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1998-03-11 00:42 Wolfram Gloger <wmglo@dent.med.uni-muenchen.de> * linuxthreads/manager.c: Enable resetting of the thread scheduling policy to SCHED_OTHER when the parent thread has a different one. 1998-02-01 13:51 Ulrich Drepper <drepper@cygnus.com> * sysdeps/unix/sysv/linux/bits/posix_opt.h: Define _POSIX_ASYNCHRONOUS_IO. * sysdeps/pthread/pthread.h: Define bits for Unix98 variants of mutexes. * mutex.c: Implement new mutex types. * internals.h: Include <signal.h>. * libpthread.map: Add __erno_location and __h_errno_location. * errno.c: Return pointer to variable actually in use. This might not be the one in the thread structure. * internals.h (struct _pthread_descr_struct): Add new fields p_errnop and p_h_errnop. * manager.c (__pthread_manager): Set p_errnop and p_h_errnop member of manager thread structure. (pthread_handle_create): Set p_errnop and p_h_errnop members for new thread. * pthread.c: Adapt initializer for thread structures. (__pthread_initial_thread): Set p_errnop and p_h_errnop member. (__pthread_reset_main_thread): Reset p_errnop and p_h_errnop of current thread to global variables. 1998-01-31 17:27 Ulrich Drepper <drepper@cygnus.com> * rwlock.c: New file. * Makefile (libpthread-routines): Add rwlock. * sysdeps/pthread/pthread.h: Define data structures and declare functions. * libpthread.map: Add new functions. 1997-12-18 13:50 Philip Blundell <pb@nexus.co.uk> * sysdeps/arm/pt-machine.h: New file; add ARM support. * sysdeps/arm/Implies: likewise. * README: Document it. 1997-12-13 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de> * signals.c: Remove unneeded initializer for sigwaited, saving a 1997-04-11 01:18 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de> * semaphore.c (sem_init): Set sem_spinlock only if available. 1997-12-04 01:48 Ulrich Drepper <drepper@cygnus.com> * mutex.c: Implement PTHREAD_MUTEX_CHECKERROR. * sysdeps/pthread/pthread.h: Define PTHREAD_MUTEX_CHECKERROR. * Makefile: Update from LinuxThreads 0.7. * internals.h. Likewise. * manager.c: Likewise. * mutex.c: Likewise. * pthread.c: Likewise. * signals.c: Likewise. * specific.c: Likewise. * Examples/ex3.c: Likewise. 1997-11-20 18:13 Ulrich Drepper <drepper@cygnus.com> * pthread.c (__pthread_reset_main_thread): Close pipe only if still open. 1997-10-29 05:38 Ulrich Drepper <drepper@cygnus.com> * wrapsyscall.c: Add socket functions which are also cancelation points. 1997-10-19 21:40 Wolfram Gloger <wg@wolfram.dent.med.uni-muenchen.de> * specific.c (__libc_internal_tsd_set, __libc_internal_tsd_get): New functions for fast thread specific data within libc. * internals.h: Add new array p_libc_specific to struct _pthread_descr_struct. * sysdeps/pthread/bits/libc-lock.h: Declare new functions. 1997-10-13 05:39 Ulrich Drepper <drepper@cygnus.com> * semaphore.h: Add __BEGIN_DECLS/__END_DECLS. Reported by Ralf Corsepius <corsepiu@faw.uni-ulm.de>. 1997-08-29 03:05 Ulrich Drepper <drepper@cygnus.com> * internals.h (struct _pthread_descr_struct): Add definitions for two-level specific key handling. * manager.c (pthread_handle_create): Initialize specific memory array. * specific.c: Implement two-level key handling. * weaks.c: Don't provide dummy key handling. * sysdeps/pthread/bits/libc-lock.h: Typedef __libc_lock_t (no #define). Add definition of __libc_key_t. * sysdeps/unix/sysv/linux/bits/local_lim.h: Define PTHREAD_KEYS_MAX as 1024. Add definition of _POSIX_THREAD_DESTRUCTOR_ITERATIONS and PTHREAD_DESTRUCTOR_ITERATIONS. * manager.c (pthread_handle_create): Compare mmap result with MAP_FAILED. * ptfork.c: Rename to __pthread_atfork and make old name a weak alias. * sysdeps/pthread/bits/pthread.h: Add prototype for __pthread_atfork. 