Reland "uinput: use nanoseconds for delay durations"

(This CL is unchanged. Original description below, with additional Test:
line)

evemu recordings use microseconds for their time intervals, but we can
only schedule handler calls in Device at millisecond precision. So far
we've converted the microseconds into milliseconds in EvemuParser, which
means that the precision losses compound over time (since each delay
will be slightly shorter than it should be, and the next delay will
start from that slightly earlier time, etc.). Keeping the delay
durations in a more precise unit up until the very last moment means
that we'll only get the precision loss once for each event. Since it's
somewhat uncommon to use microseconds elsewhere in Android code, and we
get the system time in nanoseconds, we may as well use nanoseconds
rather than microseconds.

Bug: 310958309
Test: play an evemu recording through uinput
Test: atest UinputTests
Test: atest android.view.cts.input.InputDeviceKeyLayoutMapTest \
            android.view.cts.input.InputDeviceSensorManagerTest \
	    --rerun-until-failure=10
Change-Id: Ibb968487ed114a4c464ac7061af4cda188e92498

cmds/uinput/src/com/android/commands/uinput/Device.java

@@ -55,7 +55,7 @@ public class Device {
     private final SparseArray<InputAbsInfo> mAbsInfo;
     private final OutputStream mOutputStream;
     private final Object mCond = new Object();
-    private long mTimeToSend;
+    private long mTimeToSendNanos;
 
     static {
         System.loadLibrary("uinputcommand_jni");
@@ -101,7 +101,13 @@ public Device(int id, String name, int vendorId, int productId, int versionId, i
         }
 
         mHandler.obtainMessage(MSG_OPEN_UINPUT_DEVICE, args).sendToTarget();
-        mTimeToSend = SystemClock.uptimeMillis();
+        mTimeToSendNanos = SystemClock.uptimeNanos();
+    }
+
+    private long getTimeToSendMillis() {
+        // This should be the same as (long) Math.ceil(mTimeToSendNanos / 1_000_000.0), except
+        // without the precision loss that comes from converting from long to double and back.
+        return mTimeToSendNanos / 1_000_000 + ((mTimeToSendNanos % 1_000_000 > 0) ? 1 : 0);
     }
 
     /**
@@ -112,16 +118,26 @@ public Device(int id, String name, int vendorId, int productId, int versionId, i
     public void injectEvent(int[] events) {
         // if two messages are sent at identical time, they will be processed in order received
         Message msg = mHandler.obtainMessage(MSG_INJECT_EVENT, events);
-        mHandler.sendMessageAtTime(msg, mTimeToSend);
+        mHandler.sendMessageAtTime(msg, getTimeToSendMillis());
     }
 
     /**
-     * Impose a delay to the device for execution.
+     * Delay subsequent device activity by the specified amount of time.
+     *
+     * <p>Note that although the delay is specified in nanoseconds, due to limitations of {@link
+     * Handler}'s API, scheduling only occurs with millisecond precision. When scheduling an
+     * injection or sync, the time at which it is scheduled will be rounded up to the nearest
+     * millisecond. While this means that a particular injection cannot be scheduled precisely,
+     * rounding errors will not accumulate over time. For example, if five injections are scheduled
+     * with a delay of 1,200,000ns before each one, the total delay will be 6ms, as opposed to the
+     * 10ms it would have been if each individual delay had been rounded up (as {@link EvemuParser}
+     * would otherwise have to do to avoid sending timestamps that are in the future).
      *
-     * @param delay  Time to delay in unit of milliseconds.
+     * @param delayNanos  Time to delay in unit of nanoseconds.
      */
-    public void addDelay(int delay) {
-        mTimeToSend = Math.max(SystemClock.uptimeMillis(), mTimeToSend) + delay;
+    public void addDelayNanos(long delayNanos) {
+        mTimeToSendNanos =
+                Math.max(SystemClock.uptimeNanos(), mTimeToSendNanos) + delayNanos;
     }
 
