[Qemu-devel] [PATCH for-2.3 1/5] poll: Introduce QEMU Poll API

[Fam Zheng]

This is abstract of underlying poll implementation. A glib
implementation is included.

Signed-off-by: Fam Zheng <address@hidden>
---
 Makefile.objs           |   2 +-
 include/qemu/poll.h     |  40 +++++++++++++++
 include/qemu/typedefs.h |   2 +
 poll-glib.c             | 130 ++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 173 insertions(+), 1 deletion(-)
 create mode 100644 include/qemu/poll.h
 create mode 100644 poll-glib.c

diff --git a/Makefile.objs b/Makefile.objs
index 18fd35c..57184eb 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -9,7 +9,7 @@ util-obj-y = util/ qobject/ qapi/ qapi-types.o qapi-visit.o 
qapi-event.o
 block-obj-y = async.o thread-pool.o
 block-obj-y += nbd.o block.o blockjob.o
 block-obj-y += main-loop.o iohandler.o qemu-timer.o
-block-obj-$(CONFIG_POSIX) += aio-posix.o
+block-obj-$(CONFIG_POSIX) += aio-posix.o poll-glib.o
 block-obj-$(CONFIG_WIN32) += aio-win32.o
 block-obj-y += block/
 block-obj-y += qemu-io-cmds.o
diff --git a/include/qemu/poll.h b/include/qemu/poll.h
new file mode 100644
index 0000000..597975f
--- /dev/null
+++ b/include/qemu/poll.h
@@ -0,0 +1,40 @@
+#ifndef QEMU_POLL_H
+#define QEMU_POLL_H
+
+#include "qemu/typedefs.h"
+#include "qemu-common.h"
+
+struct QEMUPollEvent {
+    int fd;
+    int events;
+    int revents;
+    void *opaque;
+};
+
+QEMUPoll *qemu_poll_new(void);
+void qemu_poll_free(QEMUPoll *qpoll);
+int qemu_poll(QEMUPoll *qpoll, int64_t timeout_ns);
+
+/* Add an fd to poll. Return -EEXIST if fd already registered. */
+int qemu_poll_add(QEMUPoll *qpoll, int fd, int gio_events, void *opaque);
+
+/* Delete a previously added fd. Return -ENOENT if fd not registered. */
+int qemu_poll_del(QEMUPoll *qpoll, int fd);
+
+/**
+ * A shortcut to:
+ * 1) remove all the existing fds;
+ * 2) add all in @fds, while setting each fd's opaque pointer to the pollfd
+ * struct itself.
+ */
+int qemu_poll_set_fds(QEMUPoll *qpoll, GPollFD *fds, int nfds);
+
+/**
+ * Query the events from last qemu_poll. ONLY revent and opaque are valid in
+ * @events after return.
+ */
+int qemu_poll_get_events(QEMUPoll *qpoll,
+                         QEMUPollEvent *events,
+                         int max_events);
+
+#endif
diff --git a/include/qemu/typedefs.h b/include/qemu/typedefs.h
index 3475177..f9a5e60 100644
--- a/include/qemu/typedefs.h
+++ b/include/qemu/typedefs.h
@@ -7,6 +7,8 @@ typedef struct QEMUTimer QEMUTimer;
 typedef struct QEMUTimerListGroup QEMUTimerListGroup;
 typedef struct QEMUFile QEMUFile;
 typedef struct QEMUBH QEMUBH;
+typedef struct QEMUPoll QEMUPoll;
+typedef struct QEMUPollEvent QEMUPollEvent;
 
 typedef struct AioContext AioContext;
 
