Dump top binder proxy interface names in dumpsys.

To facilitate real-time debugging.

Bug: 109888955
Test: builds, adb shell dumpsys activity binder-proxies shows output
Merged-In: Iffcbbb824f4050b6fb8f556c8b4d09115e53da18
Change-Id: Iffcbbb824f4050b6fb8f556c8b4d09115e53da18

2 files changed, 76 insertions, 17 deletions

diff --git a/core/java/android/os/BinderProxy.java b/core/java/android/os/BinderProxy.java
index e492f88d4329..fd43adff5587 100644
--- a/core/java/android/os/BinderProxy.java
+++ b/core/java/android/os/BinderProxy.java
@@ -225,10 +225,11 @@ public final class BinderProxy implements IBinder {
             }
         }
 
-        /**
-         * Dump a histogram to the logcat. Used to diagnose abnormally large proxy maps.
-         */
-        private void dumpProxyInterfaceCounts() {
+        private InterfaceCount[] getSortedInterfaceCounts(int maxToReturn) {
+            if (maxToReturn < 0) {
+                throw new IllegalArgumentException("negative interface count");
+            }
+
             Map<String, Integer> counts = new HashMap<>();
             for (ArrayList<WeakReference<BinderProxy>> a : mMainIndexValues) {
                 if (a != null) {
@@ -258,13 +259,30 @@ public final class BinderProxy implements IBinder {
             }
             Map.Entry<String, Integer>[] sorted = counts.entrySet().toArray(
                     new Map.Entry[counts.size()]);
+
             Arrays.sort(sorted, (Map.Entry<String, Integer> a, Map.Entry<String, Integer> b)
                     -> b.getValue().compareTo(a.getValue()));
-            Log.v(Binder.TAG, "BinderProxy descriptor histogram (top ten):");
-            int printLength = Math.min(10, sorted.length);
-            for (int i = 0; i < printLength; i++) {
-                Log.v(Binder.TAG, " #" + (i + 1) + ": " + sorted[i].getKey() + " x"
-                        + sorted[i].getValue());
+
+            int returnCount = Math.min(maxToReturn, sorted.length);
+            InterfaceCount[] ifaceCounts = new InterfaceCount[returnCount];
+            for (int i = 0; i < returnCount; i++) {
+                ifaceCounts[i] = new InterfaceCount(sorted[i].getKey(), sorted[i].getValue());
+            }
+            return ifaceCounts;
+        }
+
+        static final int MAX_NUM_INTERFACES_TO_DUMP = 10;
+
+        /**
+         * Dump a histogram to the logcat. Used to diagnose abnormally large proxy maps.
+         */
+        private void dumpProxyInterfaceCounts() {
+            final InterfaceCount[] sorted = getSortedInterfaceCounts(MAX_NUM_INTERFACES_TO_DUMP);
+
+            Log.v(Binder.TAG, "BinderProxy descriptor histogram "
+                    + "(top " + Integer.toString(MAX_NUM_INTERFACES_TO_DUMP) + "):");
+            for (int i = 0; i < sorted.length; i++) {
+                Log.v(Binder.TAG, " #" + (i + 1) + ": " + sorted[i]);
             }
         }
 
@@ -299,13 +317,42 @@ public final class BinderProxy implements IBinder {
     private static ProxyMap sProxyMap = new ProxyMap();
 
     /**
-      * Dump proxy debug information.
-      *
-      * Note: this method is not thread-safe; callers must serialize with other
-      * accesses to sProxyMap, in particular {@link #getInstance(long, long)}.
-      *
-      * @hide
-      */
+     * Simple pair-value class to store number of binder proxy interfaces live in this process.
+     */
+    public static final class InterfaceCount {
+        private final String mInterfaceName;
+        private final int mCount;
+
+        InterfaceCount(String interfaceName, int count) {
+            mInterfaceName = interfaceName;
+            mCount = count;
+        }
+
+        @Override
+        public String toString() {
+            return mInterfaceName + " x" + Integer.toString(mCount);
+        }
+    }
+
+    /**
+     * Get a sorted array with entries mapping proxy interface names to the number
+     * of live proxies with those names.
+     *
+     * @param num maximum number of proxy interface counts to return. Use
+     *            Integer.MAX_VALUE to retrieve all
+     * @hide
+     */
+    public static InterfaceCount[] getSortedInterfaceCounts(int num) {
+        synchronized (sProxyMap) {
+            return sProxyMap.getSortedInterfaceCounts(num);
+        }
+    }
+
+    /**
+     * Dump proxy debug information.
+     *
+     * @hide
+     */
     private static void dumpProxyDebugInfo() {
         if (Build.IS_DEBUGGABLE) {
             sProxyMap.dumpProxyInterfaceCounts();
diff --git a/services/core/java/com/android/server/am/ActivityManagerService.java b/services/core/java/com/android/server/am/ActivityManagerService.java
index 7aadcd400f0e..e35855a9a21b 100644
--- a/services/core/java/com/android/server/am/ActivityManagerService.java
+++ b/services/core/java/com/android/server/am/ActivityManagerService.java
@@ -318,6 +318,7 @@ import android.net.ProxyInfo;
 import android.net.Uri;
 import android.os.BatteryStats;
 import android.os.Binder;
+import android.os.BinderProxy;
 import android.os.Build;
 import android.os.Bundle;
 import android.os.Debug;
@@ -16061,8 +16062,10 @@ public class ActivityManagerService extends IActivityManager.Stub
                 }
             } else if ("binder-proxies".equals(cmd)) {
                 if (opti >= args.length) {
+                    dumpBinderProxyInterfaceCounts(pw,
+                            "Top proxy interface names held by SYSTEM");
                     dumpBinderProxiesCounts(pw, BinderInternal.nGetBinderProxyPerUidCounts(),
-                            "Counts of Binder Proxies held by SYSTEM");
+                            "Number of proxies per uid held by SYSTEM");
                 } else {
                     String uid = args[opti];
                     opti++;
@@ -16565,6 +16568,15 @@ public class ActivityManagerService extends IActivityManager.Stub
         return printed;
     }
 
+    void dumpBinderProxyInterfaceCounts(PrintWriter pw, String header) {
+        final BinderProxy.InterfaceCount[] proxyCounts = BinderProxy.getSortedInterfaceCounts(50);
+
+        pw.println(header);
+        for (int i = 0; i < proxyCounts.length; i++) {
+            pw.println("    #" + (i + 1) + ": " + proxyCounts[i]);
+        }
+    }
+
     boolean dumpBinderProxiesCounts(PrintWriter pw, SparseIntArray counts, String header) {
         if(counts != null) {
             pw.println(header);