Add weak symbol-based async logging calls

Summary: Stub interface for logging functions to integrate with the GlobalExecutor and Futures.

Reviewed By: andriigrynenko

Differential Revision: D18229089

fbshipit-source-id: ad57de08a8bd6a80e2d0af9a9792de86a8267176

folly/detail/AsyncTrace.cpp

+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * 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 <folly/detail/AsyncTrace.h>
+#include <folly/Portability.h>
+
+namespace folly {
+namespace async_tracing {
+FOLLY_ATTR_WEAK void logSetGlobalCPUExecutor(Executor*) noexcept {}
+FOLLY_ATTR_WEAK void logSetGlobalCPUExecutorToImmutable() noexcept {}
+FOLLY_ATTR_WEAK void logGetGlobalCPUExecutor(Executor*) noexcept {}
+FOLLY_ATTR_WEAK void logGetImmutableCPUExecutor(Executor*) noexcept {}
+FOLLY_ATTR_WEAK void logSetGlobalIOExecutor(IOExecutor*) noexcept {}
+FOLLY_ATTR_WEAK void logGetGlobalIOExecutor(IOExecutor*) noexcept {}
+FOLLY_ATTR_WEAK void logGetImmutableIOExecutor(IOExecutor*) noexcept {}
+FOLLY_ATTR_WEAK void logSemiFutureVia(Executor*, Executor*) noexcept {}
+FOLLY_ATTR_WEAK void logFutureVia(Executor*, Executor*) noexcept {}
+} // namespace async_tracing
+} // namespace folly

folly/detail/AsyncTrace.h

+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * 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 <folly/Optional.h>
+
+namespace folly {
+class Executor;
+class IOExecutor;
+namespace async_tracing {
+void logSetGlobalCPUExecutor(Executor*) noexcept;
+void logSetGlobalCPUExecutorToImmutable() noexcept;
+void logGetGlobalCPUExecutor(Executor*) noexcept;
+void logGetImmutableCPUExecutor(Executor*) noexcept;
+void logSetGlobalIOExecutor(IOExecutor*) noexcept;
+void logGetGlobalIOExecutor(IOExecutor*) noexcept;
+void logGetImmutableIOExecutor(IOExecutor*) noexcept;
+void logSemiFutureVia(Executor*, Executor*) noexcept;
+void logFutureVia(Executor*, Executor*) noexcept;
+} // namespace async_tracing
+} // namespace folly

folly/detail/test/AsyncTraceTest.cpp

+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * 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 <folly/detail/AsyncTrace.h>
+#include <folly/portability/GTest.h>
+
+TEST(FollyCountersTest, Trivial) {
+  folly::Executor* exec = nullptr;
+  folly::IOExecutor* io_exec = nullptr;
+  folly::async_tracing::logSetGlobalCPUExecutor(exec);
+  folly::async_tracing::logGetGlobalCPUExecutor(exec);
+  folly::async_tracing::logSetGlobalIOExecutor(io_exec);
+  folly::async_tracing::logGetGlobalIOExecutor(io_exec);
+  folly::async_tracing::logSetGlobalCPUExecutorToImmutable();
+  folly::async_tracing::logGetImmutableCPUExecutor(exec);
+  folly::async_tracing::logGetImmutableIOExecutor(io_exec);
+
+  folly::Executor* lastExec = nullptr;
+  folly::async_tracing::logSemiFutureVia(lastExec, exec);
+  folly::async_tracing::logFutureVia(lastExec, exec);
+
+  folly::async_tracing::logSemiFutureVia(lastExec, exec);
+  folly::async_tracing::logFutureVia(lastExec, exec);
+}