kode yard

Wednesday, December 12, 2012

Stackoverflow User Details in python

#------------------------------------------------------------------------------- # Name:        StackOverFlow.py # Purpose: # # Author:      asit # # Created: # Copyright:   (c) asit #------------------------------------------------------------------------------- import urllib2 import json import zlib import sys class StackOverFlow(object):     def __init__(self, userId):         try:             f = urllib2.urlopen("http://api.stackoverflow.com/1.1/users/" + str(userId) )             response = f.read()         except urllib2.HTTPError as e:             print e.reason             sys.exit(1)         except urllib2.URLError as e:             print e.reason             sys.exit(1)         res_data = zlib.decompress(response, 16+zlib.MAX_WBITS)         data = json.loads(res_data)         self._data = data         self._user_mentioned_url   = data['users'][0]['user_mentioned_url']         self._user_type            = data['users'][0]['user_type']         self._creation_date        = data['users'][0]['creation_date']         self._view_count           = data['users'][0]['view_count']         self._display_name         = data['users'][0]['display_name']         self._last_access_date     = data['users'][0]['last_access_date']         self._user_questions_url   = data['users'][0]['user_questions_url']         self._user_badges_url      = data['users'][0]['user_badges_url']         self._user_answers_url     = data['users'][0]['user_answers_url']         self._email_hash           = data['users'][0]['email_hash']         self._answer_count         = data['users'][0]['answer_count']         self._user_tags_url        = data['users'][0]['user_tags_url']         self._user_timeline_url    = data['users'][0]['user_timeline_url']         self._question_count       = data['users'][0]['question_count']         self._down_vote_count      = data['users'][0]['down_vote_count']         self._reputation           = data['users'][0]['reputation']         self._user_comments_url    = data['users'][0]['user_comments_url']         self._user_reputation_url  = data['users'][0]['user_reputation_url']         self._badge_counts_bronze  = data['users'][0]['badge_counts']['bronze']         self._badge_counts_silver  = data['users'][0]['badge_counts']['silver']         self._badge_counts_gold    = data['users'][0]['badge_counts']['gold']         self._up_vote_count        = data['users'][0]['up_vote_count']         self.user_details_dict = data['users'][0].copy()         del self.user_details_dict['badge_counts']         self.user_details_dict['badge_counts_bronze'] = data['users'][0]['badge_counts']['bronze']         self.user_details_dict['badge_counts_silver'] = data['users'][0]['badge_counts']['silver']         self.user_details_dict['badge_counts_gold']   = data['users'][0]['badge_counts']['gold']     def Print(self):         for key, val in self.user_details_dict.items() :             print"%s :: %s" % (key, val)     def Describe(self):         print "Total               :: %s" % self._data['total']         print "Page                :: %s" % self._data['page']         print "Page Size           :: %s" % self._data['pagesize']         print "User Mentioned Url  :: %s" % self._data['users'][0]['user_mentioned_url']         print "User Type           :: %s" % self._data['users'][0]['user_type']         print "Creation Date       :: %s" % self._data['users'][0]['creation_date']         print "View Count          :: %s" % self._data['users'][0]['view_count']         print "Display Name        :: %s" % self._data['users'][0]['display_name']         print "Last Access Date    :: %s" % self._data['users'][0]['last_access_date']         print "User Questions Url  :: %s" % self._data['users'][0]['user_questions_url']         print "User Badges Url     :: %s" % self._data['users'][0]['user_badges_url']         print "User Answers Url    :: %s" % self._data['users'][0]['user_answers_url']         print "Email Hash          :: %s" % self._data['users'][0]['email_hash']         print "Answer Count        :: %s" % self._data['users'][0]['answer_count']         print "User Tags Url       :: %s" % self._data['users'][0]['user_tags_url']         print "User Timeline Url   :: %s" % self._data['users'][0]['user_timeline_url']         print "Question Count      :: %s" % self._data['users'][0]['question_count']         print "Down Vote Count     :: %s" % self._data['users'][0]['down_vote_count']         print "Reputation          :: %s" % self._data['users'][0]['reputation']         print "User Comments Url   :: %s" % self._data['users'][0]['user_comments_url']         print "User Reputation Url :: %s" % self._data['users'][0]['user_reputation_url']         print "Badge Count(bronze) :: %s" % self._data['users'][0]['badge_counts']['bronze']         print "Badge Count(silver) :: %s" % self._data['users'][0]['badge_counts']['silver']         print "Badge Count(gold)   :: %s" % self._data['users'][0]['badge_counts']['gold']         print "Up Vote Count       :: %s" % self._data['users'][0]['up_vote_count'] def main():     user = StackOverFlow(1)     user.Print()     #user.Describe() if __name__ == '__main__':     main()

