CLASS vlt.data.cache¶
cache - Cache class
Superclasses¶
handle
Properties¶
| Property | Description |
|---|---|
| maxMemory | The maximum memory, in bytes, that can be consumed by an CACHE before it is emptied |
| replacement_rule | The rule to be used to replace entries when memory is exceeded ('FIFO','LIFO','error', etc) |
| table | The variable that has the data and metadata for the cache |
Methods¶
| Method | Description |
|---|---|
| add | add data to an NDI.CACHE |
| addlistener | ADDLISTENER Add listener for event. |
| bytes | memory size of an NDI.CACHE object in bytes |
| cache | create a new NDI cache handle |
| clear | clear data from an NDI.CACHE |
| delete | DELETE Delete a handle object. |
| eq | == (EQ) Test handle equality. |
| findobj | FINDOBJ Find objects matching specified conditions. |
| findprop | FINDPROP Find property of MATLAB handle object. |
| freebytes | remove the lowest priority entries from the cache to free a certain amount of memory |
| ge | >= (GE) Greater than or equal relation for handles. |
| gt | > (GT) Greater than relation for handles. |
| isvalid | ISVALID Test handle validity. |
| le | <= (LE) Less than or equal relation for handles. |
| listener | LISTENER Add listener for event without binding the listener to the source object. |
| lookup | retrieve the NDI.CACHE data table corresponding to KEY and TYPE |
| lt | < (LT) Less than relation for handles. |
| ne | ~= (NE) Not equal relation for handles. |
| notify | NOTIFY Notify listeners of event. |
| remove | remove data from an NDI.CACHE |
| set_replacement_rule | set the replacement rule for an CACHE object |
Methods help¶
add - add data to an NDI.CACHE
CACHE_OBJ = ADD(CACHE_OBJ, KEY, TYPE, DATA, [PRIORITY])
Adds DATA to the CACHE_OBJ that is referenced by a KEY and TYPE.
If desired, a PRIORITY can be added; items with greatest PRIORITY will be
deleted last.
addlistener - ADDLISTENER Add listener for event.
el = ADDLISTENER(hSource, Eventname, callbackFcn) creates a listener
for the event named Eventname. The source of the event is the handle
object hSource. If hSource is an array of source handles, the listener
responds to the named event on any handle in the array. callbackFcn
is a function handle that is invoked when the event is triggered.
el = ADDLISTENER(hSource, PropName, Eventname, Callback) adds a
listener for a property event. Eventname must be one of
'PreGet', 'PostGet', 'PreSet', or 'PostSet'. Eventname can be
a string scalar or character vector. PropName must be a single
property name specified as string scalar or character vector, or a
collection of property names specified as a cell array of character
vectors or a string array, or as an array of one or more
meta.property objects. The properties must belong to the class of
hSource. If hSource is scalar, PropName can include dynamic
properties.
For all forms, addlistener returns an event.listener. To remove a
listener, delete the object returned by addlistener. For example,
delete(el) calls the handle class delete method to remove the listener
and delete it from the workspace.
ADDLISTENER binds the listener's lifecycle to the object that is the
source of the event. Unless you explicitly delete the listener, it is
destroyed only when the source object is destroyed. To control the
lifecycle of the listener independently from the event source object,
use listener or the event.listener constructor to create the listener.
See also LISTENER, EVENT.LISTENER, VLT.DATA.CACHE, NOTIFY, DELETE, META.PROPERTY, EVENTS
Help for vlt.data.cache/addlistener is inherited from superclass handle
bytes - memory size of an NDI.CACHE object in bytes
B = BYTES(CACHE_OBJ)
Return the current memory that is occupied by the table of CACHE_OBJ.
cache - create a new NDI cache handle
CACHE_OBJ = vlt.data.cache(...)
Creates a new vlt.data.cache object. Additional arguments can be specified as
name value pairs:
Parameter (default) | Description
------------------------------------------------------------
maxMemory (100e6) | Max memory for cache, in bytes (100MB default)
replacement_rule ('fifo') | Replacement rule (see CACHE/SET_REPLACEMENT_RULE
Note that the cache is not 'secure', any function can query the data added.
