Docker Swarm Code Analysis Note (6) Newcluster function of--swarm driver

This is a creation in Article, where the information may have evolved or changed.

Swarm driverThe NewCluster core functions of the function are as follows ( cluster/swarm/cluster.go ):

discoveryCh, errCh := cluster.discovery.Watch(nil)go cluster.monitorDiscovery(discoveryCh, errCh)go cluster.monitorPendingEngines()

cluster.discovery.Watchis defined as follows:

Watch(stopCh <-chan struct{}) (<-chan Entries, <-chan error)

Returns two channel : the first channel type is Entries ( type Entries []*Entry ), which transmits the cluster contained host information, and the second is channel used to notify whether an error occurred.

Cluster.monitorDiscoveryfunction is to organize Cluster.engines :

select {    case entries := <-ch:        added, removed := currentEntries.Diff(entries)        currentEntries = entries        // Remove engines first. `addEngine` will refuse to add an engine        // if there's already an engine with the same ID.  If an engine        // changes address, we have to first remove it then add it back.        for _, entry := range removed {            c.removeEngine(entry.String())        }        for _, entry := range added {            c.addEngine(entry.String())        }    case err := <-errCh:        log.Errorf("Discovery error: %v", err)    }

Instead, Cluster.monitorPendingEngines Verify that pending the status is Cluster.engines now able to connect:

for _, e := range pEngines {        if e.TimeToValidate() {            go c.validatePendingEngine(e)        }    }