feat: support to modify configs without restart (#682)

include/dsn/utility/flags.h

@@ -7,6 +7,13 @@
 #include <string>
 #include <cstdint>
 #include <functional>
+#include "errors.h"
+#include "utils.h"
+
+enum class flag_tag
+{
+    FT_MUTABLE = 0, /** flag data is mutable */
+};
 
 // Example:
 //    DSN_DEFINE_string("core", filename, "my_file.txt", "The file to read");
@@ -52,6 +59,10 @@
         dassert(FLAGS_VALIDATOR_FN_##name(FLAGS_##name), "validation failed: %s", #name);          \
     })
 
+#define DSN_TAG_VARIABLE(name, tag)                                                                \
+    COMPILE_ASSERT(sizeof(decltype(FLAGS_##name)), exist_##name##_##tag);                          \
+    static dsn::flag_tagger FLAGS_TAGGER_##name##_##tag(#name, flag_tag::tag)
+
 namespace dsn {
 
 // An utility class that registers a flag upon initialization.
@@ -74,7 +85,18 @@ class flag_validator
     flag_validator(const char *name, std::function<void()>);
 };
 
+class flag_tagger
+{
+public:
+    flag_tagger(const char *name, const flag_tag &tag);
+};
+
 // Loads all the flags from configuration.
 extern void flags_initialize();
 
+// update the specified flag to val
+extern error_s update_flag(const std::string &name, const std::string &val);
+
+// determine if the tag is exist for the specified flag
+extern bool has_tag(const std::string &name, const flag_tag &tag);
 } // namespace dsn

include/dsn/utility/string_conv.h

@@ -116,6 +116,11 @@ inline bool buf2int64(string_view buf, int64_t &result)
     return internal::buf2signed(buf, result);
 }
 
+inline bool buf2uint32(string_view buf, uint32_t &result)
+{
+    return internal::buf2unsigned(buf, result);
+}
+
 inline bool buf2uint64(string_view buf, uint64_t &result)
 {
     return internal::buf2unsigned(buf, result);

include/dsn/utility/utils.h

@@ -43,6 +43,26 @@
 
 #define TIME_MS_MAX 0xffffffff
 
+// The COMPILE_ASSERT macro can be used to verify that a compile time
+// expression is true. For example, you could use it to verify the
+// size of a static array:
+//
+//   COMPILE_ASSERT(ARRAYSIZE(content_type_names) == CONTENT_NUM_TYPES,
+//                  content_type_names_incorrect_size);
+//
+// or to make sure a struct is smaller than a certain size:
+//
+//   COMPILE_ASSERT(sizeof(foo) < 128, foo_too_large);
+//
+// The second argument to the macro is the name of the variable. If
+// the expression is false, most compilers will issue a warning/error
+// containing the name of the variable.
+struct CompileAssert
+{
+};
+
+#define COMPILE_ASSERT(expr, msg) static const CompileAssert msg[bool(expr) ? 1 : -1]
+
 namespace dsn {
 namespace utils {
 
@@ -88,5 +108,5 @@ bool hostname(const dsn::rpc_address &address, std::string *hostname_result);
 // valid_ip_network_order -> return TRUE && hostname_result=hostname	|
 // invalid_ip_network_order -> return FALSE
 bool hostname_from_ip(uint32_t ip, std::string *hostname_result);
-}
-}
+} // namespace utils
+} // namespace dsn

src/http/builtin_http_calls.cpp

@@ -72,6 +72,11 @@ namespace dsn {
             get_perf_counter_handler(req, resp);
         })
         .with_help("Gets the value of a perf counter");
+
+    register_http_call("updateConfig")
+        .with_callback(
+            [](const http_request &req, http_response &resp) { update_config(req, resp); })
+        .with_help("Updates the value of a config");
 }
 
 } // namespace dsn

src/http/builtin_http_calls.h

@@ -32,4 +32,6 @@ extern void get_help_handler(const http_request &req, http_response &resp);
 
 extern void get_recent_start_time_handler(const http_request &req, http_response &resp);
 
