add a linux timer

paddle/fluid/platform/timer.h

@@ -0,0 +1,87 @@
+/* Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
+
+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. */
+
+#pragma once
+#include <sys/time.h>
+#include <pmmintrin.h>
+#include <string>
+#include <vector>
+
+namespace paddle {
+namespace platform {
+
+// A Standard Timer implementation for debugging
+
+class Timer {
+ public:
+    Timer() {
+        reset();
+    }
+
+    inline void reset() {
+        _start.tv_sec = 0;
+        _start.tv_usec = 0;
+
+        _count = 0;
+        _elapsed = 0;
+        _paused = true;
+    }
+
+    inline void start() {
+        reset();
+        resume();
+    }
+
+    inline void pause() {
+        if (_paused) {
+            return;
+        }
+        _elapsed += tickus();
+        ++_count;
+        _paused = true;
+    }
+
+    inline void resume() {
+        gettimeofday(&_start, NULL);
+        _paused = false;
+    }
+
+    inline int count() const {
+        return _count;
+    }
+
+    inline double elapsed_us() const {
+        return static_cast<double>(_elapsed);
+    }
+    inline double elapsed_ms() const {
+        return _elapsed / 1000.0;
+    }
+    inline double elapsed_sec() const {
+        return _elapsed / 1000000.0;
+    }
+
+ private:
+    struct timeval _start;
+    struct timeval _now;
+
+    int32_t _count;
+    int64_t _elapsed;
+    bool _paused;
+
+    inline int64_t tickus() {
+        gettimeofday(&_now, NULL);
+        return (_now.tv_sec - _start.tv_sec) * 1000 * 1000L +
+            (_now.tv_usec - _start.tv_usec);
+    }
+};