Inotify#take releases GVL unconditionally

Avoids using select(2) if we want blocking functionality on
Ruby 1.9.

1 files changed, 39 insertions, 20 deletions

diff --git a/ext/sleepy_penguin/inotify.c b/ext/sleepy_penguin/inotify.c
index 28359a6..9ba4245 100644
--- a/ext/sleepy_penguin/inotify.c
+++ b/ext/sleepy_penguin/inotify.c
@@ -134,6 +134,19 @@ static VALUE event_new(struct inotify_event *e)
         return rb_struct_new(cEvent, wd, mask, cookie, name);
 }
 
+struct inread_args {
+        int fd;
+        struct inotify_event *ptr;
+        long len;
+};
+
+static VALUE inread(void *ptr)
+{
+        struct inread_args *args = ptr;
+
+        return (VALUE)read(args->fd, args->ptr, args->len);
+}
+
 /*
  * call-seq:
  *        in.take([nonblock]) -> Inotify::Event or nil
@@ -143,12 +156,10 @@ static VALUE event_new(struct inotify_event *e)
  */
 static VALUE take(int argc, VALUE *argv, VALUE self)
 {
-        int fd = rb_sp_fileno(self);
-        VALUE buf = rb_ivar_get(self, id_inotify_buf);
+        struct inread_args args;
+        VALUE buf;
         VALUE tmp = rb_ivar_get(self, id_inotify_tmp);
-        struct inotify_event *ptr;
         struct inotify_event *e, *end;
-        long len;
         ssize_t r;
         VALUE rv = Qnil;
         VALUE nonblock;
@@ -158,33 +169,41 @@ static VALUE take(int argc, VALUE *argv, VALUE self)
 
         rb_scan_args(argc, argv, "01", &nonblock);
 
-        len = RSTRING_LEN(buf);
-        ptr = (struct inotify_event *)RSTRING_PTR(buf);
+        args.fd = rb_sp_fileno(self);
+        buf = rb_ivar_get(self, id_inotify_buf);
+        args.len = RSTRING_LEN(buf);
+        args.ptr = (struct inotify_event *)RSTRING_PTR(buf);
+
+        if (RTEST(nonblock))
+                rb_sp_set_nonblock(args.fd);
+        else
+                blocking_io_prepare(args.fd);
         do {
-                rb_sp_set_nonblock(fd);
-                r = read(fd, ptr, len);
-                if (r == 0 || (r < 0 && errno == EINVAL)) {
+                r = rb_sp_io_region(inread, &args);
+                if (r == 0 /* Linux < 2.6.21 */
+                    ||
+                    (r < 0 && errno == EINVAL) /* Linux >= 2.6.21 */
+                   ) {
                         /* resize internal buffer */
                         int newlen;
-                        if (len > 0x10000)
+                        if (args.len > 0x10000)
                                 rb_raise(rb_eRuntimeError, "path too long");
-                        if (ioctl(fd, FIONREAD, &newlen) != 0)
+                        if (ioctl(args.fd, FIONREAD, &newlen) != 0)
                                 rb_sys_fail("ioctl(inotify,FIONREAD)");
                         rb_str_resize(buf, newlen);
-                        ptr = (struct inotify_event *)RSTRING_PTR(buf);
-                        len = newlen;
+                        args.ptr = (struct inotify_event *)RSTRING_PTR(buf);
+                        args.len = newlen;
                 } else if (r < 0) {
-                        if (errno == EAGAIN) {
-                                if (RTEST(nonblock))
-                                        return Qnil;
-                                rb_io_wait_readable(fd);
+                        if (errno == EAGAIN && RTEST(nonblock)) {
+                                return Qnil;
                         } else {
-                                rb_sys_fail("read(inotify)");
+                                if (!rb_io_wait_readable(args.fd))
+                                        rb_sys_fail("read(inotify)");
                         }
                 } else {
                         /* buffer in userspace to minimize read() calls */
-                        end = (struct inotify_event *)((char *)ptr + r);
-                        for (e = ptr; e < end; ) {
+                        end = (struct inotify_event *)((char *)args.ptr + r);
+                        for (e = args.ptr; e < end; ) {
                                 VALUE event = event_new(e);
                                 if (NIL_P(rv))
                                         rv = event;