[service] Add a CompilerGymServiceContext class.

Issue facebookresearch#591.

compiler_gym/service/BUILD

@@ -37,6 +37,18 @@ cc_library(
     ],
 )
 
+cc_library(
+    name = "CompilerGymServiceContext",
+    srcs = ["CompilerGymServiceContext.cc"],
+    hdrs = ["CompilerGymServiceContext.h"],
+    visibility = ["//visibility:public"],
+    deps = [
+        "//compiler_gym/service/proto:compiler_gym_service_cc",
+        "@boost//:filesystem",
+        "@com_github_grpc_grpc//:grpc++",
+    ],
+)
+
 py_library(
     name = "connection",
     srcs = ["connection.py"],

compiler_gym/service/CompilerGymServiceContext.cc

@@ -0,0 +1,21 @@
+// Copyright (c) Facebook, Inc. and its affiliates.
+//
+// This source code is licensed under the MIT license found in the
+// LICENSE file in the root directory of this source tree.
+#pragma once
+
+#include "compiler_gym/service/CompilerGymServiceContext.h"
+
+using grpc::Status;
+
+namespace compiler_gym {
+
+CompilerGymServiceContext::CompilerGymServiceContext(
+    const boost::filesystem::path& workingDirectory)
+    : workingDirectory_(workingDirectory) {}
+
+virtual Status CompilerGymServiceContext::init() { return Status::OK; }
+
+virtual Status CompilerGymServiceContext::shutdown() { return Status::OK; }
+
+}  // namespace compiler_gym

compiler_gym/service/CompilerGymServiceContext.h

@@ -0,0 +1,90 @@
+// Copyright (c) Facebook, Inc. and its affiliates.
+//
+// This source code is licensed under the MIT license found in the
+// LICENSE file in the root directory of this source tree.
+#pragma once
+
+#include <grpcpp/grpcpp.h>
+
+#include "boost/filesystem.hpp"
+
+namespace compiler_gym {
+
+/**
+ * Execution context of a compiler gym service.
+ *
+ * This class encapsulates mutable state that is shared between all compilation
+ * sessions. An instance of this class is passed to every new
+ * CompilationSession.
+ *
+ * You may subclass CompilerGymServiceContext to add additional mutable state.
+ * The subclass .
+ *
+ * \code{.cpp}
+ *
+ *     #include "compiler_gym/service/CompilationSession.h"
+ *     #include "compiler_gym/service/CompilerGymServiceContext.h"
+ *     #include "compiler_gym/service/runtime/Runtime.h"
+ *
+ *     using namespace compiler_gym;
+ *
+ *     class MyServiceContext final : public ServiceContext { ... }
+ *
+ *     class MyCompilationSession final : public CompilationSession { ... }
+ *
+ *     int main(int argc, char** argv) {
+ *         return runtime::createAndRunCompilerGymService<MyCompilationSession, MyServiceContext>();
+ *     }
+ * \endcode
+ */
+class CompilerGymServiceContext {
+ public:
+  CompilerGymServiceContext(const boost::filesystem::path& workingDirectory);
+
+  /**
+   * Initialize context.
+   *
+   * Called before any compilation sessions are created. Use this method to
+   * initialize any mutable state. If this routine returns an error, the service
+   * will terminate.
+   *
+   * @return A status.
+   */
+  [[nodiscard]] virtual grpc::Status init();
+
+  /**
+   * Uninitialize context.
+   *
+   * Called after all compilation sessions have ended, before a service
+   * terminates. Use this method to perform tidying up. This method is always
+   * called, even if init() fails. If this routine returns an error, the service
+   * will terminate with a nonzero error code.
+   *
+   * @return A status.
+   */
+  [[nodiscard]] virtual grpc::Status shutdown();
+
+  /**
+   * Get the working directory.
+   *
+   * The working directory is a local filesystem directory that compilation
+   * sessions can use to store temporary files such as build artifacts. The
+   * directory is guaranteed to exist.
+   *
+   * \note When possible, an in-memory filesystem will be used for the working
+   *    directory. This means that the working directory is not suitable for
+   *    very large files or executables, as some systems prevent execution of
+   *    in-memory files.
+   *
+   * \note A single working directory is shared by all of the compilation
+   * sessions of a service. Do not assume that you have exclusive access.
+   *
+   * @return A path.
+   */
+  inline const boost::filesystem::path& workingDirectory() const { return workingDirectory_; };
+
+ private:
+  const boost::filesystem::path workingDirectory_;
+};
+
+}  // namespace compiler_gym