[Qemu-devel] [PULL 08/18] replay: asynchronous events infrastructure

[Paolo Bonzini <pbonzini@redhat.com>]

From: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>

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 <pavel.dovgaluk@ispras.ru>
Message-Id: <20150917162422.8676.88696.stgit@PASHA-ISP.def.inno>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 include/sysemu/replay.h  |   6 ++
 replay/Makefile.objs     |   1 +
 replay/replay-events.c   | 225 +++++++++++++++++++++++++++++++++++++++++++++++
 replay/replay-internal.h |  29 ++++++
 4 files changed, 261 insertions(+)
 create mode 100644 replay/replay-events.c

diff --git a/include/sysemu/replay.h b/include/sysemu/replay.h
index 8915523..c2a7651 100644
--- a/include/sysemu/replay.h
+++ b/include/sysemu/replay.h
@@ -43,5 +43,11 @@ 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);
+/*! Returns true when saving events is enabled */
+bool replay_events_enabled(void);
 
 #endif
diff --git a/replay/Makefile.objs b/replay/Makefile.objs
index e67a932..6b439c2 100644
--- a/replay/Makefile.objs
+++ b/replay/Makefile.objs
@@ -1,2 +1,3 @@
 common-obj-y += replay.o
 common-obj-y += replay-internal.o
+common-obj-y += replay-events.o
diff --git a/replay/replay-events.c b/replay/replay-events.c
new file mode 100644
index 0000000..7634882
--- /dev/null
+++ b/replay/replay-events.c
@@ -0,0 +1,225 @@
+/*
+ * 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 "qemu/error-report.h"
+#include "sysemu/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);
+static unsigned int read_event_kind = -1;
+static uint64_t read_id = -1;
+static int read_checkpoint = -1;
+
+static bool events_enabled;
+
+/* Functions */
+
+static void replay_run_event(Event *event)
+{
+    switch (event->event_kind) {
+    default:
+        error_report("Replay: invalid async event ID (%d) in the queue",
+                    event->event_kind);
+        exit(1);
+        break;
+    }
+}
+
+void replay_enable_events(void)
+{
+    events_enabled = true;
+}
+
+bool replay_has_events(void)
+{
+    return !QTAILQ_EMPTY(&events_list);
+}
+
+void replay_flush_events(void)
+{
+    replay_mutex_lock();
+    while (!QTAILQ_EMPTY(&events_list)) {
+        Event *event = QTAILQ_FIRST(&events_list);
+        replay_mutex_unlock();
+        replay_run_event(event);
+        replay_mutex_lock();
+        QTAILQ_REMOVE(&events_list, event, events);
+        g_free(event);
+    }
+    replay_mutex_unlock();
+}
+
+void replay_disable_events(void)
+{
+    if (replay_mode != REPLAY_MODE_NONE) {
+        events_enabled = false;
+        /* Flush events queue before waiting of completion */
+        replay_flush_events();
+    }
+}
+
+void replay_clear_events(void)
+{
+    replay_mutex_lock();
+    while (!QTAILQ_EMPTY(&events_list)) {
+        Event *event = QTAILQ_FIRST(&events_list);
+        QTAILQ_REMOVE(&events_list, event, events);
+
+        g_free(event);
+    }
+    replay_mutex_unlock();
+}
+
+/*! Adds specified async event to the queue */
+static void replay_add_event(ReplayAsyncEventKind event_kind,
+                             void *opaque,
+                             void *opaque2, uint64_t id)
+{
+    assert(event_kind < REPLAY_ASYNC_COUNT);
+
+    if (!replay_file || replay_mode == REPLAY_MODE_NONE
+        || !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;
+
+    replay_mutex_lock();
+    QTAILQ_INSERT_TAIL(&events_list, event, events);
+    replay_mutex_unlock();
+}
+
+static void replay_save_event(Event *event, int checkpoint)
+{
+    if (replay_mode != REPLAY_MODE_PLAY) {
+        /* put the event into the file */
+        replay_put_event(EVENT_ASYNC);
+        replay_put_byte(checkpoint);
+        replay_put_byte(event->event_kind);
+
+        /* save event-specific data */
+        switch (event->event_kind) {
+        default:
+            error_report("Unknown ID %d of replay event", read_event_kind);
+            exit(1);
+            break;
+        }
+    }
+}
+
+/* Called with replay mutex locked */
+void replay_save_events(int checkpoint)
+{
+    while (!QTAILQ_EMPTY(&events_list)) {
+        Event *event = QTAILQ_FIRST(&events_list);
+        replay_save_event(event, checkpoint);
+
+        replay_mutex_unlock();
+        replay_run_event(event);
+        replay_mutex_lock();
+        QTAILQ_REMOVE(&events_list, event, events);
+        g_free(event);
+    }
+}
+
+static Event *replay_read_event(int checkpoint)
+{
+    Event *event;
+    if (read_event_kind == -1) {
+        read_checkpoint = replay_get_byte();
+        read_event_kind = replay_get_byte();
+        read_id = -1;
+        replay_check_error();
+    }
+
+    if (checkpoint != read_checkpoint) {
+        return NULL;
+    }
+
+    /* Events that has not to be in the queue */
+    switch (read_event_kind) {
+    default:
+        error_report("Unknown ID %d of replay event", read_event_kind);
+        exit(1);
+        break;
+    }
+
+    QTAILQ_FOREACH(event, &events_list, events) {
+        if (event->event_kind == read_event_kind
+            && (read_id == -1 || read_id == event->id)) {
+            break;
+        }
+    }
+
+    if (event) {
+        QTAILQ_REMOVE(&events_list, event, events);
+    } else {
+        return NULL;
+    }
+
+    /* Read event-specific data */
+
+    return event;
+}
+
+/* Called with replay mutex locked */
+void replay_read_events(int checkpoint)
+{
+    while (replay_data_kind == EVENT_ASYNC) {
+        Event *event = replay_read_event(checkpoint);
+        if (!event) {
+            break;
+        }
+        replay_mutex_unlock();
+        replay_run_event(event);
+        replay_mutex_lock();
+
+        g_free(event);
+        replay_finish_event();
+        read_event_kind = -1;
+    }
+}
+
+void replay_init_events(void)
+{
+    read_event_kind = -1;
+}
+
+void replay_finish_events(void)
+{
+    events_enabled = false;
+    replay_clear_events();
+}
+
+bool replay_events_enabled(void)
+{
+    return events_enabled;
+}
diff --git a/replay/replay-internal.h b/replay/replay-internal.h
index 5ff1c14..23807ca 100644
--- a/replay/replay-internal.h
+++ b/replay/replay-internal.h
@@ -21,9 +21,19 @@ enum ReplayEvents {
     EVENT_INTERRUPT,
     /* for emulated exceptions */
     EVENT_EXCEPTION,
+    /* for async events */
+    EVENT_ASYNC,
     EVENT_COUNT
 };
 
+/* 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;
@@ -75,4 +85,23 @@ void replay_save_instructions(void);
     \return true, if event was found */
 bool replay_next_event_is(int event);
 
+/* 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 checkpoint);
+/*! Read events from the file into the input queue */
+void replay_read_events(int checkpoint);
+
 #endif
-- 
1.8.3.1