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.TH SDL_LockRWLockForReading 3 "SDL 3.1.0" "SDL" "SDL3 FUNCTIONS"
.SH NAME
SDL_LockRWLockForReading \- Lock the read/write lock for _read only_ operations\[char46]
.SH SYNOPSIS
.nf
.B #include \(dqSDL3/SDL.h\(dq
.PP
.BI "void SDL_LockRWLockForReading(SDL_RWLock *rwlock) SDL_ACQUIRE_SHARED(rwlock);
.fi
.SH DESCRIPTION
This will block until the rwlock is available, which is to say it is not
locked for writing by any other thread\[char46] Of all threads waiting to lock the
rwlock, all may do so at the same time as long as they are requesting
read-only access; if a thread wants to lock for writing, only one may do so
at a time, and no other threads, read-only or not, may hold the lock at the
same time\[char46]

It is legal for the owning thread to lock an already-locked rwlock for
reading\[char46] It must unlock it the same number of times before it is actually
made available for other threads in the system (this is known as a
"recursive rwlock")\[char46]

Note that locking for writing is not recursive (this is only available to
read-only locks)\[char46]

It is illegal to request a read-only lock from a thread that already holds
the write lock\[char46] Doing so results in undefined behavior\[char46] Unlock the write
lock before requesting a read-only lock\[char46] (But, of course, if you have the
write lock, you don't need further locks to read in any case\[char46])

This function does not fail; if rwlock is NULL, it will return immediately
having locked nothing\[char46] If the rwlock is valid, this function will always
block until it can lock the mutex, and return with it locked\[char46]

.SH FUNCTION PARAMETERS
.TP
.I rwlock
the read/write lock to lock
.SH AVAILABILITY
This function is available since SDL 3\[char46]0\[char46]0\[char46]

.SH SEE ALSO
.BR SDL_LockRWLockForWriting (3),
.BR SDL_TryLockRWLockForReading (3),
.BR SDL_UnlockRWLock (3)