+extern void update_config(const http_request &req, http_response &resp);
+
 } // namespace dsn

src/http/config_http_service.cpp

@@ -0,0 +1,40 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#include <dsn/http/http_server.h>
+#include <dsn/utility/flags.h>
+#include <dsn/utility/output_utils.h>
+
+namespace dsn {
+void update_config(const http_request &req, http_response &resp)
+{
+    if (req.query_args.size() != 1) {
+        resp.status_code = http_status_code::bad_request;
+        return;
+    }
+
+    auto iter = req.query_args.begin();
+    auto res = update_flag(iter->first, iter->second);
+
+    utils::table_printer tp;
+    tp.add_row_name_and_data("update_status", res.description());
+    std::ostringstream out;
+    tp.output(out, dsn::utils::table_printer::output_format::kJsonCompact);
+    resp.body = out.str();
+    resp.status_code = http_status_code::ok;
+}
+} // namespace dsn

src/utils/flags.cpp

@@ -5,8 +5,11 @@
 #include <dsn/utility/flags.h>
 #include <dsn/utility/config_api.h>
 #include <dsn/utility/singleton.h>
+#include <dsn/utility/errors.h>
+#include <dsn/utility/string_conv.h>
 #include <dsn/c/api_utilities.h>
 #include <boost/optional/optional.hpp>
+#include <fmt/format.h>
 
 #include <map>
 
@@ -37,6 +40,19 @@ class flag_data
         }                                                                                          \
         break
 
+#define FLAG_DATA_UPDATE_CASE(type, type_enum, suffix)                                             \
+    case type_enum:                                                                                \
+        type tmpval_##type_enum;                                                                   \
+        if (!dsn::buf2##suffix(val, tmpval_##type_enum)) {                                         \
+            return error_s::make(ERR_INVALID_PARAMETERS, fmt::format("{} in invalid", val));       \
+        }                                                                                          \
+        value<type>() = tmpval_##type_enum;                                                        \
+        break
+
+#define FLAG_DATA_UPDATE_STRING()                                                                  \
+    case FV_STRING:                                                                                \
+        return error_s::make(ERR_INVALID_PARAMETERS, "string modifications are not supported")
+
     void load()
     {
         switch (_type) {
@@ -55,9 +71,30 @@ class flag_data
     {
     }
 
+    error_s update(const std::string &val)
+    {
+        if (!has_tag(flag_tag::FT_MUTABLE)) {
+            return error_s::make(ERR_INVALID_PARAMETERS, fmt::format("{} is not mutable", _name));
+        }
+
+        switch (_type) {
+            FLAG_DATA_UPDATE_CASE(int32_t, FV_INT32, int32);
+            FLAG_DATA_UPDATE_CASE(int64_t, FV_INT64, int64);
+            FLAG_DATA_UPDATE_CASE(uint32_t, FV_UINT32, uint32);
+            FLAG_DATA_UPDATE_CASE(uint64_t, FV_UINT64, uint64);
+            FLAG_DATA_UPDATE_CASE(bool, FV_BOOL, bool);
+            FLAG_DATA_UPDATE_CASE(double, FV_DOUBLE, double);
+            FLAG_DATA_UPDATE_STRING();
+        }
+        return error_s::make(ERR_OK);
+    }
+
     void set_validator(validator_fn &validator) { _validator = std::move(validator); }
     const validator_fn &validator() const { return _validator; }
 
+    void add_tag(const flag_tag &tag) { _tags.insert(tag); }
+    bool has_tag(const flag_tag &tag) const { return _tags.find(tag) != _tags.end(); }
+
 private:
     template <typename T>
     T &value()
@@ -72,13 +109,23 @@ class flag_data
     const char *_name;
     const char *_desc;
     validator_fn _validator;
+    std::unordered_set<flag_tag> _tags;
 };
 
 class flag_registry : public utils::singleton<flag_registry>
 {
 public:
     void add_flag(const char *name, flag_data flag) { _flags.emplace(name, flag); }
 
+    error_s update_flag(const std::string &name, const std::string &val)
+    {
+        auto it = _flags.find(name);
+        if (it == _flags.end()) {
+            return error_s::make(ERR_OBJECT_NOT_FOUND, fmt::format("{} is not found", name));
+        }
+        return it->second.update(val);
+    }
+
     void add_validator(const char *name, validator_fn &validator)
     {
         auto it = _flags.find(name);
@@ -97,6 +144,22 @@ class flag_registry : public utils::singleton<flag_registry>
         }
     }
 
+    void add_tag(const char *name, const flag_tag &tag)
+    {
+        auto it = _flags.find(name);
+        dassert(it != _flags.end(), "flag \"%s\" does not exist", name);
+        it->second.add_tag(tag);
+    }
+
+    bool has_tag(const std::string &name, const flag_tag &tag) const
+    {
+        auto it = _flags.find(name);
+        if (it == _flags.end()) {
+            return false;
+        }
+        return it->second.has_tag(tag);
+    }
+
 private:
     friend class utils::singleton<flag_registry>;
     flag_registry() = default;
@@ -125,6 +188,21 @@ flag_validator::flag_validator(const char *name, validator_fn validator)
     flag_registry::instance().add_validator(name, validator);
 }
 
