Example 2
Author: Ambreen Ilyas

/////////////////////////////////////////////////////////////////////////////////////////////////////////////////
//// This example is from the ACE Programmers Guide.
//// Chapter: "The Message Queue"
//// For details please see the guide at
//// http://www.cs.wustl.edu/~schmidt/ACE.html
//// AUTHOR: Umar Syyid (usyyid@hns.com)
//// and Ambreen Ilyas (ambreen@bitsmart.com)
/////////////////////////////////////////////////////////////////////////////////////////////////////////////

//Example 2

#include "ace/Message_Queue.h"
#include "ace/Get_Opt.h"
#include "ace/Malloc_T.h"
#define SIZE_BLOCK 1

class Args{
public:
Args(int argc, char*argv[],int& no_msgs, ACE_Message_Queue<ACE_NULL_SYNCH>* &mq){
ACE_Get_Opt get_opts(argc,argv,"h:l:t:n:xsd");
while((opt=get_opts())!=-1)
switch(opt){
case 'n':
//set the number of messages we wish to enqueue and dequeue
no_msgs=ACE_OS::atoi(get_opts.optarg);
ACE_DEBUG((LM_INFO,"Number of Messages %d \n",no_msgs));
break;

case 'h':
//set the high water mark
hwm=ACE_OS::atoi(get_opts.optarg);
mq->high_water_mark(hwm);
ACE_DEBUG((LM_INFO,"High Water Mark %d msgs \n",hwm));
break;
case 'l':
//set the low water mark
lwm=ACE_OS::atoi(get_opts.optarg);
mq->low_water_mark(lwm);
ACE_DEBUG((LM_INFO,"Low Water Mark %d msgs \n",lwm));
break;
default:
ACE_DEBUG((LM_ERROR, "Usage -n<no. messages> -h<hwm> -l<lwm>\n"));
break;
}
}

private:
int opt;
int hwm;
int lwm;
};

class QTest{
public:
QTest(int argc, char*argv[]){
//First create a message queue of default size.
if(!(this->mq_=new ACE_Message_Queue<ACE_NULL_SYNCH> ()))
ACE_DEBUG((LM_ERROR,"Error in message queue initialization \n"));
//Use the arguments to set the water marks and the no of messages
args_ = new Args(argc,argv,no_msgs_,mq_);
}
int start_test(){
for(int i=0; i<no_msgs_;i++){
//Create a new message block of data buffer size 1
ACE_Message_Block * mb= new ACE_Message_Block(SIZE_BLOCK);
//Insert data into the message block using the rd_ptr
*mb->wr_ptr()=i;
//Be careful to advance the wr_ptr
mb->wr_ptr(1);

//Enqueue the message block onto the message queue
if(this->mq_->enqueue_prio(mb)==-1){
ACE_DEBUG((LM_ERROR,"\nCould not enqueue on to mq!!\n"));
return -1;
}
ACE_DEBUG((LM_INFO,"EQd data: %d\n",*mb->rd_ptr()));
}
//Use the iterators to read
this->read_all();

//Dequeue all the messages
this->dequeue_all();
return 0;
}

void read_all(){
ACE_DEBUG((LM_INFO,"No. of Messages on Q:%d Bytes on Q:%d \n", mq_->message_count(),mq_->message_bytes()));
ACE_Message_Block *mb;

//Use the forward iterator
ACE_DEBUG((LM_INFO,"\n\nBeginning Forward Read \n"));
ACE_Message_Queue_Iterator<ACE_NULL_SYNCH> mq_iter_(*mq_);
while(mq_iter_.next(mb)){
mq_iter_.advance();
ACE_DEBUG((LM_INFO,"Read data %d\n",*mb->rd_ptr()));
}
//Use the reverse iterator
ACE_DEBUG((LM_INFO,"\n\nBeginning Reverse Read \n"));
ACE_Message_Queue_Reverse_Iterator<ACE_NULL_SYNCH>
mq_rev_iter_(*mq_);
while(mq_rev_iter_.next(mb)){
mq_rev_iter_.advance();
ACE_DEBUG((LM_INFO,"Read data %d\n",*mb->rd_ptr()));
}
}

void dequeue_all(){
ACE_DEBUG((LM_INFO,"\n\nBeginning DQ \n"));
ACE_DEBUG((LM_INFO,"No. of Messages on Q:%d Bytes on Q:%d \n", mq_->message_count(),mq_->message_bytes()));
ACE_Message_Block *mb;

//dequeue the head of the message queue until no more messages are left
for(int i=0;i<no_msgs_;i++){
mq_->dequeue_head(mb);
ACE_DEBUG((LM_INFO,"DQd data %d\n",*mb->rd_ptr()));
}
}

private:
Args *args_;
ACE_Message_Queue<ACE_NULL_SYNCH> *mq_;
int no_msgs_;
};

int main(int argc, char* argv[]){
QTest test(argc,argv);
if(test.start_test()<0)
ACE_DEBUG((LM_ERROR,"Program failure \n"));
}

Next Example