pthread_getspecific(3c) [opensolaris man page]
pthread_getspecific(3C) Standard C Library Functions pthread_getspecific(3C) NAME
pthread_getspecific, pthread_setspecific - manage thread-specific data SYNOPSIS
cc -mt [ flag... ] file... -lpthread [ library... ] #include <pthread.h> int pthread_setspecific(pthread_key_t key, const void *value); void *pthread_getspecific(pthread_key_t key); DESCRIPTION
The pthread_setspecific() function associates a thread-specific value with a key obtained by way of a previous call to pthread_key_cre- ate(). Different threads may bind different values to the same key. These values are typically pointers to blocks of dynamically allocated memory that have been reserved for use by the calling thread. The pthread_getspecific() function returns the value currently bound to the specified key on behalf of the calling thread. The effect of calling pthread_setspecific() or pthread_getspecific() with a key value not obtained from pthread_key_create() or after key has been deleted with pthread_key_delete() is undefined. Both pthread_setspecific() and pthread_getspecific() may be called from a thread-specific data destructor function. However, calling pthread_setspecific() from a destructor may result in lost storage or infinite loops. RETURN VALUES
The pthread_getspecific() function returns the thread-specific data value associated with the given key. If no thread-specific data value is associated with key, then the value NULL is returned. Upon successful completion, the pthread_setspecific() function returns 0. Otherwise, an error number is returned to indicate the error. ERRORS
The pthread_setspecific() function will fail if: ENOMEM Insufficient memory exists to associate the value with the key. The pthread_setspecific() function may fail if: EINVAL The key value is invalid. The pthread_getspecific() function does not return errors. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |MT-Safe | +-----------------------------+-----------------------------+ SEE ALSO
pthread_key_create(3C), attributes(5), standards(5) SunOS 5.11 23 Mar 2005 pthread_getspecific(3C)
Check Out this Related Man Page
PTHREAD_GETSPECIFIC(3P) POSIX Programmer's Manual PTHREAD_GETSPECIFIC(3P) PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the correspond- ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux. NAME
pthread_getspecific, pthread_setspecific - thread-specific data management SYNOPSIS
#include <pthread.h> void *pthread_getspecific(pthread_key_t key); int pthread_setspecific(pthread_key_t key, const void *value); DESCRIPTION
The pthread_getspecific() function shall return the value currently bound to the specified key on behalf of the calling thread. The pthread_setspecific() function shall associate a thread-specific value with a key obtained via a previous call to pthread_key_create(). Different threads may bind different values to the same key. These values are typically pointers to blocks of dynamically allocated memory that have been reserved for use by the calling thread. The effect of calling pthread_getspecific() or pthread_setspecific() with a key value not obtained from pthread_key_create() or after key has been deleted with pthread_key_delete() is undefined. Both pthread_getspecific() and pthread_setspecific() may be called from a thread-specific data destructor function. A call to pthread_get- specific() for the thread-specific data key being destroyed shall return the value NULL, unless the value is changed (after the destructor starts) by a call to pthread_setspecific(). Calling pthread_setspecific() from a thread-specific data destructor routine may result either in lost storage (after at least PTHREAD_DESTRUCTOR_ITERATIONS attempts at destruction) or in an infinite loop. Both functions may be implemented as macros. RETURN VALUE
The pthread_getspecific() function shall return the thread-specific data value associated with the given key. If no thread-specific data value is associated with key, then the value NULL shall be returned. If successful, the pthread_setspecific() function shall return zero; otherwise, an error number shall be returned to indicate the error. ERRORS
No errors are returned from pthread_getspecific(). The pthread_setspecific() function shall fail if: ENOMEM Insufficient memory exists to associate the value with the key. The pthread_setspecific() function may fail if: EINVAL The key value is invalid. These functions shall not return an error code of [EINTR]. The following sections are informative. EXAMPLES
None. APPLICATION USAGE
None. RATIONALE
Performance and ease-of-use of pthread_getspecific() are critical for functions that rely on maintaining state in thread-specific data. Since no errors are required to be detected by it, and since the only error that could be detected is the use of an invalid key, the func- tion to pthread_getspecific() has been designed to favor speed and simplicity over error reporting. FUTURE DIRECTIONS
None. SEE ALSO
pthread_key_create(), the Base Definitions volume of IEEE Std 1003.1-2001, <pthread.h> COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol- ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html . IEEE
/The Open Group 2003 PTHREAD_GETSPECIFIC(3P)