Output:-

badge_counts_bronze :: 115
email_hash :: 51d623f33f8b83095db84ff35e15dbe8
badge_counts_silver :: 104
badge_counts_gold :: 34
user_mentioned_url :: /users/1/mentioned
user_type :: moderator
answer_count :: 138
creation_date :: 1217514151
user_tags_url :: /users/1/tags
user_timeline_url :: /users/1/timeline
about_me :: Stack Overflow Valued Associate #00001

Wondering how our software development process works? Take a look!

Find me on twitter, or read my blog. Don't say I didn't warn you because I totally did.

However, I no longer work at Stack Exchange, Inc. I'll miss you all. Well, some of you, anyway. :)

up_vote_count :: 2729
user_id :: 1
question_count :: 15
reputation :: 23510
view_count :: 92244
user_favorites_url :: /users/1/favorites
display_name :: Jeff Atwood
age :: 41
down_vote_count :: 543
last_access_date :: 1355227926
association_id :: febfb878-3f6f-4215-9323-46d15d62ac7d
user_questions_url :: /users/1/questions
location :: El Cerrito, CA
accept_rate :: 100
user_reputation_url :: /users/1/reputation
user_badges_url :: /users/1/badges
user_answers_url :: /users/1/answers
website_url :: http://www.codinghorror.com/blog/
user_comments_url :: /users/1/comments

Tuesday, August 7, 2012

Fetch web page in libcurl

#include <iostream>
#include <iostream>
#include <string>
#include <exception>

extern "C"
{
#include <curl/curl.h>
#include <stdlib.h>
}

//Exception class for curl exception

class CurlException : std::exception
{
public:
   CurlException(std::string message):m_message(message) {  }
   CurlException(CURLcode error)
   {
      m_message = curl_easy_strerror(error);
   }
   const char* what() throw()
   {
      return m_message.c_str();
   }
   ~CurlException() throw() { }

private:
   std::string m_message;
};


//A tiny wrapper around Curl C Library

class CppCurl
{
public:
   CppCurl(std::string url) throw (CurlException)
   {
      m_handle = curl_easy_init();
      if ( m_handle == NULL )
         throw CurlException("Unable to initialize curl handler");
      if ( url.length() == 0 )
         throw CurlException("URL can't be of zero length");
      m_url = url;
   }

   std::string Fetch() throw (CurlException)
   {
      SetOptions();
      SendGetRequest();
      return m_data;
   }


   ~CppCurl() throw()
   {
      curl_easy_cleanup(m_handle);
   }

private:

   void SetOptions() throw (CurlException)
   {
      CURLcode res;

      //set the url
      res = curl_easy_setopt(m_handle, CURLOPT_URL, m_url.c_str());
      if ( res != CURLE_OK)
         throw CurlException(res);

      //progress bar is not require
      res = curl_easy_setopt(m_handle, CURLOPT_NOPROGRESS, 1L);
      if ( res != CURLE_OK )
         throw CurlException(res);

      //set the callback function
      res = curl_easy_setopt(m_handle, CURLOPT_WRITEFUNCTION,
                              CppCurl::WriteDataCallback);
      if ( res != CURLE_OK )
         throw CurlException(res);

      //set pointer in call back function
      res = curl_easy_setopt(m_handle, CURLOPT_WRITEDATA, this);
      if ( res != CURLE_OK )
         throw CurlException(res);

