BUG/MINOR: poll: the I/O handler was called twice for polled I/Os
When a polled I/O event is detected, the event is added to the updates
list and the I/O handler is called. Upon return, if the event handler
did not experience an EAGAIN, the event remains in the updates list so
that it will be processed later. But if the event was already in the
spec list, its state is updated and it will be called again immediately
upon exit, by fd_process_spec_events(), so this creates unfairness
between speculative events and polled events.
So don't call the I/O handler upon I/O detection when the FD already is
in the spec list. The fd events are still updated so that the spec list
is up to date with the possible I/O change.
diff --git a/src/ev_epoll.c b/src/ev_epoll.c
index 5f7b7c3..90efaee 100644
--- a/src/ev_epoll.c
+++ b/src/ev_epoll.c
@@ -179,6 +179,11 @@
if (fdtab[fd].ev & FD_POLL_OUT)
fd_ev_set(fd, DIR_WR);
+ if (fdtab[fd].spec_p) {
+ /* This fd was already scheduled for being called as a speculative I/O */
+ continue;
+ }
+
/* Save number of updates to detect creation of new FDs. */
old_updt = fd_nbupdt;
fdtab[fd].iocb(fd);
diff --git a/src/ev_kqueue.c b/src/ev_kqueue.c
index 36a7b7f..2142132 100644
--- a/src/ev_kqueue.c
+++ b/src/ev_kqueue.c
@@ -158,6 +158,13 @@
if (fdtab[fd].ev & FD_POLL_OUT)
fd_ev_set(fd, DIR_WR);
+ if (fdtab[fd].spec_p) {
+ /* This fd was already scheduled for being
+ * called as a speculative I/O.
+ */
+ continue;
+ }
+
fdtab[fd].iocb(fd);
}
}
diff --git a/src/ev_poll.c b/src/ev_poll.c
index c09232e..e3ea4db 100644
--- a/src/ev_poll.c
+++ b/src/ev_poll.c
@@ -181,6 +181,13 @@
if (fdtab[fd].ev & FD_POLL_OUT)
fd_ev_set(fd, DIR_WR);
+ if (fdtab[fd].spec_p) {
+ /* This fd was already scheduled for being
+ * called as a speculative I/O
+ */
+ continue;
+ }
+
fdtab[fd].iocb(fd);
}
}
diff --git a/src/ev_select.c b/src/ev_select.c
index 48a62da..dba5928 100644
--- a/src/ev_select.c
+++ b/src/ev_select.c
@@ -167,6 +167,13 @@
if (fdtab[fd].ev & FD_POLL_OUT)
fd_ev_set(fd, DIR_WR);
+ if (fdtab[fd].spec_p) {
+ /* This fd was already scheduled for being
+ * called as a speculative I/O.
+ */
+ continue;
+ }
+
fdtab[fd].iocb(fd);
}
}