ipc.h

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/*
 * This file is part of the Code::Blocks IDE and licensed under the GNU General Public License, version 3
 * http://www.gnu.org/licenses/gpl-3.0.html
 */

#ifndef IPC_H
#define IPC_H


#include "sdk.h"

#include <wx/wx.h>


#ifdef __WIN32__

    #define WIN32_LEAN_AND_MEAN
    #define NOGDI
    #include <windows.h>
    typedef HANDLE shm_handle_t;
    typedef HANDLE semaphore_t;

#else

    #include <fcntl.h>
    #include <errno.h>
    #include <sys/types.h>
    #include <sys/sem.h>
    #include <sys/ipc.h>
    #include <sys/shm.h>

    #if defined(__APPLE__) && defined(__MACH__)
        typedef int shm_handle_t;
        typedef mach_port_t semaphore_t;
    #else
        typedef int shm_handle_t;
        typedef int semaphore_t;
    #endif

#endif

static const int ipc_buf_size = 1024*64;


class SharedMemory
{
    shm_handle_t handle;

    union
    {
        semaphore_t semid;
        semaphore_t sem[2];
    };

    void* shared;
    bool ok;
    bool server;

public:

    enum rw_t{ reader, writer };

    SharedMemory();
    ~SharedMemory();

    bool OK() const { return ok; };

    void* BasePointer() const { return shared; };
    size_t Size() const { return ipc_buf_size; };

    bool Server() const { return server; };
    bool Client() const { return !server; };


    /*
     * Lock(reader) locks "as reader", not "the reader semaphore", i.e. it
     *   1. locks the reader semaphore
     *   2. locks the writer mutex, so the shared memory cannot be written while we read it
     *
     * Lock(writer) locks "as writer", this is equivalent to locking "the writer mutex"
     *
     * Unlock(reader) unlocks "as reader", i.e. it actually unlocks the writer mutex
     *   which the caller is still holding, so another process can write to the shared memory area again.
     *   It does not release the reader semaphore, since it should block on it on the next iteration.
     *
     * Unlock(writer) locks "as writer", i.e. it
     *   1. unlocks the reader semaphore, waking up the Server thread
     *   2. unlocks the writer mutex, so the Server thread can acquire it and prevent other processes from writing
     */
    bool Lock(rw_t rw);
    void Unlock(rw_t rw);
};


class IPC : public wxThread
{
    volatile bool is_shutdown;
    SharedMemory  shm;

public:
    IPC() : is_shutdown(false) {};

    virtual ExitCode Entry();

    bool Server() const { return shm.Server(); };

    void Shutdown();

    void Send(const wxString& value);
};


/*
 *  expemplary code for app.cpp, specifically CodeBlocksApp::ParseCmdLine  >>>>>>>>>>>>>>>
 *
 *
IPC *ipc = new IPC; // don't delete

if (ipc->Server())
{
    ipc->Run();
}
else
{
    // parser is the wxCmdLineParser
    wxString item;
    wxString buf;

    static const unsigned int max_size = ipc_buf_size / sizeof(wxChar);

    buf.Alloc(4096);

    int count = parser.GetParamCount();

    for (int i = 0; i < count; ++i)
    {
        item = parser.GetParam(i);
        item.append(_T('\n'));

        if (buf.length() + item.length() + 1) >= max_size)
        {
            buf.append(_T('\0'));
            ipc->Send(buf);
            buf.Empty();
        }
        buf.append(item);
    }

    if (buf.length())
    {
        buf.append(_T('\0'));
        ipc->Send(buf);
    }
}
 *
 *
 *  <<<<<<<<<<<<<<< expemplary code
 */




#endif