Re: Select is not blocking.
[email]naresh.ganapathineedi@gmail.com[/email] wrote:[color=blue]
> Hi,
>
> I have created two tasks. one creates a socket and sends only one
> message. The other one first wait on select to read the data and if
> the data is availble, it will read it.
>
> What happend is select is returned correctly for the first time when
> the socket has the data and read it. Afterthat also select is
> returting 1 eventhough my socket has nothing to read. Here is my code.[/color]
Select() is returning because the sender closed the socket. Your code
needs to look at the case where the fd is readable but the read returns
0 bytes as the case where the receiver will close its fd and remove it
from the select list.
Mark
[color=blue]
>
> #define MAX_MESSAGE_LENGTH 1024
>
> typedef enum {
> BOOL_FALSE = 0,
> BOOL_TRUE = 1
> } Boolean_t;
>
>
> void nar_sender_task( void )
> {
>
> int mbxSock;
> int noOfMsg ;
> char *msg;
> int msglen;
>
>
> printf ("\n Entered into the sender task");
>
> msg = (char *)malloc( MAX_MESSAGE_LENGTH );
>
> if (NULL == msg)
> {
> printf("\n Memory allocation failed");
> exit(1);
> }
>
> memset(msg, 0xAA , MAX_MESSAGE_LENGTH - 1);
> msg[MAX_MESSAGE_LENGTH - 1] = '\0';
>
> msglen = strlen ( msg ) + 1;
>
> printf("\n msglen : %d", msglen);
>
>
> // create socket and init parameters
> mbxSock = socket(AF_INET, SOCK_STREAM,0);
> if ( -1 == mbxSock )
> {
> printf("\n Socket creation failed");
> exit(1);
> }
>
> printf("\n Socket creation successful : sender");
> int reuse = 1;
> setsockopt(mbxSock, SOL_SOCKET, SO_REUSEADDR, (char *) &reuse,
> sizeof(int));
>
> // connect socket to receiver task
> struct sockaddr_in addrPtr;
>
> addrPtr.sin_family = AF_INET;
> addrPtr.sin_port = 1299;
>
> // use loopback device
> addrPtr.sin_addr.s_addr = inet_addr("127.0.0.1");
>
> while (0 != connect(mbxSock,
> (struct sockaddr *) &addrPtr,
> sizeof(addrPtr)))
> {
> printf("\n Error during socket connection, still trying...");
>
> taskDelay(1000);
> }
>
> int flag = 1;
> setsockopt(mbxSock, IPPROTO_TCP, TCP_NODELAY, (char *) &flag,
> sizeof(int));
>
> int bufferSize = 16384;
> setsockopt(mbxSock,SOL_SOCKET,SO_SNDBUF,(char
> *)&bufferSize,sizeof(int));
>
> noOfMsg = 0;
> do
> {
> int tmpsent;
>
> // Call send to send the message block to receiver.
> //
> printf ( "\n Calling send
> --------------------------------------------------");
>
>
> tmpsent = send(mbxSock, (char *)msg, msglen, 0);
>
> if( -1 == tmpsent )
> {
> // send failed !
> // assume it is because there is no more free mbufs
> // so, we wait a bit, and try again !
>
> printf("send to other thread failed !");
>
> taskDelay(250);
> continue;
> }
> noOfMsg++;
> }while (1 != noOfMsg );
>
> free ( msg );
>
> shutdown(mbxSock,2);
> close(mbxSock);
>
> printf("\n -----------------------------------------");
> printf("\n Existing from nar_sender_task");
> printf("\n -----------------------------------------");
> }
>
>
> void nar_receiver_task ( void )
> {
>
> struct fd_set fdMasks;
>
> int maxSockId = -1;
> int listenSock;
> int mailboxSock = -1;
>
> int count = 0;
>
> FD_ZERO(&fdMasks);
>
> listenSock = socket( AF_INET, SOCK_STREAM,0 );
>
> if ( -1 == listenSock )
> {
> printf("\n Listen socket creation failed");
> exit(1);
> }
>
> printf ("\n Listen socket created");
>
> int reuse = 1;
> setsockopt(listenSock, SOL_SOCKET, SO_REUSEADDR,(char *)
> &reuse,sizeof(int));
>
>
> sockaddr_in add;
>
> add.sin_family = AF_INET;
> add.sin_port = 1299;
> add.sin_addr.s_addr = INADDR_ANY;
>
> // Bind address to the socket.
