#include <pthread.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <limits.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <errno.h>
#include <sys/wait.h>
#include <signal.h>

#define SOCKET_SERVER

const int NUM_THREADS = 100000;
//const int THREAD_STACK_SIZE = 1024 * 78;
const int THREAD_STACK_SIZE = 1024 * 4;
//const int THREAD_STACK_SIZE = 1024 * 64;
const int PORT = 7501;
const int SOCKET_ACCEPT_BACKLOG = 8192;
const int ECHO_BUFSIZE = 8192;
const int NUM_PROCS = 1;

// 64: 32292
// 78: 32292
// 79: 32290
// 80: 32290

void *waste_time(void *args) {
  char buf[1024];
  int i = 0;
  while(1) {
    buf[i] = i;
    i = (i + 1) % 1024;
    pause();
  }
}

void *echo_socket(void *args) {
  int fd = (int) args;
  char buf[ECHO_BUFSIZE];
  int readBytes, justWroteBytes, alreadyWroteBytes;
  
  while ((readBytes = read(fd, buf, ECHO_BUFSIZE)) > 0) {
    alreadyWroteBytes = 0;
    do {
      if ((justWroteBytes = write(fd,buf + alreadyWroteBytes,readBytes-alreadyWroteBytes)) <= 0) {
        if (justWroteBytes < 0)
          perror("write failed in thread");
        return NULL;
      }
      alreadyWroteBytes += justWroteBytes;
    } while (readBytes > alreadyWroteBytes);
  }

  /* If we get here, readBytes is either 0 for EOF, or -1 for error. */
  if (readBytes < 0) {
    perror("read failed in thread");
  }
  
  return NULL;
}

int main() {
  pthread_attr_t thread_attr;
  pthread_t thr[NUM_THREADS];
  int i;
#ifdef SOCKET_SERVER
  int sock;
  struct sockaddr_in serverAddr;
  const int on = 1;
#endif

#ifdef SOCKET_SERVER
  if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
    perror("Error creating socket");
    exit(1);
  }

  if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) < 0) {
    perror("Error setting socket option SO_REUSEADDR");
    exit(1);
  }

  memset((void *)&serverAddr, 0, sizeof(serverAddr));
  serverAddr.sin_family = AF_INET;
  serverAddr.sin_addr.s_addr = INADDR_ANY;
  serverAddr.sin_port = htons(PORT);
  if (bind(sock,(const struct sockaddr*)&serverAddr, sizeof(serverAddr)) < 0) {
    perror("Error binding socket");
    exit(1);
  }

  if (listen(sock, SOCKET_ACCEPT_BACKLOG) < 0)
    return -1;
#endif
  if (pthread_attr_init(&thread_attr) != 0) {
    perror("Error initializing thread attributes");
    exit(1);
  }
  if (pthread_attr_setstacksize(&thread_attr, PTHREAD_STACK_MIN + THREAD_STACK_SIZE) != 0) {
    perror("Error initializing thread attributes");
    exit(1);    
  }
  
  pid_t pid;
  int forkRet;
  for(i=0;i<NUM_PROCS;i++) {
    forkRet = fork();
    if (forkRet == -1) {
      perror("fork error");
      exit(-1);      
    } else if (forkRet == 0) {
      /* child */
      break;
    } else {
      printf("Parent %d created child %d\n",getpid(),forkRet);
    }
  }

  pid = getpid();
  if (forkRet != 0) {
    /* Original process */
    for(i=0;i<NUM_PROCS;i++) {
      int childStatus;
      int waitRet = wait(&childStatus);
      if (waitRet == -1) {
        perror("wait error");
        exit(1);
      } else {
        fprintf(stderr,"PID %d exited with status %d\n",waitRet,childStatus);
        if (childStatus != 0) {
          fprintf(stderr,"Child failed, exiting...");
          kill(0,SIGINT);
          exit(1);
        }
      }
    }
  }
  
  for(i=0;i<NUM_THREADS/NUM_PROCS;i++) {
#ifdef SOCKET_SERVER
    int connfd = 0;
    struct sockaddr clientAddr;
    size_t len = sizeof(clientAddr);
    if ((connfd = accept(sock, (struct sockaddr*)&clientAddr, &len)) < 0) {
      fprintf(stderr,"PID %d error creating thread %d: %s\n",pid,i,strerror(errno));
      exit(1);
    }
    if (pthread_create(thr + i, &thread_attr, echo_socket, (void *) connfd) != 0) {
#else
    if (pthread_create(thr + i, &thread_attr, waste_time, NULL) != 0) {
#endif
      fprintf(stderr,"PID %d error #%d creating thread %d: %s\n",pid,errno,i,strerror(errno));
      if (errno == EAGAIN) {
        fprintf(stderr,"PID %d retrying...\n",pid);
        i--;
        continue;
      } else {
        sleep(10);
        exit(1);
      }
    }
    printf("PID %d accepted connection %d\n",pid,i);
    
  }
  
  exit(0);
}