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| | #ifdef HAVE_SYS_EVENTFD_H
#include "sleepy_penguin.h"
#include <sys/eventfd.h>
/*
* call-seq:
* EventFD.new(initial_value [, flags]) -> EventFD IO object
*
* Creates an EventFD object. +initial_value+ is a non-negative Integer
* to start the internal counter at.
*
* Starting with Linux 2.6.27, +flags+ may be a mask that consists of any
* of the following:
*
* - :CLOEXEC - set the close-on-exec flag on the new object
* - :NONBLOCK - set the non-blocking I/O flag on the new object
*
* Since Linux 2.6.30, +flags+ may also include:
* - :SEMAPHORE - provides semaphore-like semantics (see EventFD#value)
*/
static VALUE s_new(int argc, VALUE *argv, VALUE klass)
{
VALUE _initval, _flags, rv;
unsigned initval;
int flags;
int fd;
rb_scan_args(argc, argv, "11", &_initval, &_flags);
initval = NUM2UINT(_initval);
flags = rb_sp_get_flags(klass, _flags, RB_SP_CLOEXEC(EFD_CLOEXEC));
fd = eventfd(initval, flags);
if (fd < 0) {
if (rb_sp_gc_for_fd(errno))
fd = eventfd(initval, flags);
if (fd < 0)
rb_sys_fail("eventfd");
}
rv = INT2FIX(fd);
return rb_call_super(1, &rv);
}
struct efd_args {
int fd;
uint64_t val;
};
static VALUE efd_write(void *_args)
{
struct efd_args *args = _args;
ssize_t w = write(args->fd, &args->val, sizeof(uint64_t));
return (VALUE)w;
}
static VALUE efd_read(void *_args)
{
struct efd_args *args = _args;
ssize_t r = read(args->fd, &args->val, sizeof(uint64_t));
return (VALUE)r;
}
/*
* call-seq:
* efd.incr(integer_value[, nonblock ]) -> true or nil
*
* Increments the internal counter by +integer_value+ which is an unsigned
* Integer value.
*
* If +nonblock+ is specified and true, this will return +nil+ if the
* internal counter will overflow the value of EventFD::MAX.
* Otherwise it will block until the counter may be incremented without
* overflowing.
*/
static VALUE incr(int argc, VALUE *argv, VALUE self)
{
struct efd_args x;
ssize_t w;
VALUE value, nonblock;
rb_scan_args(argc, argv, "11", &value, &nonblock);
x.fd = rb_sp_fileno(self);
if (RTEST(nonblock))
rb_sp_set_nonblock(x.fd);
x.val = (uint64_t)NUM2ULL(value);
retry:
w = (ssize_t)rb_sp_fd_region(efd_write, &x, x.fd);
if (w < 0) {
if (errno == EAGAIN && RTEST(nonblock))
return Qfalse;
if (rb_sp_wait(rb_io_wait_writable, self, &x.fd))
goto retry;
rb_sys_fail("write(eventfd)");
}
return Qtrue;
}
/*
* call-seq:
* efd.value([nonblock]) -> Integer or nil
*
* If not created as a semaphore, returns the current value and resets
* the counter to zero.
*
* If created as a semaphore, this decrements the counter value by one
* and returns +1+.
*
* If the counter is zero at the time of the call, this will block until
* the counter becomes non-zero unless +nonblock+ is +true+, in which
* case it returns +nil+.
*/
static VALUE getvalue(int argc, VALUE *argv, VALUE self)
{
struct efd_args x;
ssize_t w;
VALUE nonblock;
rb_scan_args(argc, argv, "01", &nonblock);
x.fd = rb_sp_fileno(self);
if (RTEST(nonblock))
rb_sp_set_nonblock(x.fd);
retry:
w = (ssize_t)rb_sp_fd_region(efd_read, &x, x.fd);
if (w < 0) {
if (errno == EAGAIN && RTEST(nonblock))
return Qnil;
if (rb_sp_wait(rb_io_wait_readable, self, &x.fd))
goto retry;
rb_sys_fail("read(eventfd)");
}
return ULL2NUM(x.val);
}
void sleepy_penguin_init_eventfd(void)
{
VALUE mSleepyPenguin, cEventFD;
mSleepyPenguin = rb_define_module("SleepyPenguin");
/*
* Document-class: SleepyPenguin::EventFD
*
* Applications may use EventFD instead of a pipe in cases where
* a pipe is only used to signal events. The kernel overhead for
* an EventFD descriptor is much lower than that of a pipe.
*
* As of Linux 2.6.30, an EventFD may also be used as a semaphore.
*/
cEventFD = rb_define_class_under(mSleepyPenguin, "EventFD", rb_cIO);
rb_define_singleton_method(cEventFD, "new", s_new, -1);
/*
* the maximum value that may be stored in an EventFD,
* currently 0xfffffffffffffffe
*/
rb_define_const(cEventFD, "MAX", ULL2NUM(0xfffffffffffffffeULL));
#ifdef EFD_NONBLOCK
NODOC_CONST(cEventFD, "NONBLOCK", INT2NUM(EFD_NONBLOCK));
#endif
#ifdef EFD_CLOEXEC
NODOC_CONST(cEventFD, "CLOEXEC", INT2NUM(EFD_CLOEXEC));
#endif
#ifdef EFD_SEMAPHORE
NODOC_CONST(cEventFD, "SEMAPHORE", INT2NUM(EFD_SEMAPHORE));
#endif
rb_define_method(cEventFD, "value", getvalue, -1);
rb_define_method(cEventFD, "incr", incr, -1);
}
#endif /* HAVE_SYS_EVENTFD_H */
|