LRUCache.CacheEntry

java.lang.Object
- jdbm.helper.LRUCache.CacheEntry

Enclosing class:: LRUCache<K,V>

private class LRUCache.CacheEntry
extends java.lang.Object

Field Summary

Fields
Modifier and Type	Field and Description
`private long`	`endVersion` End of valid range.
`private int`	`hashIndex` hash index of the key
`private K`	`key` identifier of the entry
`(package private) int`	`lruid` id of lru this cache entry lives on
`private ExplicitList.Link<LRUCache.CacheEntry>`	`lruLink` Used to put on lru list
`(package private) boolean`	`neverReplace` true if entry should not be replaced
`private int`	`numWaiters` Number of waiters waiting on state change
`private long`	`startVersion` Starting version for which entry is valid
`private LRUCache.EntryState`	`state` Current state
`private java.util.concurrent.locks.Condition`	`stateCondition` Used when waiting on being initialized entries
`private V`	`value` value of the entry
`private ExplicitList.Link<LRUCache.CacheEntry>`	`versionsLink` Used to build a sorted chain of versions with the most current entry at the head

Constructor Summary

Constructors
Constructor and Description

CacheEntry(int lruid)

Constructors
Constructor and Description
`CacheEntry(int lruid)`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`boolean`	`anyWaiters()`
`void`	`bumpWaiters()`
`boolean`	`canReadFrom(long readVersion)` Checks if read for the given version can be satisfied from the entry
`void`	`clearNeverReplace()`
`void`	`decrementWaiters()`
`long`	`getEndVersion()`
`int`	`getHashIndex()`
`K`	`getKey()`
`LRUCache.LRU`	`getLru()`
`ExplicitList.Link<LRUCache.CacheEntry>`	`getLruLink()`
`long`	`getStartVersion()`
`LRUCache.EntryState`	`getState()`
`java.util.concurrent.locks.Condition`	`getStateCondition(java.util.concurrent.locks.Lock lock)`
`V`	`getValue()`
`ExplicitList.Link<LRUCache.CacheEntry>`	`getVersionsLink()`
`void`	`initialize(K key)` inits the fields..used after a cache entry is replaced
`boolean`	`isCurrentVersion()` Check if entry is the most recent version for its key
`boolean`	`isEntryFreeable()`
`boolean`	`isNeverReplace()`
`void`	`setAsCurrentVersion(V newValue, long startVersion)`
`void`	`setAsSnapshotVersion(long newEndVersion)`
`void`	`setNeverReplace()`
`void`	`setState(LRUCache.EntryState newState)`
`java.lang.String`	`toString()`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail
- key
```
private K key
```
  identifier of the entry
- value
```
private V value
```
  value of the entry
- startVersion
```
private long startVersion
```
  Starting version for which entry is valid
- endVersion
```
private long endVersion
```
  End of valid range. endVersion == Long.MAX_VALUE iff entry current version
- hashIndex
```
private int hashIndex
```
  hash index of the key
- stateCondition
```
private java.util.concurrent.locks.Condition stateCondition
```
  Used when waiting on being initialized entries
- numWaiters
```
private int numWaiters
```
  Number of waiters waiting on state change
- state
```
private LRUCache.EntryState state
```
  Current state
- versionsLink
```
private ExplicitList.Link<LRUCache.CacheEntry> versionsLink
```
  Used to build a sorted chain of versions with the most current entry at the head
- lruLink
```
private ExplicitList.Link<LRUCache.CacheEntry> lruLink
```
  Used to put on lru list
- lruid
```
int lruid
```
  id of lru this cache entry lives on
- neverReplace
```
boolean neverReplace
```
  true if entry should not be replaced

Constructor Detail
- CacheEntry
```
public CacheEntry(int lruid)
```

Method Detail

initialize
```
public void initialize(K key)
```
inits the fields..used after a cache entry is replaced

Parameters:

key - new identifier for the entry

setNeverReplace
```
public void setNeverReplace()
```

clearNeverReplace
```
public void clearNeverReplace()
```

isNeverReplace
```
public boolean isNeverReplace()
```

getKey
```
public K getKey()
```

getValue
```
public V getValue()
```

getHashIndex
```
public int getHashIndex()
```

getLru
```
public LRUCache.LRU getLru()
```

getStateCondition

public java.util.concurrent.locks.Condition getStateCondition(java.util.concurrent.locks.Lock lock)

bumpWaiters
```
public void bumpWaiters()
```

decrementWaiters
```
public void decrementWaiters()
```

anyWaiters
```
public boolean anyWaiters()
```

getEndVersion
```
public long getEndVersion()
```

getStartVersion
```
public long getStartVersion()
```

isCurrentVersion
```
public boolean isCurrentVersion()
```
Check if entry is the most recent version for its key

Returns:

true if entry is current

canReadFrom
```
public boolean canReadFrom(long readVersion)
```
Checks if read for the given version can be satisfied from the entry

Parameters:

readVersion -

Returns:

true if

getState
```
public LRUCache.EntryState getState()
```

setState

public void setState(LRUCache.EntryState newState)

getVersionsLink

public ExplicitList.Link<LRUCache.CacheEntry> getVersionsLink()

getLruLink

public ExplicitList.Link<LRUCache.CacheEntry> getLruLink()

setAsCurrentVersion

public void setAsCurrentVersion(V newValue,
                                long startVersion)

setAsSnapshotVersion

public void setAsSnapshotVersion(long newEndVersion)

isEntryFreeable
```
public boolean isEntryFreeable()
```

toString
```
public java.lang.String toString()
```
Overrides:

toString in class java.lang.Object

Class LRUCache.CacheEntry

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

key

value

startVersion

endVersion

hashIndex

stateCondition

numWaiters

state

versionsLink

lruLink

lruid

neverReplace

Constructor Detail

CacheEntry

Method Detail

initialize

setNeverReplace

clearNeverReplace

isNeverReplace

getKey

getValue

getHashIndex

getLru

getStateCondition

bumpWaiters

decrementWaiters

anyWaiters

getEndVersion

getStartVersion

isCurrentVersion

canReadFrom

getState

setState

getVersionsLink

getLruLink

setAsCurrentVersion

setAsSnapshotVersion

isEntryFreeable

toString