See also: vlt.data.namevaluepair
Documentation for vlt.data.cache/cache
doc vlt.data.cache
clear - clear data from an NDI.CACHE
CACHE_OBJ = CLEAR(CACHE_OBJ)
Clears all entries from the NDI.CACHE object CACHE_OBJ.
delete - DELETE Delete a handle object.
DELETE(H) deletes all handle objects in array H. After the delete
function call, H is an array of invalid objects.
See also VLT.DATA.CACHE, VLT.DATA.CACHE/ISVALID, CLEAR
Help for vlt.data.cache/delete is inherited from superclass handle
eq - == (EQ) Test handle equality.
Handles are equal if they are handles for the same object.
H1 == H2 performs element-wise comparisons between handle arrays H1 and
H2. H1 and H2 must be of the same dimensions unless one is a scalar.
The result is a logical array of the same dimensions, where each
element is an element-wise equality result.
If one of H1 or H2 is scalar, scalar expansion is performed and the
result will match the dimensions of the array that is not scalar.
TF = EQ(H1, H2) stores the result in a logical array of the same
dimensions.
See also VLT.DATA.CACHE, VLT.DATA.CACHE/GE, VLT.DATA.CACHE/GT, VLT.DATA.CACHE/LE, VLT.DATA.CACHE/LT, VLT.DATA.CACHE/NE
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findobj - FINDOBJ Find objects matching specified conditions.
The FINDOBJ method of the HANDLE class follows the same syntax as the
MATLAB FINDOBJ command, except that the first argument must be an array
of handles to objects.
HM = FINDOBJ(H, <conditions>) searches the handle object array H and
returns an array of handle objects matching the specified conditions.
Only the public members of the objects of H are considered when
evaluating the conditions.
See also FINDOBJ, VLT.DATA.CACHE
Help for vlt.data.cache/findobj is inherited from superclass handle
findprop - FINDPROP Find property of MATLAB handle object.
p = FINDPROP(H,PROPNAME) finds and returns the META.PROPERTY object
associated with property name PROPNAME of scalar handle object H.
PROPNAME can be a string scalar or character vector. It can be the
name of a property defined by the class of H or a dynamic property
added to scalar object H.
If no property named PROPNAME exists for object H, an empty
META.PROPERTY array is returned.
See also VLT.DATA.CACHE, VLT.DATA.CACHE/FINDOBJ, DYNAMICPROPS, META.PROPERTY
Help for vlt.data.cache/findprop is inherited from superclass handle
freebytes - remove the lowest priority entries from the cache to free a certain amount of memory
CACHE_OBJ = FREEBYTES(CACHE_OBJ, FREEBYTES)
Remove entries to free at least FREEBYTES memory. Entries will be removed, first by PRIORITY and then by
the replacement_rule parameter.
See also: NDI.CACHE/ADD, NDI.CACHE/SET_REPLACEMENT_RULE
ge - >= (GE) Greater than or equal relation for handles.
H1 >= H2 performs element-wise comparisons between handle arrays H1 and
H2. H1 and H2 must be of the same dimensions unless one is a scalar.
The result is a logical array of the same dimensions, where each
element is an element-wise >= result.
If one of H1 or H2 is scalar, scalar expansion is performed and the
result will match the dimensions of the array that is not scalar.
TF = GE(H1, H2) stores the result in a logical array of the same
dimensions.
See also VLT.DATA.CACHE, VLT.DATA.CACHE/EQ, VLT.DATA.CACHE/GT, VLT.DATA.CACHE/LE, VLT.DATA.CACHE/LT, VLT.DATA.CACHE/NE
Help for vlt.data.cache/ge is inherited from superclass handle
gt - > (GT) Greater than relation for handles.
