ghiper.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: ghiper.c,v 1.3 2006-10-12 21:26:50 bagder Exp $
 *
 * Example application source code using the multi socket interface to
 * download many files at once.
 *
 * Written by Jeff Pohlmeyer

Requires glib-2.x and a (POSIX?) system that has mkfifo().

This is an adaptation of libcurl's "hipev.c" and libevent's "event-test.c"
sample programs, adapted to use glib's g_io_channel in place of libevent.

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.

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

*/


#include <glib.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <curl/curl.h>


#define MSG_OUT g_print   /* Change to "g_error" to write to stderr */
#define SHOW_VERBOSE 0    /* Set to non-zero for libcurl messages */
#define SHOW_PROGRESS 0   /* Set to non-zero to enable progress callback */



/* Global information, common to all connections */
typedef struct _GlobalInfo {
  CURLM *multi;
  guint timer_event;
  int prev_running;
  int still_running;
  int requested; /* count: curl_easy_init() */
  int completed; /* count: curl_easy_cleanup() */
} 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;
  GIOChannel *ch;
  guint ev;
  GlobalInfo *global;
} SockInfo;




/* Die if we get a bad CURLMcode somewhere */
static 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";
    }
    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;

    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);
          MSG_OUT("DONE: %s => (%d) %s\n", eff_url, res, conn->error);
          curl_multi_remove_handle(g->multi, easy);
          g_free(conn->url);
          curl_easy_cleanup(easy);
          g_free(conn);
          g->completed++;
      }
    } while ( easy );
    MSG_OUT("Requested: %d Completed:%d\n", g->requested, g->completed);
  }
  g->prev_running = g->still_running;
}




/* Called by glib when our timeout expires */
static gboolean timer_cb(gpointer data)
{
  GlobalInfo *g = (GlobalInfo *)data;
  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);
  return FALSE;
}



/* Update the event timer after curl_multi library calls */
static int update_timeout_cb(CURLM *multi, long timeout_ms, void *userp)
{
  struct timeval timeout;
  GlobalInfo *g=(GlobalInfo *)userp;
  timeout.tv_sec = timeout_ms/1000;
  timeout.tv_usec = (timeout_ms%1000)*1000;

  MSG_OUT("*** update_timeout_cb %ld => %ld:%ld ***\n",
              timeout_ms, timeout.tv_sec, timeout.tv_usec);

  g->timer_event = g_timeout_add(timeout_ms, timer_cb, g);
  return 0;
}




/* Called by glib when we get action on a multi socket */
static gboolean event_cb(GIOChannel *ch, GIOCondition condition, gpointer data)
{
  GlobalInfo *g = (GlobalInfo*) data;
  CURLMcode rc;
  int fd=g_io_channel_unix_get_fd(ch);
  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) {
    return TRUE;
  } else {
    MSG_OUT("last transfer done, kill timeout\n");
    if (g->timer_event) { g_source_remove(g->timer_event); }
    return FALSE;
  }
}



/* Clean up the SockInfo structure */
static void remsock(SockInfo *f)
{
  if (!f) { return; }
  if (f->ev) { g_source_remove(f->ev); }
  g_free(f);
}



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

  f->sockfd = s;
  f->action = act;
  f->easy = e;
  if (f->ev) { g_source_remove(f->ev); }
  f->ev=g_io_add_watch(f->ch, kind, event_cb,g);

}



/* Initialize a new SockInfo structure */
static void addsock(curl_socket_t s, CURL *easy, int action, GlobalInfo *g)
{
  SockInfo *fdp = g_malloc0(sizeof(SockInfo));

  fdp->global = g;
  fdp->ch=g_io_channel_unix_new(s);
  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" };

