queue: clear next before re-enqueue

Author: dacheng-gao

src/backend/kqueue.zig

@@ -194,6 +194,7 @@ pub const Loop = struct {
                         const ecanceled = -1 * @as(i32, @intCast(@intFromEnum(posix.system.E.CANCELED)));
                         c.result = c.syscall_result(ecanceled);
                         c.flags.state = .dead;
+                        c.next = null;
                         self.completions.push(c);
 
                         events[events_len] = ev;
@@ -254,6 +255,7 @@ pub const Loop = struct {
                 }
 
                 assert(c.result != null);
+                c.next = null;
                 self.completions.push(c);
             }
         }
@@ -447,7 +449,10 @@ pub const Loop = struct {
                     },
 
                     // Only resubmit if we aren't already active (in the queue)
-                    .rearm => if (!c_active) self.submissions.push(c),
+                    .rearm => if (!c_active) {
+                        c.next = null;
+                        self.submissions.push(c);
+                    },
                 }
 
                 // If we filled the events slice, we break to avoid overflow.

src/watcher/file.zig

@@ -190,7 +190,10 @@ fn FileStream(comptime xev: type) type {
 
                     // Rearm requeues this request, it doesn't return rearm
                     // on the actual callback here...
-                    if (action == .rearm) q_inner.push(req_inner);
+                    if (action == .rearm) {
+                        req_inner.next = null;
+                        q_inner.push(req_inner);
+                    }
 
                     // If we have another request, add that completion next.
                     if (q_inner.head) |req_next| l_inner.add(&req_next.completion);

src/watcher/stream.zig

@@ -840,7 +840,10 @@ pub fn Writeable(comptime xev: type, comptime T: type, comptime options: Options
 
                     // Rearm requeues this request, it doesn't return rearm
                     // on the actual callback here...
-                    if (action == .rearm) q_inner.push(req_inner);
+                    if (action == .rearm) {
+                        req_inner.next = null;
+                        q_inner.push(req_inner);
+                    }
 
                     // If we have another request, add that completion next.
                     if (q_inner.head) |req_next| l_inner.add(&req_next.completion);