11-01-2010
Quote:
Originally Posted by
sehang
At such case, is critical section better than mutux?
What's controlling the critical section, if not a mutex?
You could try implementing a reader-writer lock if threads do a lot more reading than writing, otherwise, a mutex is about as good.
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LEARN ABOUT DEBIAN
ns_masterlock
Ns_Master(3aolserver) AOLserver Library Procedures Ns_Master(3aolserver)
__________________________________________________________________________________________________________________________________________________
NAME
Ns_MasterLock, Ns_MasterUnlock - Enter and leave the single master critical section lock
SYNOPSIS
#include "ns.h"
void
Ns_MasterLock(void)
void
Ns_MasterUnlock(void)
_________________________________________________________________
DESCRIPTION
The single master critical section lock is used throughout the core server to protect portions of code from being run by more than one
thread at a time. These are convenience functions which actually make calls to Ns_CsEnter and Ns_CsLeave to perform the locking and unlock-
ing function.
You should not use these functions in your modules. To protect critical sections in your modules you should create and initialize your own
named locks, then wrap your critical sections with calls to Ns_CsEnter and Ns_CsLeave.
Ns_MasterLock()
Enter the single master lock. The thread that holds this lock is guaranteed exclusive access to the section of code that follows the
call to Ns_MasterLock. Other threads that attempt to enter the master critical section while another thread owns the master lock
will block until the owning thread releases the master lock.
Be extremely careful with code you place within the master critical section. If the thread that owns the master lock blocks for any
reason while in the master critical section, other threads that need to enter that section of code will block until the master lock
is released.
Ns_MasterUnlock()
Leave the single master critical section. The thread that owns the lock must release it after the critical section of code has com-
pleted so that other threads may execute the critical section code.
SEE ALSO
nsd(1), info(n), Ns_CsEnter(3), Ns_CsLeave(3)
KEYWORDS
AOLserver 4.0 Ns_Master(3aolserver)