[Qemu-devel] [RFC PATCH v8 10/21] replay: asynchronous events infrastructure

[Pavel Dovgalyuk]

This patch adds module for saving and replaying asynchronous events.
These events include network packets, keyboard and mouse input,
USB packets, thread pool and bottom halves callbacks.
All events are stored in the queue to be processed at synchronization points
such as beginning of TB execution, or checkpoint in the iothread.

Signed-off-by: Pavel Dovgalyuk <address@hidden>
---
 replay/Makefile.objs     |    1 
 replay/replay-events.c   |  228 ++++++++++++++++++++++++++++++++++++++++++++++
 replay/replay-internal.h |   33 ++++++-
 replay/replay.h          |    4 +
 4 files changed, 265 insertions(+), 1 deletions(-)
 create mode 100755 replay/replay-events.c

diff --git a/replay/Makefile.objs b/replay/Makefile.objs
index 1148f45..56da09c 100755
--- a/replay/Makefile.objs
+++ b/replay/Makefile.objs
@@ -1,2 +1,3 @@
 obj-y += replay.o
 obj-y += replay-internal.o
+obj-y += replay-events.o
diff --git a/replay/replay-events.c b/replay/replay-events.c
new file mode 100755
index 0000000..dfd5efd
--- /dev/null
+++ b/replay/replay-events.c
@@ -0,0 +1,228 @@
+/*
+ * replay-events.c
+ *
+ * Copyright (c) 2010-2015 Institute for System Programming
+ *                         of the Russian Academy of Sciences.
+ *
+ * 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 "replay.h"
+#include "replay-internal.h"
+
+typedef struct Event {
+    ReplayAsyncEventKind event_kind;
+    void *opaque;
+    void *opaque2;
+    uint64_t id;
+
+    QTAILQ_ENTRY(Event) events;
+} Event;
+
+static QTAILQ_HEAD(, Event) events_list = QTAILQ_HEAD_INITIALIZER(events_list);
+/* Mutex to protect events_list modifications */
+static QemuMutex lock;
+static unsigned int read_event_kind = -1;
+static uint64_t read_id = -1;
+static int read_opt = -1;
+
+static bool replay_events_enabled = false;
+
+/* Functions */
+
+static void replay_run_event(Event *event)
+{
+    switch (event->event_kind) {
+    default:
+        fprintf(stderr, "Replay: invalid async event ID (%d) in the queue\n",
+                event->event_kind);
+        exit(1);
+        break;
+    }
+}
+
+void replay_enable_events(void)
+{
+    replay_events_enabled = true;
+}
+
+bool replay_has_events(void)
+{
+    return !QTAILQ_EMPTY(&events_list);
+}
+
+void replay_flush_events(void)
+{
+    qemu_mutex_lock(&lock);
+    while (!QTAILQ_EMPTY(&events_list)) {
+        Event *event = QTAILQ_FIRST(&events_list);
+        qemu_mutex_unlock(&lock);
+        replay_run_event(event);
+        qemu_mutex_lock(&lock);
+        QTAILQ_REMOVE(&events_list, event, events);
+        g_free(event);
+    }
+    qemu_mutex_unlock(&lock);
+}
+
+void replay_disable_events(void)
+{
+    replay_events_enabled = false;
+    /* Flush events queue before waiting of completion */
+    replay_flush_events();
+}
+
+void replay_clear_events(void)
+{
+    qemu_mutex_lock(&lock);
+    while (!QTAILQ_EMPTY(&events_list)) {
+        Event *event = QTAILQ_FIRST(&events_list);
+        QTAILQ_REMOVE(&events_list, event, events);
+
+        g_free(event);
+    }
+    qemu_mutex_unlock(&lock);
+}
+
+static void replay_add_event_internal(ReplayAsyncEventKind event_kind,
+                                      void *opaque,
+                                      void *opaque2, uint64_t id)
+{
+    if (event_kind >= REPLAY_ASYNC_COUNT) {
+        fprintf(stderr, "Replay: invalid async event ID (%d)\n", event_kind);
+        exit(1);
+    }
+    if (!replay_file || replay_mode == REPLAY_MODE_NONE
+        || !replay_events_enabled) {
+        Event e;
+        e.event_kind = event_kind;
+        e.opaque = opaque;
+        e.opaque2 = opaque2;
+        e.id = id;
+        replay_run_event(&e);
+        return;
+    }
+
+    Event *event = g_malloc0(sizeof(Event));
+    event->event_kind = event_kind;
+    event->opaque = opaque;
+    event->opaque2 = opaque2;
+    event->id = id;
+
+    qemu_mutex_lock(&lock);
+    QTAILQ_INSERT_TAIL(&events_list, event, events);
+    qemu_mutex_unlock(&lock);
+}
+
+void replay_add_event(ReplayAsyncEventKind event_kind, void *opaque)
+{
+    replay_add_event_internal(event_kind, opaque, NULL, 0);
+}
+
+/* Called with replay mutex locked */
+void replay_save_events(int opt)
+{
+    qemu_mutex_lock(&lock);
+    while (!QTAILQ_EMPTY(&events_list)) {
+        Event *event = QTAILQ_FIRST(&events_list);
+        if (replay_mode != REPLAY_MODE_PLAY) {
+            /* put the event into the file */
+            replay_put_event(EVENT_ASYNC);
+            replay_put_byte(opt);
+            replay_put_byte(event->event_kind);
+
+            /* save event-specific data */
+            switch (event->event_kind) {
+            }
+        }
+
+        qemu_mutex_unlock(&lock);
+        replay_mutex_unlock();
+        replay_run_event(event);
+        replay_mutex_lock();
+        qemu_mutex_lock(&lock);
+        QTAILQ_REMOVE(&events_list, event, events);
+        g_free(event);
+    }
+    qemu_mutex_unlock(&lock);
+}
+
+/* Called with replay mutex locked */
+void replay_read_events(int opt)
+{
+    replay_fetch_data_kind();
+    while (replay_data_kind == EVENT_ASYNC) {
+        if (read_event_kind == -1) {
+            read_opt = replay_get_byte();
+            read_event_kind = replay_get_byte();
+            read_id = -1;
+            replay_check_error();
+        }
+
+        if (opt != read_opt) {
+            break;
+        }
+        /* Execute some events without searching them in the queue */
+        switch (read_event_kind) {
+        default:
+            fprintf(stderr, "Unknown ID %d of replay event\n", 
read_event_kind);
+            exit(1);
+            break;
+        }
+
+        qemu_mutex_lock(&lock);
+
+        Event *event = NULL;
+        Event *curr = NULL;
+        QTAILQ_FOREACH(curr, &events_list, events) {
+            if (curr->event_kind == read_event_kind
+                && (read_id == -1 || read_id == curr->id)) {
+                event = curr;
+                break;
+            }
+        }
+
+        if (event) {
+            /* read event-specific reading data */
+
+            QTAILQ_REMOVE(&events_list, event, events);
+
+            qemu_mutex_unlock(&lock);
+
+            /* reset unread data and other parameters to allow
+               reading other data from the log while
+               running the event */
+            replay_has_unread_data = 0;
+            read_event_kind = -1;
+            read_id = -1;
+            read_opt = -1;
+
+            replay_mutex_unlock();
+            replay_run_event(event);
+            replay_mutex_lock();
+            g_free(event);
+
+            replay_fetch_data_kind();
+        } else {
+            qemu_mutex_unlock(&lock);
+            /* No such event found in the queue */
+            break;
+        }
+    }
+}
+
+void replay_init_events(void)
+{
+    read_event_kind = -1;
+    qemu_mutex_init(&lock);
+}
+
+void replay_finish_events(void)
+{
+    replay_events_enabled = false;
+    replay_clear_events();
+    qemu_mutex_destroy(&lock);
+}
diff --git a/replay/replay-internal.h b/replay/replay-internal.h
index 64cc3b2..1666d6e 100755
--- a/replay/replay-internal.h
+++ b/replay/replay-internal.h
@@ -20,9 +20,19 @@ enum ReplayEvents {
     /* for software interrupt */
     EVENT_INTERRUPT,
     /* for emulated exceptions */
-    EVENT_EXCEPTION
+    EVENT_EXCEPTION,
+    /* for async events */
+    EVENT_ASYNC
 };
 
