Android/frameworks_base
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

DO NOT MERGE: ViewRootImpl: Add P2P sync primitive

Browse Source 
Expose consumeNextDraw from ViewRootImpl to enable
one-off sync between two ViewRoots.

Bug: 201046726
Test: Existing tests pass
Change-Id: Iaf30830dc529eac83276a76d1908a06d12175b00
This commit is contained in:
Robert Carr
2021-10-13 13:09:34 -07:00
committed by Rob Carr
parent 6ebf85244c
commit e5d1324755
1 changed files with 42 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

42
core/java/android/view/ViewRootImpl.java
View File

@@ -208,6 +208,7 @@ import java.io.PrintWriter;
import java.io.StringWriter;
import java.lang.ref.WeakReference;
import java.util.ArrayList;
import java.util.function.Consumer;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
@@ -757,6 +758,8 @@ public final class ViewRootImpl implements ViewParent,
*/
private boolean mNextDrawUseBlastSync = false;
private Consumer<SurfaceControl.Transaction> mBLASTDrawConsumer;
/**
* Wait for the blast sync transaction complete callback before drawing and queuing up more
* frames. This will prevent out of order buffers submissions when WM has requested to
@@ -3351,6 +3354,9 @@ public final class ViewRootImpl implements ViewParent,
}
boolean cancelDraw = mAttachInfo.mTreeObserver.dispatchOnPreDraw() || !isViewVisible;
if (mBLASTDrawConsumer != null) {
mNextDrawUseBlastSync = true;
}
if (!cancelDraw) {
if (mPendingTransitions != null && mPendingTransitions.size() > 0) {
@@ -4049,6 +4055,8 @@ public final class ViewRootImpl implements ViewParent,
*/
private HardwareRenderer.FrameCompleteCallback createFrameCompleteCallback(Handler handler,
boolean reportNextDraw, ArrayList<Runnable> commitCallbacks) {
final Consumer<SurfaceControl.Transaction> blastSyncConsumer = mBLASTDrawConsumer;
mBLASTDrawConsumer = null;
return frameNr -> {
if (DEBUG_BLAST) {
Log.d(mTag, "Received frameCompleteCallback frameNum=" + frameNr);
@@ -4061,6 +4069,9 @@ public final class ViewRootImpl implements ViewParent,
// is only true when the UI thread is paused. Therefore, no one should be
// modifying this object until the next vsync.
mSurfaceChangedTransaction.merge(mRtBLASTSyncTransaction);
if (blastSyncConsumer != null) {
blastSyncConsumer.accept(mSurfaceChangedTransaction);
}
}
if (reportNextDraw) {
@@ -10548,4 +10559,35 @@ public final class ViewRootImpl implements ViewParent,
listener.onBufferTransformHintChanged(hint);
}
}
/**
* Redirect the next draw of this ViewRoot (from the UI thread perspective)
* to the passed in consumer. This can be used to create P2P synchronization
* between ViewRoot's however it comes with many caveats.
*
* 1. You MUST consume the transaction, by either applying it immediately or
* merging it in to another transaction. The threading model doesn't
* allow you to hold in the passed transaction.
* 2. If you merge it in to another transaction, this ViewRootImpl will be
* paused until you finally apply that transaction and it receives
* the callback from SF. If you lose track of the transaction you will
* ANR the app.
* 3. Only one person can consume the transaction at a time, if you already
* have a pending consumer for this frame, the function will return false
* 4. Someone else may have requested to consume the next frame, in which case
* this function will return false and you will not receive a callback.
* 5. This function does not trigger drawing so even if it returns true you
* may not receive a callback unless there is some other UI thread work
* to trigger drawing. If it returns true, and a draw occurs, the callback
* will be called (Though again watch out for the null transaction case!)
* 6. This function must be called on the UI thread. The consumer will likewise
* be called on the UI thread.
*/
public boolean consumeNextDraw(Consumer<SurfaceControl.Transaction> consume) {
if (mBLASTDrawConsumer != null) {
return false;
}
mBLASTDrawConsumer = consume;
return true;
}
}