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/* Copyright (C) 2003 MySQL AB
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
#ifndef MemoryChannelOSE_H
#define MemoryChannelOSE_H
//===========================================================================
//
// .DESCRIPTION
// Pointer based communication channel for communication between two
// thread. It sends the pointer to the other signal via an OSE signal
//
// .TYPICAL USE:
// to communicate between threads.
//
// .EXAMPLE:
// See AsyncFile.C
//===========================================================================
//
//
// MemoryChannel( int size= 256);
// Constuctor
// Parameters:
// size : is ignored in OSE version
//
// void operator ++ ();
// increments the index with one, if size is reached it is set to zero
//
// virtual void write( T *t);
// Puts the item in the channel if the channel is full an error is reported.
// Parameters:
// t: pointer to item to put in the channel, after this the item
// is shared with the other thread.
// errors
// AFS_ERROR_CHANNALFULL, channel is full
//
// T* read();
// Reads a itemn from the channel, if channel is empty it blocks untill
// an item can be read.
// return
// T : item from the channel
//
// T* tryRead();
// Reads a item from the channel, if channel is empty it returns zero.
// return
// T : item from the channel or zero if channel is empty.
//
#include <ose.h>
#include "ErrorHandlingMacros.hpp"
#include "Error.hpp"
#include "NdbMutex.h"
#include "NdbCondition.h"
template <class T>
class MemoryChannel
{
public:
MemoryChannel( int size= 256);
virtual ~MemoryChannel( );
virtual void writeChannel( T *t);
T* readChannel();
T* tryReadChannel();
private:
PROCESS theReceiverPid;
};
template <class T> class MemoryChannelMultipleWriter:public MemoryChannel<T>
{
public:
MemoryChannelMultipleWriter( int size= 256);
~MemoryChannelMultipleWriter( );
void writeChannel( T *t);
private:
};
#define MEMCHANNEL_SIGBASE 5643
#define MEMCHANNEL_SIGNAL (MEMCHANNEL_SIGBASE + 1) /* !-SIGNO(struct MemChannelSignal)-! */
struct MemChannelSignal
{
SIGSELECT sigNo;
void* ptr;
};
union SIGNAL
{
SIGSELECT sigNo;
struct MemChannelSignal memChanSig;
};
template <class T> MemoryChannel<T>::MemoryChannel( int size )
{
// Default receiver for this channel is the creating process
theReceiverPid = current_process();
}
template <class T> MemoryChannel<T>::~MemoryChannel( )
{
}
template <class T> void MemoryChannel<T>::writeChannel( T *t)
{
union SIGNAL* sig;
sig = alloc(sizeof(struct MemChannelSignal), MEMCHANNEL_SIGNAL);
((struct MemChannelSignal*)sig)->ptr = t;
send(&sig, theReceiverPid);
}
template <class T> T* MemoryChannel<T>::readChannel()
{
T* tmp;
static const SIGSELECT sel_mem[] = {1, MEMCHANNEL_SIGNAL};
union SIGNAL* sig;
tmp = NULL; /* Default value */
sig = receive((SIGSELECT*)sel_mem);
if (sig != NIL){
if (sig->sigNo == MEMCHANNEL_SIGNAL){
tmp = (T*)(((struct MemChannelSignal*)sig)->ptr);
}else{
assert(1==0);
}
free_buf(&sig);
}
return tmp;
}
template <class T> T* MemoryChannel<T>::tryReadChannel()
{
T* tmp;
static const SIGSELECT sel_mem[] = {1, MEMCHANNEL_SIGNAL};
union SIGNAL* sig;
tmp = NULL; /* Default value */
sig = receive_w_tmo(0, (SIGSELECT*)sel_mem);
if (sig != NIL){
if (sig->sigNo == MEMCHANNEL_SIGNAL){
tmp = (T*)(((struct MemChannelSignal*)sig)->ptr);
}else{
assert(1==0);
}
free_buf(&sig);
}
return tmp;
}
#endif // MemoryChannel_H
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