utils: use flags to define configuration item

include/dsn/utility/flags.h

@@ -0,0 +1,78 @@
+// Copyright (c) 2017-present, Xiaomi, Inc.  All rights reserved.
+// This source code is licensed under the Apache License Version 2.0, which
+// can be found in the LICENSE file in the root directory of this source tree.
+
+#pragma once
+
+#include <string>
+#include <cstdint>
+#include <functional>
+
+// Example:
+//    DSN_DEFINE_string("core", filename, "my_file.txt", "The file to read")
+//    DSN_DEFINE_validator(filename, [](const char *fname){ return is_file(fname); });
+
+#define DSN_DECLARE_VARIABLE(type, name) extern type FLAGS_##name
+
+#define DSN_DECLARE_int32(name) DSN_DECLARE_VARIABLE(int32_t, name)
+#define DSN_DECLARE_uint32(name) DSN_DECLARE_VARIABLE(uint32_t, name)
+#define DSN_DECLARE_int64(name) DSN_DECLARE_VARIABLE(int64_t, name)
+#define DSN_DECLARE_uint64(name) DSN_DECLARE_VARIABLE(uint64_t, name)
+#define DSN_DECLARE_double(name) DSN_DECLARE_VARIABLE(double, name)
+#define DSN_DECLARE_bool(name) DSN_DECLARE_VARIABLE(bool, name)
+#define DSN_DECLARE_string(name) DSN_DECLARE_VARIABLE(const char *, name)
+
+#define DSN_DEFINE_VARIABLE(type, section, name, default_value, desc)                              \
+    type FLAGS_##name = default_value;                                                             \
+    static dsn::flag_registerer FLAGS_REG_##name(section, #name, desc, &FLAGS_##name)
+
+#define DSN_DEFINE_int32(section, name, val, desc)                                                 \
+    DSN_DEFINE_VARIABLE(int32_t, section, name, val, desc)
+#define DSN_DEFINE_uint32(section, name, val, desc)                                                \
+    DSN_DEFINE_VARIABLE(uint32_t, section, name, val, desc)
+#define DSN_DEFINE_int64(section, name, val, desc)                                                 \
+    DSN_DEFINE_VARIABLE(int64_t, section, name, val, desc)
+#define DSN_DEFINE_uint64(section, name, val, desc)                                                \
+    DSN_DEFINE_VARIABLE(uint64_t, section, name, val, desc)
+#define DSN_DEFINE_double(section, name, val, desc)                                                \
+    DSN_DEFINE_VARIABLE(double, section, name, val, desc)
+#define DSN_DEFINE_bool(section, name, val, desc)                                                  \
+    DSN_DEFINE_VARIABLE(bool, section, name, val, desc)
+#define DSN_DEFINE_string(section, name, val, desc)                                                \
+    DSN_DEFINE_VARIABLE(const char *, section, name, val, desc)
+
+// Convenience macro for the registration of a flag validator
+// `validator` must be a std::function<bool(FLAG_TYPE)> and receives the flag value as argument,
+// returns true if validation passed.
+#define DSN_DEFINE_validator(name, validator)                                                      \
+    static auto FLAGS_VALIDATOR_FN_##name = validator;                                             \
+    static const dsn::flag_validator FLAGS_VALIDATOR_##name(#name, []() {                          \
+        dassert(FLAGS_VALIDATOR_FN_##name(FLAGS_##name), "validation failed: %s", #name);          \
+    })
+
+namespace dsn {
+
+// An utility class that registers a flag upon initialization.
+class flag_registerer
+{
+public:
+    flag_registerer(const char *section, const char *name, const char *desc, int32_t *val);
+    flag_registerer(const char *section, const char *name, const char *desc, uint32_t *val);
+    flag_registerer(const char *section, const char *name, const char *desc, int64_t *val);
+    flag_registerer(const char *section, const char *name, const char *desc, uint64_t *val);
+    flag_registerer(const char *section, const char *name, const char *desc, double *val);
+    flag_registerer(const char *section, const char *name, const char *desc, bool *val);
+    flag_registerer(const char *section, const char *name, const char *desc, const char **val);
+};
+
+// An utility class that registers a validator upon initialization.
+class flag_validator
+{
+public:
+    flag_validator(const char *name, std::function<void()>);
+};
+
+// Loads all the flags from configuration.
+extern void flags_initialize();
+
+} // namespace dsn

