OSB_LIB::PersProductCache Class Reference

Collaboration diagram for OSB_LIB::PersProductCache:

Detailed Description

Cache for personalised products.

This class stores the assignment of resources to personalised products in memory.
The validity of a cached entry is verified after cacheTime_ seconds have elapsed since the entry was read from the database. The flag useLocks_ determines if the cache is used in a multi-thread application and must locks its data structures.

Internally the cache uses 3 STL containers:
PersProductCache::Keys stored the assignment of resources to pers. products. For one pers. product multiple keys can exist.

PersProductCache::Queue keeps the most recently used (MRU) pers. products at its begin.
If the cache size is exceeded, the least recently used entries are evicted.

PersProductCache::PersProducts stored the pers. personalized products.
For efficient cache maintenance, an entry stores the links to its keys and its position in the MRU queue.

Definition at line 77 of file persproductcache.h.

Public Member Functions

PersProductCache (bool useLocks)
Constructor with maximum chache size.
~PersProductCache ()
Default d'tor.
void setMaxSize (long maxSize)
Set the maximum cache size.
void setCacheTime (long cacheTime)
Set the cache time in seconds.
ReadGuard< PersProduct * > find (const OSB_DB::Session &session, const ResourceKey &resourceKey, const DateTime &timestamp)
Find the personalized product of a resource.
void logStats () const
Print cache statistics to Log.

Private Types

typedef std::map< PersProduct::Oid,
Entry * > PersProducts
Container of personalised product and it's related information.
typedef std::map< Key, PersProduct::Oid > Keys
Map of resources to pers. products.
typedef std::list< PersProduct::Oid > Queue
MRU queue of pers. product ids.
ppFound = 0
Pers. product found.
ppNotFound
Pers. product not found.
enum GuardStatus { ppFound = 0, ppNotFound }
Status of the pers. product guard. More...

Private Member Functions

PersProductCache (const PersProductCache &)
Prevent copying: not implemented.
PersProductCache & operator= (PersProductCache &)
Prevent assignment: not implemented.
Entry * find (const Key &key)
Get an existing entry.
Entry * load (const OSB_DB::Session &session, Key &key, const DateTime &timestamp, bool isReload)
Load data for a key from the database.
Entry * add (Key &key, const PersProduct &persProduct)
Add a resource and pers. product to the cache.
Entry * addMiss (const OSB_DB::Session &session, Key &key, const DateTime &timestamp)
Add an entry for which no assignment exits.
void addKey (Entry *entry, Key &key)
Add a resource for a pers. product.
void remove (const PersProduct::Oid &ppId, bool force)
Remove a pers. product from the cache.
void adjustSize ()
Adjust the cache size.

Private Attributes

PersProducts persProducts_
Pers. product and related information by id.
Keys resources_
Resource key and time to pers product id.
Queue queue_
Queue with MRU pers. products at the begin.
bool useLocks_
Flag to use locks or not.
unsigned long maxSize_
Maximum size of the cache.
long cacheTime_
Number of seconds a cached pers. product is considered valid.
long nextMiss_
Next id to use for non-existing assignments.
Mutex mutex_
Mutex to protect the cache.
MutexUnlock unlock_
Object to unlock the cache.
Stats stats_
Cache statistics.

Classes

class Entry
Chache entry for one pers. product. More...
struct Key
Key for the map resource -> pers. product id. More...
struct Stats
Structure for cache statistics. More...

Member Typedef Documentation

typedef std::map<Key, PersProduct::Oid> OSB_LIB::PersProductCache::Keys [private]

Map of resources to pers. products.

The container links the resource key and assignment period to the pers. product who owned the resource during this time.

Definition at line 213 of file persproductcache.h.

typedef std::map<PersProduct::Oid, Entry*> OSB_LIB::PersProductCache::PersProducts [private]

Container of personalised product and it's related information.

This is the most important container. For a pers. product id (key), it keeps a pointer to the pers. product and other info. If an entry is added or deleted to/from this container, the other two containers are updated as well.

Definition at line 129 of file persproductcache.h.

typedef std::list<PersProduct::Oid> OSB_LIB::PersProductCache::Queue [private]

MRU queue of pers. product ids.

Definition at line 218 of file persproductcache.h.

Member Enumeration Documentation

enum OSB_LIB::PersProductCache::GuardStatus [private]

Status of the pers. product guard.

Enumerator:

ppFound	Pers. product found.
ppNotFound	Pers. product not found.

Definition at line 142 of file persproductcache.h.

Constructor & Destructor Documentation

OSB_LIB::PersProductCache::PersProductCache ( bool useLocks ) [explicit]

Constructor with maximum chache size.

OSB_LIB::PersProductCache::~PersProductCache ( )

Default d'tor.

OSB_LIB::PersProductCache::PersProductCache ( const PersProductCache & ) [private]

Prevent copying: not implemented.

Member Function Documentation

Entry* OSB_LIB::PersProductCache::add	(	Key &	key,
		const PersProduct &	persProduct
	)			`[private]`

Add a resource and pers. product to the cache.

void OSB_LIB::PersProductCache::addKey	(	Entry *	entry,
		Key &	key
	)			`[private]`

Add a resource for a pers. product.

Entry* OSB_LIB::PersProductCache::addMiss	(	const OSB_DB::Session &	session,
		Key &	key,
		const DateTime &	timestamp
	)			`[private]`

Add an entry for which no assignment exits.

void OSB_LIB::PersProductCache::adjustSize ( ) [private]

Adjust the cache size.

Entry* OSB_LIB::PersProductCache::find ( const Key & key ) [private]

Get an existing entry.

ReadGuard<PersProduct*> OSB_LIB::PersProductCache::find	(	const OSB_DB::Session &	session,
		const ResourceKey &	resourceKey,
		const DateTime &	timestamp
	)

Find the personalized product of a resource.

Parameters:

	session	Database session to use.
	resourceKey	Resource to find.
	timestamp	Date and time for which to find the pers. product.

Exceptions:

	OsbException	if pers. product can not be read from the database.
	OsbException	in case of an internal error.

Returns:: A read guard to the pers. product that owns resourceKey at timestamp.
If no matching pers. product exists in the database, its pointer is 0 and the status is ppNotFound.