pthread_key_create(3C) Standard C Library Functions pthread_key_create(3C)NAMEpthread_key_create - create thread-specific data key
SYNOPSIS
cc -mt [ flag... ] file... -lpthread [ library... ]
#include <pthread.h>
int pthread_key_create(pthread_key_t *key,
void (*destructor)(void*));
DESCRIPTION
This function creates a thread-specific data key visible to all threads
in the process. Key values provided by pthread_key_create() are opaque
objects used to locate thread-specific data. Although the same key
value may be used by different threads, the values bound to the key by
pthread_setspecific() are maintained on a per-thread basis and persist
for the life of the calling thread.
Upon key creation, the value NULL is associated with the new key in
all active threads. Upon thread creation, the value NULL is associated
with all defined keys in the new thread.
An optional destructor function may be associated with each key value.
At thread exit, if a key value has a non-NULL destructor pointer, and
the thread has a non-NULL value associated with that key, the function
pointed to is called with the current associated value as its sole
argument. Destructors can be called in any order.
If, after all the destructors have been called for all keys with non-
NULL values, there are still some keys with non-NULL values, the
process will be repeated. If, after at least PTHREAD_DESTRUCTOR_ITERA‐
TIONS iterations of destructor calls for outstanding non-NULL values,
there are still some keys with non-NULL values, the process is contin‐
ued, even though this might result in an infinite loop.
An exiting thread runs with all signals blocked. All thread termination
functions, including thread-specific data destructor functions, are
called with all signals blocked.
RETURN VALUES
If successful, the pthread_key_create() function stores the newly cre‐
ated key value at *key and returns 0. Otherwise, an error number is
returned to indicate the error.
ERRORS
The pthread_key_create() function will fail if:
EAGAIN The system lacked the necessary resources to create another
thread-specific data key, or the system-imposed limit on the
total number of keys per process PTHREAD_KEYS_MAX has been
exceeded.
ENOMEM Insufficient memory exists to create the key.
The pthread_key_create() function will not return an error code of
EINTR.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Standard │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │MT-Safe │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOpthread_getspecific(3C), pthread_setspecific(3C),
pthread_key_delete(3C), attributes(5), standards(5)SunOS 5.10 2 Nov 2007 pthread_key_create(3C)
