commit 791e466ea0b4283b53cf41ef9dfa37118b345df4
author Steven Moreland <smoreland@google.com> Mon Sep 13 15:22:58 2021 -0700
committer Steven Moreland <smoreland@google.com> Mon Sep 13 15:31:33 2021 -0700
tree 0229c4afdf8da8b1609237a5abe0808f0f9d03b3
parent 5623d1a7fac2fca2d8cd51af65a764aadd31bc43

libbinder: shutdownAndWait based on # of in conns

shutdownAndWait no longer waits when it is called on a zero-thread
session (the session only needs to be deleted). However, more
importantly, we save a small amount of memory, and the log here is much
better (we can see how many incoming threads are stuck).

Bug: N/A
Test: binderRpcTest
Change-Id: I5924a82c33b4c3c2c970e6c6e86f1b8e2af074f5

libs/binder/RpcSession.cpp

diff --git a/libs/binder/RpcSession.cpp b/libs/binder/RpcSession.cpp
index ffa1255..e8f984c 100644
--- a/libs/binder/RpcSession.cpp
+++ b/libs/binder/RpcSession.cpp
@@ -202,7 +202,7 @@
 
     if (wait) {
         LOG_ALWAYS_FATAL_IF(mShutdownListener == nullptr, "Shutdown listener not installed");
-        mShutdownListener->waitForShutdown(_l);
+        mShutdownListener->waitForShutdown(_l, sp<RpcSession>::fromExisting(this));
 
         LOG_ALWAYS_FATAL_IF(!mThreads.empty(), "Shutdown failed");
     }
@@ -256,17 +256,19 @@
 void RpcSession::WaitForShutdownListener::onSessionAllIncomingThreadsEnded(
         const sp<RpcSession>& session) {
     (void)session;
-    mShutdown = true;
 }
 
 void RpcSession::WaitForShutdownListener::onSessionIncomingThreadEnded() {
     mCv.notify_all();
 }
 
-void RpcSession::WaitForShutdownListener::waitForShutdown(std::unique_lock<std::mutex>& lock) {
-    while (!mShutdown) {
+void RpcSession::WaitForShutdownListener::waitForShutdown(std::unique_lock<std::mutex>& lock,
+                                                          const sp<RpcSession>& session) {
+    while (session->mIncomingConnections.size() > 0) {
         if (std::cv_status::timeout == mCv.wait_for(lock, std::chrono::seconds(1))) {
-            ALOGE("Waiting for RpcSession to shut down (1s w/o progress).");
+            ALOGE("Waiting for RpcSession to shut down (1s w/o progress): %zu incoming connections "
+                  "still.",
+                  session->mIncomingConnections.size());
         }
     }
 }

libs/binder/include/binder/RpcSession.h

diff --git a/libs/binder/include/binder/RpcSession.h b/libs/binder/include/binder/RpcSession.h
index 24df0e8..9c7c970 100644
--- a/libs/binder/include/binder/RpcSession.h
+++ b/libs/binder/include/binder/RpcSession.h
@@ -182,12 +182,12 @@
     public:
         void onSessionAllIncomingThreadsEnded(const sp<RpcSession>& session) override;
         void onSessionIncomingThreadEnded() override;
-        void waitForShutdown(std::unique_lock<std::mutex>& lock);
+        void waitForShutdown(std::unique_lock<std::mutex>& lock, const sp<RpcSession>& session);
 
     private:
         std::condition_variable mCv;
-        volatile bool mShutdown = false;
     };
+    friend WaitForShutdownListener;
 
     struct RpcConnection : public RefBase {
         std::unique_ptr<RpcTransport> rpcTransport;