()
void	updateMaxIdleTime(long idleTimeMillis) Prolongs the maxIdleTime by the given idleTime. 0 means immediate expiration, -1 means to not change anything, any positive value is the prolongation in seconds.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

AccessTimeObjectHolder

public AccessTimeObjectHolder(V value,
                              CacheWriteMode writeMode)
                       throws javax.cache.CacheException

Construct a holder. The holder will be incomplete and not accessible by cache users, until you call complete(long, long)

Parameters:

value - The value to store in this holder

writeMode - The CacheWriteMode that defines how to serialize the data

Throws:

javax.cache.CacheException - when there is a problem serializing the value

AccessTimeObjectHolder

public AccessTimeObjectHolder(V value,
                              long maxIdleTimeMillis,
                              long maxCacheTimeSecs,
                              CacheWriteMode writeMode)
                       throws javax.cache.CacheException

Throws:

javax.cache.CacheException

Method Detail

isValid

public static boolean isValid(AccessTimeObjectHolder<?> holder)

Returns whether the holder is valid. It must be non-null and not expired.

Parameters:

holder - The holder to check

Returns:

true if the holder is valid

release

protected boolean release()

Releases all references to objects that this holder holds. This makes sure that the data object can be collected by the GC, even if the holder would still be referenced by someone.

This is the end-of-life for the instance, and isInvalid() yields true from now on. If a reference to this holder is stored for a longer time, a Thread should check isInvalid().

Returns:

true, if the call has released the holder. false, if the holder was already released before.

setMaxIdleTime

public void setMaxIdleTime(int idleTime,
                           TimeUnit timeUnit)

updateMaxIdleTime

public void updateMaxIdleTime(long idleTimeMillis)

Prolongs the maxIdleTime by the given idleTime. 0 means immediate expiration, -1 means to not change anything, any positive value is the prolongation in seconds.

Parameters:

idleTimeMillis - The time for prolong in milliseconds. See description for the special values 0 and -1.

getExpirationTime

public long getExpirationTime()

Description copied from interface: TCacheHolder

Returns the expiration time, given in ms since EPOCH.

Specified by:

getExpirationTime in interface TCacheHolder<V>

Returns:

The expiration time in ms

get

public V get()

Returns the value, that this holder holds. Statistics effects: Updates the access time and the use count.

TODO The use count is not yet updated here. This makes behavior inconsistent, e.g. in the iterator

Specified by:

get in interface TCacheHolder<V>

Returns:

The value

peek

public V peek()

Description copied from interface: TCacheHolder

Returns the value, that this holder holds. This method differs from TCacheHolder.get() in that peek has no side effects on entry statistics.

Specified by:

peek in interface TCacheHolder<V>

Returns:

The value

getLastAccessTime

public long getLastAccessTime()

Description copied from interface: TCacheHolder

Returns the last access time, given in MILLISECONDS since EPOCH

Specified by:

getLastAccessTime in interface TCacheHolder<V>

Returns:

the last access time

getUseCount

public int getUseCount()

Description copied from interface: TCacheHolder

Returns the number of times this holder was accessed.

Specified by:

getUseCount in interface TCacheHolder<V>

Returns:

the use count

incrementUseCount

public void incrementUseCount()

getCreationTime

public long getCreationTime()

Description copied from interface: TCacheHolder

Returns the creation time of this holder, given in ms since EPOCH. The creation time represents the time the holder was put into the cache. Any put including replacing an existing entry will create a new holder with the current time as creation time.

Specified by:

getCreationTime in interface TCacheHolder<V>

Returns:

The creation time in ms

isInvalid

public boolean isInvalid()

Description copied from interface: TCacheHolder

Returns whether this holder is valid. A formerly valid holder can become invalid when it expires, and this method reflects that: An expired holder is invalid.

Specified by:

isInvalid in interface TCacheHolder<V>

Returns:

true if it is invalid. This includes expired holders.

setExpireUntil

public void setExpireUntil(int maxDelay,
                           TimeUnit timeUnit,
                           Random random)

   |-------------- maxCacheTimeMillis --------------|
   |                                                |
   |--- newMaxCacheTimeMillis ---|                  |
   |                             |                  |
  -|---------|-------------------|------------------|------------------------------------- time
   |         |                   |                  |
   |         now                 now + delayMillis  |
   |                  = expirationOnNewExpireUntil  |
   |                                                |
   inputDate + baseTimeMillis = creationTime        creationTime + maxCacheTime
 

Parameters:

maxDelay - The maximum delay time until the object will be expired

timeUnit - The time unit for maxDelay

random - The random generator to use

toString

public String toString()

Overrides:

toString in class Object