src/core/core/flags.cpp

@@ -0,0 +1,127 @@
+// Copyright (c) 2017-present, Xiaomi, Inc.  All rights reserved.
+// This source code is licensed under the Apache License Version 2.0, which
+// can be found in the LICENSE file in the root directory of this source tree.
+
+#include <dsn/utility/flags.h>
+#include <dsn/utility/config_api.h>
+#include <dsn/utility/singleton.h>
+#include <dsn/c/api_utilities.h>
+#include <boost/optional/optional.hpp>
+
+#include <map>
+
+namespace dsn {
+
+enum value_type
+{
+    FV_BOOL = 0,
+    FV_INT32 = 1,
+    FV_UINT32 = 2,
+    FV_INT64 = 3,
+    FV_UINT64 = 4,
+    FV_DOUBLE = 5,
+    FV_STRING = 6,
+    FV_MAX_INDEX = 6,
+};
+
+using validator_fn = std::function<void()>;
+
+class flag_data
+{
+public:
+#define FLAG_DATA_LOAD_CASE(type, type_enum, suffix)                                               \
+    case type_enum:                                                                                \
+        value<type>() = dsn_config_get_value_##suffix(_section, _name, value<type>(), _desc);      \
+        if (_validator) {                                                                          \
+            _validator();                                                                          \
+        }                                                                                          \
+        break
+
+    void load()
+    {
+        switch (_type) {
+            FLAG_DATA_LOAD_CASE(int32_t, FV_INT32, int64);
+            FLAG_DATA_LOAD_CASE(int64_t, FV_INT64, int64);
+            FLAG_DATA_LOAD_CASE(uint32_t, FV_UINT32, uint64);
+            FLAG_DATA_LOAD_CASE(uint64_t, FV_UINT64, uint64);
+            FLAG_DATA_LOAD_CASE(bool, FV_BOOL, bool);
+            FLAG_DATA_LOAD_CASE(double, FV_DOUBLE, double);
+            FLAG_DATA_LOAD_CASE(const char *, FV_STRING, string);
+        }
+    }
+
+    flag_data(const char *section, const char *name, const char *desc, value_type type, void *val)
+        : _type(type), _val(val), _section(section), _name(name), _desc(desc)
+    {
+    }
+
+    void set_validator(validator_fn &validator) { _validator = std::move(validator); }
+    const validator_fn &validator() const { return _validator; }
+
+private:
+    template <typename T>
+    T &value()
+    {
+        return *reinterpret_cast<T *>(_val);
+    }
+
+private:
+    const value_type _type;
+    void *const _val;
+    const char *_section;
+    const char *_name;
+    const char *_desc;
+    validator_fn _validator;
+};
+
+class flag_registry : public utils::singleton<flag_registry>
+{
+public:
+    flag_registry() {}
+
+    void add_flag(const char *name, flag_data flag) { _flags.emplace(name, flag); }
+
+    void add_validator(const char *name, validator_fn &validator)
+    {
+        auto it = _flags.find(name);
+        dassert(it != _flags.end(), "flag \"%s\" does not exist", name);
+        flag_data &flag = it->second;
+        dassert(!flag.validator(), "\"%s\" validator already registered", name);
+        flag.set_validator(validator);
+    }
+
+    void load_from_config()
+    {
+        for (auto &kv : _flags) {
+            flag_data &flag = kv.second;
+            flag.load();
+        }
+    }
+
+private:
+    std::map<std::string, flag_data> _flags;
+};
+
+#define FLAG_REG_CONSTRUCTOR(type, type_enum)                                                      \
+    flag_registerer::flag_registerer(                                                              \
+        const char *section, const char *name, const char *desc, type *val)                        \
+    {                                                                                              \
+        flag_registry::instance().add_flag(name, flag_data(section, name, desc, type_enum, val));  \
+    }
+
+FLAG_REG_CONSTRUCTOR(int32_t, FV_INT32);
+FLAG_REG_CONSTRUCTOR(uint32_t, FV_UINT32);
+FLAG_REG_CONSTRUCTOR(int64_t, FV_INT64);
+FLAG_REG_CONSTRUCTOR(uint64_t, FV_UINT64);
+FLAG_REG_CONSTRUCTOR(bool, FV_BOOL);
+FLAG_REG_CONSTRUCTOR(double, FV_DOUBLE);
+FLAG_REG_CONSTRUCTOR(const char *, FV_STRING);
+
+flag_validator::flag_validator(const char *name, validator_fn validator)
+{
+    flag_registry::instance().add_validator(name, validator);
+}
+
+/*extern*/ void flags_initialize() { flag_registry::instance().load_from_config(); }
+
+} // namespace dsn