   }

   void SendGetRequest()
   {
      CURLcode res;
      res = curl_easy_perform(m_handle);
      if ( res != CURLE_OK )
         throw CurlException(res);
   }

   static size_t WriteDataCallback(void *ptr, size_t size,
                                    size_t nmemb, void* pInstance)
   {
      return (static_cast<CppCurl*>(pInstance))->write_data(ptr, size, nmemb);
   }

   size_t write_data(void* ptr, size_t size, size_t nmemb)
   {
      size_t numOfBytes = size * nmemb;

      char *iter = (char*)ptr;
      char *iterEnd = iter + numOfBytes;

      //while ( iter != iterEnd )
      //{
      //   cout<<*iter;
      //   iter ++;
      //}

      m_data += std::string(iter, iterEnd);

      return numOfBytes;
   }

   CURL *m_handle;
   std::string m_url;
   std::string m_data;

};


int main()
{
   try
   {
      CppCurl ob("http://kodeyard.blogspot.in/");
      std::cout<<ob.Fetch();
      std::cout<<std::endl;
   }
   catch ( CurlException e)
   {
      std::cerr<<"Exception thrown..."<<std::endl;
      std::cerr<<e.what()<<std::endl;
   }

   return 0;

}

Saturday, July 14, 2012

Pthread in c++ class

In pthread API, the pthread_create() takes function which takes a generic pointer and returns a generic pointer. Here is a sample pthread implementation in c

#include <pthread.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>

//thread callback function
void* thread_func(void *arg)
{
   char *msg = (char*)arg;
   fprintf(stdout,"In thread....\n");
   sleep(1);
   fprintf(stdout, "Message : %s\n", msg);
   sleep(1);
   fprintf(stdout, "Thread exiting...\n");
   return NULL;
}


int main()
{
   pthread_t tid;
   int rc = 0;
   char *msg = "Hello";
   
   rc = pthread_create(&tid, NULL, thread_func, (void*)msg);
   if ( rc != 0)
   {
      fprintf(stderr, "Thread creation failed\n");
      fprintf(stderr, "%s\n",strerror(rc));
      exit(EXIT_FAILURE);
   }

   rc = pthread_join(tid, NULL);
   if ( rc != 0)
   {   
      fprintf(stderr, "Thread creation failed\n");
      fprintf(stderr, "%s\n",strerror(rc));
      exit(EXIT_FAILURE);
   }   

   return 0;
}

Output:-

In thread....
Message : Hello
Thread exiting...

The problem with pthread_create in c++ is that it can't take member function as a thread function. Because, pthread_create expects a normal function, not a c++ member function. If we pass a member function, then the implicit this pointer won't be available inside this, hence the purpose of member function won't be fulfilled. For this reason, we need to make the thread function static and pass this pointer as object. Inside the function, everything should be accessed through the this pointer. Here is a sample code of pthread_create in C++

#include <iostream>
#include <string>

extern "C"
{
#include <pthread.h>
#include <string.h>
#include <stdlib.h>
}

using namespace std;


class MyThread
{
   string strMsg;
   pthread_t Tid;

public:
   MyThread(string strMsg):strMsg(strMsg) { }

   //Callback function for thread
   static void* thread_func(void *pThisArg)
   {
      //This pointer is passed as an argument
      MyThread *pThis = static_cast<MyThread*>(pThisArg);
      pThis->Run();
      return NULL;
   }

   void CreateThread()
   {
      int rc = pthread_create(&Tid, NULL, thread_func, static_cast<void*>(this));
      if ( rc != 0 )
      {
         cerr<<"Error in thread creation..."<<endl;
         cerr<<strerror(rc)<<endl;
         exit(EXIT_FAILURE);
      }
   }

   void JoinThread()
   {
      int rc = pthread_join(Tid, NULL);
      if ( rc != 0 )
      {
         cerr<<"Error in thread join...."<<endl;
         cerr<<strerror(rc)<<endl;
         exit(EXIT_FAILURE);
      }
   }

   void Run() 
   {
      cout<<"In Thread..."<<endl;
      sleep(1);
      cout<<"Message : "<<strMsg<<endl;
      sleep(1);
      cout<<"Thread exiting..."<<endl;
   }

};

int main() 
{
   MyThread ThreadOb("Hi Hi");
   ThreadOb.CreateThread();
   ThreadOb.JoinThread();
   return 0;
}

Output:-

In Thread...
Message : Hi Hi
Thread exiting...

