Merge "Extend am profile command to also collect lowoverhead traces." into main
diff --git a/core/java/android/app/ActivityThread.java b/core/java/android/app/ActivityThread.java
index 5e69ec1..fb7030f 100644
--- a/core/java/android/app/ActivityThread.java
+++ b/core/java/android/app/ActivityThread.java
@@ -6859,21 +6859,44 @@
 
     final void handleProfilerControl(boolean start, ProfilerInfo profilerInfo, int profileType) {
         if (start) {
-            try {
-                switch (profileType) {
-                    default:
+            switch (profileType) {
+                case ProfilerInfo.PROFILE_TYPE_LOW_OVERHEAD:
+                    if (!com.android.art.flags.Flags.alwaysEnableProfileCode()) {
+                        Slog.w(TAG, "Low overhead tracing feature is not enabled");
+                        break;
+                    }
+                    VMDebug.startLowOverheadTrace();
+                    break;
+                default:
+                    try {
                         mProfiler.setProfiler(profilerInfo);
                         mProfiler.startProfiling();
                         break;
-                }
-            } catch (RuntimeException e) {
-                Slog.w(TAG, "Profiling failed on path " + profilerInfo.profileFile
-                        + " -- can the process access this path?");
-            } finally {
-                profilerInfo.closeFd();
+                    } catch (RuntimeException e) {
+                        Slog.w(TAG, "Profiling failed on path " + profilerInfo.profileFile
+                                + " -- can the process access this path?");
+                    } finally {
+                        profilerInfo.closeFd();
+                    }
             }
         } else {
             switch (profileType) {
+                case ProfilerInfo.PROFILE_TYPE_LOW_OVERHEAD:
+                    if (!com.android.art.flags.Flags.alwaysEnableProfileCode()) {
+                        if (profilerInfo != null) {
+                            profilerInfo.closeFd();
+                        }
+                        Slog.w(TAG, "Low overhead tracing feature is not enabled");
+                        break;
+                    }
+                    if (profilerInfo != null) {
+                        FileDescriptor fd = profilerInfo.profileFd.getFileDescriptor();
+                        VMDebug.TraceDestination dst =
+                                VMDebug.TraceDestination.fromFileDescriptor(fd);
+                        VMDebug.dumpLowOverheadTrace(dst);
+                    }
+                    VMDebug.stopLowOverheadTrace();
+                    break;
                 default:
                     mProfiler.stopProfiling();
                     break;
diff --git a/core/java/android/app/ProfilerInfo.java b/core/java/android/app/ProfilerInfo.java
index bcae22a..0348b6d 100644
--- a/core/java/android/app/ProfilerInfo.java
+++ b/core/java/android/app/ProfilerInfo.java
@@ -32,6 +32,12 @@
  * {@hide}
  */
 public class ProfilerInfo implements Parcelable {
+    // Regular profiling which provides different modes of profiling at some performance cost.
+    public static final int PROFILE_TYPE_REGULAR = 0;
+
+    // Low overhead profiling that captures a simple sliding window of past events.
+    public static final int PROFILE_TYPE_LOW_OVERHEAD = 1;
+
     // Version of the profiler output
     public static final int OUTPUT_VERSION_DEFAULT = 1;
     // CLOCK_TYPE_DEFAULT chooses the default used by ART. ART uses CLOCK_TYPE_DUAL by default (see
diff --git a/services/core/java/com/android/server/am/ActivityManagerService.java b/services/core/java/com/android/server/am/ActivityManagerService.java
index 4a4a1b4..0152f94 100644
--- a/services/core/java/com/android/server/am/ActivityManagerService.java
+++ b/services/core/java/com/android/server/am/ActivityManagerService.java
@@ -7609,7 +7609,7 @@
     }
 
     void setProfileApp(ApplicationInfo app, String processName, ProfilerInfo profilerInfo,
-            ApplicationInfo sdkSandboxClientApp) {
+            ApplicationInfo sdkSandboxClientApp, int profileType) {
         synchronized (mAppProfiler.mProfilerLock) {
             if (!Build.IS_DEBUGGABLE) {
                 boolean isAppDebuggable = (app.flags & ApplicationInfo.FLAG_DEBUGGABLE) != 0;
@@ -7625,7 +7625,7 @@
                             + "and not profileable by shell: " + app.packageName);
                 }
             }
-            mAppProfiler.setProfileAppLPf(processName, profilerInfo);
+            mAppProfiler.setProfileAppLPf(processName, profilerInfo, profileType);
         }
     }
 