  MSG_OUT("socket callback: s=%d e=%p what=%s ", s, e, whatstr[what]);
  if (what == CURL_POLL_REMOVE) {
    MSG_OUT("\n");
    remsock(fdp);
  } else {
    if (!fdp) {
      MSG_OUT("Adding data: %s%s\n",
             what&CURL_POLL_IN?"READ":"",
             what&CURL_POLL_OUT?"WRITE":"" );
      addsock(s, e, what, g);
    }
    else {
      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 */
static int prog_cb (void *p, double dltotal, double dlnow, double ult, double uln)
{
  ConnInfo *conn = (ConnInfo *)p;
  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 */
static void new_conn(char *url, GlobalInfo *g )
{
  ConnInfo *conn;
  CURLMcode rc;

  conn = g_malloc0(sizeof(ConnInfo));

  conn->error[0]='\0';

  conn->easy = curl_easy_init();
  if (!conn->easy) {
    MSG_OUT("curl_easy_init() failed, exiting!\n");
    exit(2);
  }
  conn->global = g;
  conn->url = g_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, SHOW_VERBOSE);
  curl_easy_setopt(conn->easy, CURLOPT_ERRORBUFFER, conn->error);
  curl_easy_setopt(conn->easy, CURLOPT_PRIVATE, conn);
  curl_easy_setopt(conn->easy, CURLOPT_NOPROGRESS, SHOW_PROGRESS?0:1);
  curl_easy_setopt(conn->easy, CURLOPT_PROGRESSFUNCTION, prog_cb);
  curl_easy_setopt(conn->easy, CURLOPT_PROGRESSDATA, conn);
  curl_easy_setopt(conn->easy, CURLOPT_FOLLOWLOCATION, 1);
  curl_easy_setopt(conn->easy, CURLOPT_CONNECTTIMEOUT, 30);
  curl_easy_setopt(conn->easy, CURLOPT_LOW_SPEED_LIMIT, 1);
  curl_easy_setopt(conn->easy, CURLOPT_LOW_SPEED_TIME, 30);

  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);
  g->requested++;
  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 by glib whenever data is received from the fifo */
static gboolean fifo_cb (GIOChannel *ch, GIOCondition condition, gpointer data)
{
  #define BUF_SIZE 1024
  gsize len, tp;
  gchar *buf, *tmp, *all=NULL;
  GIOStatus rv;

  do {
    GError *err=NULL;
    rv = g_io_channel_read_line (ch,&buf,&len,&tp,&err);
    if ( buf ) {
      if (tp) { buf[tp]='\0'; }
      new_conn(buf,(GlobalInfo*)data);
      g_free(buf);
    } else {
      buf = g_malloc(BUF_SIZE+1);
      while (TRUE) {
        buf[BUF_SIZE]='\0';
        g_io_channel_read_chars(ch,buf,BUF_SIZE,&len,&err);
        if (len) {
          buf[len]='\0';
          if (all) {
            tmp=all;
            all=g_strdup_printf("%s%s", tmp, buf);
            g_free(tmp);
          } else {
            all = g_strdup(buf);
          }
        } else {
           break;
        }
      }
      if (all) {
        new_conn(all,(GlobalInfo*)data);
        g_free(all);
      }
      g_free(buf);
    }
    if ( err ) {
      g_error("fifo_cb: %s", err->message);
      g_free(err);
      break;
    }
  } while ( (len) && (rv == G_IO_STATUS_NORMAL) );
  return TRUE;
}




int init_fifo(void)
{
 struct stat st;
 char *fifo = "hiper.fifo";
 int socket;

 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);
 }
 MSG_OUT("Now, pipe some URL's into > %s\n", fifo);

 return socket;

}




int main(int argc, char **argv)
{
  GlobalInfo *g;
  CURLMcode rc;
  GMainLoop*gmain;
  int fd;
  GIOChannel* ch;
  g=g_malloc0(sizeof(GlobalInfo));

  fd=init_fifo();
  ch=g_io_channel_unix_new(fd);
  g_io_add_watch(ch,G_IO_IN,fifo_cb,g);
  gmain=g_main_loop_new(NULL,FALSE);
  g->multi = curl_multi_init();
  curl_multi_setopt(g->multi, CURLMOPT_SOCKETFUNCTION, sock_cb);
  curl_multi_setopt(g->multi, CURLMOPT_SOCKETDATA, g);
  curl_multi_setopt(g->multi, CURLMOPT_TIMERFUNCTION, update_timeout_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);
  g_main_loop_run(gmain);
  curl_multi_cleanup(g->multi);
  return 0;
}