Here, the problem is we need to write a static member function for every class that needs to use pthread_create(). I have made a wrapper class for this. Here is the code along with how to use it.

/*
* Copyright 2012 Asit
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

#include <iostream>
#include <string>

extern "C" 
{
#include <pthread.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
}

using namespace std; 


//Abstract Class responsible for creating and lunching thread

class AbstractThread 
{

public:
   
   AbstractThread():m_pThreadArg(NULL) { }   
   ~AbstractThread() 
   { 
      if ( m_pThreadArg != NULL )
         delete m_pThreadArg;
   }

   //Concrete Class needs to implement the method Process()   
   virtual void Process() = 0;
   
   //Start() should be called to create the thread and execute the method Process()
   void Start() 
   {
      int iRetVal = 0;

      m_pThreadArg = new ThreadParamType;
      m_pThreadArg->m_pThis = this;
      m_pThreadArg->m_pThreadFun = &AbstractThread::Process;
      iRetVal = pthread_create(&m_ThreadId,   //Thread Id
                               NULL,          //Thread Attribute Object
                               &AbstractThread::CallThreadFunc,  //Thread Function
                               static_cast<void*>(m_pThreadArg)  //Argument to thread func
                              );
      if ( iRetVal != 0 ) 
      {
         cerr<<"Error in thread creation.."<<endl;
         cerr<<strerror(iRetVal)<<endl;
         exit(EXIT_FAILURE);
      }
   }
   
   //Join() should be called to wait for the thread to finish
   void Join()
   {
      int iRetVal = 0;
      iRetVal = pthread_join(m_ThreadId, NULL);
      if ( iRetVal != 0 )
      {
         cerr<<"Error in thread join.."<<endl;
         cerr<<strerror(iRetVal)<<endl;
         exit(EXIT_FAILURE);
      }
   }
   
private:

   //ThreadParamType contains a pointer (m_pThis) to AbstractThread object 
   //and a member function pointer (m_pThreadFun) which will be called by
   //static function CallThreadFunc()
   struct ThreadParamType 
   {   
      AbstractThread *m_pThis;
      void (AbstractThread::*m_pThreadFun) (void);    
   };  

   pthread_t m_ThreadId;
   pthread_attr_t m_Attribute;
   ThreadParamType *m_pThreadArg;

private:
   //CallThreadFunc is the callback function which is executed in the new thread
   //Expects a pointer to ThreadParamType object.
   static void* CallThreadFunc(void *pArg) 
   {
      ThreadParamType *pThreadParam = static_cast<ThreadParamType *>(pArg);
      void (AbstractThread::*pMemberFunc) (void);
      AbstractThread *pThis = pThreadParam->m_pThis;
      pMemberFunc = pThreadParam->m_pThreadFun;
      ((*pThis).*pMemberFunc)();
      return NULL;
   }   
};


class ConcreteThread : public AbstractThread 
{

public:
   ConcreteThread(string strMsg):strMsg(strMsg) {}
   ~ConcreteThread() {}

   //Mandatory to implement Process()
   void Process() 
   {
      cout<<"In Thread..."<<endl;
      sleep(1);
      cout<<"Message : "<<strMsg<<endl;
      sleep(1);
      cout<<"Thread exiting..."<<endl;
   }
private:
   string strMsg;

};     


int main() 
{

   ConcreteThread Ob("Ho Ho");
   Ob.Start();
   cout<<"Control in Main"<<endl;
   Ob.Join();
   
   return 0;
}

Output

Control in Main
In Thread...
Message : Ho Ho
Thread exiting...