---
name: "ACE_FIFO_Caching_Strategy"
section: "3"
platform: "linux"
package: "libace-doc"
version: "5.0.7-4"
release: "Debian 2.2 (Potato)"
platforms: ["linux"]
url: "https://new.carta.tech/ACE_FIFO_Caching_Strategy"
---

# ACE\_FIFO\_Caching\_Strategy(3)

The First In First Out strategy is implemented wherein each item is ordered.

## NAME

ACE\_FIFO\_Caching\_Strategy -  The First In First Out strategy is implemented wherein each item is ordered.

## SYNOPSIS

```
#include <ace/Caching_Strategies_T.h>
template<class ATTRIBUTES, class CACHING_UTILITY>
class ACE_FIFO_Caching_Strategy
{
  public:
    typedef ATTRIBUTES CACHING_ATTRIBUTES;
    ACE_FIFO_Caching_Strategy (void);
    ATTRIBUTES attributes (void);
    double purge_percent (void);
    void purge_percent (double percentage);
    int notify_bind (int result, const ATTRIBUTES &attr);
    int notify_find (int result, ATTRIBUTES &attr);
    int notify_unbind (int result, const ATTRIBUTES &attr);
    int notify_trybind (int result, ATTRIBUTES &attr);
    int notify_rebind (int result, const ATTRIBUTES &attr);
    CACHING_UTILITY &caching_utility (void);
    void dump (void) const;
  private:
    ATTRIBUTES order_;
    double purge_percent_;
    CACHING_UTILITY caching_utility_;
};
```

## DESCRIPTION

The order tag of each item is used to decide the item to be removed from the cache. The items with least order are removed.

Explanation of the template parameter list: CONTAINER is any map with entries of type KEY, VALUE. The ATTRIBUTES are the deciding factor for purging of entries and should logically be included with the VALUE. Some ways of doing this are: As being a member of the VALUE or VALUE being ACE\_Pairx, ATTRIBUTES. The CACHING\_UTILITY is the class which can be plugged in and which decides the entries to purge.

## Initialisation and termination.

```
ACE_FIFO_Caching_Strategy (void);
```

The container is the map in which the entries reside.  The timer attribute is initialed to zero in this constructor.  And the purge\_percent field denotes the percentage of the entries in the cache which can be purged automagically and by default is set to 10%.

## Strategy methods.

```
ATTRIBUTES attributes (void);
```

Accessor method.

## Accessor methods for the percentage of entries to purge.

```
double purge_percent (void);
```

```
void purge_percent (double percentage);
```

\=  Strategy related Operations

```
int notify_bind (int result, const ATTRIBUTES &attr);
```

Notification for an item getting bound into the cache.

```
int notify_find (int result, ATTRIBUTES &attr);
```

This method acts as a notification about the CONTAINERs find method call

```
int notify_unbind (int result, const ATTRIBUTES &attr);
```

This method acts as a notification about the CONTAINERs unbind method call

```
int notify_trybind (int result, ATTRIBUTES &attr);
```

This method acts as a notification about the CONTAINERs trybind method call

```
int notify_rebind (int result, const ATTRIBUTES &attr);
```

Notification for an item getting bound again into the cache.

```
CACHING_UTILITY &caching_utility (void);
```

Purge the cache.

```
void dump (void) const;
```

Dumps the state of the object.

## AUTHOR

Kirthika Parameswaran kirthika@cs.wustl.edu

## LIBRARY

ace