gcam: Add empty SysTrace class

Bug: 11071158
Change-Id: I31f8c449dc4c47c610b0ef3c24849e0402634c86
diff --git a/camera2/public/src/com/android/ex/camera2/utils/SysTrace.java b/camera2/public/src/com/android/ex/camera2/utils/SysTrace.java
new file mode 100644
index 0000000..fd92216
--- /dev/null
+++ b/camera2/public/src/com/android/ex/camera2/utils/SysTrace.java
@@ -0,0 +1,121 @@
+/*
+ * Copyright 2013 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.
+ */
+package com.android.ex.camera2.utils;
+
+import android.util.Log;
+
+/**
+ * Writes trace events to the system trace buffer.  These trace events can be
+ * collected and visualized using the Systrace tool.
+ *
+ * <p>
+ * This tracing mechanism is independent of the method tracing mechanism
+ * offered by {@link Debug#startMethodTracing}.  In particular, it enables
+ * tracing of events that occur across multiple processes.
+ * </p>
+ *
+ * <p>
+ * All traces are written using the <pre>APP</pre> tag.
+ * </p>
+ */
+public final class SysTrace {
+
+    private static final String TAG = "SysTrace";
+    private static final boolean VERBOSE = Log.isLoggable(TAG, Log.VERBOSE);
+
+    private static int sNestingLevel = 0;
+
+    /**
+     * Writes trace message to indicate the value of a given counter.
+     *
+     * @param counterName The counter name to appear in the trace.
+     * @param counterValue The counter value.
+     *
+     */
+    public static void traceCounter(String counterName, int counterValue) {
+        if (VERBOSE) {
+            Log.v(TAG, "traceCounter " + counterName + " " + counterValue);
+        }
+    }
+
+    /**
+     * Writes a trace message to indicate that a given section of code has begun. This call must
+     * be followed by a corresponding call to {@link #endSection()} on the same thread.
+     *
+     * <p class="note"> At this time the vertical bar character '|', newline character '\n', and
+     * null character '\0' are used internally by the tracing mechanism.  If sectionName contains
+     * these characters they will be replaced with a space character in the trace.
+     *
+     * @param sectionName The name of the code section to appear in the trace.  This may be at
+     * most 127 Unicode code units long.
+     */
+    public static void beginSection(String sectionName) {
+        if (VERBOSE) {
+            Log.v(TAG, String.format("beginSection[%d] %s", sNestingLevel, sectionName));
+            sNestingLevel++;
+        }
+    }
+
+    /**
+     * Writes a trace message to indicate that a given section of code has
+     * ended.
+     * <p>
+     * This call must be preceded by a corresponding call to
+     * {@link #beginSection(String)}. Calling this method will mark the end of
+     * the most recently begun section of code, so care must be taken to ensure
+     * that beginSection / endSection pairs are properly nested and called from
+     * the same thread.
+     * </p>
+     */
+    public static void endSection() {
+        if (VERBOSE) {
+            sNestingLevel--;
+            Log.v(TAG, String.format("endSection[%d]", sNestingLevel));
+        }
+    }
+
+    /**
+     * Writes a trace message to indicate that a given section of code has
+     * begun.
+     *
+     * <p>Must be followed by a call to {@link #endSectionAsync} using the same
+     * tag. Unlike {@link #beginSection} and {@link #endSection},
+     * asynchronous events do not need to be nested. The name and cookie used to
+     * begin an event must be used to end it.</p>
+     *
+     * @param methodName The method name to appear in the trace.
+     * @param cookie Unique identifier for distinguishing simultaneous events
+     */
+    public static void beginSectionAsync(String methodName, int cookie) {
+        if (VERBOSE) {
+            Log.v(TAG, "beginSectionAsync " + methodName + " " + cookie);
+        }
+    }
+
+    /**
+     * Writes a trace message to indicate that the current method has ended.
+     * Must be called exactly once for each call to {@link #beginSectionAsync}
+     * using the same tag, name and cookie.
+     *
+     * @param methodName The method name to appear in the trace.
+     * @param cookie Unique identifier for distinguishing simultaneous events
+     */
+    public static void endSectionAsync(String methodName, int cookie) {
+        if (VERBOSE) {
+            Log.v(TAG, "endSectionAsync " + methodName + " " + cookie);
+        }
+    }
+}