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timerfindall

Class: timer

Find timer object, regardless of visibility

Syntax

Description

example

out = timerfindall finds timer objects existing in memory, regardless of visibility and returns an array, out. Use the ObjectVisibility property to set the object's visibility.

example

out = timerfindall(Name,Value) finds timer objects existing in memory, regardless of visibility whose property values match those passed as Name,Value pair arguments and returns an array, out.

example

out = timerfindall(t,Name,Value) matches Name,Value pair arguments to the timer objects listed in t, where t can be an array of timer objects, and returns an array, out.

example

out = timerfindall(S) matches property values defined in the structure, S and returns an array, out. The field names of S are timer object property names and the field values are the corresponding property values.

Tips

  • timerfindall finds timer objects in memory, regardless of the value of the ObjectVisibility property. To limit the search to objects with ObjectVisibility set to 'on', use timerfind. .

Input Arguments

t

Array of objects of class timer.

S

Structure with field names corresponding to timer object property names. Field values are the corresponding property values.

Name-Value Pair Arguments

Specify optional comma-separated pairs of Name,Value arguments. Name is the argument name and Value is the corresponding value. Name must appear inside single quotes (' '). You can specify several name and value pair arguments in any order as Name1,Value1,...,NameN,ValueN.

'BusyMode'

String that indicates action taken when a timer has to execute TimerFcn before the completion of previous execution of the TimerFcn. When Running='on', BusyMode is read only. This table summarizes the busy modes.

BusyMode Values

Behavior if Queue Empty

Behavior if Queue Not Empty

Notes

'drop'

Adds task to queue

Drops task

Possible skipping of TimerFcn calls

'error'

Adds task to queue

Completes task; throws error specified by ErrorFcn; stops timer

Stops timer after completing task in execution queue

'queue'

Adds task to queue

Waits for queue to clear, and then enters task in queue

Adjusts Period property to manage tasks in execution queue

See Handling Timer Queuing Conflicts for more information.

Default: 'drop'

'ErrorFcn'

String, function handle, or cell array defining the function that the timer executes when an error occurs. If there is an error, this function executes, and then calls StopFcn.

'ExecutionMode'

String that defines how the timer object schedules timer events. When Running='on', ExecutionMode is read only. This table summarizes the execution modes.

Execution Mode

Time Period Start Point

'singleShot'

In this mode, the timer callback function is only executed once. Therefore, the Period property has no effect. This is the default execution mode.

'fixedRate'

Starts immediately after the timer callback function is added to the MATLAB® execution queue

'fixedDelay'

Starts when the timer function callback restarts execution after a time lag due to delays in the MATLAB execution queue

'fixedSpacing'

Starts when the timer callback function finishes executing.

  • 'singleShot' is the single execution mode for the timer class, and is the default value.

  • 'fixedDelay', 'fixedRate', and 'fixedSpacing' are the three supported multiexecution modes. These modes define the starting point of the Period property. The Period property specifies the amount of time between executions, which remains the same. Only the point at which execution begins is different.

Default: 'singleShot'

'Name'

String representing the timer name.

Default: 'timer-i', where i is a number indicating the ith timer object created this session. To reset i to 1, execute the clear classes command.

'ObjectVisibility'

String with possible values of 'on' or 'off', that provides a way for you to discourage end-user access to the timer objects your application creates. The timerfind function does not return an object whose ObjectVisibility property is set to 'off'. Objects that are not visible are still valid. To retrieve a list of all the timer objects in memory, including the invisible ones, use the timerfindall function.

Default: 'on'

'Period'

Number greater than 0.001 that specifies the delay, in seconds, between executions of TimerFcn. For the timer to use Period, you must set ExecutionMode and TasksToExecute to schedule multiple timer object callback events.

Default: 1.0

'StartDelay'

Number greater than or equal to 0 that specifies the delay, in seconds, between the start of the timer and the first execution of the function specified in TimerFcn. When Running = 'on', StartDelay is read only.

Default: 0

'StartFcn'

String, function handle, or cell array defining the function that executes when the timer starts.

'StopFcn'

String, function handle, or cell array defining the function that executes when the timer stops. The timer stops when

  • You call the timer stop method.

  • The timer finishes executing TimerFcn. In other words, the value of TasksExecuted reaches the limit set by TasksToExecute.

  • An error occurs. The ErrorFcn callback is called first, followed by the StopFcn callback.

You can use StopFcn to define clean up actions, such as deleting the timer object from memory.

'Tag'

String that represents a label for the object.

'TasksToExecute'

Number greater than 0, indicating the number of times the timer object is to execute the TimerFcn callback. Use the TasksToExecute property to set the number of executions. To use TasksToExecute, you must set ExecutionMode to schedule multiple timer callback events.

Default: Inf

'TimerFcn'

String, function handle, or cell array defining the timer callback function. You must define this property before you can start the timer.

'UserData'

Generic field for data that you want to add to the object.

Read Only Name-Value Pair Arguments

AveragePeriod

Average time in seconds between TimerFcn executions since the timer started. Value is NaN until timer executes two timer callbacks.

InstantPeriod

The time in seconds between the last two executions of TimerFcn. Value is NaN until timer executes two timer callbacks.

Running

String defined as 'off' or 'on', indicating whether the timer is currently executing callback functions.

TasksExecuted

The number of times the timer called TimerFcn since the timer started.

Type

String that identifies the object type.

