TrackRecord: add a method to return callbacks since last poll
This change adds a backtrace() method which returns a list of events
that were received since the last time a user called poll() on a
ReadHead. This is particularly useful for logging observed events while
a poll was in progress that did not end up matching an event.
Test: atest EthernetManagerTest
Change-Id: If019cf9eb5e3e9268c5e6b74edbd8f49959cc71c
diff --git a/staticlibs/testutils/hostdevice/com/android/net/module/util/TrackRecord.kt b/staticlibs/testutils/hostdevice/com/android/net/module/util/TrackRecord.kt
index efd77d1..f24e4f1 100644
--- a/staticlibs/testutils/hostdevice/com/android/net/module/util/TrackRecord.kt
+++ b/staticlibs/testutils/hostdevice/com/android/net/module/util/TrackRecord.kt
@@ -213,6 +213,9 @@
private val slock = StampedLock()
private var readHead = 0
+ // A special mark used to track the start of the last poll() operation.
+ private var pollMark = 0
+
/**
* @return the current value of the mark.
*/
@@ -223,6 +226,7 @@
val stamp = slock.tryWriteLock()
if (0L == stamp) concurrentAccessDetected()
readHead = v
+ pollMark = v
slock.unlockWrite(stamp)
}
@@ -261,6 +265,7 @@
fun poll(timeoutMs: Long, predicate: (E) -> Boolean = { true }): E? {
val stamp = slock.tryWriteLock()
if (0L == stamp) concurrentAccessDetected()
+ pollMark = readHead
try {
lock.withLock {
val index = pollForIndexReadLocked(timeoutMs, readHead, predicate)
@@ -273,6 +278,25 @@
}
/**
+ * Returns a list of events that were observed since the last time poll() was called on this
+ * ReadHead.
+ *
+ * @return list of events since poll() was called.
+ */
+ fun backtrace(): List<E> {
+ val stamp = slock.tryReadLock()
+ if (0L == stamp) concurrentAccessDetected()
+
+ try {
+ lock.withLock {
+ return ArrayList(subList(pollMark, mark))
+ }
+ } finally {
+ slock.unlockRead(stamp)
+ }
+ }
+
+ /**
* Returns the first element after the mark or null. This never blocks.
*
* This method is subject to threading restrictions. It can be used concurrently on