Allow adding an event callback

io.c

@@ -198,6 +198,7 @@ static void clear_res(struct io_resource *res)
 {
     res->type = IO_RES_VOID;
     res->pending = 0;
+    res->callback = NULL;
 
     #if IO_PLATFORM_WINDOWS
     res->os_handle = INVALID_HANDLE_VALUE;
@@ -818,8 +819,8 @@ op_from_ov(struct io_os_overlap *ov)
 
 #if IO_PLATFORM_WINDOWS
 static void
-io_wait_windows(struct io_context *ioc,
+io_wait_internal_windows(struct io_context *ioc,
-                struct io_event *ev)
+                         struct io_event *ev)
 {
     int timeout = -1;
 
@@ -928,8 +929,8 @@ io_wait_windows(struct io_context *ioc,
 
 #if IO_PLATFORM_LINUX
 static void
-io_wait_linux(struct io_context *ioc,
+io_wait_internal_linux(struct io_context *ioc,
-              struct io_event *ev)
+                       struct io_event *ev)
 {
     /* --- Read barrier --- */
     unsigned int head = atomic_load(ioc->completions.head);
@@ -984,8 +985,9 @@ io_wait_linux(struct io_context *ioc,
 }
 #endif
 
-void io_wait(struct io_context *ioc,
+static void
-             struct io_event *ev)
+io_wait_internal(struct io_context *ioc,
+                 struct io_event *ev)
 {
     #if IO_PLATFORM_WINDOWS
     io_wait_windows(ioc, ev);
@@ -995,3 +997,37 @@ void io_wait(struct io_context *ioc,
     io_wait_linux(ioc, ev);
     #endif
 }
+
+void io_wait(struct io_context *ioc,
+             struct io_event *ev)
+{
+    for (;;) {
+
+        io_wait_internal(ioc, ev);
+
+        if (ev->handle == IO_INVALID)
+            break;
+
+        assert(ev->handle != IO_INVALID);
+
+        struct io_resource *res;
+        res = res_from_handle(ioc, ev->handle);
+        assert(res);
+
+        if (res->callback == NULL)
+            break;
+
+        res->callback(*ev);
+    }
+}
+
+void io_set_callback(struct io_context *ioc,
+                     io_handle handle,
+                     io_callback callback)
+{
+    struct io_resource *res;
+    res = res_from_handle(ioc, handle);
+    if (res == NULL)
+        return;
+    res->callback = callback;
+}

io.h

@@ -63,18 +63,40 @@ struct io_operation {
     #endif
 };
 
+enum io_evtype {
+    IO_ERROR,
+    IO_ABORT,
+    IO_COMPLETE,
+};
+
+struct io_event {
+    enum io_evtype evtype;
+    enum io_optype optype;
+    io_handle handle;
+    void *user;
+
+    union {
+        uint32_t num;
+        io_handle accepted;
+    };
+};
+
 enum io_restype {
     IO_RES_VOID,
     IO_RES_FILE,
     IO_RES_SOCKET,
 };
 
+typedef void (*io_callback)(struct io_event);
+
 struct io_resource {
     enum io_restype type;
     io_os_handle os_handle;
     uint16_t pending;
     uint16_t gen;
 
+    io_callback callback;
+
     #if IO_PLATFORM_WINDOWS
     void *acceptfn;
     char accept_buffer[2 * (IO_SOCKADDR_IN_SIZE + 16)];
@@ -121,24 +143,6 @@ struct io_context {
     #endif
 };
 
-enum io_evtype {
-    IO_ERROR,
-    IO_ABORT,
-    IO_COMPLETE,
-};
-
-struct io_event {
-    enum io_evtype evtype;
-    enum io_optype optype;
-    io_handle handle;
-    void *user;
-
-    union {
-        uint32_t num;
-        io_handle accepted;
-    };
-};
-
 bool io_global_init(void);
 void io_global_free(void);
 
@@ -185,3 +189,7 @@ io_handle io_create_file(struct io_context *ioc,
 
 io_handle io_start_server(struct io_context *ioc,
                           const char *addr, int port);
+
+void io_set_callback(struct io_context *ioc,
+                     io_handle handle,
+                     io_callback callback);