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raft service: insert a new raft instance into the servers' list only after it is started

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RPC module starts to dispatching calls to a server the moment it is in the
servers' list, but until raft::server::start() completes the instance is
not fully created yet and is not ready to accept anything. Fix the code
that initialize new raft group to insert new raft instance into the list
only after it is started.

Message-Id: <YZTFFW9v0NlV7spR@scylladb.com>
This commit is contained in:
Gleb Natapov
2021-11-17 11:02:13 +02:00
committed by Tomasz Grabiec
parent 94eb5c55c8
commit f2ab5f4e60
1 changed files with 22 additions and 11 deletions
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33
service/raft/raft_group_registry.cc
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@@ -209,27 +209,38 @@ raft::server& raft_group_registry::group0() {
future<> raft_group_registry::start_server_for_group(raft_server_for_group new_grp) {
auto gid = new_grp.gid;
auto [it, inserted] = _servers.emplace(std::move(gid), std::move(new_grp));
if (!inserted) {
if (_servers.contains(gid)) {
on_internal_error(rslog, format("Attempt to add the second instance of raft server with the same gid={}", gid));
}
if (_servers.size() == 1 && this_shard_id() == 0) {
_group0_id = gid;
}
auto& grp = it->second;
try {
// start the server instance prior to arming the ticker timer.
// By the time the tick() is executed the server should already be initialized.
co_await grp.server->start();
co_await new_grp.server->start();
} catch (...) {
// remove server from the map to prevent calling `abort()` on a
// non-started instance when `raft_group_registry::uninit` is called.
_servers.erase(it);
on_internal_error(rslog, std::current_exception());
}
grp.ticker->arm_periodic(raft_tick_interval);
std::exception_ptr ex;
raft::server& server = *new_grp.server;
try {
auto [it, inserted] = _servers.emplace(std::move(gid), std::move(new_grp));
if (_servers.size() == 1 && this_shard_id() == 0) {
_group0_id = gid;
}
it->second.ticker->arm_periodic(raft_tick_interval);
} catch (...) {
ex = std::current_exception();
}
if (ex) {
co_await server.abort();
std::rethrow_exception(ex);
}
}
unsigned raft_group_registry::shard_for_group(const raft::group_id& gid) const {