hiperfifo.c

专门介绍网络爬虫设计的论文,写得非常好啊.希望大家好好学习

/*****************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * $Id: hiperfifo.c,v 1.3 2007-05-02 13:52:38 bagder Exp $
 *
 * Example application source code using the multi socket interface to
 * download many files at once.
 *
 * Written by Jeff Pohlmeyer

Requires libevent and a (POSIX?) system that has mkfifo().

This is an adaptation of libcurl's "hipev.c" and libevent's "event-test.c"
sample programs.

When running, the program creates the named pipe "hiper.fifo"

Whenever there is input into the fifo, the program reads the input as a list
of URL's and creates some new easy handles to fetch each URL via the
curl_multi "hiper" API.


Thus, you can try a single URL:
  % echo http://www.yahoo.com > hiper.fifo

Or a whole bunch of them:
  % cat my-url-list > hiper.fifo

The fifo buffer is handled almost instantly, so you can even add more URL's
while the previous requests are still being downloaded.

Note:
  For the sake of simplicity, URL length is limited to 1023 char's !

This is purely a demo app, all retrieved data is simply discarded by the write
callback.

*/

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/time.h>
#include <time.h>
#include <unistd.h>
#include <sys/poll.h>
#include <curl/curl.h>
#include <event.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <errno.h>


#define MSG_OUT stdout /* Send info to stdout, change to stderr if you want */


/* Global information, common to all connections */
typedef struct _GlobalInfo {
  struct event fifo_event;
  struct event timer_event;
  CURLM *multi;
  int prev_running;
  int still_running;
  FILE* input;
} GlobalInfo;


/* Information associated with a specific easy handle */
typedef struct _ConnInfo {
  CURL *easy;
  char *url;
  GlobalInfo *global;
  char error[CURL_ERROR_SIZE];
} ConnInfo;


/* Information associated with a specific socket */
typedef struct _SockInfo {
  curl_socket_t sockfd;
  CURL *easy;
  int action;
  long timeout;
  struct event ev;
  int evset;
  GlobalInfo *global;
} SockInfo;



/* Update the event timer after curl_multi library calls */
static int multi_timer_cb(CURLM *multi, long timeout_ms, GlobalInfo *g)
{
  struct timeval timeout;

  timeout.tv_sec = timeout_ms/1000;
  timeout.tv_usec = (timeout_ms%1000)*1000;
  fprintf(MSG_OUT, "multi_timer_cb: Setting timeout to %ld ms\n", timeout_ms);
  evtimer_add(&g->timer_event, &timeout);
  return 0;
}



/* Die if we get a bad CURLMcode somewhere */
void mcode_or_die(char *where, CURLMcode code) {
  if ( CURLM_OK != code ) {
    char *s;
    switch (code) {
      case     CURLM_CALL_MULTI_PERFORM: s="CURLM_CALL_MULTI_PERFORM"; break;
      case     CURLM_OK:                 s="CURLM_OK";                 break;
      case     CURLM_BAD_HANDLE:         s="CURLM_BAD_HANDLE";         break;
      case     CURLM_BAD_EASY_HANDLE:    s="CURLM_BAD_EASY_HANDLE";    break;
      case     CURLM_OUT_OF_MEMORY:      s="CURLM_OUT_OF_MEMORY";      break;
      case     CURLM_INTERNAL_ERROR:     s="CURLM_INTERNAL_ERROR";     break;
      case     CURLM_BAD_SOCKET:         s="CURLM_BAD_SOCKET";         break;
      case     CURLM_UNKNOWN_OPTION:     s="CURLM_UNKNOWN_OPTION";     break;
      case     CURLM_LAST:               s="CURLM_LAST";               break;
      default: s="CURLM_unknown";
    }
    fprintf(MSG_OUT, "ERROR: %s returns %s\n", where, s);
    exit(code);
  }
}



/* Check for completed transfers, and remove their easy handles */
static void check_run_count(GlobalInfo *g)
{
  if (g->prev_running > g->still_running) {
    char *eff_url=NULL;
    CURLMsg *msg;
    int msgs_left;
    ConnInfo *conn=NULL;
    CURL*easy;
    CURLcode res;

    fprintf(MSG_OUT, "REMAINING: %d\n", g->still_running);
    /*
      I am still uncertain whether it is safe to remove an easy handle
      from inside the curl_multi_info_read loop, so here I will search
      for completed transfers in the inner "while" loop, and then remove
      them in the outer "do-while" loop...
   */
    do {
      easy=NULL;
      while ((msg = curl_multi_info_read(g->multi, &msgs_left))) {
        if (msg->msg == CURLMSG_DONE) {
          easy=msg->easy_handle;
          res=msg->data.result;
          break;
        }
      }
      if (easy) {
          curl_easy_getinfo(easy, CURLINFO_PRIVATE, &conn);
          curl_easy_getinfo(easy, CURLINFO_EFFECTIVE_URL, &eff_url);
          fprintf(MSG_OUT, "DONE: %s => (%d) %s\n", eff_url, res, conn->error);
          curl_multi_remove_handle(g->multi, easy);
          free(conn->url);
          curl_easy_cleanup(easy);
          free(conn);
      }
    } while ( easy );
  }
  g->prev_running = g->still_running;
}