1997-08-22 19:04 Richard Henderson <rth@cygnus.com> sysdeps/sparc -> sysdeps/sparc/sparc32 sysdeps/sparc64 -> sysdeps/sparc/sparc64 * internals.h: Change definition of THREAD_SELF to be an expression, not a statement that did a return. * sysdeps/alpha/pt-machine.h (THREAD_SELF): Update accordingly. * sysdeps/sparc/sparc32/pt-machine.h (THREAD_SELF, INIT_THREAD_SELF): Follow Solaris and use a "system reserved" register (%g6) to hold the thread descriptor. * sysdeps/sparc/sparc64/pt-machine.h: Likewise. 1997-08-03 00:09 Ulrich Drepper <drepper@cygnus.com> * mutex.c: Correct pthread_once. Patch by Xavier Leroy. * sysdeps/pthread/pthread.h: Add prototype for __pthread_once. * sysdeps/pthread/bits/pthread.h: Add macros for __libc_once. * semaphore.c: Include spinlock.h only when needed. * specific.c (__pthread_setsepcific, __pthread_getspecific): Reject keys for entries not in use. * weaks.c: Implement key handling functions for real. 1997-06-29 01:04 Richard Henderson <richard@gnu.ai.mit.edu> Initial sparc64-linux support: * linuxthreads/sysdeps/sparc64/Implies: New file. * linuxthreads/sysdeps/sparc64/pt-machine.h: Likewise. 1997-06-29 00:48 Ulrich Drepper <drepper@cygnus.com> * semaphore.c: Include spinlock.h at correct place. Patch by HJ Lu. 1997-06-13 10:06 Richard Henderson <rth@tamu.edu> The Great Bit File Move: * sysdeps/alpha/semaphorebits.h: -> .../bits/semaphore.h. * sysdeps/powerpc/semaphorebits.h: Likewise. * sysdeps/pthread/cmpxchg/semaphorebits.h: Likewise. * sysdeps/pthread/no-cmpxchg/semaphorebits.h: Likewise. * sysdeps/pthread/libc-lock.h: -> bits/ * sysdeps/pthread/stdio-lock.h: Likewise. * sysdeps/unix/sysv/linux/local_lim.h: Likewise. * sysdeps/unix/sysv/linux/posix_opt.h: Likewise. * semaphore.h: Likewise. * sysdeps/pthread/pthread.h: Likewise. * lockfile.c: <foo.h> -> <bits/foo.h>. * semaphore.h: Likewise. * Makefile: (headers): foo.h -> bits/foo.h. * sysdeps/pthread/Makefile: Likewise. 1997-04-11 01:18 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de> * semaphore.c (sem_init): Set sem_spinlock only if available. * sysdeps/m68k/pt-machine.h (testandset, __compare_and_swap): Fix asm constraints. 1997-04-09 03:00 Ulrich Drepper <drepper@cygnus.com> Update from LinuxThreads 0.6. * attr.c (pthread_attr_getdetachstate): Use __sched_get_priority_max and __sched_get_priority_min instead of names without `__'. * manager.c: Rewrite large parts to implement opaque pthread_t. * cancel.c: Adapt for opaque pthread_t type. * condvar.c: Likewise. * errno.c: Likewise. * join.c: Likewise. * mutex.c: Likewise. * pthread.c: Likewise. * signals.c: Likewise. * specific.c: Likewise. * restart.h: Likewise. * queue.h: Likewise. * Examples/ex3.c: Likewise. * Examples/ex4.c: Likewise. * sysdeps/pthread/pthread.h: Likewise. * pthread.c: Accumulate time for all threads in thread manager. * semaphore.c: Implement fallback implementation for architectures sometimes missing compare-exchange operations. * cancel.c (pthread_cancel): Validate handle argument. * join.c (pthread_join): Likewise. (pthread_detach): Likewise. * signals.c (pthread_kill): Likewise. * spinlock.h (acquire): Use __sched_yield not sched_yield. * queue.h (enqueue): Enqueue thread according to priority. * internals.c (struct pthread_start_args): New struct for passing args to cloning function. (struct _pthread): Rename to _pthread_descr_struct and adapt for opaque pthread_t. * Examples/Makefile (clean): Pass -f option to rm. * sysdeps/i386/pt-machine.h: Add check for compare-exchange instruction and define TEST_FOR_COMPARE_AND_SWAP. * sysdeps/i386/i486/pt-machine.h: Removed. * sysdeps/unix/sysv/linux/local_lim.h (PTHREAD_THREADS_MAX): Increase to 1024. 