+flag_tagger::flag_tagger(const char *name, const flag_tag &tag)
+{
+    flag_registry::instance().add_tag(name, tag);
+}
+
 /*extern*/ void flags_initialize() { flag_registry::instance().load_from_config(); }
 
+/*extern*/ error_s update_flag(const std::string &name, const std::string &val)
+{
+    return flag_registry::instance().update_flag(name, val);
+}
+
+/*extern*/ bool has_tag(const std::string &name, const flag_tag &tag)
+{
+    return flag_registry::instance().has_tag(name, tag);
+}
+
 } // namespace dsn

src/utils/test/flag_test.cpp

@@ -0,0 +1,105 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#include <gtest/gtest.h>
+#include <dsn/utility/flags.h>
+
+namespace dsn {
+namespace utils {
+
+DSN_DEFINE_int32("flag_test", test_int32, 5, "");
+DSN_TAG_VARIABLE(test_int32, FT_MUTABLE);
+
+DSN_DEFINE_uint32("flag_test", test_uint32, 5, "");
+DSN_TAG_VARIABLE(test_uint32, FT_MUTABLE);
+
+DSN_DEFINE_int64("flag_test", test_int64, 5, "");
+DSN_TAG_VARIABLE(test_int64, FT_MUTABLE);
+
+DSN_DEFINE_uint64("flag_test", test_uint64, 5, "");
+DSN_TAG_VARIABLE(test_uint64, FT_MUTABLE);
+
+DSN_DEFINE_double("flag_test", test_double, 5.0, "");
+DSN_TAG_VARIABLE(test_double, FT_MUTABLE);
+
+DSN_DEFINE_bool("flag_test", test_bool, true, "");
+DSN_TAG_VARIABLE(test_bool, FT_MUTABLE);
+
+DSN_DEFINE_string("flag_test", test_string_immutable, "immutable_string", "");
+
+TEST(flag_test, update_config)
+{
+    auto res = update_flag("test_int32", "3");
+    ASSERT_TRUE(res.is_ok());
+    ASSERT_EQ(FLAGS_test_int32, 3);
+
+    res = update_flag("test_uint32", "3");
+    ASSERT_TRUE(res.is_ok());
+    ASSERT_EQ(FLAGS_test_uint32, 3);
+
+    res = update_flag("test_int64", "3");
+    ASSERT_TRUE(res.is_ok());
+    ASSERT_EQ(FLAGS_test_int64, 3);
+
+    res = update_flag("test_uint64", "3");
+    ASSERT_TRUE(res.is_ok());
+    ASSERT_EQ(FLAGS_test_uint64, 3);
+
+    res = update_flag("test_double", "3.0");
+    ASSERT_TRUE(res.is_ok());
+    ASSERT_EQ(FLAGS_test_double, 3.0);
+
+    res = update_flag("test_bool", "false");
+    ASSERT_TRUE(res.is_ok());
+    ASSERT_FALSE(FLAGS_test_bool);
+
+    // string modifications are not supported
+    res = update_flag("test_string_immutable", "update_string");
+    ASSERT_EQ(res.code(), ERR_INVALID_PARAMETERS);
+    ASSERT_EQ(strcmp(FLAGS_test_string_immutable, "immutable_string"), 0);
+
+    // test flag is not exist
+    res = update_flag("test_not_exist", "test_string");
+    ASSERT_EQ(res.code(), ERR_OBJECT_NOT_FOUND);
+
+    // test to update invalid value
+    res = update_flag("test_int32", "3ab");
+    ASSERT_EQ(res.code(), ERR_INVALID_PARAMETERS);
+    ASSERT_EQ(FLAGS_test_int32, 3);
+}
+
+DSN_DEFINE_int32("flag_test", has_tag, 5, "");
+DSN_TAG_VARIABLE(has_tag, FT_MUTABLE);
+
+DSN_DEFINE_int32("flag_test", no_tag, 5, "");
+
+TEST(flag_test, tag_flag)
+{
+    // has tag
+    auto res = has_tag("has_tag", flag_tag::FT_MUTABLE);
+    ASSERT_TRUE(res);
+
+    // doesn't has tag
+    res = has_tag("no_tag", flag_tag::FT_MUTABLE);
+    ASSERT_FALSE(res);
+
+    // flag is not exist
+    res = has_tag("no_flag", flag_tag::FT_MUTABLE);
+    ASSERT_FALSE(res);
+}
+} // namespace utils
+} // namespace dsn