Add noms root command for getting and setting root of entire db (#2992)

* Add `noms root` command for getting and setting root of entire db

* fix missing import

* rebase, review feedback

* review feedback

* moar review

cmd/noms/noms.go

@@ -23,6 +23,7 @@ var commands = []*util.Command{
 	nomsLog,
 	nomsMerge,
 	nomsMigrate,
+	nomsRoot,
 	nomsServe,
 	nomsShow,
 	nomsSync,

cmd/noms/noms_root.go

@@ -0,0 +1,112 @@
+// Copyright 2016 Attic Labs, Inc. All rights reserved.
+// Licensed under the Apache License, version 2.0:
+// http://www.apache.org/licenses/LICENSE-2.0
+
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"strings"
+
+	"github.com/attic-labs/noms/cmd/util"
+	"github.com/attic-labs/noms/go/config"
+	"github.com/attic-labs/noms/go/d"
+	"github.com/attic-labs/noms/go/datas"
+	"github.com/attic-labs/noms/go/hash"
+	"github.com/attic-labs/noms/go/types"
+	flag "github.com/juju/gnuflag"
+)
+
+var nomsRoot = &util.Command{
+	Run:       runRoot,
+	UsageLine: "root <db-spec>",
+	Short:     "Get or set the current root hash of the entire database",
+	Long:      "See Spelling Objects at https://github.com/attic-labs/noms/blob/master/doc/spelling.md for details on the database argument.",
+	Flags:     setupRootFlags,
+	Nargs:     1,
+}
+
+var updateRoot = ""
+
+func setupRootFlags() *flag.FlagSet {
+	flagSet := flag.NewFlagSet("root", flag.ExitOnError)
+	flagSet.StringVar(&updateRoot, "update", "", "Replaces the entire database with the one with the given hash")
+	return flagSet
+}
+
+func runRoot(args []string) int {
+	if len(args) < 1 {
+		fmt.Fprintln(os.Stderr, "Not enough arguments")
+		return 0
+	}
+
+	cfg := config.NewResolver()
+	rt, err := cfg.GetRootTracker(args[0])
+	d.CheckErrorNoUsage(err)
+
+	currRoot := rt.Root()
+
+	if updateRoot == "" {
+		fmt.Println(currRoot)
+		return 0
+	}
+
+	if updateRoot[0] == '#' {
+		updateRoot = updateRoot[1:]
+	}
+	h, ok := hash.MaybeParse(updateRoot)
+	if !ok {
+		fmt.Fprintf(os.Stderr, "Invalid hash: %s\n", h.String())
+		return 1
+	}
+
+	db, err := cfg.GetDatabase(args[0])
+	d.CheckErrorNoUsage(err)
+	defer db.Close()
+	if !validate(db.ReadValue(h)) {
+		return 1
+	}
+
+	fmt.Println(`WARNING
+
+This operation replaces the entire database with the instance having the given
+hash. The old database becomes eligible for GC.
+
+ANYTHING NOT SAVED WILL BE LOST
+
+Continue?
+`)
+	var input string
+	n, err := fmt.Scanln(&input)
+	d.CheckErrorNoUsage(err)
+	if n != 1 || strings.ToLower(input) != "y" {
+		return 0
+	}
+
+	ok = rt.UpdateRoot(h, currRoot)
+	if !ok {
+		fmt.Fprintln(os.Stderr, "Optimistic concurrency failure")
+		return 1
+	}
+
+	fmt.Printf("Success. Previous root was: %s\n", currRoot)
+	return 0
+}
+
+func validate(r types.Value) bool {
+	rootType := types.MakeMapType(types.StringType, types.MakeRefType(types.ValueType))
+	if !types.IsSubtype(rootType, r.Type()) {
+		fmt.Fprintf(os.Stderr, "Root of database must be %s, but you specified: %s\n", rootType.Describe(), r.Type().Describe())
+		return false
+	}
+
+	return r.(types.Map).Any(func(k, v types.Value) bool {
+		if !datas.IsRefOfCommitType(v.Type()) {
+			fmt.Fprintf(os.Stderr, "Invalid root map. Value for key '%s' is not a ref of commit.", string(k.(types.String)))
+			return false
+		}
+		return true
+	})
+}

cmd/noms/noms_root_test.go

@@ -0,0 +1,43 @@
+// Copyright 2016 Attic Labs, Inc. All rights reserved.
+// Licensed under the Apache License, version 2.0:
+// http://www.apache.org/licenses/LICENSE-2.0
+
+package main
+
+import (
+	"testing"
+
+	"github.com/attic-labs/noms/go/spec"
+	"github.com/attic-labs/noms/go/types"
+	"github.com/attic-labs/noms/go/util/clienttest"
+	"github.com/attic-labs/testify/suite"
+)
+
+func TestNomsRoot(t *testing.T) {
+	suite.Run(t, &nomsRootTestSuite{})
+}
+
+type nomsRootTestSuite struct {
+	clienttest.ClientTestSuite
+}
+
+func (s *nomsRootTestSuite) TestBasic() {
+	datasetName := "root-get"
+	dsSpec := spec.CreateValueSpecString("ldb", s.LdbDir, datasetName)
+	sp, err := spec.ForDataset(dsSpec)
+	s.NoError(err)
+	defer sp.Close()
+
+	ds := sp.GetDataset()
+	dbSpecStr := spec.CreateDatabaseSpecString("ldb", s.LdbDir)
+	ds, _ = ds.Database().CommitValue(ds, types.String("hello!"))
+	c1, _ := s.MustRun(main, []string{"root", dbSpecStr})
+	s.Equal("gt8mq6r7hvccp98s2vpeu9v9ct4rhloc\n", c1)
+
+	ds, _ = ds.Database().CommitValue(ds, types.String("goodbye"))
+	c2, _ := s.MustRun(main, []string{"root", dbSpecStr})
+	s.Equal("8tj5ctfhbka8fag417huneepg5ji283u\n", c2)
+
+	// TODO: Would be good to test successful --update too, but requires changes to MustRun to allow
+	// input because of prompt :(.
+}

go/config/resolver.go

@@ -104,6 +104,19 @@ func (r *Resolver) GetChunkStore(str string) (chunks.ChunkStore, error) {
 	return sp.NewChunkStore(), nil
 }
 
