wpiutil: Add C++ libuv wrappers (#1166)

- Provide an EventLoopRunner to run uv::Loop on a separate thread.

- Add raw_ostream wrapper for uv::Buffer.

wpiutil/src/test/native/cpp/uv/UvGetAddrInfoTest.cpp

@@ -0,0 +1,108 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2018 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+/* Copyright Joyent, Inc. and other Node contributors. All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include "wpi/uv/GetAddrInfo.h"  // NOLINT(build/include_order)
+
+#include "gtest/gtest.h"  // NOLINT(build/include_order)
+
+#include "wpi/uv/Loop.h"
+
+#define CONCURRENT_COUNT 10
+
+namespace wpi {
+namespace uv {
+
+TEST(UvGetAddrInfo, BothNull) {
+  int fail_cb_called = 0;
+
+  auto loop = Loop::Create();
+  loop->error.connect([&](Error err) {
+    ASSERT_EQ(err.code(), UV_EINVAL);
+    fail_cb_called++;
+  });
+
+  GetAddrInfo(loop, [](const addrinfo&) { FAIL(); }, Twine::createNull());
+  loop->Run();
+  ASSERT_EQ(fail_cb_called, 1);
+}
+
+TEST(UvGetAddrInfo, FailedLookup) {
+  int fail_cb_called = 0;
+
+  auto loop = Loop::Create();
+  loop->error.connect([&](Error err) {
+    ASSERT_EQ(fail_cb_called, 0);
+    ASSERT_LT(err.code(), 0);
+    fail_cb_called++;
+  });
+
+  // Use a FQDN by ending in a period
+  GetAddrInfo(loop, [](const addrinfo&) { FAIL(); }, "xyzzy.xyzzy.xyzzy.");
+  loop->Run();
+  ASSERT_EQ(fail_cb_called, 1);
+}
+
+TEST(UvGetAddrInfo, Basic) {
+  int getaddrinfo_cbs = 0;
+
+  auto loop = Loop::Create();
+  loop->error.connect([](Error) { FAIL(); });
+
+  GetAddrInfo(loop, [&](const addrinfo&) { getaddrinfo_cbs++; }, "localhost");
+
+  loop->Run();
+
+  ASSERT_EQ(getaddrinfo_cbs, 1);
+}
+
+TEST(UvGetAddrInfo, Concurrent) {
+  int getaddrinfo_cbs = 0;
+  int callback_counts[CONCURRENT_COUNT];
+
+  auto loop = Loop::Create();
+  loop->error.connect([](Error) { FAIL(); });
+
+  for (int i = 0; i < CONCURRENT_COUNT; i++) {
+    callback_counts[i] = 0;
+    GetAddrInfo(loop,
+                [i, &callback_counts, &getaddrinfo_cbs](const addrinfo&) {
+                  callback_counts[i]++;
+                  getaddrinfo_cbs++;
+                },
+                "localhost");
+  }
+
+  loop->Run();
+
+  for (int i = 0; i < CONCURRENT_COUNT; i++) {
+    ASSERT_EQ(callback_counts[i], 1);
+  }
+}
+
+}  // namespace uv
+}  // namespace wpi