1997-04-04 16:38 Ulrich Drepper <drepper@cygnus.com> * restart.h (suspend): Clear p_signal before suspending. (suspend_with_cancellation): Likewise. Patch by Xavier Leroy <Xavier.Leroy@inria.fr>. * weaks.c: Make __pthread_key_create return 1. * sysdeps/pthread/libc-lock.h: Define __libc_key_create, __libc_getspecific, __libc_setspecific, and __libc_key_t. * sysdeps/pthread/stdio-lock.h: Don't care for implementation not using libio. 1997-03-19 15:13 Miguel de Icaza <miguel@nuclecu.unam.mx> * sysdeps/sparc/pt-machine (RELEASE): Fix. 1997-03-01 07:55 Geoff Keating <geoffk@ozemail.com.au> * sysdeps/powerpc/Implies: Added. * sysdeps/powerpc/pt-machine.h: Added. * sysdeps/powerpc/semaphorebits.h: Added. 1997-01-22 01:22 Ulrich Drepper <drepper@cygnus.com> * linuxtheads/pthread.c (__pthread_initial_thread): Correct initializer. (__pthread_manager_thread): Likewise. Reported by Andreas Jaeger. 1997-01-18 22:15 Richard Henderson <rth@tamu.edu> Since sigset_t no longer fits in a register, we can't pass in the thread's initial mask so easily. Take this opportunity to simplify the clone implementation by only accepting a single void* argument. * linuxthreads/manager.c (__pthread_manager): Put thread vitals in the thread struct instead of as arguments through clone. (pthread_start_thread): Look for them there. * linuxthreads/internals.h (struct _pthread): Add p_initial_fn, p_initial_fn_arg, p_initial_mask. Fix __pthread_manager proto. * linuxthreads/pthread.c (pthread_initialize_manager): Revise clone invocation.
152 lines
4.7 KiB
Groff
152 lines
4.7 KiB
Groff
.TH PTHREAD_SPECIFIC 3 LinuxThreads
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.SH NAME
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pthread_key_create, pthread_key_delete, pthread_setspecific, pthread_getspecific \- management of thread-specific data
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.SH SYNOPSIS
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#include <pthread.h>
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int pthread_key_create(pthread_key_t *key, void (*destr_function) (void *));
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int pthread_key_delete(pthread_key_t key);
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int pthread_setspecific(pthread_key_t key, const void *pointer);
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void * pthread_getspecific(pthread_key_t key);
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.SH DESCRIPTION
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Programs often need global or static variables that have different
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values in different threads. Since threads share one memory space,
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this cannot be achieved with regular variables. Thread-specific data
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is the POSIX threads answer to this need.
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Each thread possesses a private memory block, the thread-specific data
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area, or TSD area for short. This area is indexed by TSD keys. The TSD
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area associates values of type !void *! to TSD keys. TSD keys are
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common to all threads, but the value associated with a given TSD key
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can be different in each thread.
