C++ Threading Bi-Directional Rendezvous

static char internet[8];

static semaphore emptyBuffers[8];

static semaphore fullBuffers[0];

static void writer() {

    for( int i = 0; i < 400; i++) {

        char ch = randomChar();  // calculate the next char to be written to the internet

        // need a slot on the shared internet to write this char

        emptyBuffers.wait();

        internet[ i % 8 ] = ch;        // the exact spot where the next char goes

        fullBuffers.signal();

    }

}

static void reader() {

    for( int i = 0; i < 400; i++) {

        // reader needs to wait for there to be a character to read

        fullBuffers.wait();

        char ch = internet[ i % 8 ];   // from shared internet to a local var

        emptyBuffers.signal();

        processChar(ch);

    }

}

int main(  ) {

    thread w(writer);

    thread r(reader);

    w.join();

    r.join();

    return 0;

}

Myth-Buster example to show polling a bunch of servers to find out how many processes are running on each server. Goal is to surface the least used server.

Sequential Version

short countProcesses(unsigned short num, const set<string> &studentids);

void compileProcessCountMap(map<short, int> &m, const set<string> &studentids) {

    for( unsigned short num = 1; num <= highestServerNumber; num++) {

        short count = countProcesses(num, studentids);

        if(count >= 0) {

            m[num] = count;  // add the new key/value to the map

        }

    }

}

int main() {

    set<string> studentids;

    readStudentids(studentids, “/class/studentids.txt”);

    map<short, int> processCountMap; // map of server ids to the number of processes

    // pass in the map to update and the student’s ids from the class

    compileProcessCountMap(processCountMap, studentids);

    return 0;

}