diff options
Diffstat (limited to 'man3/pthread_rwlockattr_setkind_np.3')
| -rw-r--r-- | man3/pthread_rwlockattr_setkind_np.3 | 119 |
1 files changed, 0 insertions, 119 deletions
diff --git a/man3/pthread_rwlockattr_setkind_np.3 b/man3/pthread_rwlockattr_setkind_np.3 deleted file mode 100644 index f2998ca..0000000 --- a/man3/pthread_rwlockattr_setkind_np.3 +++ /dev/null @@ -1,119 +0,0 @@ -.\"Copyright (c) 2010 Novell Inc., written by Robert Schweikert -.\" -.\" SPDX-License-Identifier: Linux-man-pages-copyleft -.\" -.TH pthread_rwlockattr_setkind_np 3 2023-10-31 "Linux man-pages 6.7" -.SH NAME -pthread_rwlockattr_setkind_np, pthread_rwlockattr_getkind_np \- set/get -the read-write lock kind of the thread read-write lock attribute object -.SH LIBRARY -POSIX threads library -.RI ( libpthread ", " \-lpthread ) -.SH SYNOPSIS -.nf -.B #include <pthread.h> -.P -.BI "int pthread_rwlockattr_setkind_np(pthread_rwlockattr_t *" attr , -.BI " int " pref ); -.B int pthread_rwlockattr_getkind_np( -.BI " const pthread_rwlockattr_t *restrict " attr , -.BI " int *restrict " pref ); -.P -.fi -.RS -4 -Feature Test Macro Requirements for glibc (see -.BR feature_test_macros (7)): -.RE -.P -.BR pthread_rwlockattr_setkind_np (), -.BR pthread_rwlockattr_getkind_np (): -.nf - _XOPEN_SOURCE >= 500 || _POSIX_C_SOURCE >= 200809L -.fi -.SH DESCRIPTION -The -.BR pthread_rwlockattr_setkind_np () -function sets the "lock kind" attribute of the -read-write lock attribute object referred to by -.I attr -to the value specified in -.IR pref . -The argument -.I pref -may be set to one of the following: -.TP -.B PTHREAD_RWLOCK_PREFER_READER_NP -This is the default. -A thread may hold multiple read locks; that is, read locks are recursive. -According to The Single Unix Specification, the behavior is unspecified when a -reader tries to place a lock, and there is no write lock but writers are -waiting. -Giving preference to the reader, as is set by -.BR PTHREAD_RWLOCK_PREFER_READER_NP , -implies that the reader will receive the requested lock, even if -a writer is waiting. -As long as there are readers, the writer will be -starved. -.TP -.B PTHREAD_RWLOCK_PREFER_WRITER_NP -This is intended as the write lock analog of -.BR PTHREAD_RWLOCK_PREFER_READER_NP . -This is ignored by glibc because the POSIX requirement to support -recursive read locks would cause this option to create trivial -deadlocks; instead use -.B PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP -which ensures the application developer will not take recursive -read locks thus avoiding deadlocks. -.\" --- -.\" Here is the relevant wording: -.\" -.\" A thread may hold multiple concurrent read locks on rwlock (that is, -.\" successfully call the pthread_rwlock_rdlock() function n times). If -.\" so, the thread must perform matching unlocks (that is, it must call -.\" the pthread_rwlock_unlock() function n times). -.\" -.\" By making write-priority work correctly, I broke the above requirement, -.\" because I had no clue that recursive read locks are permissible. -.\" -.\" If a thread which holds a read lock tries to acquire another read lock, -.\" and now one or more writers is waiting for a write lock, then the algorithm -.\" will lead to an obvious deadlock. The reader will be suspended, waiting for -.\" the writers to acquire and release the lock, and the writers will be -.\" suspended waiting for every existing read lock to be released. -.\" --- -.\" https://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_rwlock_rdlock.html -.\" https://sourceware.org/legacy-ml/libc-alpha/2000-01/msg00055.html -.\" https://sourceware.org/bugzilla/show_bug.cgi?id=7057 -.TP -.B PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP -Setting the lock kind to this -avoids writer starvation as long as any read locking is not done in a -recursive fashion. -.P -The -.BR pthread_rwlockattr_getkind_np () -function returns the value of the lock kind attribute of the -read-write lock attribute object referred to by -.I attr -in the pointer -.IR pref . -.SH RETURN VALUE -On success, these functions return 0. -Given valid pointer arguments, -.BR pthread_rwlockattr_getkind_np () -always succeeds. -On error, -.BR pthread_rwlockattr_setkind_np () -returns a nonzero error number. -.SH ERRORS -.TP -.B EINVAL -.I pref -specifies an unsupported value. -.SH STANDARDS -GNU; -hence the suffix "_np" (nonportable) in the names. -.SH HISTORY -glibc 2.1. -.SH SEE ALSO -.BR pthreads (7) |