+/* Asynchronous events IDs */
+
+enum ReplayAsyncEventKind {
+    REPLAY_ASYNC_COUNT
+};
+
+typedef enum ReplayAsyncEventKind ReplayAsyncEventKind;
+
 typedef struct ReplayState {
     /*! Current step - number of processed instructions and timer events. */
     uint64_t current_step;
@@ -78,4 +88,25 @@ bool skip_async_events(int stop_event);
     reports an error and stops the execution. */
 void skip_async_events_until(unsigned int kind);
 
+/* Asynchronous events queue */
+
+/*! Initializes events' processing internals */
+void replay_init_events(void);
+/*! Clears internal data structures for events handling */
+void replay_finish_events(void);
+/*! Enables storing events in the queue */
+void replay_enable_events(void);
+/*! Flushes events queue */
+void replay_flush_events(void);
+/*! Clears events list before loading new VM state */
+void replay_clear_events(void);
+/*! Returns true if there are any unsaved events in the queue */
+bool replay_has_events(void);
+/*! Saves events from queue into the file */
+void replay_save_events(int opt);
+/*! Read events from the file into the input queue */
+void replay_read_events(int opt);
+/*! Adds specified async event to the queue */
+void replay_add_event(ReplayAsyncEventKind event_id, void *opaque);
+
 #endif
diff --git a/replay/replay.h b/replay/replay.h
index eb3b0ff..31ca3b9 100755
--- a/replay/replay.h
+++ b/replay/replay.h
@@ -43,5 +43,9 @@ bool replay_interrupt(void);
     Returns true, when interrupt request is pending */
 bool replay_has_interrupt(void);
 
+/* Asynchronous events queue */
+
+/*! Disables storing events in the queue */
+void replay_disable_events(void);
 
 #endif