[1/3] Add support for generic notifier lists

Commit Message

Maximilian Heyne March 13, 2020, 12:33 p.m. UTC

From: Anthony Liguori <[e-mail]>

Notifiers are data-less callbacks and a notifier list is a list of registered
notifiers that all are interested in a particular event.

We'll use this in a few patches to implement mouse change notification.

Signed-off-by: Anthony Liguori <[e-mail]>
---
v1 -> v2
 - Do not do memory allocations by placing list nodes in notifier

[cherry-picked from d1e70c5e6d1472856c52969301247fe8c3c8389d
    conflicts: used the sys-qeue interface and added required
    LIST_REMOVE_SAFE function to that]
Signed-off-by: Maximilian Heyne <[e-mail]>
---
 Makefile    |  1 +
 notify.c    | 39 +++++++++++++++++++++++++++++++++++++++
 notify.h    | 43 +++++++++++++++++++++++++++++++++++++++++++
 sys-queue.h |  5 +++++
 4 files changed, 88 insertions(+)
 create mode 100644 notify.c
 create mode 100644 notify.h

Comments

Paul Durrant April 8, 2020, 2:58 p.m. UTC | #1

> -----Original Message-----
> From: Maximilian Heyne <[e-mail]>
> Sent: 13 March 2020 12:33
> To: [e-mail]
> Cc: Ian Jackson <[e-mail]>; Paul Durrant <[e-mail]>
> Subject: [PATCH 1/3] Add support for generic notifier lists
> 
> From: Anthony Liguori <[e-mail]>
> 
> Notifiers are data-less callbacks and a notifier list is a list of registered
> notifiers that all are interested in a particular event.
> 
> We'll use this in a few patches to implement mouse change notification.
> 
> Signed-off-by: Anthony Liguori <[e-mail]>
> ---
> v1 -> v2
>  - Do not do memory allocations by placing list nodes in notifier
> 
> [cherry-picked from d1e70c5e6d1472856c52969301247fe8c3c8389d
>     conflicts: used the sys-qeue interface and added required
>     LIST_REMOVE_SAFE function to that]
> Signed-off-by: Maximilian Heyne <[e-mail]>

Reviewed-by: Paul Durrant <[e-mail]>

Patch

diff --git a/Makefile b/Makefile
index 0fbec990b..d921bcdf8 100644
--- a/Makefile
+++ b/Makefile
@@ -93,6 +93,7 @@  OBJS+=sd.o ssi-sd.o
 OBJS+=bt.o bt-host.o bt-vhci.o bt-l2cap.o bt-sdp.o bt-hci.o bt-hid.o usb-bt.o
 OBJS+=buffered_file.o migration.o migration-tcp.o net.o qemu-sockets.o
 OBJS+=qemu-char.o aio.o net-checksum.o savevm.o cache-utils.o
+OBJS+=notify.o
 
 ifdef CONFIG_BRLAPI
 OBJS+= baum.o
diff --git a/notify.c b/notify.c
new file mode 100644
index 000000000..59e1e7c7d
--- /dev/null
+++ b/notify.c
@@ -0,0 +1,39 @@ 
+/*
+ * Notifier lists
+ *
+ * Copyright IBM, Corp. 2010
+ *
+ * Authors:
+ *  Anthony Liguori   <[e-mail]>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+#include "qemu-common.h"
+#include "notify.h"
+
+void notifier_list_init(NotifierList *list)
+{
+    LIST_INIT(&list->notifiers);
+}
+
+void notifier_list_add(NotifierList *list, Notifier *notifier)
+{
+    LIST_INSERT_HEAD(&list->notifiers, notifier, node);
+}
+
+void notifier_list_remove(Notifier *notifier)
+{
+    LIST_REMOVE(notifier, node);
+}
+
+void notifier_list_notify(NotifierList *list)
+{
+    Notifier *notifier, *next;
+
+    LIST_FOREACH_SAFE(notifier, &list->notifiers, node, next) {
+        notifier->notify(notifier);
+    }
+}
diff --git a/notify.h b/notify.h
new file mode 100644
index 000000000..093c63f19
--- /dev/null
+++ b/notify.h
@@ -0,0 +1,43 @@ 
+/*
+ * Notifier lists
+ *
+ * Copyright IBM, Corp. 2010
+ *
+ * Authors:
+ *  Anthony Liguori   <[e-mail]>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+#ifndef QEMU_NOTIFY_H
+#define QEMU_NOTIFY_H
+
+#include "sys-queue.h"
+
+typedef struct Notifier Notifier;
+
+struct Notifier
+{
+    void (*notify)(Notifier *notifier);
+    LIST_ENTRY(Notifier) node;
+};
+
+typedef struct NotifierList
+{
+    LIST_HEAD(, Notifier) notifiers;
+} NotifierList;
+
+#define NOTIFIER_LIST_INITIALIZER(head) \
+    { LIST_HEAD_INITIALIZER((head).notifiers) }
+
+void notifier_list_init(NotifierList *list);
+
+void notifier_list_add(NotifierList *list, Notifier *notifier);
+
+void notifier_list_remove(Notifier *notifier);
+
+void notifier_list_notify(NotifierList *list);
+
+#endif
diff --git a/sys-queue.h b/sys-queue.h
index 55c26fe7f..81ab044a8 100644
--- a/sys-queue.h
+++ b/sys-queue.h
@@ -132,6 +132,11 @@  struct {                                                                \
                 (var);                                                  \
                 (var) = ((var)->field.le_next))
 
+#define LIST_FOREACH_SAFE(var, head, field, next_var)                   \
+        for ((var) = ((head)->lh_first);                                \
+                (var) && ((next_var) = ((var)->field.le_next), 1);      \
+                (var) = (next_var))
+
 /*
  * List access methods.
  */