Input dispatcher ANR handling enhancements.

This change is essentially a rewrite of the main input dispatcher loop
with the target identification folded in.  Since the input dispatcher now
has all of the window state, it can make better decisions about
when to ANR.

Added a .5 second deadline for processing app switch keys.  This behavior
predates Gingerbread but had not previously been ported.

Fixed some timing inaccuracies in the ANR accounting that could cause
applications to ANR sooner than they should have.

Added a mechanism for tracking key and motion events that have been
dispatched to a window so that appropriate cancelation events can be
synthesized when recovering from ANR.  This change helps to keep
applications in sync so they don't end up with stuck buttons upon
recovery from ANRs.

Added more comments to describe the tricky parts of PollLoop.

Change-Id: I13dffca27acb436fc383980db536abc4d8b9e6f1

1 files changed, 7 insertions, 1 deletions

diff --git a/libs/utils/PollLoop.cpp b/libs/utils/PollLoop.cpp
index 6d3eeee..fe76cd0 100644
--- a/libs/utils/PollLoop.cpp
+++ b/libs/utils/PollLoop.cpp
@@ -119,7 +119,8 @@ int32_t PollLoop::pollOnce(int timeoutMillis, int* outEvents, void** outData) {
         if (outData != NULL) *outData = pending.data;
         return pending.ident;
     }
-    
+
+    // Wait for wakeAndLock() waiters to run then set mPolling to true.
     mLock.lock();
     while (mWaiters != 0) {
         mResume.wait(mLock);
@@ -127,6 +128,7 @@ int32_t PollLoop::pollOnce(int timeoutMillis, int* outEvents, void** outData) {
     mPolling = true;
     mLock.unlock();
 
+    // Poll.
     int32_t result;
     size_t requestedCount = mRequestedFds.size();
 
@@ -168,6 +170,7 @@ int32_t PollLoop::pollOnce(int timeoutMillis, int* outEvents, void** outData) {
     }
 #endif
 
+    // Process the poll results.
     mPendingCallbacks.clear();
     mPendingFds.clear();
     mPendingFdsPos = 0;
@@ -218,6 +221,7 @@ int32_t PollLoop::pollOnce(int timeoutMillis, int* outEvents, void** outData) {
     }
 
 Done:
+    // Set mPolling to false and wake up the wakeAndLock() waiters.
     mLock.lock();
     mPolling = false;
     if (mWaiters != 0) {
@@ -357,11 +361,13 @@ ssize_t PollLoop::getRequestIndexLocked(int fd) {
 
 void PollLoop::wakeAndLock() {
     mLock.lock();
+
     mWaiters += 1;
     while (mPolling) {
         wake();
         mAwake.wait(mLock);
     }
+
     mWaiters -= 1;
     if (mWaiters == 0) {
         mResume.signal();