Calling a member function from begin_request_handler

[Jared]

Hi,

I'm new to mongoose. I edited hello.c and added a Web class into it and moved some original code around. I was able to build and execute it like its original behavior. However, when I added a member function and called in from begin_request_handler, the new function could not be called. Can you please help me? Thanks!

    Web::get_Instance()->callback();   // unable to call this function

================= hello.cpp ====================

#include <stdio.h>

#include <string.h>

#include "mongoose.h"

class Web

{

private:

    Web();

   ~Web() {};

    static Web* m_instance;

public:

    void callback (void);

    static Web* get_Instance();

};

Web* Web::m_instance = 0;

void Web::callback (void)

{

    printf ("%s\n", __FUNCTION__);

}

// This function will be called by mongoose on every new request.

static int begin_request_handler(struct mg_connection *conn) 

{

    Web::get_Instance()->callback();   // unable to call this function

  const struct mg_request_info *request_info = mg_get_request_info(conn);

  char content[100];

  // Prepare the message we're going to send

  int content_length = snprintf(content, sizeof(content),

                                "Hello from mongoose! Remote port: %d",

                                request_info->remote_port);

  // Send HTTP reply to the client

  mg_printf(conn,

            "HTTP/1.1 200 OK\r\n"

            "Content-Type: text/plain\r\n"

            "Content-Length: %d\r\n"        // Always set Content-Length

            "\r\n"

            "%s",

            content_length, content);

  // Returning non-zero tells mongoose that our function has replied to

  // the client, and mongoose should not send client any more data.

  return 1;

}

Web::Web()

{

  struct mg_context *ctx;

  struct mg_callbacks callbacks;

  // List of options. Last element must be NULL.

  const char *options[] = {"listening_ports", "8080", NULL};

  // Prepare callbacks structure. We have only one callback, the rest are NULL.

  memset(&callbacks, 0, sizeof(callbacks));

  callbacks.begin_request = begin_request_handler;

  // Start the web server.

  ctx = mg_start(&callbacks, NULL, options);

  // Wait until user hits "enter". Server is running in separate thread.

  // Navigating to http://localhost:8080 will invoke begin_request_handler().

  getchar();

  // Stop the server.

  mg_stop(ctx);

}

Web* Web::get_Instance()

{

    if (!m_instance)

        m_instance = new Web;

    return m_instance;

}

int main(void) 

{

    Web::get_Instance();

    return 0;

}

[Ulrich Hertlein]

Hi Jared,

the code looks fine to me.

What do you mean 'unable to call'?  Are you getting a compiler error?  Or a crash at runtime?

Cheers,

/ulrich

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[Jared]

Hi Ulrich,

I'm able to compile it successfully. And not a crash.

This is what the output looks like if I added printf("%s\n",__FUNCTION); to each function and I did not call the callback() function.

main

get_Instance

Web

begin_request_handler

begin_request_handler

This is how it looks like if I added a call to the callback() function.

main

get_Instance

Web

begin_request_handler

get_Instance

Web

[Ulrich Hertlein]

Hi Jared,

I noticed that you have a 'getchar' in the Web constructor.

This prevents the Web ctor from ever finishing (well, until someone has pressed a key).

Since the constructor never returns, the 'm_instance' variable is never set and every call to 'get_Instance' will try to create a new instance.

The usual way would be to call 'mg_start' in the constructor and 'mg_stop' in the destructor.  The main can then call 'getchar' to wait for completion.

Cheers,

/ulrich

[Jared]

Hi Ulrich,

Your solution worked! Thank you.

Have a great day!

--

Jared