static _shm_queue_t* _shm_queue_create(const char* shm_path,
size_t shm_size,
int* shm_fd)
{
struct _shm_queue* q;
struct stat st;
off_t mmap_size = ROUND_TO_PAGESIZE(shm_size + sizeof(struct _shm_queue));
int fd = shm_open(shm_path,
O_CREAT | O_RDWR,
S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
if(-1 == (*shm_fd = fd))
return NULL;
fstat(fd, &st);
if(0 == st.st_size)
ftruncate(fd,mmap_size);
else
mmap_size = st.st_size;
q = mmap(0,mmap_size,PROT_READ | PROT_WRITE,MAP_SHARED,fd,0);
if(MAP_FAILED == q)
{
printf("mmap failed: %s\n",strerror(errno));
return NULL;
}
q->allocated = mmap_size;
return q;
}
int eMPEGStreamInformation::loadCache(int index)
{
//eDebug("[eMPEGStreamInformation::loadCache] index=%d", index);
if (m_structure_cache != NULL)
{
//eDebug("[eMPEGStreamInformation] munmap %p size %d index %d", m_structure_cache, m_structure_cache_entries * entry_size, m_cache_index);
::munmap(m_structure_cache, m_structure_cache_entries * entry_size);
m_structure_cache = NULL;
m_structure_cache_entries = 0;
m_cache_index = -1;
}
off_t where = ROUND_TO_PAGESIZE(index * entry_size);
off_t until = ::lseek(m_structure_read_fd, 0, SEEK_END);
size_t bytes;
if (where + MAPSIZE <= until)
{
bytes = MAPSIZE;
}
else
{
if (index * entry_size >= until)
{
eDebug("[eMPEGStreamInformation] index %d is past EOF", index);
return 0;
}
bytes = (size_t)(until-where);
if (bytes == 0)
{
eDebug("[eMPEGStreamInformation] mmap file is empty");
return 0;
}
}
//eDebug("[eMPEGStreamInformation] mmap offset=%lld size %d", where, bytes);
m_structure_cache = (unsigned long long*) ::mmap(NULL, bytes, PROT_READ, MAP_SHARED, m_structure_read_fd, where);
if (m_structure_cache == NULL)
{
eDebug("[eMPEGStreamInformation] failed to mmap cache: %m");
m_cache_index = -1;
m_structure_cache_entries = 0;
return -1;
}
m_cache_index = (int)(where / entry_size);
//eDebug("[eMPEGStreamInformation] cache index %d starts at %d (%lld) bytes: %d", index, m_cache_index, where, bytes);
int num = (int)bytes / entry_size;
m_structure_cache_entries = num;
return num;
}