src/core/core/logging.cpp

@@ -24,24 +24,21 @@
  * THE SOFTWARE.
  */
 
-/*
- * Description:
- * Description:
- *     What is this file about?
- *
- * Revision history:
- *     xxxx-xx-xx, author, first version
- *     xxxx-xx-xx, author, fix bug about xxx
- */
-
 #include <dsn/service_api_c.h>
 #include <dsn/tool-api/command_manager.h>
 #include <dsn/tool-api/logging_provider.h>
 #include <dsn/tool_api.h>
 #include "service_engine.h"
 #include <dsn/tool-api/auto_codes.h>
+#include <dsn/utility/flags.h>
 
 DSN_API dsn_log_level_t dsn_log_start_level = dsn_log_level_t::LOG_LEVEL_INFORMATION;
+DSN_DEFINE_string("core",
+                  logging_start_level,
+                  "LOG_LEVEL_INFORMATION",
+                  "logs with level below this will not be logged");
+
+DSN_DEFINE_bool("core", logging_flush_on_exit, true, "flush log when exit system");
 
 static void log_on_sys_exit(::dsn::sys_exit_type)
 {
@@ -53,20 +50,14 @@ static void log_on_sys_exit(::dsn::sys_exit_type)
 
 void dsn_log_init()
 {
-    dsn_log_start_level = enum_from_string(
-        dsn_config_get_value_string("core",
-                                    "logging_start_level",
-                                    enum_to_string(dsn_log_start_level),
-                                    "logs with level below this will not be logged"),
-        dsn_log_level_t::LOG_LEVEL_INVALID);
+    dsn_log_start_level =
+        enum_from_string(FLAGS_logging_start_level, dsn_log_level_t::LOG_LEVEL_INVALID);
 
     dassert(dsn_log_start_level != dsn_log_level_t::LOG_LEVEL_INVALID,
             "invalid [core] logging_start_level specified");
 
     // register log flush on exit
-    bool logging_flush_on_exit = dsn_config_get_value_bool(
-        "core", "logging_flush_on_exit", true, "flush log when exit system");
-    if (logging_flush_on_exit) {
+    if (FLAGS_logging_flush_on_exit) {
         ::dsn::tools::sys_exit.put_back(log_on_sys_exit, "log.flush");
     }
 
@@ -89,12 +80,8 @@ void dsn_log_init()
         [](const std::vector<std::string> &args) {
             dsn_log_level_t start_level;
             if (args.size() == 0) {
-                start_level = enum_from_string(
-                    dsn_config_get_value_string("core",
-                                                "logging_start_level",
-                                                enum_to_string(dsn_log_start_level),
-                                                "logs with level below this will not be logged"),
-                    dsn_log_level_t::LOG_LEVEL_INVALID);
+                start_level =
+                    enum_from_string(FLAGS_logging_start_level, dsn_log_level_t::LOG_LEVEL_INVALID);
             } else {
                 std::string level_str = "LOG_LEVEL_" + args[0];
                 start_level =

src/core/core/service_api_c.cpp

@@ -29,6 +29,7 @@
 #include <dsn/cpp/serialization.h>
 #include <dsn/utility/filesystem.h>
 #include <dsn/utility/process_utils.h>
+#include <dsn/utility/flags.h>
 #include <dsn/tool-api/command_manager.h>
 #include <fstream>
 #ifdef DSN_ENABLE_GPERF
@@ -318,6 +319,8 @@ bool run(const char *config_file,
         return false;
     }
 
+    dsn::flags_initialize();
+
     // pause when necessary
     if (dsn_config_get_value_bool("core",
                                   "pause_on_start",