TransactionalCache (Alfresco Repository)

java.lang.Object
- org.alfresco.repo.cache.TransactionalCache

All Implemented Interfaces:

org.alfresco.repo.cache.SimpleCache, TransactionListener, org.springframework.beans.factory.InitializingBean
```
public class TransactionalCache
extends java.lang.Object
implements org.alfresco.repo.cache.SimpleCache, TransactionListener, org.springframework.beans.factory.InitializingBean
```
A 2-level cache that mainains both a transaction-local cache and wraps a non-transactional (shared) cache.
It uses the Ehcache Cache for it's per-transaction caches as these provide automatic size limitations, etc.
Instances of this class do not require a transaction. They will work directly with the shared cache when no transaction is present. There is virtually no overhead when running out-of-transaction.
The first phase of the commit ensures that any values written to the cache in the current transaction are not already superceded by values in the shared cache. In this case, the transaction is failed for concurrency reasons and will have to retry. The second phase occurs post-commit. We are sure that the transaction committed correctly, but things may have changed in the cache between the commit and post-commit. If this is the case, then the offending values are merely removed from the shared cache.
When the cache is cleared, a flag is set on the transaction. The shared cache, instead of being cleared itself, is just ignored for the remainder of the tranasaction. At the end of the transaction, if the flag is set, the shared transaction is cleared before updates are added back to it.
Because there is a limited amount of space available to the in-transaction caches, when either of these becomes full, the cleared flag is set. This ensures that the shared cache will not have stale data in the event of the transaction-local caches dropping items. It is therefore important to size the transactional caches correctly.

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class TransactionalCache.CacheRegionKey

Nested Classes
Modifier and Type	Class and Description
`static class`	`TransactionalCache.CacheRegionKey`

Constructor Summary

Constructors
Constructor and Description

TransactionalCache()
Public constructor.

Constructors
Constructor and Description
`TransactionalCache()` Public constructor.

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`afterCommit()` Merge the transactional caches into the shared cache
`void`	`afterPropertiesSet()` Ensures that all properties have been set
`void`	`afterRollback()` Transfers cache removals or clears.
`void`	`beforeCommit(boolean readOnly)` Merge the transactional caches into the shared cache
`void`	`beforeCompletion()` NO-OP
`void`	`clear()` Clears out all the caches.
`boolean`	`contains(java.io.Serializable key)` Checks the transactional removed and updated caches before checking the shared cache.
`boolean`	`equals(java.lang.Object obj)`
`void`	`flush()` NO-OP
`java.lang.Object`	`get(java.io.Serializable keyIn)` Checks the per-transaction caches for the object before going to the shared cache.
`java.util.Collection`	`getKeys()` The keys returned are a union of the set of keys in the current transaction and those in the backing cache.
`int`	`hashCode()`
`void`	`put(java.io.Serializable keyIn, java.lang.Object value)` Goes direct to the shared cache in the absence of a transaction.
`void`	`remove(java.io.Serializable keyIn)` Goes direct to the shared cache in the absence of a transaction.
`void`	`setAllowEqualsChecks(boolean allowEqualsChecks)` Allow equality checking of values before they are written to the shared cache on commit.
`void`	`setDisableSharedCache(boolean disableSharedCache)` Set whether values must be written through to the shared cache or not
`void`	`setDisableSharedCacheReadForTransaction(boolean noSharedCacheRead)` Transaction-long setting to force all the share cache to be bypassed for the current transaction.
`void`	`setMaxCacheSize(int maxCacheSize)` Set the maximum number of elements to store in the update and remove caches.
`void`	`setMutable(boolean isMutable)`
`void`	`setName(java.lang.String name)` Set the name that identifies this cache from other instances.
`void`	`setSharedCache(org.alfresco.repo.cache.SimpleCache sharedCache)` Set the shared cache to use during transaction synchronization or when no transaction is present.
`void`	`setTenantAware(boolean isTenantAware)`
`java.lang.String`	`toString()`

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

- Constructor Detail
  - TransactionalCache
```
public TransactionalCache()
```
    Public constructor.
- Method Detail
  - toString
```
public java.lang.String toString()
```
    Overrides:
    
    toString in class java.lang.Object
    
    See Also:
    TransactionalCache.setName(String)
  - equals
```
public boolean equals(java.lang.Object obj)
```
    Overrides:
    
    equals in class java.lang.Object
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class java.lang.Object
  - setSharedCache
```
public void setSharedCache(org.alfresco.repo.cache.SimpleCache sharedCache)
```
    Set the shared cache to use during transaction synchronization or when no transaction is present.
    
