boost thread - shared_mutex and condition variable

[Muthuveerappan]

Hi,

1) I would like to know the how I can put an exclusive lock on wait using a condition variable ?

Given below is my attempt, it contains 4 questions.

#include "boost/thread.hpp"

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    boost :: shared_mutex m1;
    boost :: condition_variable_any c1;

    //Do all the 3 locks below behave like scoped_lock (will they get unlocked when they go out of scope) ?
    boost :: shared_lock<boost :: shared_mutex> l1(m1);     //Shared Access
    boost :: upgrade_lock<boost :: shared_mutex> l2(m1);    //2) Is this read lock ? no other thread can read ?
    boost :: upgrade_to_unique_lock<boost :: shared_mutex> l3(l2); //Exclusive Access

    c1.wait(l3); //Throws an error, how would I be able to put the l3 on wait ?
                       //3) Also when I do so, what happens to l2, will it also be unlocked when l3 is put on wait ??
                       //4) Can I create l3 without creating l2 ?

    //I would like to put l3 on wait, so that what ever lock established is revoked, and when notified it can get the lock back.
    //5) How would I be able to achieve this ?

    return(0);

}

[Codeplug]

>> c1.wait(l3);
This shouldn't compile, because "upgrade_to_unique_lock" does not implement the "Lockable Concept". It's more a utility, RAII class for going from "upgrade ownership" to "exclusive ownership" in the constructor - and then back to "upgrade ownership" in the destructor.

The current 1.42 boost docs are kinda lite on motivation behind "shared" vs "upgrade" ownership. A quick read of N2094 should help fill in some details: http://www.open-std.org/jtc1/sc22/wg...mutex_concepts

gg

[Muthuveerappan]

Thanks a lot Codeplug, will read through that article and come back.

Yeah I wish boost had more detailed documentation on how and in what situations to use them.

Thanks again,
Muthu