diff --git a/poll-glib.c b/poll-glib.c
new file mode 100644
index 0000000..64fde69
--- /dev/null
+++ b/poll-glib.c
@@ -0,0 +1,130 @@
+/*
+ * g_poll implementation for QEMU Poll API
+ *
+ * Copyright Red Hat, Inc. 2014
+ *
+ * Authors:
+ *   Fam Zheng <address@hidden>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#include "qemu-common.h"
+#include "qemu/timer.h"
+#include "qemu/poll.h"
+
+struct QEMUPoll {
+    /* Array of GPollFD for g_poll() */
+    GArray *gpollfds;
+
+    /* Array of opaque pointers, should be in sync with gpollfds */
+    GArray *opaque;
+};
+
+QEMUPoll *qemu_poll_new(void)
+{
+    QEMUPoll *qpoll = g_new0(QEMUPoll, 1);
+    qpoll->gpollfds = g_array_new(FALSE, FALSE, sizeof(GPollFD));
+    qpoll->opaque = g_array_new(FALSE, FALSE, sizeof(void *));
+    return qpoll;
+}
+
+
+void qemu_poll_free(QEMUPoll *qpoll)
+{
+    g_array_unref(qpoll->gpollfds);
+    g_array_unref(qpoll->opaque);
+    g_free(qpoll);
+}
+
+int qemu_poll(QEMUPoll *qpoll, int64_t timeout_ns)
+{
+    int i;
+    for (i = 0; i < qpoll->gpollfds->len; i++) {
+        GPollFD *p = &g_array_index(qpoll->gpollfds, GPollFD, i);
+        p->revents = 0;
+    }
+    return g_poll((GPollFD *)qpoll->gpollfds->data,
+                  qpoll->gpollfds->len,
+                  qemu_timeout_ns_to_ms(timeout_ns));
+}
+
+/* Add an fd to poll. Return -EEXIST if fd already registered. */
+int qemu_poll_add(QEMUPoll *qpoll, int fd, int gio_events, void *opaque)
+{
+    int i;
+    GPollFD pfd = (GPollFD) {
+        .fd = fd,
+        .revents = 0,
+        .events = gio_events,
+    };
+
+    for (i = 0; i < qpoll->gpollfds->len; i++) {
+        GPollFD *p = &g_array_index(qpoll->gpollfds, GPollFD, i);
+        if (p->fd == fd) {
+            return -EEXIST;
+        }
+    }
+    g_array_append_val(qpoll->gpollfds, pfd);
+    g_array_append_val(qpoll->opaque, opaque);
+    assert(qpoll->gpollfds->len == qpoll->opaque->len);
+    return 0;
+}
+
+/* Delete a previously added fd. Return -ENOENT if fd not registered. */
+int qemu_poll_del(QEMUPoll *qpoll, int fd)
+{
+    int i;
+    int found = -1;
+
+    for (i = 0; i < qpoll->gpollfds->len; i++) {
+        GPollFD *p = &g_array_index(qpoll->gpollfds, GPollFD, i);
+        if (p->fd == fd) {
+            found = i;
+            break;
+        }
+    }
+    if (found >= 0) {
+        g_array_remove_index(qpoll->gpollfds, found);
+        g_array_remove_index(qpoll->opaque, found);
+        assert(qpoll->gpollfds->len == qpoll->opaque->len);
+        return 0;
+    } else {
+        return -ENOENT;
+    }
+}
+
+int qemu_poll_set_fds(QEMUPoll *qpoll, GPollFD *fds, int nfds)
+{
+    int i;
+    g_array_set_size(qpoll->gpollfds, 0);
+    g_array_set_size(qpoll->opaque, 0);
+    for (i = 0; i < nfds; i++) {
+        void *opaque = &fds[i];
+        g_array_append_val(qpoll->gpollfds, fds[i]);
+        g_array_append_val(qpoll->opaque, opaque);
+        assert(qpoll->gpollfds->len == qpoll->opaque->len);
+    }
+    return nfds;
+}
+
+int qemu_poll_get_events(QEMUPoll *qpoll,
+                         QEMUPollEvent *events,
+                         int max_events)
+{
+    int i;
+    int r = 0;
+    for (i = 0; i < qpoll->gpollfds->len && r < max_events; i++) {
+        GPollFD *fd = &g_array_index(qpoll->gpollfds, GPollFD, i);
+        if (fd->revents & fd->events) {
+            events[r].fd = fd->fd;
+            events[r].revents = fd->revents;
+            events[r].events = fd->events;
+            events[r].opaque = g_array_index(qpoll->opaque, void *, i);
+            r++;
+        }
+    }
+    return r;
+}
-- 
1.9.3