@@ -17883,7 +17883,8 @@
                     + android.Manifest.permission.SET_ACTIVITY_WATCHER);
         }
 
-        if (start && (profilerInfo == null || profilerInfo.profileFd == null)) {
+        if (start && profileType == ProfilerInfo.PROFILE_TYPE_REGULAR
+                && (profilerInfo == null || profilerInfo.profileFd == null)) {
             throw new IllegalArgumentException("null profile info or fd");
         }
 
@@ -19499,7 +19500,9 @@
                     }
 
                     if (profilerInfo != null) {
-                        setProfileApp(aInfo.applicationInfo, aInfo.processName, profilerInfo, null);
+                        // We only support normal method tracing along with app startup for now.
+                        setProfileApp(aInfo.applicationInfo, aInfo.processName, profilerInfo,
+                                null, /*profileType= */ ProfilerInfo.PROFILE_TYPE_REGULAR);
                     }
                     wmLock.notify();
                 }
diff --git a/services/core/java/com/android/server/am/ActivityManagerShellCommand.java b/services/core/java/com/android/server/am/ActivityManagerShellCommand.java
index 955437b..1853973 100644
--- a/services/core/java/com/android/server/am/ActivityManagerShellCommand.java
+++ b/services/core/java/com/android/server/am/ActivityManagerShellCommand.java
@@ -1081,7 +1081,7 @@
         String profileFile = null;
         boolean start = false;
         int userId = UserHandle.USER_CURRENT;
-        int profileType = 0;
+        int profileType = ProfilerInfo.PROFILE_TYPE_REGULAR;
         mSamplingInterval = 0;
         mStreaming = false;
         mClockType = ProfilerInfo.CLOCK_TYPE_DEFAULT;
@@ -1123,6 +1123,18 @@
                 }
             }
             process = getNextArgRequired();
+        } else if ("lowoverhead".equals(cmd)) {
+            // This is an experimental low overhead profiling.
+            profileType = ProfilerInfo.PROFILE_TYPE_LOW_OVERHEAD;
+            cmd = getNextArgRequired();
+            if ("start".equals(cmd)) {
+                start = true;
+            } else if ("stop".equals(cmd)) {
+                start = false;
+            } else {
+                throw new IllegalArgumentException("Profile command not valid");
+            }
+            process = getNextArgRequired();
         } else {
             // Compatibility with old syntax: process is specified first.
             process = cmd;
@@ -1142,7 +1154,12 @@
         ParcelFileDescriptor fd = null;
         ProfilerInfo profilerInfo = null;
 
-        if (start) {
+        // For regular method tracing  profileFile should be provided with the start command. For
+        // low overhead method tracing the profileFile is optional and provided with the stop
+        // command.
+        if ((start && profileType == ProfilerInfo.PROFILE_TYPE_REGULAR)
+                || (profileType == ProfilerInfo.PROFILE_TYPE_LOW_OVERHEAD
+                  && !start && getRemainingArgsCount() > 0)) {
             profileFile = getNextArgRequired();
             fd = openFileForSystem(profileFile, "w");
             if (fd == null) {
diff --git a/services/core/java/com/android/server/am/AppProfiler.java b/services/core/java/com/android/server/am/AppProfiler.java
index dda48ad..79a0d73 100644
--- a/services/core/java/com/android/server/am/AppProfiler.java
+++ b/services/core/java/com/android/server/am/AppProfiler.java
@@ -1990,7 +1990,7 @@
     }
 
