Building PHP extensions with C++, the easy way (update: MySQL, threads)

Here is an easy way to build a PHP extension with C++ and default PHP packages on a Ubuntu system. I use SWIG to wrap C++ code to the Zend API. When using loops and recursion intensively, porting a few functions to C++ can give you some extra power.

First, install all required packages (tested with Ubuntu 12.10): 

apt-get install php5-cli php5-dev swig g++

Second, write the code:


// example.swig
%{
#include <iostream>
#include <vector>
using namespace std;

int HelloWorld(char *str) {
    cout << "Hello World: " << str << endl;

    // run some slow code
    vector<int> array;
    for (int i=0; i < 10000000; i++) array.push_back(i*2);
    for (int i=0; i < array.size(); i++) array[i]++;
    return 0;
}
%}

%module example
int HelloWorld(char *str);

Third, compile the code and load the exension:


swig -c++ -php5 example.swig
g++ `php-config --includes` -O2 -march=native -mtune=native -std=c++11 -fPIC -c *.cpp
g++ -shared *.o -o example.so

echo extension=`pwd`/example.so >/etc/php5/mods-available/example.ini
php5enmod example

And finally run: php test.php


// test.php
<?php
HelloWorld("C++"); // gives: Hello World: C++

HelloWorld("foo\0bar"); // gives: Hello World: foo

Note: To send the output to a web server, zend_printf() needs be used instead of std::cout or printf().

Note: When using Apache2 MPM-Prefork, processes are re-used for a client until the keep-alive ends (see KeepAlive* in your apache2.conf). Therefore, global variables in the C++ code need to be reset with %rshutdown {...}.

Returning vectors is also possible:


// example.swig
%{
#include <vector>
using namespace std;

vector<string> HelloArray() {
    vector<string> v;
    v.push_back("hello world");
    return v;
}
%}

%typemap(out) vector { # convert vector to php-array[string]
    array_init(return_value);
    for (int i=0; i<$1.size(); ++i) add_next_index_string(return_value, $1[i].c_str(), 1);
}

%module example
vector<string> HelloArray();

// test.php
print_r( HelloArray() ); // Array( [0] => hello world )

You can also start Threads from an extension (C++11 is really nice here): 


// example.swig
%{
#include <iostream>
#include <vector>
#include <thread>
using namespace std;

void someThread(int i) {
  for (int j=0; j < 100; j++) {
    cout << " thread: " << i << endl ;
    vector<int> array;
    for (int i=0; i < 10000000; i++) array.push_back(i*2);
    for (int i=0; i < array.size(); i++) array[i] *= 2;
  }
}

int HelloWorld(char *str) {
  cout << "Hallo World: " << str << endl;

  // start some threads
  thread t1(someThread, 1);
  thread t2(someThread, 2);
  thread t3(someThread, 3);
  // wait for threads to finish
  t1.join();
  t2.join();
  t3.join();
  return 0;
}
%}

%module example
int HelloWorld(char *str);

A small MySQL example looks like this: 

// apt-get install mysql-server-5.5 libmysqlcppconn-dev
// g++ -shared *.o -lmysqlcppconn -o example.so

// example.swig
%{
#include <iostream>
#include <cppconn/driver.h>
#include <cppconn/statement.h>
#include <cppconn/resultset.h>
#include <cppconn/exception.h>
#include "mysql_connection.h"

using namespace std;
using namespace sql;

int HelloWorld(char *str) {
  try {
    auto_ptr<Connection> con( get_driver_instance()->connect("127.0.0.1", "root", "") );
    con->setSchema("test");

    auto_ptr<Statement> stmt( con->createStatement() );
    auto_ptr<ResultSet> res( stmt->executeQuery("SELECT 'Hello World!' AS result") );
    while (res->next()) {
      cout << res->getString("result") << endl;
      cout << res->getString(1) << endl;
    }
  } catch (SQLException &e) {
    cout << __FILE__ << " " << __FUNCTION__ << " " << __LINE__ << endl;
    cout << e.what() << " " << e.getSQLState() << " " << e.getErrorCode() << endl;
  }
  return 0;
}
%}

%module example
int HelloWorld(char *str);

Note: Inside extensions, php.ini settings like open_basedir and memory_limit are not active.

Other resources:

Comments

Post a Comment

Popular posts from this blog

How to show only month and year fields in android Date-picker?

Image
Android default DatePicker show day/month/year fields but you have to customize this DatePicker as your requirements. Suppose that you want to show only month and year fields in android datepicker . To do this, you have to customize the Dialog DatePicker source code but it is not an easy task. In this tutorial I will show you a tricky way to solve this problem. Lets see how to show only month and year field in android DatePicker as a dialog.   Step to show only month and year fields in android date-picker: Some days ago I got this same problem and here I am trying to explain this in a sequential manner. I want to show a dialog datepicker when user click on an EditText. So if user click on EditText, A dialog datepicker will be invocked and it will show only month and year fields. To do this, at first we have to create a xml layout to hold the EditText fields. So create an android project and name it DatePickerExample. In the main.xml file just try to write this simple code....
Read more

How to construct a B+ tree with example

Image
A B+ tree contains n-1 search key values K1K2…….Kn-1 and have n pointers.   In a B+ tree the data are ordered  sequentially.  The leaf node may hold up to n pointers and must hold at least N/2 pointers. The root node must hold at least two pointers, unless the tree consists of only one node.  Now we construct a B+ tree. Construct a B+ tree for the following set of key values: (2,3,5,7,11,17,19,23,29,31) Assume that the tree is initially empty and values are added in ascending order. Construct a B+ tree where the pointer number is Four. Solution: When a node exceeds n-1 search key value then we split it into two nodes. First node contains (ceiling(n-1)/2) values.  2 nd node contains remaining node. Copy the smallest search key value of the second node to the parent node. Let's start, we know each node has N pointer and has N-1 search key values. In our example pointer number is 4, so the search key value is 4-1=3. So each node has 4 pointers and 3 search key val...
Read more

Conflict Serializability in database

Image
To maintains database state consistency we introduce serializability. Using serializability we can understand which schedule will ensure consistency, and which schedule will not. When we are capable of converting a concurrent schedule into a serial schedule then we cal it serializable schedule. A schedule is serializable if it is equivalent to a serial schedule. We divided this concepts into two parts 1. Conflict serializability  & 2. View serializability In this discussion I just clarify you the conflict serializability. Consider two instruction read, write and the data item A and B. When two instruction execute different data item such as read(A) and read(B), then we can swap the instruction without affecting the result of the schedule. But when the data item is equivalent to one another we need to consider following four condition.    a.   read (A ),    read ( A ).   they   don’t conflict.    b.   read ( Q),  ...
Read more