PTHREAD_RWLOCK_DESTROY(3)  POSIX Programmer's Manual PTHREAD_RWLOCK_DESTROY(3)



PPRROOLLOOGG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.

NNAAMMEE
       pthread_rwlock_destroy, pthread_rwlock_init -- destroy and initialize a
       read-write lock object

SSYYNNOOPPSSIISS
       #include <pthread.h>

       int pthread_rwlock_destroy(pthread_rwlock_t *_r_w_l_o_c_k);
       int pthread_rwlock_init(pthread_rwlock_t *restrict _r_w_l_o_c_k,
           const pthread_rwlockattr_t *restrict _a_t_t_r);
       pthread_rwlock_t _r_w_l_o_c_k = PTHREAD_RWLOCK_INITIALIZER;

DDEESSCCRRIIPPTTIIOONN
       The _p_t_h_r_e_a_d___r_w_l_o_c_k___d_e_s_t_r_o_y() function shall destroy the read-write lock
       object referenced by _r_w_l_o_c_k and release any resources used by the lock.
       The effect of subsequent use of the lock is undefined until the lock is
       reinitialized by another call to _p_t_h_r_e_a_d___r_w_l_o_c_k___i_n_i_t().  An
       implementation may cause _p_t_h_r_e_a_d___r_w_l_o_c_k___d_e_s_t_r_o_y() to set the object
       referenced by _r_w_l_o_c_k to an invalid value. Results are undefined if
       _p_t_h_r_e_a_d___r_w_l_o_c_k___d_e_s_t_r_o_y() is called when any thread holds _r_w_l_o_c_k.
       Attempting to destroy an uninitialized read-write lock results in
       undefined behavior.

       The _p_t_h_r_e_a_d___r_w_l_o_c_k___i_n_i_t() function shall allocate any resources
       required to use the read-write lock referenced by _r_w_l_o_c_k and
       initializes the lock to an unlocked state with attributes referenced by
       _a_t_t_r.  If _a_t_t_r is NULL, the default read-write lock attributes shall be
       used; the effect is the same as passing the address of a default read-
       write lock attributes object. Once initialized, the lock can be used
       any number of times without being reinitialized. Results are undefined
       if _p_t_h_r_e_a_d___r_w_l_o_c_k___i_n_i_t() is called specifying an already initialized
       read-write lock. Results are undefined if a read-write lock is used
       without first being initialized.

       If the _p_t_h_r_e_a_d___r_w_l_o_c_k___i_n_i_t() function fails, _r_w_l_o_c_k shall not be
       initialized and the contents of _r_w_l_o_c_k are undefined.

       See _S_e_c_t_i_o_n _2_._9_._9, _S_y_n_c_h_r_o_n_i_z_a_t_i_o_n _O_b_j_e_c_t _C_o_p_i_e_s _a_n_d _A_l_t_e_r_n_a_t_i_v_e
       _M_a_p_p_i_n_g_s for further requirements.

       In cases where default read-write lock attributes are appropriate, the
       macro PTHREAD_RWLOCK_INITIALIZER can be used to initialize read-write
       locks. The effect shall be equivalent to dynamic initialization by a
       call to _p_t_h_r_e_a_d___r_w_l_o_c_k___i_n_i_t() with the _a_t_t_r parameter specified as
       NULL, except that no error checks are performed.

       The behavior is undefined if the value specified by the _a_t_t_r argument
       to _p_t_h_r_e_a_d___r_w_l_o_c_k___i_n_i_t() does not refer to an initialized read-write
       lock attributes object.

RREETTUURRNN VVAALLUUEE
       If successful, the _p_t_h_r_e_a_d___r_w_l_o_c_k___d_e_s_t_r_o_y() and _p_t_h_r_e_a_d___r_w_l_o_c_k___i_n_i_t()
       functions shall return zero; otherwise, an error number shall be
       returned to indicate the error.

EERRRROORRSS
       The _p_t_h_r_e_a_d___r_w_l_o_c_k___i_n_i_t() function shall fail if:

       EEAAGGAAIINN The system lacked the necessary resources (other than memory) to
              initialize another read-write lock.

       EENNOOMMEEMM Insufficient memory exists to initialize the read-write lock.

       EEPPEERRMM  The caller does not have the privilege to perform the operation.

       These functions shall not return an error code of [[EEIINNTTRR]].

       _T_h_e _f_o_l_l_o_w_i_n_g _s_e_c_t_i_o_n_s _a_r_e _i_n_f_o_r_m_a_t_i_v_e_.

EEXXAAMMPPLLEESS
       None.

AAPPPPLLIICCAATTIIOONN UUSSAAGGEE
       Applications using these and related read-write lock functions may be
       subject to priority inversion, as discussed in the Base Definitions
       volume of POSIX.1-2017, _S_e_c_t_i_o_n _3_._2_9_1, _P_r_i_o_r_i_t_y _I_n_v_e_r_s_i_o_n.

RRAATTIIOONNAALLEE
       If an implementation detects that the value specified by the _r_w_l_o_c_k
       argument to _p_t_h_r_e_a_d___r_w_l_o_c_k___d_e_s_t_r_o_y() does not refer to an initialized
       read-write lock object, it is recommended that the function should fail
       and report an [[EEIINNVVAALL]] error.

       If an implementation detects that the value specified by the _a_t_t_r
       argument to _p_t_h_r_e_a_d___r_w_l_o_c_k___i_n_i_t() does not refer to an initialized
       read-write lock attributes object, it is recommended that the function
       should fail and report an [[EEIINNVVAALL]] error.

       If an implementation detects that the value specified by the _r_w_l_o_c_k
       argument to _p_t_h_r_e_a_d___r_w_l_o_c_k___d_e_s_t_r_o_y() or _p_t_h_r_e_a_d___r_w_l_o_c_k___i_n_i_t() refers to
       a locked read-write lock object, or detects that the value specified by
       the _r_w_l_o_c_k argument to _p_t_h_r_e_a_d___r_w_l_o_c_k___i_n_i_t() refers to an already
       initialized read-write lock object, it is recommended that the function
       should fail and report an [[EEBBUUSSYY]] error.

FFUUTTUURREE DDIIRREECCTTIIOONNSS
       None.

SSEEEE AALLSSOO
       _p_t_h_r_e_a_d___r_w_l_o_c_k___r_d_l_o_c_k(), _p_t_h_r_e_a_d___r_w_l_o_c_k___t_i_m_e_d_r_d_l_o_c_k(),
       _p_t_h_r_e_a_d___r_w_l_o_c_k___t_i_m_e_d_w_r_l_o_c_k(), _p_t_h_r_e_a_d___r_w_l_o_c_k___t_r_y_w_r_l_o_c_k(),
       _p_t_h_r_e_a_d___r_w_l_o_c_k___u_n_l_o_c_k()

       The Base Definitions volume of POSIX.1-2017, _S_e_c_t_i_o_n _3_._2_9_1, _P_r_i_o_r_i_t_y
       _I_n_v_e_r_s_i_o_n, <<pptthhrreeaadd..hh>>

CCOOPPYYRRIIGGHHTT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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 .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group                  2017            PTHREAD_RWLOCK_DESTROY(3)
