Camera2: Support early finished tasks
Add support to track finished tasks before it starts.
Bug: 30117138
Change-Id: I42eb0377f719d57d820d9c1b2484600116c8807a
diff --git a/core/java/android/hardware/camera2/utils/TaskDrainer.java b/core/java/android/hardware/camera2/utils/TaskDrainer.java
index 7c46e50..ed30ff3 100644
--- a/core/java/android/hardware/camera2/utils/TaskDrainer.java
+++ b/core/java/android/hardware/camera2/utils/TaskDrainer.java
@@ -29,8 +29,9 @@
* (and new ones won't begin).
*
* <p>The initial state is to allow all tasks to be started and finished. A task may only be started
- * once, after which it must be finished before starting again. Likewise, finishing a task
- * that hasn't been started is also not allowed.</p>
+ * once, after which it must be finished before starting again. Likewise, a task may only be
+ * finished once, after which it must be started before finishing again. It is okay to finish a
+ * task before starting it due to different threads handling starting and finishing.</p>
*
* <p>When draining begins, no more new tasks can be started. This guarantees that at some
* point when all the tasks are finished there will be no more collective new tasks,
@@ -60,6 +61,11 @@
/** Set of tasks which have been started but not yet finished with #taskFinished */
private final Set<T> mTaskSet = new HashSet<T>();
+ /**
+ * Set of tasks which have been finished but not yet started with #taskStarted. This may happen
+ * if taskStarted and taskFinished are called from two different threads.
+ */
+ private final Set<T> mEarlyFinishedTaskSet = new HashSet<T>();
private final Object mLock = new Object();
private boolean mDraining = false;
@@ -118,8 +124,12 @@
throw new IllegalStateException("Can't start more tasks after draining has begun");
}
- if (!mTaskSet.add(task)) {
- throw new IllegalStateException("Task " + task + " was already started");
+ // Try to remove the task from the early finished set.
+ if (!mEarlyFinishedTaskSet.remove(task)) {
+ // The task is not finished early. Add it to the started set.
+ if (!mTaskSet.add(task)) {
+ throw new IllegalStateException("Task " + task + " was already started");
+ }
}
}
}
@@ -128,8 +138,7 @@
/**
* Mark an asynchronous task as having finished.
*
- * <p>A task cannot be finished if it hasn't started. Once finished, a task
- * cannot be finished again (unless it's started again).</p>
+ * <p>A task cannot be finished more than once without first having started.</p>
*
* @param task a key to identify a task
*
@@ -137,7 +146,7 @@
* @see #beginDrain
*
* @throws IllegalStateException
- * If attempting to start a task which is already finished (and not re-started),
+ * If attempting to finish a task which is already finished (and not started),
*/
public void taskFinished(T task) {
synchronized (mLock) {
@@ -145,8 +154,12 @@
Log.v(TAG + "[" + mName + "]", "taskFinished " + task);
}
+ // Try to remove the task from started set.
if (!mTaskSet.remove(task)) {
- throw new IllegalStateException("Task " + task + " was already finished");
+ // Task is not started yet. Add it to the early finished set.
+ if (!mEarlyFinishedTaskSet.add(task)) {
+ throw new IllegalStateException("Task " + task + " was already finished");
+ }
}
// If this is the last finished task and draining has already begun, fire #onDrained