H1 > H2 performs element-wise comparisons between handle arrays H1 and
H2. H1 and H2 must be of the same dimensions unless one is a scalar.
The result is a logical array of the same dimensions, where each
element is an element-wise > result.
If one of H1 or H2 is scalar, scalar expansion is performed and the
result will match the dimensions of the array that is not scalar.
TF = GT(H1, H2) stores the result in a logical array of the same
dimensions.
See also VLT.DATA.CACHE, VLT.DATA.CACHE/EQ, VLT.DATA.CACHE/GE, VLT.DATA.CACHE/LE, VLT.DATA.CACHE/LT, VLT.DATA.CACHE/NE
Help for vlt.data.cache/gt is inherited from superclass handle
isvalid - ISVALID Test handle validity.
TF = ISVALID(H) performs an element-wise check for validity on the
handle elements of H. The result is a logical array of the same
dimensions as H, where each element is the element-wise validity
result.
A handle is invalid if it has been deleted or if it is an element
of a handle array and has not yet been initialized.
See also VLT.DATA.CACHE, VLT.DATA.CACHE/DELETE
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le - <= (LE) Less than or equal relation for handles.
Handles are equal if they are handles for the same object. All
comparisons use a number associated with each handle object. Nothing
can be assumed about the result of a handle comparison except that the
repeated comparison of two handles in the same MATLAB session will
yield the same result. The order of handle values is purely arbitrary
and has no connection to the state of the handle objects being
compared.
H1 <= H2 performs element-wise comparisons between handle arrays H1 and
H2. H1 and H2 must be of the same dimensions unless one is a scalar.
The result is a logical array of the same dimensions, where each
element is an element-wise >= result.
If one of H1 or H2 is scalar, scalar expansion is performed and the
result will match the dimensions of the array that is not scalar.
TF = LE(H1, H2) stores the result in a logical array of the same
dimensions.
See also VLT.DATA.CACHE, VLT.DATA.CACHE/EQ, VLT.DATA.CACHE/GE, VLT.DATA.CACHE/GT, VLT.DATA.CACHE/LT, VLT.DATA.CACHE/NE
Help for vlt.data.cache/le is inherited from superclass handle
listener - LISTENER Add listener for event without binding the listener to the source object.
el = LISTENER(hSource, Eventname, callbackFcn) creates a listener
for the event named Eventname. The source of the event is the handle
object hSource. If hSource is an array of source handles, the listener
responds to the named event on any handle in the array. callbackFcn
is a function handle that is invoked when the event is triggered.
el = LISTENER(hSource, PropName, Eventname, callback) adds a
listener for a property event. Eventname must be one of
'PreGet', 'PostGet', 'PreSet', or 'PostSet'. Eventname can be a
string sclar or character vector. PropName must be either a single
property name specified as a string scalar or character vector, or
a collection of property names specified as a cell array of character
vectors or a string array, or as an array of one ore more
meta.property objects. The properties must belong to the class of
hSource. If hSource is scalar, PropName can include dynamic
properties.
For all forms, listener returns an event.listener. To remove a
listener, delete the object returned by listener. For example,
delete(el) calls the handle class delete method to remove the listener
and delete it from the workspace. Calling delete(el) on the listener
object deletes the listener, which means the event no longer causes
the callback function to execute.
LISTENER does not bind the listener's lifecycle to the object that is
the source of the event. Destroying the source object does not impact
the lifecycle of the listener object. A listener created with LISTENER
must be destroyed independently of the source object. Calling
delete(el) explicitly destroys the listener. Redefining or clearing
the variable containing the listener can delete the listener if no
other references to it exist. To tie the lifecycle of the listener to
the lifecycle of the source object, use addlistener.
