From 06a3e2ca4d5ef65b894ab9b21e92953fa465014c Mon Sep 17 00:00:00 2001
From: Marco Ballesio <balejs@google.com>
Date: Mon, 9 Mar 2020 17:29:38 -0700
Subject: [PATCH] freezer: don't allocate stats on unfreeze

Unfreeze operations could happen quite frequently. If they're
synchronous with ApplicationManager main thread they must also be
lightweight, so avoid any unnecessary allocations and reuse message
fields for log data.

Bug: 151187166
Test: installed on a flame and verified log messages are correct.
Change-Id: Ie5e22cdc5538277dbf19b5a5fffe505ca07a8083
---
 .../android/server/am/CachedAppOptimizer.java | 63 +++++++------------
 1 file changed, 22 insertions(+), 41 deletions(-)

diff --git a/services/core/java/com/android/server/am/CachedAppOptimizer.java b/services/core/java/com/android/server/am/CachedAppOptimizer.java
index 3a6065e18ea56..86d9028f53dca 100644
--- a/services/core/java/com/android/server/am/CachedAppOptimizer.java
+++ b/services/core/java/com/android/server/am/CachedAppOptimizer.java
@@ -121,6 +121,7 @@ public final class CachedAppOptimizer {
     static final int COMPACT_PROCESS_MSG = 1;
     static final int COMPACT_SYSTEM_MSG = 2;
     static final int SET_FROZEN_PROCESS_MSG = 3;
+    static final int REPORT_UNFREEZE_MSG = 4;
 
     //TODO:change this static definition into a configurable flag.
     static final int FREEZE_TIMEOUT_MS = 500;
@@ -613,30 +614,6 @@ public final class CachedAppOptimizer {
                 FREEZE_TIMEOUT_MS);
     }
 
-    private final class UnfreezeStats {
-        final int mPid;
-        final String mName;
-        final long mFrozenDuration;
-
-        UnfreezeStats(int pid, String name, long frozenDuration) {
-            mPid = pid;
-            mName = name;
-            mFrozenDuration = frozenDuration;
-        }
-
-        public int getPid() {
-            return mPid;
-        }
-
-        public String getName() {
-            return mName;
-        }
-
-        public long getFrozenDuration() {
-            return mFrozenDuration;
-        }
-    }
-
     @GuardedBy("mAm")
     void unfreezeAppLocked(ProcessRecord app) {
         mFreezeHandler.removeMessages(SET_FROZEN_PROCESS_MSG, app);
@@ -667,12 +644,11 @@ public final class CachedAppOptimizer {
                 Slog.d(TAG_AM, "sync unfroze " + app.pid + " " + app.processName);
             }
 
-            UnfreezeStats stats = new UnfreezeStats(app.pid, app.processName,
-                    app.freezeUnfreezeTime - freezeTime);
-
             mFreezeHandler.sendMessage(
-                    mFreezeHandler.obtainMessage(SET_FROZEN_PROCESS_MSG, REPORT_UNFREEZE, 0,
-                        stats));
+                    mFreezeHandler.obtainMessage(REPORT_UNFREEZE_MSG,
+                        app.pid,
+                        (int) Math.min(app.freezeUnfreezeTime - freezeTime, Integer.MAX_VALUE),
+                        app.processName));
         }
     }
 
@@ -945,14 +921,19 @@ public final class CachedAppOptimizer {
 
         @Override
         public void handleMessage(Message msg) {
-            if (msg.what != SET_FROZEN_PROCESS_MSG) {
-                return;
-            }
+            switch (msg.what) {
+                case SET_FROZEN_PROCESS_MSG:
+                    freezeProcess((ProcessRecord) msg.obj);
+                    break;
+                case REPORT_UNFREEZE_MSG:
+                    int pid = msg.arg1;
+                    int frozenDuration = msg.arg2;
+                    String processName = (String) msg.obj;
 
-            if (msg.arg1 == DO_FREEZE) {
-                freezeProcess((ProcessRecord) msg.obj);
-            } else if (msg.arg1 == REPORT_UNFREEZE) {
-                reportUnfreeze((UnfreezeStats) msg.obj);
+                    reportUnfreeze(pid, frozenDuration, processName);
+                    break;
+                default:
+                    return;
             }
         }
 
@@ -1015,18 +996,18 @@ public final class CachedAppOptimizer {
             }
         }
 
-        private void reportUnfreeze(UnfreezeStats stats) {
+        private void reportUnfreeze(int pid, int frozenDuration, String processName) {
 
-            EventLog.writeEvent(EventLogTags.AM_UNFREEZE, stats.getPid(), stats.getName());
+            EventLog.writeEvent(EventLogTags.AM_UNFREEZE, pid, processName);
 
             // See above for why we're not taking mPhenotypeFlagLock here
             if (mRandom.nextFloat() < mFreezerStatsdSampleRate) {
                 FrameworkStatsLog.write(
                         FrameworkStatsLog.APP_FREEZE_CHANGED,
                         FrameworkStatsLog.APP_FREEZE_CHANGED__ACTION__UNFREEZE_APP,
-                        stats.getPid(),
-                        stats.getName(),
-                        stats.getFrozenDuration());
+                        pid,
+                        processName,
+                        frozenDuration);
             }
         }
     }