Collect stats to investigate the viability of UDP

net/base/test_data_stream.cc

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "net/base/test_data_stream.h"
+
+namespace net {
+
+TestDataStream::TestDataStream() {
+  Reset();
+}
+
+// Fill |buffer| with |length| bytes of data from the stream.
+void TestDataStream::GetBytes(char* buffer, int length) {
+  while (length) {
+    AdvanceIndex();
+    int bytes_to_copy = std::min(length, bytes_remaining_);
+    memcpy(buffer, buffer_ptr_, bytes_to_copy);
+    buffer += bytes_to_copy;
+    Consume(bytes_to_copy);
+    length -= bytes_to_copy;
+  }
+}
+
+bool TestDataStream::VerifyBytes(const char *buffer, int length) {
+  while (length) {
+    AdvanceIndex();
+    int bytes_to_compare = std::min(length, bytes_remaining_);
+    if (memcmp(buffer, buffer_ptr_, bytes_to_compare))
+      return false;
+    Consume(bytes_to_compare);
+    length -= bytes_to_compare;
+    buffer += bytes_to_compare;
+  }
+  return true;
+}
+
+void TestDataStream::Reset() {
+  index_ = 0;
+  bytes_remaining_ = 0;
+  buffer_ptr_ = buffer_;
+}
+
+// If there is no data spilled over from the previous index, advance the
+// index and fill the buffer.
+void TestDataStream::AdvanceIndex() {
+  if (bytes_remaining_ == 0) {
+    // Convert it to ascii, but don't bother to reverse it.
+    // (e.g. 12345 becomes "54321")
+    int val = index_++;
+    do {
+      buffer_[bytes_remaining_++] = (val % 10) + '0';
+    } while ((val /= 10) > 0);
+    buffer_[bytes_remaining_++] = '.';
+  }
+}
+
+// Consume data from the spill buffer.
+void TestDataStream::Consume(int bytes) {
+  bytes_remaining_ -= bytes;
+  if (bytes_remaining_)
+    buffer_ptr_ += bytes;
+  else
+    buffer_ptr_ = buffer_;
+}
+
+}  // namespace net
+