commit 88fc522dadbadca7ef8c510db51f63d12e71d04e
author Avichal Rakesh <arakesh@google.com> Fri Mar 03 15:00:59 2023 -0800
committer Avichal Rakesh <arakesh@google.com> Tue Mar 14 14:45:48 2023 -0700
tree 51b8508673131437864b322b29988e839400b50c
parent 91920264bafed7368dfabba967de02924ee828da

cameraservice: Add logId to correlate CameraActionEvents

Cameraservice currently triggers logging of CameraActionEvents (through
CameraServiceProxy) which are logged as independent event. For data
analysis purposes, it would be helpful to have one set of
OPEN-n*SESSION-CLOSE events correlate with each other.

To help with that, an mLogId field was added in CameraSessionStats which
will hold a string identifier. This identifier will be randomly
generated for OPEN events and reused for corresponding
ACTIVE, IDLE, and CLOSE events.

Bug: 271297241
Test: Manually tested that statsd gets the expected logId for camera
      sessions.
Change-Id: Ia26f2cd5d75bdeb15737e85d7df1a46b75993712

services/camera/libcameraservice/utils/CameraServiceProxyWrapper.cpp

diff --git a/services/camera/libcameraservice/utils/CameraServiceProxyWrapper.cpp b/services/camera/libcameraservice/utils/CameraServiceProxyWrapper.cpp
index 7aaf6b2..1b80de2 100644
--- a/services/camera/libcameraservice/utils/CameraServiceProxyWrapper.cpp
+++ b/services/camera/libcameraservice/utils/CameraServiceProxyWrapper.cpp
@@ -248,9 +248,12 @@
             apiLevel = CameraSessionStats::CAMERA_API_LEVEL_2;
         }
 
-        sessionStats = std::make_shared<CameraSessionStatsWrapper>(String16(id), facing,
-                CameraSessionStats::CAMERA_STATE_OPEN, clientPackageName,
-                apiLevel, isNdk, latencyMs);
+        // Generate a new log ID for open events
+        int64_t logId = generateLogId(mRandomDevice);
+
+        sessionStats = std::make_shared<CameraSessionStatsWrapper>(
+                String16(id), facing, CameraSessionStats::CAMERA_STATE_OPEN, clientPackageName,
+                apiLevel, isNdk, latencyMs, logId);
         mSessionStatsMap.emplace(id, sessionStats);
         ALOGV("%s: Adding id %s", __FUNCTION__, id.c_str());
     }
@@ -300,4 +303,16 @@
     return ret;
 }
 
-}; // namespace android
+int64_t CameraServiceProxyWrapper::generateLogId(std::random_device& randomDevice) {
+    int64_t ret = 0;
+    do {
+        // std::random_device generates 32 bits per call, so we call it twice
+        ret = randomDevice();
+        ret = ret << 32;
+        ret = ret | randomDevice();
+    } while (ret == 0); // 0 is not a valid identifier
+
+    return ret;
+}
+
+}  // namespace android

services/camera/libcameraservice/utils/CameraServiceProxyWrapper.h

diff --git a/services/camera/libcameraservice/utils/CameraServiceProxyWrapper.h b/services/camera/libcameraservice/utils/CameraServiceProxyWrapper.h
index f90a841..2868e26 100644
--- a/services/camera/libcameraservice/utils/CameraServiceProxyWrapper.h
+++ b/services/camera/libcameraservice/utils/CameraServiceProxyWrapper.h
@@ -24,6 +24,7 @@
 #include <utils/String16.h>
 #include <utils/StrongPointer.h>
 #include <utils/Timers.h>
+#include <random>
 
 #include <camera/CameraSessionStats.h>
 
@@ -37,7 +38,7 @@
     sp<hardware::ICameraServiceProxy> mCameraServiceProxy;
 
     class CameraSessionStatsWrapper {
-    private:
+      private:
         hardware::CameraSessionStats mSessionStats;
         Mutex mLock; // lock for per camera session stats
 
@@ -47,11 +48,12 @@
          */
         void updateProxyDeviceState(sp<hardware::ICameraServiceProxy>& proxyBinder);
 
-    public:
+      public:
         CameraSessionStatsWrapper(const String16& cameraId, int facing, int newCameraState,
-                const String16& clientName, int apiLevel, bool isNdk, int32_t latencyMs) :
-            mSessionStats(cameraId, facing, newCameraState, clientName, apiLevel, isNdk, latencyMs)
-            { }
+                                  const String16& clientName, int apiLevel, bool isNdk,
+                                  int32_t latencyMs, int64_t logId)
+            : mSessionStats(cameraId, facing, newCameraState, clientName, apiLevel, isNdk,
+                            latencyMs, logId) {}
 
         void onOpen(sp<hardware::ICameraServiceProxy>& proxyBinder);
         void onClose(sp<hardware::ICameraServiceProxy>& proxyBinder, int32_t latencyMs,
@@ -69,8 +71,15 @@
     // Map from camera id to the camera's session statistics
     std::map<String8, std::shared_ptr<CameraSessionStatsWrapper>> mSessionStatsMap;
 
+    std::random_device mRandomDevice;  // pulls 32-bit random numbers from /dev/urandom
+
     sp<hardware::ICameraServiceProxy> getCameraServiceProxy();
 
+    // Returns a randomly generated ID that is suitable for logging the event. A new identifier
+    // should only be generated for an open event. All other events for the cameraId should use the
+    // ID generated for the open event associated with them.
+    static int64_t generateLogId(std::random_device& randomDevice);
+
 public:
     CameraServiceProxyWrapper(sp<hardware::ICameraServiceProxy> serviceProxy = nullptr) :
             mCameraServiceProxy(serviceProxy)