Prevent disposed callbacks from throwing exceptions on GC

While it is considered an error to never reply to or cancel a command,
as this indicates a programming logic error, a case that shouldn't
count is when commands were interrupted by an inspector shutting
down.

The only way we could detect that a command was never replied to was by
throwing an exception at GC time. However, what was happening was you
could start an inspector, stop it, then restart it, repeat a couple
times, and eventually a command callback would be GC'ed that had been
interrupted by a previous run. This would throw an exception, killing
the current inspection session.

We now handle disposal explicitly.

Fixes: 186459719
Test: This is not trivial to test. Manually ran a case in layout
  inspector that used to repro fairly consistently but is not
  anymore.
Change-Id: I1c6faad79659a7dbafc8a63e0a5c416016a3d6fe

1 files changed, 15 insertions, 1 deletions

diff --git a/app-inspection/agent/src/main/java/com/android/tools/agent/app/inspection/InspectorContext.java b/app-inspection/agent/src/main/java/com/android/tools/agent/app/inspection/InspectorContext.java
index 3661c4dc38..c81599bcfe 100644
--- a/app-inspection/agent/src/main/java/com/android/tools/agent/app/inspection/InspectorContext.java
+++ b/app-inspection/agent/src/main/java/com/android/tools/agent/app/inspection/InspectorContext.java
@@ -174,6 +174,12 @@ final class InspectorContext {
             mInspector.onDispose();
         } catch (Throwable ignored) {
         }
+        for (WeakReference<CommandCallbackImpl> reference : mIdToCommandCallback.values()) {
+            CommandCallbackImpl callback = reference.get();
+            if (callback != null) {
+                callback.dispose();
+            }
+        }
     }
 
     public interface CrashListener {
@@ -183,7 +189,8 @@ final class InspectorContext {
     enum Status {
         PENDING,
         REPLIED,
-        CANCELLED
+        CANCELLED,
+        DISPOSED,
     }
 
     class CommandCallbackImpl implements Inspector.CommandCallback {
@@ -241,6 +248,13 @@ final class InspectorContext {
             }
         }
 
+        void dispose() {
+            synchronized (mLock) {
+                mStatus = Status.DISPOSED;
+                mIdToCommandCallback.remove(mCommandId);
+            }
+        }
+
         @Override
         protected void finalize() {
             if (mStatus == Status.PENDING) {