pthread_key_delete()--Delete Thread Local Storage Key

 #include <pthread.h>
 int pthread_key_delete(pthread_key_t key);  

The pthread_key_delete() function deletes a process-wide thread local storage key. The pthread_key_delete() function does not run any destructors for the values associated with key in any threads. After a key is deleted, it may be returned by a subsequent call to pthread_key_create().

An attempt to delete a key that is out of range or not valid fails with EINVAL. An attempt to delete a valid key that has already been deleted or has not been returned from pthread_key_create() fails with ENOENT.

Authorities and Locks

None.

Parameters

key

(Input) The thread local storage key returned from pthread_key_create()

Return Value

0

pthread_key_delete() was successful.

value

pthread_key_delete() was not successful. value is set to indicate the error condition.

Error Conditions

If pthread_key_delete() was not successful, the error condition returned usually indicates one of the following errors. Under some conditions, the value returned could indicate an error other than those listed here.

A destructor function is not called as a result of the application calling pthread_key_delete().

[EINVAL]

The value specified for the argument is not correct.

[ENOENT]

An entry for the key is not currently allocated.

Related Information

• The <pthread.h> header file. See Header files for Pthread functions.
  
  
• pthread_getspecific()--Get Thread Local Storage Value by Key
  
  
• pthread_key_create()--Create Thread Local Storage Key
  
  
• pthread_setspecific()--Set Thread Local Storage by Key

Example

See Code disclaimer information for information pertaining to code examples.

#define _MULTI_THREADED
#include <pthread.h>
#include <stdio.h>
#include "check.h"

pthread_key_t   tlsKey = 0;

void globalDestructor(void *value)
{
  printf("In global data destructor\n");
  free(value);
  pthread_setspecific(tlsKey, NULL);
}

int main(int argc, char **argv)
{
  int                   rc=0;
  int                   i=0;

  printf("Enter Testcase - %s\n", argv[0]);

  printf("Create a thread local storage key\n");
  rc = pthread_key_create(&tlsKey, globalDestructor);
  checkResults("pthread_key_create()\n", rc);
  /* The key can now be used from all threads */

  printf("Delete a thread local storage key\n");
  rc = pthread_key_delete(tlsKey);
  checkResults("pthread_key_delete()\n", rc);

  printf("- The key should not be used from any thread\n");
  printf("- after destruction.\n");
  /* The key and any remaining values are now gone. */
  printf("Main completed\n");
  return 0;
}

Output:

Enter Testcase - QP0WTEST/TPKEYD0
Create a thread local storage key
Delete a thread local storage key
- The key should not be used from any thread
- after destruction.
Main completed