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Full Discussion: Mutex in Perl
Top Forums Shell Programming and Scripting Mutex in Perl Post 302145085 by superuser84 on Monday 12th of November 2007 06:57:20 PM
Old 11-12-2007
MySQL

To Porter:
I just realized that I also have to lock the file while reading as well to prevent write while reading...Thanks

To Smiling Dragon:
Thanks a lot for the pointer...I tried the sample program and thats exactly what I was looking for

Btw, where is the information that the file is locked stored ? How does another process (still using flock) know that a file is locked and has to sleep till unlocked ?

Thanks in advance.
J.
 

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WAIT_EVENT_INTERRUPT(9) 					   Driver Basics					   WAIT_EVENT_INTERRUPT(9)

NAME
wait_event_interruptible_exclusive_locked_irq - sleep until a condition gets true SYNOPSIS
wait_event_interruptible_exclusive_locked_irq(wq, condition); ARGUMENTS
wq the waitqueue to wait on condition a C expression for the event to wait for DESCRIPTION
The process is put to sleep (TASK_INTERRUPTIBLE) until the condition evaluates to true or a signal is received. The condition is checked each time the waitqueue wq is woken up. It must be called with wq.lock being held. This spinlock is unlocked while sleeping but condition testing is done while lock is held and when this macro exits the lock is held. The lock is locked/unlocked using spin_lock_irq/spin_unlock_irq functions which must match the way they are locked/unlocked outside of this macro. The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag set thus when other process waits process on the list if this process is awaken further processes are not considered. wake_up_locked has to be called after changing any variable that could change the result of the wait condition. The function will return -ERESTARTSYS if it was interrupted by a signal and 0 if condition evaluated to true. COPYRIGHT
Kernel Hackers Manual 3.10 June 2014 WAIT_EVENT_INTERRUPT(9)
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