     /**
@@ -131,7 +147,8 @@ public void addDelay(int delay) {
      * @param syncToken  The token for this sync command.
      */
     public void syncEvent(String syncToken) {
-        mHandler.sendMessageAtTime(mHandler.obtainMessage(MSG_SYNC_EVENT, syncToken), mTimeToSend);
+        mHandler.sendMessageAtTime(
+                mHandler.obtainMessage(MSG_SYNC_EVENT, syncToken), getTimeToSendMillis());
     }
 
     /**
@@ -140,7 +157,8 @@ public void syncEvent(String syncToken) {
      */
     public void close() {
         Message msg = mHandler.obtainMessage(MSG_CLOSE_UINPUT_DEVICE);
-        mHandler.sendMessageAtTime(msg, Math.max(SystemClock.uptimeMillis(), mTimeToSend) + 1);
+        mHandler.sendMessageAtTime(
+                msg, Math.max(SystemClock.uptimeMillis(), getTimeToSendMillis()) + 1);
         try {
             synchronized (mCond) {
                 mCond.wait();

cmds/uinput/src/com/android/commands/uinput/EvemuParser.java

@@ -44,7 +44,7 @@ public class EvemuParser implements EventParser {
      * recordings, this will always be the same.
      */
     private static final int DEVICE_ID = 1;
-    private static final int REGISTRATION_DELAY_MILLIS = 500;
+    private static final int REGISTRATION_DELAY_NANOS = 500_000_000;
 
     private static class CommentAwareReader {
         private final LineNumberReader mReader;
@@ -152,7 +152,7 @@ public EvemuParser(Reader in) throws IOException {
         final Event.Builder delayEb = new Event.Builder();
         delayEb.setId(DEVICE_ID);
         delayEb.setCommand(Event.Command.DELAY);
-        delayEb.setDurationMillis(REGISTRATION_DELAY_MILLIS);
+        delayEb.setDurationNanos(REGISTRATION_DELAY_NANOS);
         mQueuedEvents.add(delayEb.build());
     }
 
@@ -204,7 +204,7 @@ public Event getNextEvent() throws IOException {
                 final Event.Builder delayEb = new Event.Builder();
                 delayEb.setId(DEVICE_ID);
                 delayEb.setCommand(Event.Command.DELAY);
-                delayEb.setDurationMillis((int) (delayMicros / 1000));
+                delayEb.setDurationNanos(delayMicros * 1000);
                 return delayEb.build();
             }
         }

cmds/uinput/src/com/android/commands/uinput/Event.java

@@ -100,7 +100,7 @@ public int getValue() {
     private int mBusId;
     private int[] mInjections;
     private SparseArray<int[]> mConfiguration;
-    private int mDurationMillis;
+    private long mDurationNanos;
     private int mFfEffectsMax = 0;
     private String mInputPort;
     private SparseArray<InputAbsInfo> mAbsInfo;
@@ -150,8 +150,8 @@ public SparseArray<int[]> getConfiguration() {
         return mConfiguration;
     }
 
-    public int getDurationMillis() {
-        return mDurationMillis;
+    public long getDurationNanos() {
+        return mDurationNanos;
     }
 
     public int getFfEffectsMax() {
@@ -182,7 +182,7 @@ public String toString() {
             + ", busId=" + mBusId
             + ", events=" + Arrays.toString(mInjections)
             + ", configuration=" + mConfiguration
-            + ", duration=" + mDurationMillis + "ms"
+            + ", duration=" + mDurationNanos + "ns"
             + ", ff_effects_max=" + mFfEffectsMax
             + ", port=" + mInputPort
             + "}";
@@ -237,8 +237,8 @@ public void setBusId(int busId) {
             mEvent.mBusId = busId;
         }
 
