Class Table

Represents a table that stores cached items identified by keys

Inheritance
System.Object
Table
Implements
Inherited Members
System.Object.Equals(System.Object)
System.Object.Equals(System.Object, System.Object)
System.Object.GetHashCode()
System.Object.GetType()
System.Object.MemberwiseClone()
System.Object.ReferenceEquals(System.Object, System.Object)
System.Object.ToString()
Namespace: Azos.Data.Access.Cache
Assembly: Azos.dll
Syntax
public sealed class Table : INamed

Fields

BUCKET_COUNT_DEFAULT

Declaration
public const int BUCKET_COUNT_DEFAULT = 25111
Field Value
Type Description
System.Int32

MAX_AGE_SEC_DEFAULT

Declaration
public const int MAX_AGE_SEC_DEFAULT = 300
Field Value
Type Description
System.Int32

MAX_AGE_SEC_MINIMUM

Declaration
public const int MAX_AGE_SEC_MINIMUM = 5
Field Value
Type Description
System.Int32

REC_PER_PAGE_DEFAULT

Declaration
public const int REC_PER_PAGE_DEFAULT = 7
Field Value
Type Description
System.Int32

Properties

BucketCount

Returns how many slots/buckets are pre-allocated per table, the higher the number the more memory will be reserved at table construction time, every slot is a reference (4 bytes on 32bit systems, 8 bytes on 64bit). For optimal performance this number should be around 75% of total record count stored in the table (table load factor).

Declaration
public int BucketCount { get; }
Property Value
Type Description
System.Int32

BucketPageLoadFactor

Returns the ratio of how many buckets are loaded with pages vs. bucket count

Declaration
public double BucketPageLoadFactor { get; }
Property Value
Type Description
System.Double

Capacity

Returns the maximum number of items that this table can hold at any given time given that no items will have any key hash collisions

Declaration
public int Capacity { get; }
Property Value
Type Description
System.Int32

Count

Returns item count in the table

Declaration
public int Count { get; }
Property Value
Type Description
System.Int32

LockCount

Returns how many locks can be used for thread coordination during table changes

Declaration
public int LockCount { get; }
Property Value
Type Description
System.Int32

MaxAgeSec

Gets/sets maximum age of items in the table expressed in seconds. After this age is exceeded, the system will delete entries. The system does not guarantee that items will expire right on time, however it does guarantee that items will be available for at least this long.

Declaration
public int MaxAgeSec { get; set; }
Property Value
Type Description
System.Int32

Name

Returns table name which is a unique string within the cache store

Declaration
public string Name { get; }
Property Value
Type Description
System.String

PageCount

Returns page count in the table

Declaration
public int PageCount { get; }
Property Value
Type Description
System.Int32

ParallelSweep

When enabled, uses parallel execution while sweeping table buckets, otherwise sweeps sequentially (default behavior)

Declaration
public bool ParallelSweep { get; set; }
Property Value
Type Description
System.Boolean

RecPerPage

Returns how many slots are pre-allocated per table's bucket(page) when more than one item produces hash collision. The higher the number, the more primary hash collisions can be accomodated by re-hashing on pages (secondary hash table within primary buckets)

Declaration
public int RecPerPage { get; }
Property Value
Type Description
System.Int32

StatComplexHitCount

Returns hit count stats for using complex keys

Declaration
public int StatComplexHitCount { get; }
Property Value
Type Description
System.Int32

StatComplexMissCount

Returns miss count stats for using complex keys

Declaration
public int StatComplexMissCount { get; }
Property Value
Type Description
System.Int32

StatHitCount

Returns hit count stats

Declaration
public int StatHitCount { get; }
Property Value
Type Description
System.Int32

StatMissCount

Returns miss count stats

Declaration
public int StatMissCount { get; }
Property Value
Type Description
System.Int32

Store

Returns the store instance that this table is a part of

Declaration
public CacheStore Store { get; }
Property Value
Type Description
CacheStore

Methods

Get(UInt64, Int32)

Retrieves an item from this table by key where item age is less or equal to requested, or null if it does not exist

Declaration
public CacheRec Get(ulong key, int ageSec = 0)
Parameters
Type Name Description
System.UInt64 key

Item key
System.Int32 ageSec

Age of item in seconds, or 0 for any age
Returns
Type Description
CacheRec

GetOrPut<TContext>(UInt64, Func<String, UInt64, TContext, Object>, TContext, Int32, Int32, Int32, Nullable<DateTime>)

Retrieves an item from this table by key where item age is less or equal to requested, or calls the itemFactory function and inserts the value in the store

Declaration
public CacheRec GetOrPut<TContext>(ulong key, Func<string, ulong, TContext, object> valueFactory, TContext factoryContext = null, int ageSec = 0, int putMaxAgeSec = 0, int putPriority = 0, DateTime? putAbsoluteExpirationUTC = default(DateTime? ))
Parameters
Type Name Description
System.UInt64 key

Item key
System.Func<System.String, System.UInt64, TContext, System.Object> valueFactory

A function that returns new value for the specified tableName, key, and context
TContext factoryContext

An object to pass into the factory function if it gets invoked
System.Int32 ageSec

Age of item in seconds, or 0 for any age
System.Int32 putMaxAgeSec

MaxAge for item if Put is called
System.Int32 putPriority

Priority for item if Put is called
System.Nullable<System.DateTime> putAbsoluteExpirationUTC

Absolute expiration UTC timestamp for item if Put is called
Returns
Type Description
CacheRec
Type Parameters
Name Description
TContext

A type of item factory context

Put(UInt64, Object, out CacheRec, Int32, Int32, Nullable<DateTime>)

Puts a key-identified item into this table. If item with such key is already in this table then replaces it and returns false, returns true otherwise

Declaration
public bool Put(ulong key, object value, out CacheRec rec, int maxAgeSec = 0, int priority = 0, DateTime? absoluteExpirationUTC = default(DateTime? ))
Parameters
Type Name Description
System.UInt64 key

Item's unique key
System.Object value

Item
CacheRec rec

Returns new or existing CacheRec
System.Int32 maxAgeSec

For how long will the item exist in cache before it gets swept out. Pass 0 to use table-level setting (default)
System.Int32 priority

Items priority relative to others in the table used during collision resolution, 0 = default
System.Nullable<System.DateTime> absoluteExpirationUTC

Sets absolute UTC time stamp when item should be swept out of cache, null is default
Returns
Type Description
System.Boolean

Put(UInt64, Object, Int32, Int32, Nullable<DateTime>)

Puts a key-identified item into this table. If item with such key is already in this table then replaces it and returns false, returns true otherwise

Declaration
public bool Put(ulong key, object value, int maxAgeSec = 0, int priority = 0, DateTime? absoluteExpirationUTC = default(DateTime? ))
Parameters
Type Name Description
System.UInt64 key

Item's unique key
System.Object value

Item
System.Int32 maxAgeSec

For how long will the item exist in cache before it gets swept out. Pass 0 to use table-level setting (default)
System.Int32 priority

Items priority relative to others in the table used during collision resolution, 0 = default
System.Nullable<System.DateTime> absoluteExpirationUTC

Sets absolute UTC time stamp when item should be swept out of cache, null is default
Returns
Type Description
System.Boolean

Remove(UInt64)

Removes a key-identified item from the named table returning true when item was deleted or false when item was not found

Declaration
public bool Remove(ulong key)
Parameters
Type Name Description
System.UInt64 key
Returns
Type Description
System.Boolean

Implements

Extension Methods