add reader_queue_speed_test_mode flag for speed test

Author: jacquesqiao

paddle/fluid/operators/reader/blocking_queue.h

@@ -14,11 +14,14 @@
 
 #pragma once
 
+#include <gflags/gflags.h>
 #include <condition_variable>  // NOLINT
 #include <deque>
 
 #include "paddle/fluid/platform/enforce.h"
 
+DECLARE_bool(reader_queue_speed_test_mode);
+
 namespace paddle {
 namespace operators {
 namespace reader {
@@ -72,7 +75,9 @@ class BlockingQueue {
     if (!queue_.empty()) {
       PADDLE_ENFORCE_NOT_NULL(elem);
       *elem = queue_.front();
-      queue_.pop_front();
+      if (LIKELY(!FLAGS_reader_queue_speed_test_mode)) {
+        queue_.pop_front();
+      }
       send_cv_.notify_one();
       return true;
     } else {

paddle/fluid/operators/reader/reader_blocking_queue_test.cc

@@ -20,6 +20,10 @@
 
 #include "paddle/fluid/operators/reader/blocking_queue.h"
 
+DEFINE_bool(reader_queue_speed_test_mode, false,
+            "If set true, the queue.pop will only get data from queue but not "
+            "remove the data from queue for speed testing");
+
 using paddle::operators::reader::BlockingQueue;
 
 TEST(BlockingQueue, CapacityTest) {

paddle/fluid/platform/enforce.h

@@ -130,6 +130,13 @@ struct EOFException : public std::exception {
 #define UNLIKELY(condition) (condition == 0)
 #endif
 
+#if !defined(_WIN32)
+#define LIKELY(condition) __builtin_expect(static_cast<bool>(condition), 1)
+#else
+// there is no equivalent intrinsics in msvc.
+#define LIKELY(condition) (condition != 0)
+#endif
+
 template <typename... Args>
 inline typename std::enable_if<sizeof...(Args) != 0, void>::type throw_on_error(
     bool stat, const Args&... args) {

paddle/fluid/pybind/pybind.cc

@@ -57,6 +57,10 @@ limitations under the License. */
 
 #include "pybind11/stl.h"
 
+DEFINE_bool(reader_queue_speed_test_mode, false,
+            "If set true, the queue.pop will only get data from queue but not "
+            "remove the data from queue for speed testing");
+
 // disable auto conversion to list in Python
 PYBIND11_MAKE_OPAQUE(paddle::framework::LoDTensorArray);