size_t ConsistentHashingLoadBalancer::AddServersInBatch(
const std::vector<ServerId> &servers) {
std::vector<Node> add_nodes;
add_nodes.reserve(servers.size() * _num_replicas);
for (size_t i = 0; i < servers.size(); ++i) {
SocketUniquePtr ptr;
if (Socket::AddressFailedAsWell(servers[i].id, &ptr) == -1) {
continue;
}
for (size_t rep = 0; rep < _num_replicas; ++rep) {
char host[32];
// To be compatible with libmemcached, we formulate the key of
// a virtual node as `|address|-|replica_index|', see
// http://fe.baidu.com/-1bszwnf at line 297.
int len = snprintf(host, sizeof(host), "%s-%lu",
endpoint2str(ptr->remote_side()).c_str(), rep);
Node node;
node.hash = _hash(host, len);
node.server_sock = servers[i];
node.server_addr = ptr->remote_side();
add_nodes.push_back(node);
}
}
std::sort(add_nodes.begin(), add_nodes.end());
bool executed = false;
const size_t ret = _db_hash_ring.ModifyWithForeground(AddBatch, add_nodes, &executed);
CHECK(ret % _num_replicas == 0);
const size_t n = ret / _num_replicas;
LOG_IF(ERROR, n != servers.size())
<< "Fail to AddServersInBatch, expected " << servers.size()
<< " actually " << n;
return n;
}
bool ConsistentHashingLoadBalancer::AddServer(const ServerId& server) {
std::vector<Node> add_nodes;
add_nodes.reserve(_num_replicas);
SocketUniquePtr ptr;
if (Socket::AddressFailedAsWell(server.id, &ptr) == -1) {
return false;
}
for (size_t i = 0; i < _num_replicas; ++i) {
char host[32];
int len = snprintf(host, sizeof(host), "%s-%lu",
endpoint2str(ptr->remote_side()).c_str(), i);
Node node;
node.hash = _hash(host, len);
node.server_sock = server;
node.server_addr = ptr->remote_side();
add_nodes.push_back(node);
}
std::sort(add_nodes.begin(), add_nodes.end());
bool executed = false;
const size_t ret = _db_hash_ring.ModifyWithForeground(
AddBatch, add_nodes, &executed);
CHECK(ret == 0 || ret == _num_replicas) << ret;
return ret != 0;
}