/* Called by libevent when we get action on a multi socket */
static void event_cb(int fd, short kind, void *userp)
{
  GlobalInfo *g = (GlobalInfo*) userp;
  CURLMcode rc;

  do {
    rc = curl_multi_socket(g->multi, fd, &g->still_running);
  } while (rc == CURLM_CALL_MULTI_PERFORM);
  mcode_or_die("event_cb: curl_multi_socket", rc);
  check_run_count(g);
  if ( g->still_running <= 0 ) {
    fprintf(MSG_OUT, "last transfer done, kill timeout\n");
    if (evtimer_pending(&g->timer_event, NULL)) {
      evtimer_del(&g->timer_event);
    }
  }
}



/* Called by libevent when our timeout expires */
static void timer_cb(int fd, short kind, void *userp)
{
  (void)fd;
  (void)kind;
  GlobalInfo *g = (GlobalInfo *)userp;
  CURLMcode rc;

  do {
    rc = curl_multi_socket(g->multi, CURL_SOCKET_TIMEOUT, &g->still_running);
  } while (rc == CURLM_CALL_MULTI_PERFORM);
  mcode_or_die("timer_cb: curl_multi_socket", rc);
  check_run_count(g);
}



/* Clean up the SockInfo structure */
static void remsock(SockInfo *f)
{
  if (!f) { return; }
  if (f->evset) { event_del(&f->ev); }
  free(f);
}



/* Assign information to a SockInfo structure */
static void setsock(SockInfo*f, curl_socket_t s, CURL*e, int act, GlobalInfo*g)
{
  int kind =
     (act&CURL_POLL_IN?EV_READ:0)|(act&CURL_POLL_OUT?EV_WRITE:0)|EV_PERSIST;

  f->sockfd = s;
  f->action = act;
  f->easy = e;
  if (f->evset) { event_del(&f->ev); }
  event_set( &f->ev, f->sockfd, kind, event_cb, g);
  f->evset=1;
  event_add(&f->ev, NULL);
}



/* Initialize a new SockInfo structure */
static void addsock(curl_socket_t s, CURL *easy, int action, GlobalInfo *g) {
  SockInfo *fdp = calloc(sizeof(SockInfo), 1);

  fdp->global = g;
  setsock(fdp, s, easy, action, g);
  curl_multi_assign(g->multi, s, fdp);
}



/* CURLMOPT_SOCKETFUNCTION */
static int sock_cb(CURL *e, curl_socket_t s, int what, void *cbp, void *sockp)
{
  GlobalInfo *g = (GlobalInfo*) cbp;
  SockInfo *fdp = (SockInfo*) sockp;
  char *whatstr[]={ "none", "IN", "OUT", "INOUT", "REMOVE" };

  fprintf(MSG_OUT,
          "socket callback: s=%d e=%p what=%s ", s, e, whatstr[what]);
  if (what == CURL_POLL_REMOVE) {
    fprintf(MSG_OUT, "\n");
    remsock(fdp);
  } else {
    if (!fdp) {
      fprintf(MSG_OUT, "Adding data: %s%s\n",
             what&CURL_POLL_IN?"READ":"",
             what&CURL_POLL_OUT?"WRITE":"" );
      addsock(s, e, what, g);
    }
    else {
      fprintf(MSG_OUT,
        "Changing action from %d to %d\n", fdp->action, what);
      setsock(fdp, s, e, what, g);
    }
  }
  return 0;
}



/* CURLOPT_WRITEFUNCTION */
static size_t write_cb(void *ptr, size_t size, size_t nmemb, void *data)
{
  size_t realsize = size * nmemb;
  ConnInfo *conn = (ConnInfo*) data;
  (void)ptr;
  (void)conn;
  return realsize;
}


/* CURLOPT_PROGRESSFUNCTION */
int prog_cb (void *p, double dltotal, double dlnow, double ult, double uln)
{
  ConnInfo *conn = (ConnInfo *)p;
  fprintf(MSG_OUT, "Progress: %s (%g/%g)\n", conn->url, dlnow, dltotal);
  return 0;
}