See also ADDLISTENER, EVENT.LISTENER, VLT.DATA.CACHE, NOTIFY, DELETE, META.PROPERTY, EVENTS
Help for vlt.data.cache/listener is inherited from superclass handle
lookup - retrieve the NDI.CACHE data table corresponding to KEY and TYPE
TABLEENTRY = LOOKUP(CACHE_OBJ, KEY, TYPE)
Performs a case-sensitive lookup of the CACHE entry whose key and type
match KEY and TYPE. The table entry is returned. The table has fields:
Fieldname | Description
-----------------------------------------------------
key | The key string
type | The type string
timestamp | The Matlab date stamp (serial date number, see NOW) when data was stored
priority | The priority of maintaining the data (higher is better)
bytes | The size of the data in this entry (bytes)
data | The data stored
lt - < (LT) Less than relation for handles.
H1 < H2 performs element-wise comparisons between handle arrays H1 and
H2. H1 and H2 must be of the same dimensions unless one is a scalar.
The result is a logical array of the same dimensions, where each
element is an element-wise < result.
If one of H1 or H2 is scalar, scalar expansion is performed and the
result will match the dimensions of the array that is not scalar.
TF = LT(H1, H2) stores the result in a logical array of the same
dimensions.
See also VLT.DATA.CACHE, VLT.DATA.CACHE/EQ, VLT.DATA.CACHE/GE, VLT.DATA.CACHE/GT, VLT.DATA.CACHE/LE, VLT.DATA.CACHE/NE
Help for vlt.data.cache/lt is inherited from superclass handle
ne - ~= (NE) Not equal relation for handles.
Handles are equal if they are handles for the same object and are
unequal otherwise.
H1 ~= H2 performs element-wise comparisons between handle arrays H1
and H2. H1 and H2 must be of the same dimensions unless one is a
scalar. The result is a logical array of the same dimensions, where
each element is an element-wise equality result.
If one of H1 or H2 is scalar, scalar expansion is performed and the
result will match the dimensions of the array that is not scalar.
TF = NE(H1, H2) stores the result in a logical array of the same
dimensions.
See also VLT.DATA.CACHE, VLT.DATA.CACHE/EQ, VLT.DATA.CACHE/GE, VLT.DATA.CACHE/GT, VLT.DATA.CACHE/LE, VLT.DATA.CACHE/LT
Help for vlt.data.cache/ne is inherited from superclass handle
notify - NOTIFY Notify listeners of event.
NOTIFY(H, eventname) notifies listeners added to the event named
eventname for handle object array H that the event is taking place.
eventname can be a string scalar or character vector.
H is the array of handles to the event source objects, and 'eventname'
must be a character vector.
NOTIFY(H,eventname,ed) provides a way of encapsulating information
about an event which can then be accessed by each registered listener.
ed must belong to the EVENT.EVENTDATA class.
See also VLT.DATA.CACHE, VLT.DATA.CACHE/ADDLISTENER, VLT.DATA.CACHE/LISTENER, EVENT.EVENTDATA, EVENTS
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remove - remove data from an NDI.CACHE
CACHE_OBJ = REMOVE(CACHE_OBJ, KEY, TYPE, ...)
or
CACHE_OBJ = REMOVE(CACHE_OBJ, INDEX, [], ...)
Removes the data at table index INDEX or data with KEY and TYPE.
INDEX can be a single entry or an array of entries.
If the data entry to be removed is a handle, the handle
will be deleted from memory unless the setting is altered with a NAME/VALUE pair.
This function can be modified by name/value pairs:
Parameter (default) | Description
----------------------------------------------------------------
leavehandle (0) | If the 'data' field of a cache entry is a handle,
| leave it in memory.
See also: vlt.data.namevaluepair
set_replacement_rule - set the replacement rule for an CACHE object
CACHE_OBJ = SET_REPLACEMENT_RULE(CACHE_OBJ, RULE)
Sets the replacement rule for a vlt.data.cache object to be used when a new entry
would exceed the allowed memory. The rule may be one of the following strings
(case is insensitive and will be stored lower case):
Rule | Description
---------------------------------------------------------
'fifo' | First in, first out; discard oldest entries first.
'lifo' | Last in, first out; discard newest entries first.
'error' | Don't discard anything, just produce an error saying cache is full