Stroika::Foundation::Cache Namespace Reference

Namespaces
namespace	LRUCacheSupport
namespace	TimedCacheSupport

Classes
class	BloomFilter
	a Bloom filter is a probablistic set, which returns either "probably in set" or "definitely not in set" More...
class	LRUCache
	LRUCache implements a simple least-recently-used caching strategy, with optional hashing (of keys) to make it faster. More...
class	Memoizer
	Cache the results of expensive computations transparently. More...
class	TimedCache
	Keep track of a bunch of objects, each with an associated time used to allow data to 'expire'. More...

Concepts
concept	IKey
	A KEY is any copyable value (or the sentinal type void - indicating a keyless - single valued - cache)
concept	IValue
	any copyable type can use used as the value, or the special sentinal type - ValuelessSentinalType, used to indicate we are just caching presence/absense of the KEY in the cache (and its expiration date).
concept	ICache
	Check if the argument CACHE is a valid 'stroika cache' class, following its api.

Typedefs
using	NonKeyedKeySentinalType = void
	This sentinal value can be used as the KEY type for a Cache to indicate it is un-keyed, and there is just one.
using	ValuelessSentinalType = void
	This sentinal value can be used as the VALUE type for a Cache to indicate it just stores ONLY the KEYS (and sometimes related time/expiration) information.
template<typename KEY , typename VALUE , LRUCacheSupport::ITraits< KEY, VALUE > TRAITS = LRUCacheSupport::DefaultTraits<KEY, VALUE>>
using	SynchronizedLRUCache = LRUCache< KEY, VALUE, LRUCacheSupport::InternallySynchronizedTraits< TRAITS > >
template<typename KEY , typename VALUE , TimedCacheSupport::ITraits< KEY, VALUE > TRAITS = TimedCacheSupport::DefaultTraits<KEY, VALUE>>
using	SynchronizedTimedCache = TimedCache< KEY, VALUE, TimedCacheSupport::InternallySynchronizedTraits< TRAITS > >
	SynchronizedTimedCache just adds eInternallySynchronized to a regular 'TimedCache' (just short-hand).

Variables
template<typename KEY >
static constexpr bool	IKeyedCache = not same_as<KEY, NonKeyedKeySentinalType>
	does this cache have a KEY type (overwhelming YES, but sometimes handy to have 'singleton' cache, where you cache something, but just one of them)
template<typename VALUE >
static constexpr bool	IValuelessCache = same_as<VALUE, ValuelessSentinalType>
	Some caches (rare) only support a KEY, with no associated value (the value is stored INSIDE the key itself)

Detailed Description

Note

Code-Status: Beta

 \file

Note

Code-Status: Beta

TODO:

Also somewhat related, _Last usage is C++ unconvnetional - though maybe OK. If not more awkward in impl, consider using _fEnd? Or if it is (I think last maybe better then document clearly why its better.

Note

Code-Status: Beta

TODO:

 \file

Note

Code-Status: Beta

TODO:

AND RELATED cleanup to spec using InOrderComparerType - as opposed to EQUALS COMPARER or other stuff like HashFunctions! MAYBE LOSE inorder comparer arg - and INSTEAD have template / template for creating container (for now its map<>??)

Implementation Note:

This module uses stl:map<> instead of a Stroika Mapping since we are comfortable with
the current implementation using btree's, and to avoid any dependencies between
Caching and Containers. We may want to re-think that, and just  use Mapping here.

Typedef Documentation

ValuelessSentinalType

using Stroika::Foundation::Cache::ValuelessSentinalType = typedef void

This sentinal value can be used as the VALUE type for a Cache to indicate it just stores ONLY the KEYS (and sometimes related time/expiration) information.

Also, this can be used like KeyedCollection - where the main object acts like a KEY and value at the same time (often just internally has a KEY field).

Definition at line 45 of file Foundation/Cache/Common.h.

SynchronizedLRUCache

template<typename KEY , typename VALUE , LRUCacheSupport::ITraits< KEY, VALUE > TRAITS = LRUCacheSupport::DefaultTraits<KEY, VALUE>>

using Stroika::Foundation::Cache::SynchronizedLRUCache = typedef LRUCache<KEY, VALUE, LRUCacheSupport::InternallySynchronizedTraits<TRAITS> >

DEPRECATED CLASS TEMPLATES

Definition at line 494 of file LRUCache.inl.

SynchronizedTimedCache

template<typename KEY , typename VALUE , TimedCacheSupport::ITraits< KEY, VALUE > TRAITS = TimedCacheSupport::DefaultTraits<KEY, VALUE>>

using Stroika::Foundation::Cache::SynchronizedTimedCache = typedef TimedCache<KEY, VALUE, TimedCacheSupport::InternallySynchronizedTraits<TRAITS> >

SynchronizedTimedCache just adds eInternallySynchronized to a regular 'TimedCache' (just short-hand).

Template Parameters

KEY
VALUE
TRAITS

Example Usage

Use TimedCache to avoid needlessly redundant lookups

optional<String> ReverseDNSLookup_ (const InternetAddress& inetAddr)
{
    static SynchronizedTimedCache<InternetAddress, optional<String>> sCache_;
    // Or could write like this
    static TimedCache<InternetAddress, optional<String>, TimedCacheSupport::InternallySynchronizedTraits<TimedCacheSupport::DefaultTraits<InternetAddress, optional<String>>>> sCache2_;
    return sCache_.LookupValue (inetAddr, [] (const InternetAddress& inetAddr) {
        return DNS::kThe.ReverseLookup (inetAddr);
    });
}

Note

this CAN be done pretty easily without defining SynchronizedTimedCache (e.g. InternallySynchronizedTraits), but this is enough more terse and common enough to be useful.

Definition at line 1171 of file TimedCache.h.

Variable Documentation

IValuelessCache

template<typename VALUE >

constexpr bool Stroika::Foundation::Cache::IValuelessCache = same_as<VALUE, ValuelessSentinalType>

staticconstexpr

Some caches (rare) only support a KEY, with no associated value (the value is stored INSIDE the key itself)

Example Usage:

Definition at line 61 of file Foundation/Cache/Common.h.