/* Create a new easy handle, and add it to the global curl_multi */
void new_conn(char *url, GlobalInfo *g ) {
  ConnInfo *conn;
  CURLMcode rc;

  conn = calloc(1, sizeof(ConnInfo));
  memset(conn, 0, sizeof(ConnInfo));
  conn->error[0]='\0';

  conn->easy = curl_easy_init();
  if (!conn->easy) {
    fprintf(MSG_OUT, "curl_easy_init() failed, exiting!\n");
    exit(2);
  }
  conn->global = g;
  conn->url = strdup(url);
  curl_easy_setopt(conn->easy, CURLOPT_URL, conn->url);
  curl_easy_setopt(conn->easy, CURLOPT_WRITEFUNCTION, write_cb);
  curl_easy_setopt(conn->easy, CURLOPT_WRITEDATA, &conn);
  curl_easy_setopt(conn->easy, CURLOPT_VERBOSE, 0);
  curl_easy_setopt(conn->easy, CURLOPT_ERRORBUFFER, conn->error);
  curl_easy_setopt(conn->easy, CURLOPT_PRIVATE, conn);
  curl_easy_setopt(conn->easy, CURLOPT_NOPROGRESS, 0);
  curl_easy_setopt(conn->easy, CURLOPT_PROGRESSFUNCTION, prog_cb);
  curl_easy_setopt(conn->easy, CURLOPT_PROGRESSDATA, conn);
  fprintf(MSG_OUT,
          "Adding easy %p to multi %p (%s)\n", conn->easy, g->multi, url);
  rc =curl_multi_add_handle(g->multi, conn->easy);
  mcode_or_die("new_conn: curl_multi_add_handle", rc);
  do {
    rc = curl_multi_socket_all(g->multi, &g->still_running);
  } while (CURLM_CALL_MULTI_PERFORM == rc);
  mcode_or_die("new_conn: curl_multi_socket_all", rc);
  check_run_count(g);
}



/* This gets called whenever data is received from the fifo */
void fifo_cb(int fd, short event, void *arg) {
  char s[1024];
  long int rv=0;
  int n=0;
  GlobalInfo *g = (GlobalInfo *)arg;

  do {
    s[0]='\0';
    rv=fscanf(g->input, "%1023s%n", s, &n);
    s[n]='\0';
    if ( n && s[0] ) {
      new_conn(s,arg);  /* if we read a URL, go get it! */
    } else break;
  } while ( rv != EOF);
}



/* Create a named pipe and tell libevent to monitor it */
int init_fifo (GlobalInfo *g) {
  struct stat st;
  char *fifo = "hiper.fifo";
  int socket;

  fprintf(MSG_OUT, "Creating named pipe \"%s\"\n", fifo);
  if (lstat (fifo, &st) == 0) {
    if ((st.st_mode & S_IFMT) == S_IFREG) {
      errno = EEXIST;
      perror("lstat");
      exit (1);
    }
  }
  unlink(fifo);
  if (mkfifo (fifo, 0600) == -1) {
    perror("mkfifo");
    exit (1);
  }
  socket = open(fifo, O_RDWR | O_NONBLOCK, 0);
  if (socket == -1) {
     perror("open");
     exit (1);
  }
  g->input = fdopen(socket, "r");

  fprintf(MSG_OUT, "Now, pipe some URL's into > %s\n", fifo);
  event_set(&g->fifo_event, socket, EV_READ | EV_PERSIST, fifo_cb, g);
  event_add(&g->fifo_event, NULL);
  return (0);
}



int main(int argc, char **argv)
{
  GlobalInfo g;
  CURLMcode rc;

  memset(&g, 0, sizeof(GlobalInfo));
  event_init();
  init_fifo(&g);
  g.multi = curl_multi_init();
  evtimer_set(&g.timer_event, timer_cb, &g);
  curl_multi_setopt(g.multi, CURLMOPT_SOCKETFUNCTION, sock_cb);
  curl_multi_setopt(g.multi, CURLMOPT_SOCKETDATA, &g);
  curl_multi_setopt(g.multi, CURLMOPT_TIMERFUNCTION, multi_timer_cb);
  curl_multi_setopt(g.multi, CURLMOPT_TIMERDATA, &g);
  do {
    rc = curl_multi_socket_all(g.multi, &g.still_running);
  } while (CURLM_CALL_MULTI_PERFORM == rc);
  event_dispatch();
  curl_multi_cleanup(g.multi);
  return 0;
}