VMS Help POSIX Threads, TIS routines, tis_read_lock  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Acquires a read-write lock for read access.

1 - C Binding

    #include <tis.h>

    int
    tis_read_lock (
             tis_rwlock_t   *lock);

2 - Arguments

 lock

    Address of the read-write lock.

3 - Description

    This routine acquires a read-write lock for read access. This
    routine waits for any existing lock holder for write access to
    relinquish its lock before granting the lock for read access.
    This routine returns when the lock is acquired. If the lock is
    already held simply for read access, the lock is granted.

    For each call to tis_read_lock() that successfully acquires the
    lock for read access, a corresponding call to tis_read_unlock()
    must be issued.

4 - Return Values

    If an error condition occurs, this routine returns an integer
    value indicating the type of error. Possible return values are as
    follows:

    Return      Description

    0           Successful completion.
    [EINVAL]    The value specified by lock is not a valid read-write
                lock.

5 - Associated Routines

       tis_read_trylock()
       tis_read_unlock()
       tis_rwlock_destroy()
       tis_rwlock_init()
       tis_write_lock()
       tis_write_trylock()
       tis_write_unlock()