tis(3)							     Library Functions Manual							    tis(3)

NAME

       tis, tis_intro - Introduction to Thread-Independent Services (tis)

DESCRIPTION

       Thread-independent  services  (tis) routines compose a Compaq-proprietary interface to the DECthreads multitasking library.  The tis inter-
       face provides services that assist with the development of thread-safe libraries.

       Thread synchronization can involve significant run-time cost, which is undesirable in a nonthreaded environment.  In the nonthreaded  envi-
       ronment,  the  tis  interface enables you to build thread-safe libraries that are efficient, yet provide the necessary synchronization when
       called from a threaded environment.

       When threads are not active within the process, tis routines execute only the minimum steps necessary: code running in a nonthreaded  envi-
       ronment	is  not  burdened  by  the  run-time  synchronization that is necessary when the same code is run in a threaded environment.  When
       threads are active, tis routines provide the necessary thread-safe synchronization.

       The tis objects created using this interface are fully interchangeable with DECthreads Pthreads (POSIX 1003.1c) objects.  So, a	mutex  can
       be  created by using static initialization (or using tis_mutex_init(3)) and can be locked, the DECthreads core library (libpthread.so) sub-
       sequently activated, and the mutex unlocked.  Keys created by tis_key_create(3) are valid when a threaded run-time environment is loaded.

       Note that errno is NOT used by the tis routines.  To indicate errors, the tis routines return integer values indicating the type of error.

       In a nonthreaded environment, condition variables should not be used to guard  operations  (for	example,  with	tis_cond_wait(3)).   In  a
       threaded environment, the guidelines for using the DECthreads Pthread routines also pertain to the use of the corresponding tis routine.

       The tis routines can be classified into the following associated groups: General routines Thread cancellation routines Thread-specific data
       key routines Mutex routines Condition variable routines Read-write lock routines

   General Routines
       Obtains a value representing a desired expiration time.	Calls a one-time initialization routine that can be executed.  Obtains the identi-
       fier of the calling thread.

   Thread Cancellation Routines
       Changes the calling thread's cancelability state.  Creates a cancellation point in the calling thread.

   Thread-Specific Data Key Routines
       Obtains	the  data associated with the specified thread-specific data key.  Generates a unique thread-specific data key.  Deletes a thread-
       specific data key.  Sets the value associated with the specified thread-specific key.

   Mutex Routines
       Locks the DECthreads global mutex.  Destroys the specified tis mutex object.  Initializes a tis mutex  object.	Locks  the  specified  tis
       mutex  if  not  already	locked.   Tries  to lock the specified tis mutex.  Unlocks the specified tis mutex.  Unlocks the DECthreads global
       mutex.

   Condition Variable Routines
       Wakes all threads waiting on the specified condition variable.  Destroys the specified condition variable object.  Initializes a  condition
       variable object.  Wakes at least one thread that is waiting on the specified condition variable.  Causes the calling thread to wait for the
       specified condition variable to be signaled or broadcast, such that it will awake after a specified period of  time.   Causes  the  calling
       thread to wait for the specified condition variable to be signaled or broadcast.

   Read-Write Lock Routines
       Acquires the specified read-write lock for read access.	Attempts to acquire the specified read-write lock for read access; returns immedi-
       ately if already locked.  Unlocks the specified read-write lock already acquired for read access.  Destroys the specified  read-write  lock
       object.	Initializes a read-write lock object.  Acquires the specified read-write lock for write access.  Attempts to acquire the specified
       read-write lock for write access; returns immediately if already locked.  Unlocks the specified read-write lock already acquired for  write
       access.	delim off

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																	    tis(3)