-        public void setDurationMillis(int durationMillis) {
-            mEvent.mDurationMillis = durationMillis;
+        public void setDurationNanos(long durationNanos) {
+            mEvent.mDurationNanos = durationNanos;
         }
 
         public void setFfEffectsMax(int ffEffectsMax) {
@@ -271,7 +271,7 @@ public Event build() {
                     }
                 }
                 case DELAY -> {
-                    if (mEvent.mDurationMillis <= 0) {
+                    if (mEvent.mDurationNanos <= 0) {
                         throw new IllegalStateException("Delay has missing or invalid duration");
                     }
                 }

cmds/uinput/src/com/android/commands/uinput/JsonStyleParser.java

@@ -71,7 +71,8 @@ public Event getNextEvent() throws IOException {
                         case "configuration" -> eb.setConfiguration(readConfiguration());
                         case "ff_effects_max" -> eb.setFfEffectsMax(readInt());
                         case "abs_info" -> eb.setAbsInfo(readAbsInfoArray());
-                        case "duration" -> eb.setDurationMillis(readInt());
+                        // Duration is specified in milliseconds in the JSON-style format.
+                        case "duration" -> eb.setDurationNanos(readInt() * 1_000_000L);
                         case "port" -> eb.setInputPort(mReader.nextString());
                         case "syncToken" -> eb.setSyncToken(mReader.nextString());
                         default -> mReader.skipValue();

cmds/uinput/src/com/android/commands/uinput/Uinput.java

@@ -135,7 +135,7 @@ private void process(Event e) {
             case REGISTER ->
                     error("Device id=" + e.getId() + " is already registered. Ignoring event.");
             case INJECT -> d.injectEvent(e.getInjections());
-            case DELAY -> d.addDelay(e.getDurationMillis());
+            case DELAY -> d.addDelayNanos(e.getDurationNanos());
             case SYNC -> d.syncEvent(e.getSyncToken());
         }
     }

cmds/uinput/tests/src/com/android/commands/uinput/tests/EvemuParserTest.java

@@ -189,10 +189,10 @@ private void assertInjectEvent(Event event, int eventType, int eventCode, int va
                 .containsExactly(eventType, eventCode, value).inOrder();
     }
 
-    private void assertDelayEvent(Event event, int durationMillis) {
+    private void assertDelayEvent(Event event, int durationMicros) {
         assertThat(event).isNotNull();
         assertThat(event.getCommand()).isEqualTo(Event.Command.DELAY);
-        assertThat(event.getDurationMillis()).isEqualTo(durationMillis);
+        assertThat(event.getDurationMicros()).isEqualTo(durationMicros);
     }
 
     @Test
@@ -231,12 +231,12 @@ public void testEventParsing_MultipleFrames() throws IOException {
         assertInjectEvent(parser.getNextEvent(), 0x1, 0x15, 1);
         assertInjectEvent(parser.getNextEvent(), 0x0, 0x0, 0);
 
-        assertDelayEvent(parser.getNextEvent(), 10);
+        assertDelayEvent(parser.getNextEvent(), 10000);
 
         assertInjectEvent(parser.getNextEvent(), 0x1, 0x15, 0);
         assertInjectEvent(parser.getNextEvent(), 0x0, 0x0, 0);
 
-        assertDelayEvent(parser.getNextEvent(), 1000);
+        assertDelayEvent(parser.getNextEvent(), 1000000);
 
         assertInjectEvent(parser.getNextEvent(), 0x1, 0x15, 1);
         assertInjectEvent(parser.getNextEvent(), 0x0, 0x0, 0);
@@ -490,7 +490,7 @@ public void testFreeDesktopEvemuRecording() throws IOException {
         assertInjectEvent(parser.getNextEvent(), 0x3, 0x18, 56);
         assertInjectEvent(parser.getNextEvent(), 0x0, 0x0, 0);
 
-        assertDelayEvent(parser.getNextEvent(), 6);
+        assertDelayEvent(parser.getNextEvent(), 6080);
 
         assertInjectEvent(parser.getNextEvent(), 0x3, 0x0035, 888);
     }