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For concreteness, the TSD areas can be viewed as arrays of !void *!
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pointers, TSD keys as integer indices into these arrays, and the value
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of a TSD key as the value of the corresponding array element in the
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calling thread.
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When a thread is created, its TSD area initially associates !NULL!
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with all keys.
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!pthread_key_create! allocates a new TSD key. The key is stored in the
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location pointed to by |key|. There is a limit of !PTHREAD_KEYS_MAX!
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on the number of keys allocated at a given time. The value initially
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associated with the returned key is !NULL! in all currently executing
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threads.
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The |destr_function| argument, if not !NULL!, specifies a destructor
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function associated with the key. When a thread terminates via
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!pthread_exit! or by cancellation, |destr_function| is called with
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arguments the value associated with the key in that thread. The
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|destr_function| is not called if that value is !NULL!. The order in
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which destructor functions are called at thread termination time is
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unspecified.
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Before the destructor function is called, the !NULL! value is
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associated with the key in the current thread. A destructor function
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might, however, re-associate non-!NULL! values to that key or some
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other key. To deal with this, if after all the destructors have been
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called for all non-!NULL! values, there are still some non-!NULL!
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values with associated destructors, then the process is repeated. The
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LinuxThreads implementation stops the process after
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!PTHREAD_DESTRUCTOR_ITERATIONS! iterations, even if some non-!NULL!
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values with associated descriptors remain. Other implementations may
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loop indefinitely.
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!pthread_key_delete! deallocates a TSD key. It does not check whether
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non-!NULL! values are associated with that key in the currently
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executing threads, nor call the destructor function associated with
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the key.
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!pthread_setspecific! changes the value associated with |key| in the
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calling thread, storing the given |pointer| instead.
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!pthread_getspecific! returns the value currently associated with
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|key| in the calling thread.
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.SH "RETURN VALUE"
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!pthread_key_create!, !pthread_key_delete!, and !pthread_setspecific!
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return 0 on success and a non-zero error code on failure. If
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successful, !pthread_key_create! stores the newly allocated key in the
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location pointed to by its |key| argument.
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!pthread_getspecific! returns the value associated with |key| on
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success, and !NULL! on error.
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.SH ERRORS
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!pthread_key_create! returns the following error code on error:
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.RS
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.TP
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!EAGAIN!
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!PTHREAD_KEYS_MAX! keys are already allocated
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.RE
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!pthread_key_delete! and !pthread_setspecific! return the following
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error code on error:
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.RS
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.TP
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!EINVAL!
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|key| is not a valid, allocated TSD key
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.RE
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!pthread_getspecific! returns !NULL! if |key| is not a valid,
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allocated TSD key.
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.SH AUTHOR
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Xavier Leroy <Xavier.Leroy@inria.fr>
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.SH "SEE ALSO"
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pthread_create(3), pthread_exit(3), pthread_testcancel(3).
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.SH EXAMPLE
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The following code fragment allocates a thread-specific array of 100
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characters, with automatic reclaimation at thread exit:
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.RS
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.ft 3
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.nf
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.sp
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/* Key for the thread-specific buffer */
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static pthread_key_t buffer_key;
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/* Once-only initialisation of the key */
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static pthread_once_t buffer_key_once = PTHREAD_ONCE_INIT;
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/* Allocate the thread-specific buffer */
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void buffer_alloc(void)
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{
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pthread_once(&buffer_key_once, buffer_key_alloc);
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pthread_setspecific(buffer_key, malloc(100));
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}
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/* Return the thread-specific buffer */
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char * get_buffer(void)
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{
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return (char *) pthread_getspecific(buffer_key);
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}
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/* Allocate the key */
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static void buffer_key_alloc()
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{
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pthread_key_create(&buffer_key, buffer_destroy);
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}
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/* Free the thread-specific buffer */
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static void buffer_destroy(void * buf)
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{
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free(buf);
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}
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.ft
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.LP
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.RE
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.fi
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