utils: move generation-number to gms

Although get_generation_number implementation is
completely generic, it is used exclusively to seed
the gossip generation number.

Following patches will define a strong gms::generation_id
type and this function should return it.

Signed-off-by: Benny Halevy <bhalevy@scylladb.com>

configure.py

@@ -700,7 +700,7 @@ scylla_core = (['message/messaging_service.cc',
                 'utils/limiting_data_source.cc',
                 'utils/updateable_value.cc',
                 'utils/directories.cc',
-                'utils/generation-number.cc',
+                'gms/generation-number.cc',
                 'utils/rjson.cc',
                 'utils/human_readable.cc',
                 'utils/histogram_metrics_helper.cc',

db/system_keyspace.cc

@@ -51,7 +51,7 @@
 #include "db/view/build_progress_virtual_reader.hh"
 #include "db/schema_tables.hh"
 #include "index/built_indexes_virtual_reader.hh"
-#include "utils/generation-number.hh"
+#include "gms/generation-number.hh"
 #include "db/virtual_table.hh"
 #include "service/storage_service.hh"
 #include "protocol_server.hh"
@@ -3125,11 +3125,11 @@ future<int> system_keyspace::increment_and_get_generation() {
         // seconds-since-epoch isn't a foolproof new generation
         // (where foolproof is "guaranteed to be larger than the last one seen at this ip address"),
         // but it's as close as sanely possible
-        generation = utils::get_generation_number();
+        generation = gms::get_generation_number();
     } else {
         // Other nodes will ignore gossip messages about a node that have a lower generation than previously seen.
         int stored_generation = rs->one().template get_as<int>("gossip_generation") + 1;
-        int now = utils::get_generation_number();
+        int now = gms::get_generation_number();
         if (stored_generation >= now) {
             slogger.warn("Using stored Gossip Generation {} as it is greater than current system time {}."
                         "See CASSANDRA-3654 if you experience problems", stored_generation, now);

gms/generation-number.cc

@@ -9,7 +9,7 @@
 #include <chrono>
 #include "generation-number.hh"
 
-namespace utils {
+namespace gms {
 
 int get_generation_number() {
     using namespace std::chrono;

gms/generation-number.hh

@@ -8,7 +8,7 @@
 
 #pragma once
 
-namespace utils {
+namespace gms {
 
 int get_generation_number();
 

gms/gossiper.cc

@@ -38,7 +38,7 @@
 #include <boost/range/algorithm/partition.hpp>
 #include <boost/algorithm/string/split.hpp>
 #include <boost/algorithm/string/classification.hpp>
-#include "utils/generation-number.hh"
+#include "gms/generation-number.hh"
 #include "locator/token_metadata.hh"
 #include "utils/exceptions.hh"
 
@@ -567,7 +567,7 @@ future<> gossiper::do_apply_state_locally(gms::inet_address node, const endpoint
         int local_generation = local_state.get_heart_beat_state().get_generation();
         int remote_generation = remote_state.get_heart_beat_state().get_generation();
         logger.trace("{} local generation {}, remote generation {}", node, local_generation, remote_generation);
-        if (remote_generation > utils::get_generation_number() + MAX_GENERATION_DIFFERENCE) {
+        if (remote_generation > get_generation_number() + MAX_GENERATION_DIFFERENCE) {
             // assume some peer has corrupted memory and is broadcasting an unbelievable generation about another peer (or itself)
             logger.warn("received an invalid gossip generation for peer {}; local generation = {}, received generation = {}",
                 node, local_generation, remote_generation);

service/storage_service.cc

@@ -59,7 +59,7 @@
 #include "repair/repair.hh"
 #include "repair/row_level.hh"
 #include "service/priority_manager.hh"
-#include "utils/generation-number.hh"
+#include "gms/generation-number.hh"
 #include <seastar/core/coroutine.hh>
 #include <seastar/coroutine/maybe_yield.hh>
 #include <seastar/coroutine/parallel_for_each.hh>
@@ -2948,7 +2948,7 @@ future<> storage_service::start_gossiping() {
                         co_await ss._sys_ks.local().get_local_tokens(),
                         cdc_gen_ts);
                 ss._gossiper.force_newer_generation();
-                co_await ss._gossiper.start_gossiping(utils::get_generation_number());
+                co_await ss._gossiper.start_gossiping(gms::get_generation_number());
             } catch (...) {
                 should_stop_gossiper = true;
             }

utils/CMakeLists.txt

@@ -21,7 +21,6 @@ target_sources(utils
     error_injection.cc
     exceptions.cc
     file_lock.cc
-    generation-number.cc
     gz/crc_combine.cc
     gz/crc_combine_table.cc
     hashers.cc