state: start allManager on demand

state/open.go

 package state
 
 import (
         "crypto/tls"
         "crypto/x509"
         "errors"
         "fmt"
         "net"
         "time"
 
         "labix.org/v2/mgo"
         "labix.org/v2/mgo/txn"
         "launchpad.net/juju-core/cert"
         "launchpad.net/juju-core/constraints"
         "launchpad.net/juju-core/environs/config"
         "launchpad.net/juju-core/log"
-        "launchpad.net/juju-core/state/multiwatcher"
         "launchpad.net/juju-core/state/presence"
         "launchpad.net/juju-core/state/watcher"
         "launchpad.net/juju-core/utils"
 )
 
 // Info encapsulates information about cluster of
 // servers holding juju state and can be used to make a
 // connection to that cluster.
 type Info struct {
         // Addrs gives the addresses of the MongoDB servers for the state.
@@ skipping 239 matching lines @@
         st.runner = txn.NewRunner(db.C("txns"))
         st.runner.ChangeLog(db.C("txns.log"))
         st.watcher = watcher.New(db.C("txns.log"))
         st.pwatcher = presence.NewWatcher(pdb.C("presence"))
         for _, item := range indexes {
                 index := mgo.Index{Key: item.key}
                 if err := db.C(item.collection).EnsureIndex(index); err != nil {
                         return nil, fmt.Errorf("cannot create database index: %v", err)
                 }
         }
-        st.allManager = multiwatcher.NewStoreManager(newAllWatcherStateBacking(st))
         return st, nil
 }
 
 // Addresses returns the list of addresses used to connect to the state.
 func (st *State) Addresses() (addrs []string) {
         return append(addrs, st.info.Addrs...)
 }
 
 // CACert returns the certificate used to validate the state connection.
 func (st *State) CACert() (cert []byte) {
         return append(cert, st.info.CACert...)
 }
 
 func (st *State) Close() error {
         err1 := st.watcher.Stop()
         err2 := st.pwatcher.Stop()
-        err3 := st.allManager.Stop()
+        st.mu.Lock()
+        var err3 error
+        if st.allManager != nil {
+                err3 = st.allManager.Stop()
+        }
+        st.mu.Unlock()
         st.db.Session.Close()
         for _, err := range []error{err1, err2, err3} {
                 if err != nil {
                         return err
                 }
         }
         return nil
 }