Function slaveIsInHandshakeState

app/redis-6.2.6/src/replication.c:1421–1424

Returns 1 if the given replication state is a handshake state, * 0 otherwise. */

/* Returns 1 if the given replication state is a handshake state,
 * 0 otherwise. */
int slaveIsInHandshakeState(void) {
    return server.repl_state >= REPL_STATE_RECEIVE_PING_REPLY &&
           server.repl_state <= REPL_STATE_RECEIVE_PSYNC_REPLY;
}

/* Avoid the master to detect the slave is timing out while loading the
 * RDB file in initial synchronization. We send a single newline character