    Parameters:
    sharedCache - underlying cache shared by transactions
  - setDisableSharedCache
```
public void setDisableSharedCache(boolean disableSharedCache)
```
    Set whether values must be written through to the shared cache or not
    
    Parameters:
    disableSharedCache - true to prevent values from being written to the shared cache
  - setMutable
```
public void setMutable(boolean isMutable)
```
    Parameters:
    isMutable - true if the data stored in the cache is modifiable
  - setAllowEqualsChecks
```
public void setAllowEqualsChecks(boolean allowEqualsChecks)
```
    Allow equality checking of values before they are written to the shared cache on commit. This allows some caches to bypass unnecessary cache updates when the values remain unchanged. Typically, this setting should be applied only to mutable caches and only where the values being stored have a fast and reliable equality check.
    
    Parameters:
    allowEqualsChecks - true if value comparisons can be made between values stored in the transactional cache and those stored in the shared cache
  - setMaxCacheSize
```
public void setMaxCacheSize(int maxCacheSize)
```
    Set the maximum number of elements to store in the update and remove caches. The maximum number of elements stored in the transaction will be twice the value given.
    The removed list will overflow to disk in order to ensure that deletions are not lost.
    
    Parameters:
    maxCacheSize - maximum number of items to be held in-transaction
  - setName
```
public void setName(java.lang.String name)
```
    Set the name that identifies this cache from other instances.
  - setTenantAware
```
public void setTenantAware(boolean isTenantAware)
```
  - afterPropertiesSet
```
public void afterPropertiesSet()
                        throws java.lang.Exception
```
    Ensures that all properties have been set
    
    Specified by:
    
    afterPropertiesSet in interface org.springframework.beans.factory.InitializingBean
    
    Throws:
    
    java.lang.Exception
  - setDisableSharedCacheReadForTransaction
```
public void setDisableSharedCacheReadForTransaction(boolean noSharedCacheRead)
```
    Transaction-long setting to force all the share cache to be bypassed for the current transaction.
    This setting is like having a null shared cache, but only lasts for the transaction.
    Use this when a read transaction must see consistent and current data i.e. go to the database. While this is active, write operations will also not be committed to the shared cache.
    
    Parameters:
    noSharedCacheRead - true to avoid reading from the shared cache for the transaction
  - contains
```
public boolean contains(java.io.Serializable key)
```
    Checks the transactional removed and updated caches before checking the shared cache.
    
    Specified by:
    
    contains in interface org.alfresco.repo.cache.SimpleCache
  - getKeys
```
public java.util.Collection getKeys()
```
    The keys returned are a union of the set of keys in the current transaction and those in the backing cache.
    
    Specified by:
    
    getKeys in interface org.alfresco.repo.cache.SimpleCache
  - get
```
public java.lang.Object get(java.io.Serializable keyIn)
```
    Checks the per-transaction caches for the object before going to the shared cache. If the thread is not in a transaction, then the shared cache is accessed directly.
    
    Specified by:
    
    get in interface org.alfresco.repo.cache.SimpleCache
  - put
```
public void put(java.io.Serializable keyIn,
       java.lang.Object value)
```
    Goes direct to the shared cache in the absence of a transaction.
    Where a transaction is present, a cache of updated items is lazily added to the thread and the Object put onto that.
    
    Specified by:
    
    put in interface org.alfresco.repo.cache.SimpleCache
  - remove
```
public void remove(java.io.Serializable keyIn)
```
    Goes direct to the shared cache in the absence of a transaction.
    Where a transaction is present, a cache of removed items is lazily added to the thread and the Object put onto that.
    
    Specified by:
    
    remove in interface org.alfresco.repo.cache.SimpleCache
  - clear
```
public void clear()
```
    Clears out all the caches.
    
    Specified by:
    
    clear in interface org.alfresco.repo.cache.SimpleCache
  - flush
```
public void flush()
```
    NO-OP
    
    Specified by:
    
    flush in interface TransactionListener
  - beforeCompletion
```
public void beforeCompletion()
```
    NO-OP
    
    Specified by:
    
    beforeCompletion in interface TransactionListener
  - beforeCommit
```
public void beforeCommit(boolean readOnly)
```
    Merge the transactional caches into the shared cache
    
    Specified by:
    
    beforeCommit in interface TransactionListener
    
    Parameters:
    readOnly - true if the transaction is read-only
  - afterCommit
```
public void afterCommit()
```
    Merge the transactional caches into the shared cache
    
    Specified by:
    
    afterCommit in interface TransactionListener
  - afterRollback
```
public void afterRollback()
```
    Transfers cache removals or clears. This allows explicit cache cleanup to be propagated to the shared cache even in the event of rollback - useful if the cause of a problem is the shared cache value.
    
    Specified by:
    
    afterRollback in interface TransactionListener

Class TransactionalCache

Nested Class Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

TransactionalCache

Method Detail

toString

equals

hashCode

setSharedCache

setDisableSharedCache

setMutable

setAllowEqualsChecks

setMaxCacheSize

setName

setTenantAware

afterPropertiesSet

setDisableSharedCacheReadForTransaction

contains

getKeys

get

put

remove

clear

flush

beforeCompletion

beforeCommit

afterCommit

afterRollback