prevents concurrent access into llvms jit

Apparently the internals of the orc jit are not thread-safe:
https://lists.llvm.org/pipermail/llvm-dev/2017-November/119108.html

The thread sanitizer in nebulastream complaints about a data-race deep within orc. The mailing lists suggests using a lock around access into orc.

nautilus/src/nautilus/compiler/backends/mlir/MLIRExecutable.cpp

@@ -6,10 +6,27 @@
 #include <mlir/IR/MLIRContext.h>
 
 namespace nautilus::compiler::mlir {
+static std::mutex llvm_jit_mutex {};
+
 MLIRExecutable::MLIRExecutable(std::unique_ptr<::mlir::ExecutionEngine> engine) : engine(std::move(engine)) {
 }
-
+MLIRExecutable::~MLIRExecutable() {
+	if (engine) {
+		std::scoped_lock lock(llvm_jit_mutex);
+		engine.reset();
+	}
+}
+MLIRExecutable::MLIRExecutable(MLIRExecutable&& other) noexcept
+    : engine(std::move(other.engine)) {
+}
+MLIRExecutable& MLIRExecutable::operator=(MLIRExecutable&& other) noexcept {
+	if (this == &other)
+		return *this;
+	engine = std::move(other.engine);
+	return *this;
+}
 void* MLIRExecutable::getInvocableFunctionPtr(const std::string& member) {
+	std::scoped_lock lock(llvm_jit_mutex);
 	return engine->lookup(member).get();
 }
 bool MLIRExecutable::hasInvocableFunctionPtr() {

nautilus/src/nautilus/compiler/backends/mlir/MLIRExecutable.hpp

@@ -11,6 +11,11 @@ namespace nautilus::compiler::mlir {
 class MLIRExecutable : public Executable {
 public:
 	MLIRExecutable(std::unique_ptr<::mlir::ExecutionEngine> engine);
+	~MLIRExecutable() override;
+	MLIRExecutable(const MLIRExecutable& other) = delete;
+	MLIRExecutable(MLIRExecutable&& other) noexcept;
+	MLIRExecutable& operator=(const MLIRExecutable& other) = delete;
+	MLIRExecutable& operator=(MLIRExecutable&& other) noexcept;
 
 protected:
 	void* getInvocableFunctionPtr(const std::string& member) override;