app: harden mirroring lifecycle and state

1 files changed, 94 insertions, 0 deletions

diff --git a/app/src/main/java/invalid/lena/scrcpy/VideoQueue.java b/app/src/main/java/invalid/lena/scrcpy/VideoQueue.java
new file mode 100644
index 0000000..a3c308f
--- /dev/null
+++ b/app/src/main/java/invalid/lena/scrcpy/VideoQueue.java
@@ -0,0 +1,94 @@
+package invalid.lena.scrcpy;
+
+import java.util.ArrayDeque;
+import java.util.Deque;
+import java.util.Iterator;
+
+// Bounded encoded-video queue. It never leaves delta frames queued without
+// the keyframe that starts their decoder generation.
+final class VideoQueue {
+
+    static final class Frame {
+        final byte[] data;
+        final long ptsUs;
+        final boolean config;
+        final boolean keyframe;
+
+        Frame(byte[] data, long ptsUs, boolean config, boolean keyframe) {
+            this.data = data;
+            this.ptsUs = ptsUs;
+            this.config = config;
+            this.keyframe = keyframe;
+        }
+    }
+
+    private final int maxFrames;
+    private final int maxBytes;
+    private final Deque<Frame> frames;
+    private int bytes;
+    private boolean needsKeyframe = true;
+
+    VideoQueue(int maxFrames, int maxBytes) {
+        if (maxFrames < 1 || maxBytes < 1) throw new IllegalArgumentException();
+        this.maxFrames = maxFrames;
+        this.maxBytes = maxBytes;
+        frames = new ArrayDeque<>(maxFrames);
+    }
+
+    boolean offer(Frame frame) {
+        if (frame.config) {
+            clear();
+            return append(frame);
+        }
+        if (frame.keyframe) {
+            removeMediaFrames();
+            needsKeyframe = false;
+            if (append(frame)) return true;
+            needsKeyframe = true;
+            return false;
+        }
+        if (needsKeyframe) return false;
+        if (append(frame)) return true;
+        needsKeyframe = true;
+        return false;
+    }
+
+    Frame poll() {
+        Frame frame = frames.pollFirst();
+        if (frame != null) bytes -= frame.data.length;
+        return frame;
+    }
+
+    boolean isEmpty() {
+        return frames.isEmpty();
+    }
+
+    boolean needsKeyframe() {
+        return needsKeyframe;
+    }
+
+    void clear() {
+        frames.clear();
+        bytes = 0;
+        needsKeyframe = true;
+    }
+
+    private boolean append(Frame frame) {
+        if (frames.size() >= maxFrames || frame.data.length > maxBytes - bytes) {
+            return false;
+        }
+        frames.offerLast(frame);
+        bytes += frame.data.length;
+        return true;
+    }
+
+    private void removeMediaFrames() {
+        for (Iterator<Frame> it = frames.iterator(); it.hasNext(); ) {
+            Frame frame = it.next();
+            if (!frame.config) {
+                it.remove();
+                bytes -= frame.data.length;
+            }
+        }
+    }
+}