Maximum Size that a Boost Message Queue can Handle? - c++

Question

What is the maximum size a Boost Message Queue can Handle?
When I am sending and receiving the below structure by using Boost binary serialization it is working fine.
typedef struct {
int msg_type;
char msg_name[100];
union {
struct {
int ID;
std::string ReportedTime;
char ReceivedAt[200];
int Number;
int Priority;
} mess1;
struct {
char host_ip[20];
char mac_addr[30];
char time_stamp[100];
} mess2;
} struct_type;
}msg_struct;
#include <boost/serialization/is_bitwise_serializable.hpp>
BOOST_IS_BITWISE_SERIALIZABLE(msg_struct)
But when I making the size of ReceivedAt[2000] to 2000 or adding a new char array variable.
It is throwing the following exception and the core is getting dumped.
terminate called after throwing an instance of 'boost::interprocess::interprocess_exception'
what(): boost::interprocess_exception::library_error
Aborted (core dumped)
Edit
Send
int ControlQueue::pushMessage(msg_struct* msg)
{
int q_size = vamsgq->get_num_msg();
int retVal = 0;
lockQueue();
//imp->ID=1;
//strcpy(imp->ReceivedAt,"10-07-14");
std::stringstream oss;
boost::archive::binary_oarchive oa(oss);
strncpy(msg->msg_name,"msg_name",sizeof(msg->msg_name));
oa << boost::serialization::make_array(msg, 1);
std::string serialized_string(oss.str());
vamsgq->send(serialized_string.data(), serialized_string.size(), 0);
std::cout <<"\n sendig type="<< msg->msg_name << std::endl;
if((retVal = pthread_cond_signal(&m_qCondSignal)) != 0)
{
cout<<__FILE__<<__LINE__<<
"{ControlQueue %x} Unable to send Cond Signal",this);
}
unlockQueue();
return 1;
}
Recieve:
msg_struct* ControlQueue::getMsg()
{
int retVal = 0;
message_queue::size_type recvd_size;
unsigned int priority;
lockQueue();
while(vamsgq->get_num_msg()==0)
{
if((retVal = pthread_cond_wait(&m_qCondSignal, &m_qMutex)) != 0)
{
cout<<__FILE__<<__LINE__<<"getMsg {ControlQueue } Unable to Cond Signal";
unlockQueue();
return NULL;
}
}
msg_struct *l_msg_struct = NULL;
if(vamsgq->get_num_msg())
{
l_msg_struct=new msg_struct();
std::stringstream iss;
std::string serialized_string;
serialized_string.resize(MAX_SIZE);
vamsgq->receive(&serialized_string[0], MAX_SIZE, recvd_size, priority);
iss << serialized_string;
boost::archive::binary_iarchive ia(iss);
ia >> boost::serialization::make_array(l_msg_struct, 1);
std::cout <<"Recieving="<< l_msg_struct->msg_name << std::endl;
}
else
{
cout<<__FILE__<<__LINE__<<"getMsg {ControlQueue } m_MsgQ empty..";
}
unlockQueue();
return l_msg_struct;
}
The Send and Receive both are running in different threads the only problem what I am getting is after increasing the size of structure or adding an char array variable.
And the exception is getting thrown by the vamsgq->send() method, Creation method(message queue) is working fine. And I am also increasing the size of Message that message queue is going to store.
Is there any complete documentation online for the boost::message_queue.

Answer 1

You broke the requirement for
BOOST_IS_BITWISE_SERIALIZABLE(msg_struct)
by no longer keeping the msg_struct a POD type:
static_assert(boost::is_pod<msg_struct>::value, "msg_struct must be POD");
will fail to compile. (In fact, with the msg_struct shown using std::string, I think default construction should fail to compile, so the new msg_struct() line in your example confuses me).
Also you don't show the construction of the message-queue, so I can't tell how you determine the maximum message size. This might be inadequately dimensioned. See below for two approaches that use/check the size limitations.
Here's what would work:
[Solution A] All POD data, no serialization
#include <boost/serialization/serialization.hpp>
#include <boost/interprocess/ipc/message_queue.hpp>
typedef struct {
int msg_type;
char msg_name[100];
union {
struct {
int ID;
char ReportedTime[100];
char ReceivedAt[2000];
int Number;
int Priority;
} mess1;
struct {
char host_ip[20];
char mac_addr[30];
char time_stamp[100];
} mess2;
} struct_type;
} msg_struct;
static_assert(boost::is_pod<msg_struct>::value, "msg_struct must be POD");
#include <boost/serialization/is_bitwise_serializable.hpp>
BOOST_IS_BITWISE_SERIALIZABLE(msg_struct)
namespace ipc = boost::interprocess;
int main() {
ipc::message_queue queue(ipc::open_or_create, "myqueue", 100, sizeof(msg_struct));
msg_struct outgoing;
outgoing.msg_type = 1;
strncpy(outgoing.msg_name, "outgoing.msg_name", sizeof(outgoing.msg_name));
outgoing.struct_type.mess1.ID = 42;
strncpy(outgoing.struct_type.mess1.ReportedTime, "outgoing.struct_type.mess1.ReportedTime", sizeof(outgoing.struct_type.mess1.ReportedTime));
strncpy(outgoing.struct_type.mess1.ReceivedAt, "outgoing.struct_type.mess1.ReceivedAt", sizeof(outgoing.struct_type.mess1.ReceivedAt));
outgoing.struct_type.mess1.Number = 123;
outgoing.struct_type.mess1.Priority = 234;
queue.send(&outgoing, sizeof(outgoing), 1);
}
As you can see, this is not using Boost Serialization because the struct is POD anyways.
[Solution B] Highlevel C++ types, using binary serialization
Alternatively, you can use Boost Serialization all the way and check that the message size doesn't exceed the maximum message size when sending:
#include <boost/serialization/serialization.hpp>
#include <boost/archive/binary_oarchive.hpp>
#include <boost/serialization/variant.hpp>
#include <boost/interprocess/ipc/message_queue.hpp>
typedef struct {
int msg_type;
std::string msg_name;
struct mess1_t {
int ID;
std::string ReportedTime;
std::string ReceivedAt;
int Number;
int Priority;
private:
friend class boost::serialization::access;
template <typename Ar>
void serialize(Ar& ar, unsigned)
{
ar & ID;
ar & ReportedTime;
ar & ReceivedAt;
ar & Number;
ar & Priority;
}
};
struct mess2_t {
std::string host_ip;
std::string mac_addr;
std::string time_stamp;
private:
friend class boost::serialization::access;
template <typename Ar>
void serialize(Ar& ar, unsigned)
{
ar & host_ip;
ar & mac_addr;
ar & time_stamp;
}
};
boost::variant<mess1_t, mess2_t> message_data;
private:
friend class boost::serialization::access;
template <typename Ar>
void serialize(Ar& ar, unsigned)
{
ar & msg_type;
ar & msg_name;
ar & message_data;
}
} msg_struct;
namespace ipc = boost::interprocess;
int main() {
ipc::message_queue queue(ipc::open_or_create, "myqueue", 100, 4*1024);
msg_struct outgoing { 1, "outgoing.msg_name", msg_struct::mess1_t {
42,
"outgoing.struct_type.mess1.ReportedTime",
"outgoing.struct_type.mess1.ReceivedAt",
123,
234 }
};
std::ostringstream oss;
boost::archive::binary_oarchive oa(oss);
oa << outgoing;
assert(oss.str().size() <= queue.get_max_msg_size());
queue.send(&outgoing, sizeof(outgoing), 1);
}