Merge "Avoid ANRs in dumpCacheInfo" into tm-dev am: 8dc0bab75e am: 50ee494d30

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/18717283

Change-Id: I6b68521b6692ff796e47f3cd2a394307a113ef1e
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

core/java/android/app/PropertyInvalidatedCache.java

@@ -33,6 +33,7 @@ import com.android.internal.util.FastPrintWriter;
 
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
+import java.io.ByteArrayOutputStream;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.PrintWriter;
@@ -1444,7 +1445,6 @@ public class PropertyInvalidatedCache<Query, Result> {
                     mCache.size(), mMaxEntries, mHighWaterMark, mMissOverflow));
             pw.println(TextUtils.formatSimple("    Enabled: %s", mDisabled ? "false" : "true"));
             pw.println("");
-            pw.flush();
 
             // No specific cache was requested.  This is the default, and no details
             // should be dumped.
@@ -1463,7 +1463,6 @@ public class PropertyInvalidatedCache<Query, Result> {
 
                 pw.println(TextUtils.formatSimple("      Key: %s\n      Value: %s\n", key, value));
             }
-            pw.flush();
         }
     }
 
@@ -1488,13 +1487,8 @@ public class PropertyInvalidatedCache<Query, Result> {
      * provided ParcelFileDescriptor.  Optional switches allow the caller to choose
      * specific caches (selection is by cache name or property name); if these switches
      * are used then the output includes both cache statistics and cache entries.
-     * @hide
      */
-    public static void dumpCacheInfo(@NonNull ParcelFileDescriptor pfd, @NonNull String[] args) {
+    private static void dumpCacheInfo(@NonNull PrintWriter pw, @NonNull String[] args) {
-        try  (
-            FileOutputStream fout = new FileOutputStream(pfd.getFileDescriptor());
-            PrintWriter pw = new FastPrintWriter(fout);
-        ) {
         if (!sEnabled) {
             pw.println("  Caching is disabled in this process.");
             return;
@@ -1516,6 +1510,31 @@ public class PropertyInvalidatedCache<Query, Result> {
             PropertyInvalidatedCache currentCache = activeCaches.get(i);
             currentCache.dumpContents(pw, detail, args);
         }
+    }
+
+    /**
+     * Without arguments, this dumps statistics from every cache in the process to the
+     * provided ParcelFileDescriptor.  Optional switches allow the caller to choose
+     * specific caches (selection is by cache name or property name); if these switches
+     * are used then the output includes both cache statistics and cache entries.
+     * @hide
+     */
+    public static void dumpCacheInfo(@NonNull ParcelFileDescriptor pfd, @NonNull String[] args) {
+        // Create a PrintWriter that uses a byte array.  The code can safely write to
+        // this array without fear of blocking.  The completed byte array will be sent
+        // to the caller after all the data has been collected and all locks have been
+        // released.
+        ByteArrayOutputStream barray = new ByteArrayOutputStream();
+        PrintWriter bout = new PrintWriter(barray);
+        dumpCacheInfo(bout, args);
+        bout.close();
+
+        try {
+            // Send the final byte array to the output.  This happens outside of all locks.
+            var out = new FileOutputStream(pfd.getFileDescriptor());
+            barray.writeTo(out);
+            out.close();
+            barray.close();
         } catch (IOException e) {
             Log.e(TAG, "Failed to dump PropertyInvalidatedCache instances");
         }