Caches¶

This section contains the API documentation for the caches module.

class DLL(val)¶

Bases: handle

An element of a doubly-linked list. This is a list where each element consists of a value, a reference to the previous element and a reference to the next element.

Based on the work by Richard Lange (2022). Least-Recently Used (LRU) Cache (https://www.mathworks.com/matlabcentral/fileexchange/68836-least-recently-used-lru-cache), MATLAB Central File Exchange. Retrieved June 18, 2022.

Properties: val (any) – data stored in this element

DLL(val)¶

Construct an element of a doubly-linked list. By default, the detached links point to the object itself.

Arguments: val (any) – data stored in this element.
Returns: dll (DLL) – data wrapped in a doubly-linked list format.

pop()¶

Remove an object from a doubly-linked list, updating the links on the next and previous element.

Arguments: obj (DLL) – object to remove from the list.
Returns: obj (DLL) – removed object, with detached links.

append(other)¶

Append an object to a doubly-linked list, updating the links.

Arguments

obj (DLL) – list to append to.
other (DLL) – object to append.

Returns

obj (DLL) – updated list.

uplus()¶

Get the next element in the list.

Usage

other = +obj;

other = uplus(obj);

Arguments: obj (:class`.DLL`) – current element in the list.
Returns: other (:class`.DLL`) – next element in the list.

uminus()¶

Get the previous element in the list.

Usage

other = -obj;

other = uminus(obj);

Arguments: obj (:class`.DLL`) – current element in the list.
Returns: other (:class`.DLL`) – previous element in the list.

class LRU(itemlimit, memlimit)¶

Bases: handle

A least-recently-used cache. Stores data up to a preset memory limit, then removes the least-recently-used elements to free up space for additional data.

Properties

sentinel (DLL) – sentinel of DLL, +sentinel is MRU, -sentinel is LRU
map (containers.Map) – map of key –> dll
itemlimit (int) – maximum size of cache in number of items
memlimit (double) – maximum size of cache in bytes
mem (double) – current memory usage in bytes.

LRU(itemlimit, memlimit)¶

Construct a new LRU cache.

Arguments

itemlimit (int) – maximum size of cache in number of items.
memlimit (double) – maximum size of cache in number of bytes.

Returns

cache (LRU) – empty LRU cache.

get(cache, key)¶

Retrieve a value from the cache.

Arguments

cache (LRU) – data cache.
key (uint8) – data key.

Returns

val (any) – value that is stored with a key, or empty if key not in cache.

set(cache, key, val)¶

Add a value to the cache.

Arguments

cache (LRU) – data cache.
key (uint8) – data key.
val (any) – data value.

Returns

cache (LRU) – updated cache.

GetMD5¶

GetMD5(varargin)¶

Calculates a 128 bit MD5 checksum for arrays or files.

Usage

digest = GetMD5(Data, Mode, Format)

Arguments

Data – input data on which the checksum is computed.
Mode (char) – optional declaration of the type of the input data.
- ‘File’ : data is a file name as a char.
- ‘8Bit’ : If data is a char array, only the 8 bit ASCII part is used. Then the
digest is the same as for a ASCII text file e.g. created by fwrite(fid, data, ‘uchar’). - ‘Binary’ : The MD5 sum is obtained for the contents of data. This works for numerical, char and logical arrays. - ‘Array’ : Include the class and size information of data in the MD5 sum. This can be applied for (nested) structs, objects, cells and sparse arrays also.
Format (char) – Format of the output, default value is ‘hex’.
- ‘hex’ : (1, 32) lowercase hexadecimal char.
- ‘HEX’ : (1, 32) uppercase hexadecimal char.
- ‘double’ : (1, 16) double vector with uint8 values.
- ‘uint8’ : (1, 16) uint8 vector.
- ‘base64’ : (1, 22) char vector, encoded in base 64 (A:Z, a:z, 0:9, +, /), unpadded.

Returns

digest – A 128 bit number in the specified format.

Notes

For sparse arrays, function handles, java and user-defined objects GetMD5_helper() is called to convert into a data format that can be handled.

The C-Mex-file is compiled automatically when this function is called for the first time. See GetMD5.c for details or a manual installation.

References

License: This program is derived from the RSA Data Security, Inc.: MD5 Message Digest Algorithm, RFC 1321, R. Rivest, April 1992 This implementation is published under the BSD license.