# Freeze::Evictor

## Overview

### local interface Evictor extends ::Ice::ServantLocator

An automatic Ice object persistence manager, based on the evictor pattern. The evictor is a servant locator implementation that stores the persistent state of its objects in a database. Any number of objects can be registered with an evictor, but only a configurable number of servants are active at a time. These active servants reside in a queue; the least recently used servant in the queue is the first to be evicted when a new servant is activated.

#### Derived Classes and Interfaces

BackgroundSaveEvictor
TransactionalEvictor

#### See Also

ServantInitializer

## Operation Index

setSize
  Set the size of the evictor's servant queue.
getSize
  Get the size of the evictor's servant queue.
add
  Add a servant to this evictor.
addFacet
  Like add, but with a facet.
remove
  Permanently destroy an Ice object.
removeFacet
  Like remove, but with a facet.
hasObject
  Returns true if the given identity is managed by the evictor with the default facet.
hasFacet
  Like hasObject, but with a facet.
getIterator
  Get an iterator for the identities managed by the evictor.

## Operations

### void setSize(int sz)

Set the size of the evictor's servant queue. This is the maximum number of servants the evictor keeps active. Requests to set the queue size to a value smaller than zero are ignored.

#### Parameters

sz
  The size of the servant queue. If the evictor currently holds more than `sz` servants in its queue, it evicts enough servants to match the new size. Note that this operation can block if the new queue size is smaller than the current number of servants that are servicing requests. In this case, the operation waits until a sufficient number of servants complete their requests.

#### Exceptions

EvictorDeactivatedException
  Raised if a the evictor has been deactivated.

#### See Also

getSize

### int getSize()

Get the size of the evictor's servant queue.

#### Return Value

The size of the servant queue.

#### Exceptions

EvictorDeactivatedException
  Raised if a the evictor has been deactivated.

#### See Also

setSize

### Object* add(Object servant, ::Ice::Identity id)

Add a servant to this evictor. The state of the servant passed to this operation will be saved in the evictor's persistent store.

#### Parameters

servant
  The servant to add.
id
  The identity of the Ice object that is implemented by the servant.

#### Return Value

A proxy that matches the given identity and this evictor's object adapter.

#### Exceptions

::Ice::AlreadyRegisteredException
  Raised if the evictor already has an object with this identity.
DatabaseException
  Raised if a database failure occurred.
EvictorDeactivatedException
  Raised if the evictor has been deactivated.

#### See Also

addFacet
remove
removeFacet

### Object* addFacet(Object servant, ::Ice::Identity id, string facet)

Like add, but with a facet. Calling `add(servant, id)` is equivalent to calling addFacet with an empty facet.

#### Parameters

servant
  The servant to add.
id
  The identity of the Ice object that is implemented by the servant.
facet
  The facet. An empty facet means the default facet.

#### Return Value

A proxy that matches the given identity and this evictor's object adapter.

#### Exceptions

::Ice::AlreadyRegisteredException
  Raised if the evictor already has an object with this identity.
DatabaseException
  Raised if a database failure occurred.
EvictorDeactivatedException
  Raised if the evictor has been deactivated.

#### See Also

add
remove
removeFacet

### Object remove(::Ice::Identity id)

Permanently destroy an Ice object.

#### Parameters

id
  The identity of the Ice object.

#### Return Value

The removed servant.

#### Exceptions

::Ice::NotRegisteredException
  Raised if this identity was not registered with the evictor.
DatabaseException
  Raised if a database failure occurred.
EvictorDeactivatedException
  Raised if the evictor has been deactivated.

#### See Also

add
removeFacet

### Object removeFacet(::Ice::Identity id, string facet)

Like remove, but with a facet. Calling `remove(id)` is equivalent to calling removeFacet with an empty facet.

#### Parameters

id
  The identity of the Ice object.
facet
  The facet. An empty facet means the default facet.

#### Return Value

The removed servant.

#### Exceptions

::Ice::NotRegisteredException
  Raised if this identity was not registered with the evictor.
DatabaseException
  Raised if a database failure occurred.
EvictorDeactivatedException
  Raised if the evictor has been deactivated.

#### See Also

remove
addFacet

### bool hasObject(::Ice::Identity id)

Returns true if the given identity is managed by the evictor with the default facet.

#### Return Value

true if the identity is managed by the evictor, false otherwise.

#### Exceptions

DatabaseException
  Raised if a database failure occurred.
EvictorDeactivatedException
  Raised if a the evictor has been deactivated.

### bool hasFacet(::Ice::Identity id, string facet)

Like hasObject, but with a facet. Calling `hasObject(id)` is equivalent to calling hasFacet with an empty facet.

#### Return Value

true if the identity is managed by the evictor for the given facet, false otherwise.

#### Exceptions

DatabaseException
  Raised if a database failure occurred.
EvictorDeactivatedException
  Raised if a the evictor has been deactivated.

### EvictorIterator getIterator(string facet, int batchSize)

Get an iterator for the identities managed by the evictor.

#### Parameters

facet
  The facet. An empty facet means the default facet.
batchSize
  Internally, the Iterator retrieves the identities in batches of size batchSize. Selecting a small batchSize can have an adverse effect on performance.

#### Return Value

A new iterator.

#### Exceptions

EvictorDeactivatedException
  Raised if a the evictor has been deactivated.