Better way to find the name of the calling class of logger (#70)

Walk stack instead of hard-coded depth

1 files changed, 28 insertions, 4 deletions

diff --git a/third_party/sl4a/src/main/java/com/google/android/mobly/snippet/util/Log.java b/third_party/sl4a/src/main/java/com/google/android/mobly/snippet/util/Log.java
index c68631a..b5b1d9b 100644
--- a/third_party/sl4a/src/main/java/com/google/android/mobly/snippet/util/Log.java
+++ b/third_party/sl4a/src/main/java/com/google/android/mobly/snippet/util/Log.java
@@ -25,6 +25,9 @@ import android.os.Bundle;
 public final class Log {
     public static volatile String APK_LOG_TAG = null;
 
+    private static final String MY_CLASS_NAME = Log.class.getName();
+    private static final String ANDROID_LOG_CLASS_NAME = android.util.Log.class.getName();
+
     private Log() {}
 
     public static synchronized void initLogTag(Context context) {
@@ -56,10 +59,31 @@ public final class Log {
             throw new IllegalStateException("Logging called before initLogTag()");
         }
         StackTraceElement[] stackTraceElements = Thread.currentThread().getStackTrace();
-        String fullClassName = stackTraceElements[4].getClassName();
-        String className = fullClassName.substring(fullClassName.lastIndexOf(".") + 1);
-        int lineNumber = stackTraceElements[4].getLineNumber();
-        return logTag + "." + className + ":" + lineNumber;
+
+        boolean isCallerClassNameFound = false;
+        String fullClassName = null;
+        int lineNumber = 0;
+        // Walk up the stack and look for the first class name that is neither us nor
+        // android.util.Log: that's the caller.
+        // Do not used hard-coded stack depth: that does not work all the time because of proguard
+        // inline optimization.
+        for (StackTraceElement element : stackTraceElements) {
+          fullClassName = element.getClassName();
+          if (!fullClassName.equals(MY_CLASS_NAME) &&
+              !fullClassName.equals(ANDROID_LOG_CLASS_NAME)) {
+            lineNumber = element.getLineNumber();
+            isCallerClassNameFound = true;
+            break;
+          }
+        }
+
+        if (!isCallerClassNameFound) {
+          // Failed to determine caller's class name, fall back the the minimal one.
+          return logTag;
+        } else {
+          String className = fullClassName.substring(fullClassName.lastIndexOf(".") + 1);
+          return logTag + "." + className + ":" + lineNumber;
+        }
     }
 
     public static void v(String message) {