> //
> if ( -1 == bind(listenSock, (struct sockaddr *)&add, sizeof(struct
> sockaddr_in)) )
> {
> printf("\n Socket bind failed with error no : %d",errno);
> shutdown(listenSock,2);
> close(listenSock);
>
> exit(1);
> }
>
> printf ("\n Bind Successful");
>
> if ( -1 == listen(listenSock, 5) )
> {
> printf("\n Socket listen failed with error no : %d",errno);
> shutdown(listenSock,2);
> close(listenSock);
>
> exit(1);
> }
>
> printf("\n Listen successful");
>
> struct sockaddr clientAddress;
> int addrlg; // socket address structure length.
>
> printf("\n Calling accept .... Naresh");
>
> addrlg = sizeof(clientAddress);
> int tmp_sock_id = accept(listenSock,
> ( sockaddr *) &clientAddress, &addrlg);
>
> if (-1 == tmp_sock_id)
> {
>
> printf("\n Socket accept failed with error no : %d",errno);
> shutdown(listenSock,2);
> close(listenSock);
>
> exit(1);
> }
>
>
> printf ("\n tmp_sock_id : %d", tmp_sock_id);
>
> unsigned long remoteIp = ((struct sockaddr_in *)
> &clientAddress)->sin_addr.s_addr;
>
> // socket ID is valid
> // check if it is the local socket from the other task
> if( remoteIp == inet_addr("127.0.0.1") )
> {
> mailboxSock = tmp_sock_id;
> /* int blocking = 1;
> ioctl(mailboxSock,FIONBIO,(int)&blocking); */
>
> FD_SET(mailboxSock, &fdMasks);
>
> // and update maxSockId
> if ( mailboxSock > maxSockId )
> maxSockId = mailboxSock;
>
> printf ("\n mailboxSock : %d", mailboxSock);
> printf("\n maxSockId : %d", maxSockId);
> }
>
> int select_code;
>
> while(1)
> {
>
> printf ("\n Calling select");
> // call select
> printf("\n maxSockId : %d", maxSockId);
>
> FD_ZERO(&fdMasks);
> FD_SET(mailboxSock, &fdMasks);
>
> select_code = select( maxSockId + 1,
> &fdMasks, NULL, NULL, NULL);
>
> if( -1 == select_code )
> {
> printf("\n Select is failed ............");
> exit(1);
> }
>
> if ( errno == EINTR )
> {
> printf("\n Select returned EINTR");
> continue;
> }
>
> // measure of 'empty' select()
> if ( 0 == select_code )
> {
> printf ("empty select with errno = %d", errno);
> continue;
> }
>
>
> printf ("\n Printing select return code : %d", select_code);
>
> if( (-1 != mailboxSock ) && (FD_ISSET(mailboxSock, &fdMasks)) )
> {
> int rcvBytes;
> char bufferToRec[MAX_MESSAGE_LENGTH];
>
> rcvBytes = recv(mailboxSock,(char
> *)bufferToRec,MAX_MESSAGE_LENGTH,0);
>
> if (rcvBytes == -1)
> {
> printf("\n Socket Recv failed with error no :
> %d",errno);
> shutdown(listenSock,2);
> close(listenSock);
> exit(1);
> }
>
> if ( 0 != rcvBytes )
> {
> printf(" \n Message : %d", count++);
> printf("\n
> ------------------------------------------");
> printf("\n ( --- No.of bytes Received : %d --- )",
> rcvBytes );
> printf( "\n Read message : %s", bufferToRec);
> }
> else
> {
> printf ("\n recv retured %d as return value with error
> no : %d", rcvBytes, errno);
> }
> }
> }
>
> }
>
> Can some body help me why the select is not blocking eventhough my
> socket has nothing to read.
>[/color]
Re: Select is not blocking.
Thank u Mark.
It is working now.
