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Consistent hashing support server tag #2994

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Merged
wwbmmm merged 2 commits into from
Jun 20, 2025
Merged

Consistent hashing support server tag #2994

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1f35b54
fix: consistent hashing support server tag
egolearner Jun 12, 2025
4512205
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egolearner Jun 16, 2025
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18 changes: 16 additions & 2 deletions src/brpc/policy/consistent_hashing_load_balancer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,8 @@ namespace policy {
// TODO: or 160?
DEFINE_int32(chash_num_replicas, 100,
"default number of replicas per server in chash");
DEFINE_bool(consistent_hashing_enable_server_tag, false,
"if consistent hashing enable server with tag");

// Defined in hasher.cpp.
const char* GetHashName(HashFunc hasher);
Expand Down Expand Up @@ -71,8 +73,14 @@ bool DefaultReplicaPolicy::Build(ServerId server,
replicas->clear();
for (size_t i = 0; i < num_replicas; ++i) {
char host[256];
int len = snprintf(host, sizeof(host), "%s-%lu",
int len = 0;
if (!FLAGS_consistent_hashing_enable_server_tag) {
len = snprintf(host, sizeof(host), "%s-%lu",
endpoint2str(ptr->remote_side()).c_str(), i);
} else {
len = snprintf(host, sizeof(host), "%s-%lu-%s",
endpoint2str(ptr->remote_side()).c_str(), i, server.tag.c_str());
}
ConsistentHashingLoadBalancer::Node node;
node.hash = _hash_func(host, len);
node.server_sock = server;
Expand Down Expand Up @@ -104,8 +112,14 @@ bool KetamaReplicaPolicy::Build(ServerId server,
<< "Ketam hash replicas number(" << num_replicas << ") should be n*4";
for (size_t i = 0; i < num_replicas / points_per_hash; ++i) {
char host[256];
int len = snprintf(host, sizeof(host), "%s-%lu",
int len = 0;
if (!FLAGS_consistent_hashing_enable_server_tag) {
len = snprintf(host, sizeof(host), "%s-%lu",
endpoint2str(ptr->remote_side()).c_str(), i);
} else {
len = snprintf(host, sizeof(host), "%s-%lu-%s",
endpoint2str(ptr->remote_side()).c_str(), i, server.tag.c_str());
}
unsigned char digest[MD5_DIGEST_LENGTH];
MD5HashSignature(host, len, digest);
for (size_t j = 0; j < points_per_hash; ++j) {
Expand Down
5 changes: 4 additions & 1 deletion src/brpc/policy/consistent_hashing_load_balancer.h
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Original file line number Diff line number Diff line change
Expand Up @@ -50,7 +50,10 @@ class ConsistentHashingLoadBalancer : public LoadBalancer {
bool operator<(const Node &rhs) const {
if (hash < rhs.hash) { return true; }
if (hash > rhs.hash) { return false; }
return server_addr < rhs.server_addr;
if (server_addr < rhs.server_addr) { return true; }
if (server_addr > rhs.server_addr) { return false; }
// compare by tag if has the same ip-port
return server_sock.tag < rhs.server_sock.tag;
}
bool operator<(const uint32_t code) const {
return hash < code;
Expand Down
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