Re: [boost] How to implement a reader-writer lock with quick responseto writer?

Subject: Re: [boost] How to implement a reader-writer lock with quick responseto writer?
From: Paul Rose (prose_at_[hidden])
Date: 2008-09-18 11:33:18

Bill,

You can build a r/w lock that preferrs writers on top of
boost::condition_variable.

See the "Write-Priority Read/Write Locks" section of the page:

http://publib.boulder.ibm.com/infocenter/systems/topic/com.ibm.aix.genpr
ogc/doc/genprogc/complex_synchronization_objects.htm

for an example on top of pthread_cond_t.  Converting to
boost:condition_variable should be mostly an exercise in search/replace.

The site is very slow today, you might want to see the Google cache
version:

http://72.14.205.104/search?q=cache:TzrAWFUhsc8J:publib.boulder.ibm.com/
infocenter/systems/topic/com.ibm.aix.genprogc/doc/genprogc/complex_synch
ronization_objects.htm+pthread_cond_t+reader+writer+lock&hl=en&ct=clnk&c
d=4&gl=us

Essentially you keep a pair of condition variables that share a single
mutex.  State is held by two integers.  A lock count integer is -1 when
held by writer, 0 for free and >0 when held by readers.  A
waiting_writers integer counts the number of waiting writers.  New
readers can only acquire the lock when lock_count is >= 0
waiting_writers == zero.

Sincerely,
 
Paul Rose
 
 

> -----Original Message-----
> From: boost-bounces_at_[hidden] 
> [mailto:boost-bounces_at_[hidden]] On Behalf Of Bill David
> Sent: Wednesday, September 17, 2008 10:12 AM
> To: boost_at_[hidden]
> Subject: [boost] How to implement a reader-writer lock with 
> quick responseto writer?
> 
> Question:
> How to implement a reader-writer lock with quick response to writer?
>