Add a very simple helper function to log slow functions.

Change-Id: I2e2e072206d02b572a330dd25857c161b5b563bf

include/utils/Log.h

@@ -29,5 +29,43 @@
 #define _LIBS_UTILS_LOG_H
 
 #include <cutils/log.h>
+#include <sys/types.h>
+
+#ifdef __cplusplus
+
+namespace android {
+
+/*
+ * A very simple utility that yells in the log when an operation takes too long.
+ */
+class LogIfSlow {
+public:
+    LogIfSlow(const char* tag, android_LogPriority priority,
+            int timeoutMillis, const char* message);
+    ~LogIfSlow();
+
+private:
+    const char* const mTag;
+    const android_LogPriority mPriority;
+    const int mTimeoutMillis;
+    const char* const mMessage;
+    const int64_t mStart;
+};
+
+/*
+ * Writes the specified debug log message if this block takes longer than the
+ * specified number of milliseconds to run.  Includes the time actually taken.
+ *
+ * {
+ *     ALOGD_IF_SLOW(50, "Excessive delay doing something.");
+ *     doSomething();
+ * }
+ */
+#define ALOGD_IF_SLOW(timeoutMillis, message) \
+        LogIfSlow _logIfSlow(LOG_TAG, ANDROID_LOG_DEBUG, timeoutMillis, message);
+
+} // namespace android
+
+#endif // __cplusplus
 
 #endif // _LIBS_UTILS_LOG_H

libs/utils/Android.mk

@@ -26,6 +26,7 @@ commonSources:= \
 	FileMap.cpp \
 	Flattenable.cpp \
 	LinearTransform.cpp \
+	Log.cpp \
 	PropertyMap.cpp \
 	RefBase.cpp \
 	SharedBuffer.cpp \

libs/utils/Log.cpp

@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "Log"
+
+#include <utils/Log.h>
+#include <utils/Timers.h>
+
+namespace android {
+
+LogIfSlow::LogIfSlow(const char* tag, android_LogPriority priority,
+        int timeoutMillis, const char* message) :
+        mTag(tag), mPriority(priority), mTimeoutMillis(timeoutMillis), mMessage(message),
+        mStart(systemTime(SYSTEM_TIME_BOOTTIME)) {
+}
+
+LogIfSlow::~LogIfSlow() {
+    int durationMillis = nanoseconds_to_milliseconds(systemTime(SYSTEM_TIME_BOOTTIME) - mStart);
+    if (durationMillis > mTimeoutMillis) {
+        LOG_PRI(mPriority, mTag, "%s: %dms", mMessage, durationMillis);
+    }
+}
+
+} // namespace android