// threadedProbeHost tries to fetch the settings of a host. If successful, the
// host is put in the set of active hosts. If unsuccessful, the host id deleted
// from the set of active hosts.
func (hdb *HostDB) threadedProbeHosts() {
for hostEntry := range hdb.scanPool {
// Request settings from the queued host entry.
var settings modules.HostSettings
err := func() error {
conn, err := net.DialTimeout("tcp", string(hostEntry.IPAddress), hostRequestTimeout)
if err != nil {
return err
}
defer conn.Close()
err = encoding.WriteObject(conn, [8]byte{'S', 'e', 't', 't', 'i', 'n', 'g', 's'})
if err != nil {
return err
}
return encoding.ReadObject(conn, &settings, maxSettingsLen)
}()
// Now that network communication is done, lock the hostdb to modify the
// host entry.
id := hdb.mu.Lock()
{
if err != nil {
hdb.decrementReliability(hostEntry.IPAddress, UnreachablePenalty)
hdb.mu.Unlock(id)
continue
}
// Update the host settings, reliability, and weight. The old IPAddress
// must be preserved.
settings.IPAddress = hostEntry.HostSettings.IPAddress
hostEntry.HostSettings = settings
hostEntry.reliability = MaxReliability
hostEntry.weight = hdb.hostWeight(*hostEntry)
// If the host is not already in the database and 'MaxActiveHosts' has not
// been reached, add the host to the database.
_, exists1 := hdb.activeHosts[hostEntry.IPAddress]
_, exists2 := hdb.allHosts[hostEntry.IPAddress]
if !exists1 && exists2 && len(hdb.activeHosts) < MaxActiveHosts {
hdb.insertNode(hostEntry)
hdb.notifySubscribers()
}
}
hdb.mu.Unlock(id)
}
}
