source: flair-src/trunk/lib/FlairCore/src/SharedMem_impl.cpp@ 214

// %flair:license{
// This file is part of the Flair framework distributed under the
// CECILL-C License, Version 1.0.
// %flair:license}
//  created:    2014/02/10
//  filename:   SharedMem_impl.cpp
//
//  author:     Guillaume Sanahuja
//              Copyright Heudiasyc UMR UTC/CNRS 7253
//
//  version:    $Id: $
//
//  purpose:    Class defining a shared memory
//
//
/*********************************************************************/

#include "SharedMem_impl.h"
#include "SharedMem.h"
#include <fcntl.h>
#include <unistd.h>
#include <sys/mman.h>
#include <string.h>

using std::string;
using namespace flair::core;

SharedMem_impl::SharedMem_impl(const SharedMem *self, string name, size_t size, SharedMem::Type &type):self(self),type(type),size(size),
                               sem(self,1,"/" + name + "_mutex"), sem_producer(self,0,"/" + name + "_producer"),sem_consumer(self,0,"/" + name + "_consumer") {

#ifdef __XENO__
  heap_binded = false;
  int status = rt_heap_create(&heap, name.c_str(), size,
                              H_SHARED | H_FIFO | H_NONCACHED);
  if (status == -EEXIST) {
    heap_binded = true;
    status = rt_heap_bind(&heap, name.c_str(), TM_INFINITE);
  }
  if (status != 0) {
    char errorMsg[256];
    self->Err("rt_heap_create error (%s)\n", strerror_r(-status, errorMsg, sizeof(errorMsg)));
    return;
  }

  void *ptr;
  status = rt_heap_alloc(&heap, 0, TM_NONBLOCK, &ptr);
  if (status != 0) {
    char errorMsg[256];
    self->Err("rt_heap_alloc error (%s)\n", strerror_r(-status, errorMsg, sizeof(errorMsg)));
  }
  mem_segment = (char *)ptr;

#else
  shm_name = "/" + name;
  fd = shm_open(shm_name.c_str(), O_RDWR | O_CREAT, 0666);
  if (fd == -1) {
    self->Err("Error creating shared memory\n");
  }
  ftruncate(fd, size);

  mem_segment = (char *)mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
  if (mem_segment == MAP_FAILED) {
    self->Err("Failed to map memory\n");
  }
#endif
}

SharedMem_impl::~SharedMem_impl() {
  int status;
        
#ifdef __XENO__

  if (heap_binded == false) {
    status = rt_heap_delete(&heap);
    if (status != 0) {
      char errorMsg[256];
      self->Err("rt_heap_delete error (%s)\n", strerror_r(-status, errorMsg, sizeof(errorMsg)));
    }
  }

#else
  status = munmap(mem_segment, size);
  if (status != 0) {
    char errorMsg[256];
    self->Err("Failed to unmap memory (%s)\n", strerror_r(-status, errorMsg, sizeof(errorMsg)));
  }

  status = close(fd);
  if (status != 0) {
    char errorMsg[256];
    self->Err("Failed to close file (%s)\n", strerror_r(-status, errorMsg, sizeof(errorMsg)));
  }

  // do not check errors as it can be done by another process
  status = shm_unlink(shm_name.c_str()); /*
   if(status!=0)
   {
      char errorMsg[256];
       self->Err("Failed to unlink memory (%s)\n",strerror_r(-status, errorMsg, sizeof(errorMsg)));
   }
*/
#endif
}

void SharedMem_impl::ReaderReady() {
  sem_consumer.ReleaseSemaphore();
}

void SharedMem_impl::Write(const char *buf, size_t size) {
  if (type==SharedMem::Type::mutex) {
    sem.GetSemaphore();
    memcpy(mem_segment, buf, size);
    sem.ReleaseSemaphore();
  } else if (type==SharedMem::Type::producerConsumer) {
    //wait until consumer took the data away before writting a new one
    //but should not block if nobody's there to read
    if (sem_consumer.TryGetSemaphore()) {
      memcpy(mem_segment, buf, size);
      sem_producer.ReleaseSemaphore();
    }
  }
}

bool SharedMem_impl::Read(char *buf, size_t size, Time nsTimeout) {
  if (type==SharedMem::Type::mutex) {
    if (sem.GetSemaphore()) {
      memcpy(buf, mem_segment, size);
      sem.ReleaseSemaphore();
      return true;
    }
  } else if (type==SharedMem::Type::producerConsumer) {
    if (sem_producer.GetSemaphore(nsTimeout)) {
      memcpy(buf, mem_segment, size);
      sem_consumer.ReleaseSemaphore();
      return true;
    }
  }
  return false;
}