Examples

expand all

Find and Delete All Timers From Memory

Create four timer objects.

t1 = timer('TimerFcn',@(~,~)disp('Timer 1 Fired!'));
t2 = timer('TimerFcn',@(~,~)disp('Timer 2 Fired!'));
t3 = timer('TimerFcn',@(~,~)disp('Timer 3 Fired!'));
t4 = timer('TimerFcn',@(~,~)disp('Timer 4 Fired!'));

Set timers t2 and t4 to be invisible.

t2.ObjectVisibility = 'off';
t4.ObjectVisibility = 'off';

Clear timers t1 and t2 from the workspace.

clear t1 t2
whos
  Name      Size            Bytes  Class    Attributes

  t3        1x1               104  timer              
  t4        1x1               104  timer              

Find all visible timers in memory.

timerfind
Timer Object Array

   Index:  ExecutionMode:  Period:  TimerFcn:               Name:
   1       singleShot      1        1x1 function_handle arraytimer-1
   2       singleShot      1        1x1 function_handle arraytimer-3

timerfind finds only timers t1 and t2, since they are visible. Timer t2 is still valid and in memory even though it was cleared from the workspace

Find all timers in memory.

timerfindall
Timer Object Array

   Index:  ExecutionMode:  Period:  TimerFcn:               Name:
   1       singleShot      1        1x1 function_handle arraytimer-1
   2       singleShot      1        1x1 function_handle arraytimer-2
   3       singleShot      1        1x1 function_handle arraytimer-3
   4       singleShot      1        1x1 function_handle arraytimer-4

timerfindall finds all four valid timers in memory even though t2 and t4 are invisible and t1 and t2 were cleared from the workspace.

Delete all timers from memory.

delete(timerfindall)

Find Timer Objects Existing in Memory

Create several individual timers and an array of timers.

t1 = timer('Tag', 'broadcastProgress','UserData','Monday');
t2 = timer('Tag', 'displayProgress','UserData','Monday');
timerArr = [timer('Tag', 'broadcastProgress','UserData','Tuesday');
    timer('Tag', 'displayProgress','UserData','Tuesday');
    timer('Tag', 'displayProgress','UserData','Wednesday');];

Make timer t1 and timerArr(2) invisible.

t1.ObjectVisibility = 'off';
timerArr(2).ObjectVisibility = 'off';

Find all the timers in memory using timerfind.

out1 = timerfind
Timer Object Array

   Index:  ExecutionMode:  Period:  TimerFcn:               Name:
   1       singleShot      1        ''                      timer-2
   2       singleShot      1        ''                      timer-3
   3       singleShot      1        ''                      timer-5

timerfind does not find the hidden timers.

Find all the timers in memory using timerfindall.

out2 = timerfindall
Timer Object Array

   Index:  ExecutionMode:  Period:  TimerFcn:               Name:
   1       singleShot      1        ''                      timer-1
   2       singleShot      1        ''                      timer-2
   3       singleShot      1        ''                      timer-3
   4       singleShot      1        ''                      timer-4
   5       singleShot      1        ''                      timer-5

timerfindall finds all timers, even the invisible ones.

Find only those timers in memory that have the string value, 'displayProgress', as the Tag property.

out3 = timerfindall('Tag','displayProgress')
Timer Object Array

   Index:  ExecutionMode:  Period:  TimerFcn:               Name:
   1       singleShot      1        ''                      timer-2
   2       singleShot      1        ''                      timer-4
   3       singleShot      1        ''                      timer-5

Limit the search for timers that have the string value, 'displayProgress', as the Tag property to timer objects in timerArr.

out4 = timerfindall(timerArr,'Tag','displayProgress')
Timer Object Array

   Index:  ExecutionMode:  Period:  TimerFcn:               Name:
   1       singleShot      1        ''                      timer-4
   2       singleShot      1        ''                      timer-5

Define a struct containing the Tag and UserData properties of interest.

searchStruct = struct('Tag','broadcastProgress','UserData','Monday')
searchStruct = 

         Tag: 'broadcastProgress'
    UserData: 'Monday'

Use the struct as the search criteria to find timer objects in memory.

out5 = timerfindall(searchStruct)
   Timer Object: timer-1

   Timer Settings
      ExecutionMode: singleShot
             Period: 1
           BusyMode: drop
            Running: off

   Callbacks
           TimerFcn: ''
           ErrorFcn: ''
           StartFcn: ''
            StopFcn: ''

Delete the timer objects.

delete(timerfindall)

Find Invisible Timers

Create four timer objects.

t1 = timer('TimerFcn',@(~,~)disp('Timer 1 Fired!'));
t2 = timer('TimerFcn',@(~,~)disp('Timer 2 Fired!'));
t3 = timer('TimerFcn',@(~,~)disp('Timer 3 Fired!'));
t4 = timer('TimerFcn',@(~,~)disp('Timer 4 Fired!'));

Set timers t2 and t4 to be invisible, and clear timers t1 and t2 from the workspace.

t2.ObjectVisibility = 'off';
t4.ObjectVisibility = 'off';
clear t1 t2; 
whos
  Name      Size            Bytes  Class    Attributes

  t3        1x1               104  timer              
  t4        1x1               104  timer              

Find all valid invisible timers.

out = timerfindall('ObjectVisibility','off')
Timer Object Array

   Index:  ExecutionMode:  Period:  TimerFcn:               Name:
   1       singleShot      1        1x1 function_handle arraytimer-2
   2       singleShot      1        1x1 function_handle arraytimer-4

Both valid invisible timers were found by timerfindall, regardless of whether they were in the workspace.

See Also

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