ssize_t pread(int fd, void * buf, size_t count, off_t offset)
{
do_setup();
if(!isatty(fd))
{
io_stats.pread_total += count;
io_stats.pread_calls++;
}
return __libc_pread(fd, buf, count, offset);
}
static void *
handle_fildes_io (void *arg)
{
pthread_t self = pthread_self ();
struct sched_param param;
struct requestlist *runp = (struct requestlist *) arg;
aiocb_union *aiocbp;
int policy;
int fildes;
pthread_getschedparam (self, &policy, ¶m);
do
{
/* If runp is NULL, then we were created to service the work queue
in general, not to handle any particular request. In that case we
skip the "do work" stuff on the first pass, and go directly to the
"get work off the work queue" part of this loop, which is near the
end. */
if (runp == NULL)
pthread_mutex_lock (&__aio_requests_mutex);
else
{
/* Hopefully this request is marked as running. */
assert (runp->running == allocated);
/* Update our variables. */
aiocbp = runp->aiocbp;
fildes = aiocbp->aiocb.aio_fildes;
/* Change the priority to the requested value (if necessary). */
if (aiocbp->aiocb.__abs_prio != param.sched_priority
|| aiocbp->aiocb.__policy != policy)
{
param.sched_priority = aiocbp->aiocb.__abs_prio;
policy = aiocbp->aiocb.__policy;
pthread_setschedparam (self, policy, ¶m);
}
/* Process request pointed to by RUNP. We must not be disturbed
by signals. */
if ((aiocbp->aiocb.aio_lio_opcode & 127) == LIO_READ)
{
if (sizeof (off_t) != sizeof (off64_t)
&& aiocbp->aiocb.aio_lio_opcode & 128)
aiocbp->aiocb.__return_value =
TEMP_FAILURE_RETRY (__pread64 (fildes, (void *)
aiocbp->aiocb64.aio_buf,
aiocbp->aiocb64.aio_nbytes,
aiocbp->aiocb64.aio_offset));
else
aiocbp->aiocb.__return_value =
TEMP_FAILURE_RETRY (__libc_pread (fildes,
(void *)
aiocbp->aiocb.aio_buf,
aiocbp->aiocb.aio_nbytes,
aiocbp->aiocb.aio_offset));
if (aiocbp->aiocb.__return_value == -1 && errno == ESPIPE)
/* The Linux kernel is different from others. It returns
ESPIPE if using pread on a socket. Other platforms
simply ignore the offset parameter and behave like
read. */
aiocbp->aiocb.__return_value =
TEMP_FAILURE_RETRY (read (fildes,
(void *) aiocbp->aiocb64.aio_buf,
aiocbp->aiocb64.aio_nbytes));
}
else if ((aiocbp->aiocb.aio_lio_opcode & 127) == LIO_WRITE)
{
if (sizeof (off_t) != sizeof (off64_t)
&& aiocbp->aiocb.aio_lio_opcode & 128)
aiocbp->aiocb.__return_value =
TEMP_FAILURE_RETRY (__pwrite64 (fildes, (const void *)
aiocbp->aiocb64.aio_buf,
aiocbp->aiocb64.aio_nbytes,
aiocbp->aiocb64.aio_offset));
else
aiocbp->aiocb.__return_value =
TEMP_FAILURE_RETRY (__libc_pwrite (fildes, (const void *)
aiocbp->aiocb.aio_buf,
aiocbp->aiocb.aio_nbytes,
aiocbp->aiocb.aio_offset));
if (aiocbp->aiocb.__return_value == -1 && errno == ESPIPE)
/* The Linux kernel is different from others. It returns
ESPIPE if using pwrite on a socket. Other platforms
simply ignore the offset parameter and behave like
write. */
aiocbp->aiocb.__return_value =
TEMP_FAILURE_RETRY (write (fildes,
(void *) aiocbp->aiocb64.aio_buf,
aiocbp->aiocb64.aio_nbytes));
}
else if (aiocbp->aiocb.aio_lio_opcode == LIO_DSYNC)
aiocbp->aiocb.__return_value =
TEMP_FAILURE_RETRY (fdatasync (fildes));
else if (aiocbp->aiocb.aio_lio_opcode == LIO_SYNC)
aiocbp->aiocb.__return_value =
TEMP_FAILURE_RETRY (fsync (fildes));
else
{
/* This is an invalid opcode. */
aiocbp->aiocb.__return_value = -1;
__set_errno (EINVAL);
}
/* Get the mutex. */
pthread_mutex_lock (&__aio_requests_mutex);
if (aiocbp->aiocb.__return_value == -1)
aiocbp->aiocb.__error_code = errno;
else
aiocbp->aiocb.__error_code = 0;
/* Send the signal to notify about finished processing of the
request. */
__aio_notify (runp);
/* For debugging purposes we reset the running flag of the
finished request. */
assert (runp->running == allocated);
runp->running = done;
/* Now dequeue the current request. */
__aio_remove_request (NULL, runp, 0);
if (runp->next_prio != NULL)
add_request_to_runlist (runp->next_prio);
/* Free the old element. */
__aio_free_request (runp);
}
runp = runlist;
/* If the runlist is empty, then we sleep for a while, waiting for
something to arrive in it. */
if (runp == NULL && optim.aio_idle_time >= 0)
{
struct timeval now;
struct timespec wakeup_time;
++idle_thread_count;
__gettimeofday (&now, NULL);
wakeup_time.tv_sec = now.tv_sec + optim.aio_idle_time;
wakeup_time.tv_nsec = now.tv_usec * 1000;
if (wakeup_time.tv_nsec >= 1000000000)
{
wakeup_time.tv_nsec -= 1000000000;
++wakeup_time.tv_sec;
}
pthread_cond_timedwait (&__aio_new_request_notification,
&__aio_requests_mutex,
&wakeup_time);
--idle_thread_count;
runp = runlist;
}
if (runp == NULL)
--nthreads;
else
{
assert (runp->running == yes);
runp->running = allocated;
runlist = runp->next_run;
/* If we have a request to process, and there's still another in
the run list, then we need to either wake up or create a new
thread to service the request that is still in the run list. */
if (runlist != NULL)
{
/* There are at least two items in the work queue to work on.
If there are other idle threads, then we should wake them
up for these other work elements; otherwise, we should try
to create a new thread. */
if (idle_thread_count > 0)
pthread_cond_signal (&__aio_new_request_notification);
else if (nthreads < optim.aio_threads)
{
pthread_t thid;
pthread_attr_t attr;
/* Make sure the thread is created detached. */
pthread_attr_init (&attr);
pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);
/* Now try to start a thread. If we fail, no big deal,
because we know that there is at least one thread (us)
that is working on AIO operations. */
if (pthread_create (&thid, &attr, handle_fildes_io, NULL)
== 0)
++nthreads;
}
}
}
/* Release the mutex. */
pthread_mutex_unlock (&__aio_requests_mutex);
}
while (runp != NULL);
return NULL;
}
ssize_t syscall_pread(int fd, void *buf, size_t count, off_t offset){
return __libc_pread(fd, buf, count, offset);
}
