Add ability to get logging level via C API

CHANGELOG.md

@@ -2,7 +2,7 @@
 
 ### Enhancements
 * <New feature description> (PR [#????](https://github.com/realm/realm-core/pull/????))
-* None.
+* Added ability to get current log level via C API (PR [#7419](https://github.com/realm/realm-core/pull/7419))
 
 ### Fixed
 * <How do the end-user experience this issue? what was the impact?> ([#????](https://github.com/realm/realm-core/issues/????), since v?.?.?)

src/realm.h

@@ -602,7 +602,22 @@ typedef void (*realm_log_func_t)(realm_userdata_t userdata, realm_log_level_e le
 RLM_API void realm_set_log_callback(realm_log_func_t, realm_log_level_e, realm_userdata_t userdata,
                                     realm_free_userdata_func_t userdata_free) RLM_API_NOEXCEPT;
 RLM_API void realm_set_log_level(realm_log_level_e) RLM_API_NOEXCEPT;
-RLM_API void realm_set_log_level_category(const char*, realm_log_level_e) RLM_API_NOEXCEPT;
+/**
+ * Set the logging level for given category. Return the previous level.
+ */
+RLM_API realm_log_level_e realm_set_log_level_category(const char*, realm_log_level_e) RLM_API_NOEXCEPT;
+/**
+ * Get the logging level for given category.
+ */
+RLM_API realm_log_level_e realm_get_log_level_category(const char*) RLM_API_NOEXCEPT;
+/**
+ * Get the actual log category names (currently 15)
+  @param num_values number of values in the out_values array
+  @param out_values pointer to an array of size num_values
+  @return returns the number of categories returned. If num_values is zero, it will
+          return the total number of categories.
+ */
+RLM_API size_t realm_get_category_names(size_t num_values, const char** out_values);
 
 /**
  * Get a thread-safe reference representing the same underlying object as some

src/realm/object-store/c_api/logging.cpp

@@ -73,9 +73,32 @@ RLM_API void realm_set_log_level(realm_log_level_e level) noexcept
     util::LogCategory::realm.set_default_level_threshold(realm::util::LogCategory::Level(level));
 }
 
-RLM_API void realm_set_log_level_category(const char* category_name, realm_log_level_e level) noexcept
+RLM_API realm_log_level_e realm_set_log_level_category(const char* category_name, realm_log_level_e level) noexcept
 {
-    util::LogCategory::get_category(category_name)
-        .set_default_level_threshold(realm::util::LogCategory::Level(level));
+    auto& cat = util::LogCategory::get_category(category_name);
+    realm_log_level_e prev_level = realm_log_level_e(util::Logger::get_default_logger()->get_level_threshold(cat));
+    cat.set_default_level_threshold(realm::util::LogCategory::Level(level));
+    return prev_level;
 }
+
+RLM_API realm_log_level_e realm_get_log_level_category(const char* category_name) noexcept
+{
+    auto& cat = util::LogCategory::get_category(category_name);
+    return realm_log_level_e(util::Logger::get_default_logger()->get_level_threshold(cat));
+}
+
+RLM_API size_t realm_get_category_names(size_t num_values, const char** out_values)
+{
+    auto vec = util::LogCategory::get_category_names();
+    auto number_to_copy = vec.size();
+    if (num_values > 0) {
+        if (number_to_copy > num_values)
+            number_to_copy = num_values;
+        for (size_t n = 0; n < number_to_copy; n++) {
+            out_values[n] = vec[n];
+        }
+    }
+    return number_to_copy;
+}
+
 } // namespace realm::c_api

src/realm/util/logger.cpp

@@ -66,6 +66,15 @@ LogCategory& LogCategory::get_category(std::string_view name)
     return *log_catagory_map.at(name); // Throws
 }
 
+std::vector<const char*> LogCategory::get_category_names()
+{
+    std::vector<const char*> ret;
+    for (auto& it : log_catagory_map) {
+        ret.push_back(it.second->get_name().c_str());
+    }
+    return ret;
+}
+
 void LogCategory::set_default_level_threshold(Level level)
 {
     m_default_level.store(level);

src/realm/util/logger.hpp

@@ -99,6 +99,7 @@ class LogCategory {
     // Find category from fully qualified name. Will throw if
     // name does not match a category
     static LogCategory& get_category(std::string_view name);
+    static std::vector<const char*> get_category_names();
 
 private:
     friend class Logger;

test/object-store/c_api/c_api.cpp

@@ -1608,9 +1608,18 @@ TEST_CASE("C API logging", "[c_api]") {
     TestFile test_file;
 
     LogUserData userdata;
-    auto log_level_old = util::LogCategory::realm.get_default_level_threshold();
+    const char* category_names[20];
+    auto num_categories = realm_get_category_names(20, category_names);
+    auto log_level_old = realm_get_log_level_category("Realm");
+
     realm_set_log_callback(realm_log_func, RLM_LOG_LEVEL_DEBUG, &userdata, nullptr);
-    realm_set_log_level_category("Realm.Storage.Object", RLM_LOG_LEVEL_OFF);
+    for (size_t n = 0; n < num_categories; n++) {
+        CHECK(realm_get_log_level_category(category_names[n]) == RLM_LOG_LEVEL_DEBUG);
+    }
+
+    auto prev_level = realm_set_log_level_category("Realm.Storage.Object", RLM_LOG_LEVEL_OFF);
+    CHECK(prev_level == RLM_LOG_LEVEL_DEBUG);
+    CHECK(realm_get_log_level_category("Realm.Storage.Object") == RLM_LOG_LEVEL_OFF);
     auto config = make_config(test_file.path.c_str(), true);
     realm_t* realm = realm_open(config.get());
     realm_begin_write(realm);
@@ -1637,7 +1646,7 @@ TEST_CASE("C API logging", "[c_api]") {
     // Remove this logger again
     realm_set_log_callback(nullptr, RLM_LOG_LEVEL_DEBUG, nullptr, nullptr);
     // Restore old log level
-    util::LogCategory::realm.set_default_level_threshold(log_level_old);
+    realm_set_log_level(log_level_old);
 }
 
 TEST_CASE("C API - scheduler", "[c_api]") {