Add new Looper API to check whether the looper is idle.
This is just to support the watchdog to give it a faster
way to determine if a thread is deadlocked without having
to post a message to it.
Change-Id: I068dc8b9387caf94fe5811fb4aeb0f9b57b1a080
diff --git a/include/utils/Looper.h b/include/utils/Looper.h
index d4a0067..2e0651a 100644
--- a/include/utils/Looper.h
+++ b/include/utils/Looper.h
@@ -297,6 +297,13 @@
void removeMessages(const sp<MessageHandler>& handler, int what);
/**
+ * Return whether this looper's thread is currently idling -- that is, whether it
+ * stopped waiting for more work to do. Note that this is intrinsically racy, since
+ * its state can change before you get the result back.
+ */
+ bool isIdling() const;
+
+ /**
* Prepares a looper associated with the calling thread, and returns it.
* If the thread already has a looper, it is returned. Otherwise, a new
* one is created, associated with the thread, and returned.
@@ -353,6 +360,10 @@
Vector<MessageEnvelope> mMessageEnvelopes; // guarded by mLock
bool mSendingMessage; // guarded by mLock
+ // Whether we are currently waiting for work. Not protected by a lock,
+ // any use of it is racy anyway.
+ volatile bool mIdling;
+
int mEpollFd; // immutable
// Locked list of file descriptor monitoring requests.
diff --git a/libs/utils/Looper.cpp b/libs/utils/Looper.cpp
index a5e6645..c51df2d 100644
--- a/libs/utils/Looper.cpp
+++ b/libs/utils/Looper.cpp
@@ -84,6 +84,8 @@
LOG_ALWAYS_FATAL_IF(result != 0, "Could not make wake write pipe non-blocking. errno=%d",
errno);
+ mIdling = false;
+
// Allocate the epoll instance and register the wake pipe.
mEpollFd = epoll_create(EPOLL_SIZE_HINT);
LOG_ALWAYS_FATAL_IF(mEpollFd < 0, "Could not create epoll instance. errno=%d", errno);
@@ -214,9 +216,15 @@
mResponses.clear();
mResponseIndex = 0;
+ // We are about to idle.
+ mIdling = true;
+
struct epoll_event eventItems[EPOLL_MAX_EVENTS];
int eventCount = epoll_wait(mEpollFd, eventItems, EPOLL_MAX_EVENTS, timeoutMillis);
+ // No longer idling.
+ mIdling = false;
+
// Acquire lock.
mLock.lock();
@@ -558,4 +566,8 @@
} // release lock
}
+bool Looper::isIdling() const {
+ return mIdling;
+}
+
} // namespace android