[zmq] pub/sub is not reliable at all #12754
Description
The client only subscribe hashblock topic, if there's no block found over than about 30 minutes on the network, the pub/sub will timeout and the client can't detect anything unusual, the client will keep waiting forever.
I fix this by reconnecting, example code:
#define BITCOIND_ZMQ_HASHBLOCK "hashblock"
const time_t KReconnectInterval = 600; // seconds
//
// check if need to reconnect ZMQ
//
if (subscriber == nullptr || lastRecvTime + KReconnectInterval < time(nullptr)) {
// disconnect
if (subscriber != nullptr) {
delete subscriber;
subscriber = nullptr;
}
// connect
subscriber = new zmq::socket_t(zmqContext_, ZMQ_SUB);
subscriber->connect(zmqBitcoindAddr_);
// subscribe topic
subscriber->setsockopt(ZMQ_SUBSCRIBE,
BITCOIND_ZMQ_HASHBLOCK, strlen(BITCOIND_ZMQ_HASHBLOCK));
}
//
// recv ZMQ messages
//
// ...
// set last recv time
lastRecvTime = time(nullptr);
// ...I am not sure if add these options by zmq_setsockopt() could solve this issue.
// ZMQ_HEARTBEAT_xxxx available since zmq-4.2.0
ZMQ_HEARTBEAT_TTL
ZMQ_HEARTBEAT_TIMEOUT
ZMQ_HEARTBEAT_IVL
Maybe could add some heartbeat messages when there's no traffic for a while? I prefer this way.
Some links: