Refactor ring_buffer interface, add a feature and a test.

* Add a RingBuffer typedef.
* Add the ability to force a memcpy by passing a null ptr. In some cases,
  we know we want a memcpy. This allows us to skip a potential
  intermediate memcpy.
* Add a stress test.

Review URL: https://webrtc-codereview.appspot.com/1111004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@3567 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/audio_processing/utility/ring_buffer_unittest.cc

@@ -0,0 +1,140 @@
+/*
+ *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+// TODO(ajm): Make this a comprehensive test.
+
+extern "C" {
+#include "webrtc/modules/audio_processing/utility/ring_buffer.h"
+}
+
+#include <cstdlib>
+#include <ctime>
+
+#include "testing/gtest/include/gtest/gtest.h"
+#include "webrtc/system_wrappers/interface/scoped_ptr.h"
+
+namespace webrtc {
+
+typedef scoped_ptr_malloc<RingBuffer, WebRtc_FreeBuffer> scoped_ring_buffer;
+
+static void AssertElementEq(int expected, int actual) {
+  ASSERT_EQ(expected, actual);
+}
+
+static int SetIncrementingData(int* data, int num_elements,
+                               int starting_value) {
+  for (int i = 0; i < num_elements; i++) {
+    data[i] = starting_value++;
+  }
+  return starting_value;
+}
+
+static int CheckIncrementingData(int* data, int num_elements,
+                                 int starting_value) {
+  for (int i = 0; i < num_elements; i++) {
+    AssertElementEq(starting_value++, data[i]);
+  }
+  return starting_value;
+}
+
+// We use ASSERTs in this test to avoid obscuring the seed in the case of a
+// failure.
+static void RandomStressTest(int** data_ptr) {
+  const int kNumTests = 100;
+  const int kNumOps = 10000;
+  const int kMaxBufferSize = 1000;
+
+  unsigned int seed = std::time(NULL);
+  printf("seed=%u\n", seed);
+  std::srand(seed);
+  for (int i = 0; i < kNumTests; i++) {
+    const int buffer_size = std::max(rand() % kMaxBufferSize, 1);
+    scoped_array<int> write_data(new int[buffer_size]);
+    scoped_array<int> read_data(new int[buffer_size]);
+    scoped_ring_buffer buffer;
+    ASSERT_EQ(0, WebRtc_CreateBuffer(buffer.accept(), buffer_size,
+                                     sizeof(int)));
+    ASSERT_EQ(0, WebRtc_InitBuffer(buffer.get()));
+    int buffer_consumed = 0;
+    int write_element = 0;
+    int read_element = 0;
+    for (int j = 0; j < kNumOps; j++) {
+      const bool write = rand() % 2 == 0 ? true : false;
+      const int num_elements = rand() % buffer_size;
+      if (write) {
+        const int buffer_available = buffer_size - buffer_consumed;
+        ASSERT_EQ(static_cast<size_t>(buffer_available),
+                  WebRtc_available_write(buffer.get()));
+        const int expected_elements = std::min(num_elements, buffer_available);
+        write_element = SetIncrementingData(write_data.get(), expected_elements,
+                                     write_element);
+        ASSERT_EQ(static_cast<size_t>(expected_elements),
+                  WebRtc_WriteBuffer(buffer.get(), write_data.get(),
+                                     num_elements));
+        buffer_consumed = std::min(buffer_consumed + expected_elements,
+                                   buffer_size);
+      } else {
+        const int expected_elements = std::min(num_elements,
+                                               buffer_consumed);
+        ASSERT_EQ(static_cast<size_t>(buffer_consumed),
+                  WebRtc_available_read(buffer.get()));
+        ASSERT_EQ(static_cast<size_t>(expected_elements),
+                  WebRtc_ReadBuffer(buffer.get(),
+                                    reinterpret_cast<void**>(data_ptr),
+                                    read_data.get(),
+                                    num_elements));
+        int* check_ptr = read_data.get();
+        if (data_ptr) {
+          check_ptr = *data_ptr;
+        }
+        read_element = CheckIncrementingData(check_ptr, expected_elements,
+                                             read_element);
+        buffer_consumed = std::max(buffer_consumed - expected_elements, 0);
+      }
+    }
+  }
+}
+
+TEST(RingBufferTest, RandomStressTest) {
+  int* data_ptr = NULL;
+  RandomStressTest(&data_ptr);
+}
+
+TEST(RingBufferTest, RandomStressTestWithNullPtr) {
+  RandomStressTest(NULL);
+}
+
+TEST(RingBufferTest, PassingNulltoReadBufferForcesMemcpy) {
+  scoped_ring_buffer buffer;
+  const size_t kDataSize = 2;
+  int write_data[kDataSize];
+  int read_data[kDataSize];
+  int* data_ptr;
+
+  ASSERT_EQ(0, WebRtc_CreateBuffer(buffer.accept(), kDataSize, sizeof(int)));
+  ASSERT_EQ(0, WebRtc_InitBuffer(buffer.get()));
+
+  SetIncrementingData(write_data, kDataSize, 0);
+  EXPECT_EQ(kDataSize, WebRtc_WriteBuffer(buffer.get(), write_data, kDataSize));
+  SetIncrementingData(read_data, kDataSize, kDataSize);
+  EXPECT_EQ(kDataSize, WebRtc_ReadBuffer(buffer.get(),
+      reinterpret_cast<void**>(&data_ptr), read_data, kDataSize));
+  // Copying was not necessary, so |read_data| has not been updated.
+  CheckIncrementingData(data_ptr, kDataSize, 0);
+  CheckIncrementingData(read_data, kDataSize, kDataSize);
+
+  EXPECT_EQ(kDataSize, WebRtc_WriteBuffer(buffer.get(), write_data, kDataSize));
+  EXPECT_EQ(kDataSize, WebRtc_ReadBuffer(buffer.get(), NULL, read_data,
+                                         kDataSize));
+  // Passing NULL forces a memcpy, so |read_data| is now updated.
+  CheckIncrementingData(read_data, kDataSize, 0);
+}
+
+}  // namespace webrtc