     @GuardedBy("mProfilerLock")
-    private void stopProfilerLPf(ProcessRecord proc, int profileType) {
+    private void stopProfilerLPf(ProcessRecord proc, ProfilerInfo profilerInfo, int profileType) {
         if (proc == null || proc == mProfileData.getProfileProc()) {
             proc = mProfileData.getProfileProc();
             profileType = mProfileType;
@@ -2004,7 +2004,7 @@
             return;
         }
         try {
-            thread.profilerControl(false, null, profileType);
+            thread.profilerControl(false, profilerInfo, profileType);
         } catch (RemoteException e) {
             throw new IllegalStateException("Process disappeared");
         }
@@ -2039,41 +2039,58 @@
             ProfilerInfo profilerInfo, int profileType) {
         try {
             if (start) {
-                stopProfilerLPf(null, 0);
+                boolean needsFile = (profileType == ProfilerInfo.PROFILE_TYPE_REGULAR);
+                stopProfilerLPf(null, null, 0);
                 mService.setProfileApp(proc.info, proc.processName, profilerInfo,
-                        proc.isSdkSandbox ? proc.getClientInfoForSdkSandbox() : null);
+                        proc.isSdkSandbox ? proc.getClientInfoForSdkSandbox() : null, profileType);
                 mProfileData.setProfileProc(proc);
                 mProfileType = profileType;
-                ParcelFileDescriptor fd = profilerInfo.profileFd;
-                try {
-                    fd = fd.dup();
-                } catch (IOException e) {
-                    fd = null;
-                }
-                profilerInfo.profileFd = fd;
-                proc.mProfile.getThread().profilerControl(start, profilerInfo, profileType);
-                fd = null;
-                try {
-                    mProfileData.getProfilerInfo().profileFd.close();
-                } catch (IOException e) {
-                }
-                mProfileData.getProfilerInfo().profileFd = null;
 
-                if (proc.getPid() == mService.MY_PID) {
-                    // When profiling the system server itself, avoid closing the file
-                    // descriptor, as profilerControl will not create a copy.
-                    // Note: it is also not correct to just set profileFd to null, as the
-                    //       whole ProfilerInfo instance is passed down!
-                    profilerInfo = null;
-                }
-            } else {
-                stopProfilerLPf(proc, profileType);
-                if (profilerInfo != null && profilerInfo.profileFd != null) {
+                ParcelFileDescriptor fd = null;
+                if (needsFile) {
+                    fd = profilerInfo.profileFd;
                     try {
-                        profilerInfo.profileFd.close();
+                        fd = fd.dup();
+                    } catch (IOException e) {
+                        fd = null;
+                    }
+                    profilerInfo.profileFd = fd;
+                }
+
+                proc.mProfile.getThread().profilerControl(start, profilerInfo, profileType);
+
+                if (needsFile) {
+                    fd = null;
+                    try {
+                        mProfileData.getProfilerInfo().profileFd.close();
                     } catch (IOException e) {
                     }
+                    mProfileData.getProfilerInfo().profileFd = null;
+
+                    if (proc.getPid() == mService.MY_PID) {
+                        // When profiling the system server itself, avoid closing the file
+                        // descriptor, as profilerControl will not create a copy.
+                        // Note: it is also not correct to just set profileFd to null, as the
+                        //       whole ProfilerInfo instance is passed down!
+                        profilerInfo = null;
+                    }
                 }
+            } else {
+                boolean mayNeedFile = (profileType == ProfilerInfo.PROFILE_TYPE_LOW_OVERHEAD);
+                if (profilerInfo != null && profilerInfo.profileFd != null) {
+                    ParcelFileDescriptor fd = profilerInfo.profileFd;
+                    try {
+                        if (mayNeedFile) {
+                            fd = fd.dup();
+                        } else {
+                            fd.close();
+                        }
+                    } catch (IOException e) {
+                        fd = null;
+                    }
+                    profilerInfo.profileFd = fd;
+                }
+                stopProfilerLPf(proc, profilerInfo, profileType);
             }
 
             return true;
@@ -2090,7 +2107,7 @@
     }
 
     @GuardedBy("mProfilerLock")
-    void setProfileAppLPf(String processName, ProfilerInfo profilerInfo) {
+    void setProfileAppLPf(String processName, ProfilerInfo profilerInfo, int profileType) {
         mProfileData.setProfileApp(processName);
 
         if (mProfileData.getProfilerInfo() != null) {
@@ -2101,8 +2118,10 @@
                 }
             }
         }
-        mProfileData.setProfilerInfo(new ProfilerInfo(profilerInfo));
-        mProfileType = 0;
+        if (profilerInfo != null) {
+            mProfileData.setProfilerInfo(new ProfilerInfo(profilerInfo));
+        }
+        mProfileType = profileType;
     }
 
     @GuardedBy("mProfilerLock")