Add to_json method for Bucket::State

Allows for dropping the to_string() when inserting in json
objects

Change-Id: I29b304e30be71beb4fd2aa999deb1b659b9bb23b
Reviewed-on: https://review.couchbase.org/c/kv_engine/+/223805
Reviewed-by: Mohammad Zaeem <[email protected]>
Tested-by: Trond Norbye <[email protected]>

Author: trondn

daemon/bucket_manager_test.cc

@@ -337,7 +337,7 @@ TEST_F(BucketManagerTest, PauseBucket) {
         case Bucket::State::Ready:
         case Bucket::State::Destroying:
         case Bucket::State::Creating:
-            FAIL() << "Unexpected callback for state:" << to_string(state);
+            FAIL() << fmt::format("Unexpected callback for state: {}", state);
             break;
         case Bucket::State::Pausing:
             pausing = true;
@@ -435,7 +435,7 @@ void BucketManagerTest::testPauseBucketCancellable(
         case Bucket::State::Initializing:
         case Bucket::State::Destroying:
         case Bucket::State::Creating:
-            FAIL() << "Unexpected callback for state:" << to_string(state);
+            FAIL() << fmt::format("Unexpected callback for state: {}", state);
             break;
         case Bucket::State::Pausing:
             pausing = true;

daemon/buckets.cc

@@ -81,7 +81,7 @@ nlohmann::json Bucket::to_json() const {
     if (state != State::None) {
         try {
             nlohmann::json json;
-            json["state"] = to_string(state.load());
+            json["state"] = state.load();
             json["clients"] = clients.load();
             json["name"] = name;
             json["type"] = type;
@@ -423,7 +423,7 @@ std::string validateBucketName(std::string_view name) {
 }
 }
 
-std::string to_string(Bucket::State state) {
+std::string format_as(Bucket::State state) {
     switch (state) {
     case Bucket::State::None:
         return "none";

daemon/buckets.h

@@ -386,7 +386,12 @@ class Bucket {
 };
 
 void to_json(nlohmann::json& json, const Bucket& bucket);
-std::string to_string(Bucket::State state);
+std::string format_as(Bucket::State state);
+
+template <typename BasicJsonType>
+void to_json(BasicJsonType& j, Bucket::State state) {
+    j = format_as(state);
+}
 
 /**
  * All of the buckets are stored in the following array. Index 0 is reserved

daemon/protocol/mcbp/set_cluster_config_command_context.cc

@@ -114,7 +114,7 @@ cb::engine_errc SetClusterConfigCommandContext::doSetClusterConfig() {
                         {"bucket", bucketname},
                         {"global", bucketname.empty()},
                         {"status", status},
-                        {"state", to_string(state)});
+                        {"state", state});
         return status;
     }