From 46d172e339a510f9cc5e24365495a70f89dd2482 Mon Sep 17 00:00:00 2001
From: Liss Heidrich <31625940+liss-h@users.noreply.github.com>
Date: Wed, 18 Sep 2024 14:16:48 +0200
Subject: [PATCH] Fix: compatibility with older metall versions (#18)

---
 src/dice/ffi/metall.h            | 20 ++++++++++++++++++
 src/dice/ffi/metall_internal.hpp | 35 ++++++++++++++++++++++++++++++--
 test_package/example.cpp         |  2 ++
 tests/tests_Sanity.cpp           |  2 ++
 4 files changed, 57 insertions(+), 2 deletions(-)

diff --git a/src/dice/ffi/metall.h b/src/dice/ffi/metall.h
index c84d152..7689efd 100644
--- a/src/dice/ffi/metall.h
+++ b/src/dice/ffi/metall.h
@@ -4,12 +4,32 @@
 #include <stdbool.h>
 #include <stddef.h>
 
+#if __has_include(<metall/logger_interface.h>)
 #include <metall/logger_interface.h>
+#endif
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
+#if !__has_include(<metall/logger_interface.h>)
+/// \brief Log message level
+typedef enum metall_log_level {
+    /// \brief Critical logger message
+    metall_critical = 5,
+    /// \brief Error logger message
+    metall_error = 4,
+    /// \brief Warning logger message
+    metall_warning = 3,
+    /// \brief Info logger message
+    metall_info = 2,
+    /// \brief Debug logger message
+    metall_debug = 1,
+    /// \brief Verbose (lowest priority) logger message
+    metall_verbose = 0,
+} metall_log_level;
+#endif
+
 typedef struct metall_manager metall_manager;
 
 /**
diff --git a/src/dice/ffi/metall_internal.hpp b/src/dice/ffi/metall_internal.hpp
index d3dcdfc..38925a9 100644
--- a/src/dice/ffi/metall_internal.hpp
+++ b/src/dice/ffi/metall_internal.hpp
@@ -5,11 +5,42 @@
 #include <metall/metall.hpp>
 
 namespace dice::metall_ffi::internal {
-    /**
+#if METALL_VERSION >= 2800
+     /**
      * @brief The metall manager type used internally.
      *      This object type is whats actually behind the opaque ::metall_manager * in the interface
      */
-    using metall_manager = metall::manager;
+     using metall_manager = metall::manager;
+#else
+
+     /**
+      * @brief The metall manager type used internally.
+      *      This object type is whats actually behind the opaque ::metall_manager * in the interface.
+      *      This is a wrapper that contains the read_only flag for older versions that do not support read_only() yet.
+      */
+     struct metall_manager : metall::manager {
+          bool read_only_;
+
+          template<typename T>
+          using allocator_type = typename metall::manager::template allocator_type<T>;
+
+          metall_manager(metall::create_only_t op, char const *path) : metall::manager{op, path},
+                                                                       read_only_{false} {
+          }
+
+          metall_manager(metall::open_only_t op, char const *path) : metall::manager{op, path},
+                                                                     read_only_{false} {
+          }
+
+          metall_manager(metall::open_read_only_t op, char const *path) : metall::manager{op, path},
+                                                                          read_only_{true} {
+          }
+
+          [[nodiscard]] bool read_only() const noexcept {
+               return read_only_;
+          }
+     };
+#endif
 } // namespace
 
 #endif//DICE_METALLFFI_METALLINTERNAL_HPP
diff --git a/test_package/example.cpp b/test_package/example.cpp
index 9d06265..a160b9e 100644
--- a/test_package/example.cpp
+++ b/test_package/example.cpp
@@ -1,8 +1,10 @@
 #include <dice/ffi/metall.h>
 
+#if __has_include(<metall/logger_interface.h>)
 extern "C" void metall_log(metall_log_level, char const *, size_t, char const *) {
 	// noop
 }
+#endif
 
 int main() {
     metall_open("/tmp/test");
diff --git a/tests/tests_Sanity.cpp b/tests/tests_Sanity.cpp
index ac9394f..eefb935 100644
--- a/tests/tests_Sanity.cpp
+++ b/tests/tests_Sanity.cpp
@@ -6,9 +6,11 @@
 #include <string>
 #include <random>
 
+#if __has_include(<metall/logger_interface.h>)
 extern "C" void metall_log(metall_log_level lvl, char const *file, size_t line, char const *msg) {
     std::cerr << lvl << " " << file << ":" << line << ": " << msg << std::endl;
 }
+#endif
 
 TEST_SUITE("metall-ffi") {
     TEST_CASE("sanity check") {