fd sink

Signed-off-by: dentiny <[email protected]>

src/ray/util/BUILD

@@ -287,3 +287,13 @@ ray_cc_library(
         ":util",
     ],
 )
+
+ray_cc_library(
+    name = "sodlog_fd_sink",
+    hdrs = ["spdlog_fd_sink.h"],
+    deps = [
+        ":compat",
+        ":util",
+        "@com_github_spdlog//:spdlog",
+    ],
+)

src/ray/util/spdlog_fd_sink.h

@@ -0,0 +1,69 @@
+// Copyright 2025 The Ray Authors.
+//
+// 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 <spdlog/sinks/base_sink.h>
+
+#include "ray/util/compat.h"
+#include "ray/util/util.h"
+
+#if defined(__APPLE__) || defined(__linux__)
+#include <unistd.h>
+#elif defined(_WIN32)
+#include <windows.h>
+#endif
+
+namespace spdlog::sinks {
+
+// A sink which logs to the file descriptor.
+template <typename Mutex>
+class fd_sink final : public base_sink<Mutex> {
+ public:
+  // [fd] is not owned by [FdSink], which means the file descriptor should be closed by
+  // caller.
+  explicit fd_sink(int fd) : fd_(fd) {}
+
+ protected:
+  void sink_it_(const details::log_msg &msg) override {
+    memory_buf_t formatted;
+    base_sink<Mutex>::formatter_->format(msg, formatted);
+
+#if defined(__APPLE__) || defined(__linux__)
+    RAY_CHECK_EQ(write(fd_, formatted.data(), formatted.size()), formatted.size())
+        << "Fails to write because " << strerror(errno);
+#elif defined(_WIN32)
+    LPDWORD bytes_written;
+    BOOL success =
+        WriteFile(fd_, formatted.data(), (DWORD)formatted.size(), &bytes_written, NULL);
+    RAY_CHECK(success);
+    RAY_CHECK_EQ((LPDWORD)formatted.size(), bytes_written);
+#endif
+  }
+  void flush_() override {
+#if defined(__APPLE__) || defined(__linux__)
+    RAY_CHECK_EQ(close(fd_), 0) << "Fails to close file because " << strerror(errno);
+#elif defined(_WIN32)
+    RAY_CHECK(CloseHandle(fd_));
+#endif
+  }
+
+ private:
+  MEMFD_TYPE_NON_UNIQUE fd_;
+};
+
+using fd_sink_mt = fd_sink<std::mutex>;
+using fd_sink_st = fd_sink<details::null_mutex>;
+
+}  // namespace spdlog::sinks

src/ray/util/tests/BUILD

@@ -250,3 +250,14 @@ ray_cc_test(
     size = "small",
     tags = ["team:core"],
 )
+
+ray_cc_test(
+    name = "spdlog_fd_sink_test",
+    srcs = ["spdlog_fd_sink_test.cc"],
+    deps = [
+        "//src/ray/util:sodlog_fd_sink",
+        "@com_google_googletest//:gtest_main",
+    ],
+    size = "small",
+    tags = ["team:core"],
+)

src/ray/util/tests/spdlog_fd_sink_test.cc

@@ -0,0 +1,57 @@
+// Copyright 2025 The Ray Authors.
+//
+// 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.
+
+#include "ray/util/spdlog_fd_sink.h"
+
+#include <gtest/gtest.h>
+
+namespace spdlog::sinks {
+
+namespace {
+
+#if defined(__APPLE__) || defined(__linux__)
+int GetStdoutHandle() { return STDOUT_FILENO; }
+#elif defined(_WIN32)
+HANDLE GetStdoutHandle() { return GetStdHandle(STD_OUTPUT_HANDLE); }
+#endif
+
+// Returns "helloworld" for whatever message; here we don't care the what message is
+// logged, we only care whether msg has been written to the given file descriptor
+// correctly.
+class NoopFormatter : public formatter {
+ public:
+  void format(const details::log_msg &msg, memory_buf_t &dest) override {
+    dest.append(std::string{"helloworld"});
+  }
+  std::unique_ptr<formatter> clone() const override {
+    return std::make_unique<NoopFormatter>();
+  }
+};
+
+TEST(SpdlogFdSinkTest, SinkWithFd) {
+  fd_sink_st sink{GetStdoutHandle()};
+  sink.set_formatter(std::make_unique<NoopFormatter>());
+  details::log_msg msg_to_log{
+      /*logger_name=*/"logger_name", level::level_enum::info, /*msg=*/"content"};
+
+  testing::internal::CaptureStdout();
+  sink.log(msg_to_log);
+  const std::string stdout_content = testing::internal::GetCapturedStdout();
+
+  EXPECT_EQ(stdout_content, "helloworld");
+};
+
+}  // namespace
+
+}  // namespace spdlog::sinks