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Task farm (POSIX TCP/IP)
Version 1
This version uses two servers (emitter and collector). Emitter accepts requests from workers and delivers tasks to be executed. Collector accepts results from workers and print them out on the screen. Workers open a separate connection with both emitter and collector for each task. The two connections are closed after processing the task and delivering the result. Tasks and results are (positive) integers. Emitter and worker termination is handled correctly. Collector does not terminate (suggestion: each worker should propagate EOS to collector. Collector should count EOS and terminate after receiving EOS from all the workers).
Emitter code
#include <stdio.h> #include <string.h> #include <unistd.h> #include <stdlib.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <netdb.h> #include <arpa/inet.h> // on demand scheduling of tasks to workers // receive request from worker i -> send task to compute to worker i // when no more tasks are available, send an EOS termination // // usage is: // a.out portno // number of the port used to get worker task requests #define MAXHOSTNAME 80 int main(int argc, char * argv[]) { int s,si, retcode, i; unsigned int salen; struct sockaddr_in sa,sai; char hostname[MAXHOSTNAME]; int task = 0; // tasks are positive integeres, in this case int tasklimit = 100; // we'll send tasklimit tasks before stopping int eos = -1; // special task to denote End Of Stream // code needed to set up the communication infrastructure printf("Declaring socket\n"); si = socket(AF_INET,SOCK_STREAM,0); // socket for inputs if(si == -1) {perror("opening socket for input"); return -1;} sai.sin_family = AF_INET; sai.sin_port = htons(atoi(argv[1])); gethostname(hostname,MAXHOSTNAME); memcpy(&sai.sin_addr, (gethostbyname(hostname)->h_addr), sizeof(sa.sin_addr)); printf("Binding to %s\n",inet_ntoa(sai.sin_addr)); retcode = bind(si,(struct sockaddr *) & sai, sizeof(sai)); if(retcode == -1) { perror("while calling bind"); return -1; } printf("Listening socket\n"); retcode = listen(si,1); if(retcode == -1) { perror("while calling listen"); return -1; } while(1==1) { salen = sizeof(sa); printf("Accepting connections .... \n"); s = accept(si,(struct sockaddr *)&sa,&salen); // accept a connection if(s == 1) { perror("while calling an accept"); return -1; } retcode = read(s,&i,sizeof(int)); // read request from worker if(retcode == -1) { perror("while reading task from worker"); return -1; } printf("%d ",i); fflush(stdout); if(task < tasklimit) { // send a task to the requesting worker write(s,&task,sizeof(task)); printf("sent task %d to worker %d\n",task,i); task++; // next task to be sent } else { // if no more tasks, then send an EOS write(s,&eos,sizeof(task)); printf("Send EOS to worker %d\n",i); } close(s); } printf("Closing operations\n"); return 0; }
Worker code
#include <stdio.h> #include <string.h> #include <stdlib.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <netdb.h> #include <unistd.h> /* * function to be computed on the single task * this is actually the only "business logic" code */ int f(int task) { sleep(1); // just to simulate some work ... return (task*task); } /* * receives integer tasks and delivers integer results, up to the reception * of an EOS (a -1) * this version opens/closes the sockets at each task, which is not * definitely efficient ... * * usage: * a.out emitter_address emitter_port collector_address collector_port */ int main(int argc, char * argv[]) { int s, retcode; struct sockaddr_in sa; int pid = 0; pid = getpid(); // get my POSIX process id printf("This is worker %d\n",pid); while(1==1) { int task, result; s = socket(AF_INET,SOCK_STREAM,0); // socket to access emitter if(s == -1) { perror("while creating the socket to emitter"); return (-1); } sa.sin_family = AF_INET; sa.sin_port = htons(atoi(argv[2])); memcpy(&sa.sin_addr, (gethostbyname(argv[1])->h_addr), sizeof(sa.sin_addr)); retcode = connect(s,(struct sockaddr *)&sa,sizeof(sa)); if(retcode == -1) { perror("while connecting to emitter"); return(-1);} write(s,&pid,sizeof(pid)); // sends a request to the emitter retcode = read(s,&task,sizeof(task)); // get a task if(retcode != sizeof(task)) { perror("while receiving a task"); return -1; } // check for EOS if(task < 0) { printf("Received EOS\n"); break; // if EOS terminate loop iteratons } else { printf("Received task %d\n",task); // otherwise process the incoming task result = f(task); printf("Computed %d -> %d\n",task,result); // send result to the collector s = socket(AF_INET,SOCK_STREAM,0); // create socket to collector sa.sin_family = AF_INET; sa.sin_port = htons(atoi(argv[4])); memcpy(&sa.sin_addr, (gethostbyname(argv[3])->h_addr), sizeof(sa.sin_addr)); retcode = connect(s,(struct sockaddr *)&sa,sizeof(sa)); if(retcode == -1) { perror("connecting to the collector"); return(-1);} // send the result and close connection write(s,&result,sizeof(result)); close(s); // then cycle again } } close(s); return 0; }
Collector code
#include <stdio.h> #include <string.h> #include <unistd.h> #include <stdlib.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <netdb.h> // receives results from the workers and displays them on the console // usage: // a.out portno // number of the port for the result socket #define MAXHOSTNAME 80 int main(int argc, char * argv[]) { int s,si, retcode, i; unsigned int salen; struct sockaddr_in sa,sai; char hostname[MAXHOSTNAME]; si = socket(AF_INET,SOCK_STREAM,0); // socket to receive the results if(si == -1) { perror("while opening socket"); return -1;} sai.sin_family = AF_INET; sai.sin_port = htons(atoi(argv[1])); gethostname(hostname,MAXHOSTNAME); memcpy(&sai.sin_addr, (gethostbyname(hostname)->h_addr), sizeof(sa.sin_addr)); retcode = bind(si,(struct sockaddr *) & sai, sizeof(sai)); if(retcode == -1) { perror("while binding socket to addr"); return -1; } retcode = listen(si,1); if(retcode == -1) { perror("while calling listen"); return -1; } while(1==1) { salen = sizeof(sa); printf("Accepting connections\n"); s = accept(si,(struct sockaddr *)&sa,&salen); // accept a connection if(s == 1) { perror("while accepting a connection"); return -1; } retcode = read(s,&i,sizeof(int));// read a res from one of the Worker if(retcode == -1) { perror("while reading a result"); return -1; } if(i==(-1)) { printf("EOS -> terminating\n"); break; } printf("Read result: %d ",i); fflush(stdout); // and print it on console close(s); } close(si); return 0; }
Deployment code (Perl)
#!/usr/bin/perl $sourcedir = "/home/marcod/Documents/Didattica/SPM/Dispensa/Codice/FarmSocket"; foreach $m (@ARGV) { print "Deploying to $m\n"; system("rsync -avz $sourcedir $m:"); print "Done!\n"; } exit;
Deployment code (BASH)
#!/bin/bash for m in $@ do rsync -avz /home/marcod/Documents/Didattica/SPM/Dispensa/Codice/FarmSocket $m: done
Launcher code (Perl)
The launcher gets parameters from the command line (see comments) and saves the names of the machines used in the
machine.used
file. These machine names are then used by the
terminator.pl
program.
#!/usr/bin/perl ### launcher emitter_machine emitter_port collector_machine collector_port w_machine* $emachine = shift @ARGV; $eport = shift @ARGV; $cmachine = shift @ARGV; $cport = shift @ARGV; open FD, ">machines.used" or die "Cannot open log file"; system("ssh $emachine \"\( cd FarmSocket\; make emitter\; ./emitter $eport \)\" & "); print FD "$emachine\n"; sleep(5); system("ssh $cmachine \"\( cd FarmSocket\; make collector\; ./collector $cport \)\" & "); print FD "$cmachine\n"; sleep(5); foreach $w (@ARGV) { system("ssh $w \"\( cd FarmSocket\; make worker\; ./worker $emachine $eport $cmachine $cport \)\" & "); print FD "$w\n"; } close FD; exit;