+// Resolve string to a RootTracker. Like ResolveDatabase, but returns a RootTracker instead
+func (r *Resolver) GetRootTracker(str string) (chunks.RootTracker, error) {
+	sp, err := spec.ForDatabase(r.verbose(str, r.ResolveDbSpec(str)))
+	if err != nil {
+		return nil, err
+	}
+	var rt chunks.RootTracker = sp.NewChunkStore()
+	if rt == nil {
+		rt = datas.NewHTTPBatchStore(sp.Spec, "")
+	}
+	return rt, nil
+}
+
 // Resolve string to a dataset. If a config is present,
 //  - if no db prefix is present, assume the default db
 //  - if the db prefix is an alias, replace it

go/datas/database.go

@@ -94,8 +94,13 @@ type Database interface {
 	// Regardless, Datasets() is updated to match backing storage upon return.
 	FastForward(ds Dataset, newHeadRef types.Ref) (Dataset, error)
 
-	has(h hash.Hash) bool
+	// validatingBatchStore returns the BatchStore used to read and write
+	// groups of values to the database efficiently. This interface is a low-
+	// level detail of the database that should infrequently be needed by
+	// clients.
 	validatingBatchStore() types.BatchStore
+
+	has(h hash.Hash) bool
 }
 
 func NewDatabase(cs chunks.ChunkStore) Database {

go/datas/database_test.go

@@ -60,7 +60,7 @@ type RemoteDatabaseSuite struct {
 func (suite *RemoteDatabaseSuite) SetupTest() {
 	suite.cs = chunks.NewTestStore()
 	suite.makeDb = func(cs chunks.ChunkStore) Database {
-		hbs := newHTTPBatchStoreForTest(cs)
+		hbs := NewHTTPBatchStoreForTest(cs)
 		return &RemoteDatabaseClient{newDatabaseCommon(newCachingChunkHaver(hbs), types.NewValueStore(hbs), hbs)}
 	}
 	suite.db = suite.makeDb(suite.cs)

go/datas/http_batch_store.go

@@ -53,7 +53,7 @@ type httpBatchStore struct {
 	hints         types.Hints
 }
 
-func newHTTPBatchStore(baseURL, auth string) *httpBatchStore {
+func NewHTTPBatchStore(baseURL, auth string) *httpBatchStore {
 	u, err := url.Parse(baseURL)
 	d.PanicIfError(err)
 	if u.Scheme != "http" && u.Scheme != "https" {

go/datas/http_batch_store_test.go

@@ -49,10 +49,10 @@ func (serv inlineServer) Do(req *http.Request) (resp *http.Response, err error)
 
 func (suite *HTTPBatchStoreSuite) SetupTest() {
 	suite.cs = chunks.NewTestStore()
-	suite.store = newHTTPBatchStoreForTest(suite.cs)
+	suite.store = NewHTTPBatchStoreForTest(suite.cs)
 }
 
-func newHTTPBatchStoreForTest(cs chunks.ChunkStore) *httpBatchStore {
+func NewHTTPBatchStoreForTest(cs chunks.ChunkStore) *httpBatchStore {
 	serv := inlineServer{httprouter.New()}
 	serv.POST(
 		constants.WriteValuePath,
@@ -84,7 +84,7 @@ func newHTTPBatchStoreForTest(cs chunks.ChunkStore) *httpBatchStore {
 			HandleRootGet(w, req, ps, cs)
 		},
 	)
-	hcs := newHTTPBatchStore("http://localhost:9000", "")
+	hcs := NewHTTPBatchStore("http://localhost:9000", "")
 	hcs.httpClient = serv
 	return hcs
 }
@@ -102,7 +102,7 @@ func newAuthenticatingHTTPBatchStoreForTest(suite *HTTPBatchStoreSuite, hostUrl
 			HandleRootPost(w, req, ps, suite.cs)
 		},
 	)
-	hcs := newHTTPBatchStore(hostUrl, "")
+	hcs := NewHTTPBatchStore(hostUrl, "")
 	hcs.httpClient = serv
 	return hcs
 }
@@ -116,7 +116,7 @@ func newBadVersionHTTPBatchStoreForTest(suite *HTTPBatchStoreSuite) *httpBatchSt
 			w.Header().Set(NomsVersionHeader, "BAD")
 		},
 	)
-	hcs := newHTTPBatchStore("http://localhost", "")
+	hcs := NewHTTPBatchStore("http://localhost", "")
 	hcs.httpClient = serv
 	return hcs
 }
@@ -210,7 +210,7 @@ func (b *backpressureCS) PutMany(chnx []chunks.Chunk) chunks.BackpressureError {
 
 func (suite *HTTPBatchStoreSuite) TestPutChunksBackpressure() {
 	bpcs := &backpressureCS{ChunkStore: suite.cs}
-	bs := newHTTPBatchStoreForTest(bpcs)
+	bs := NewHTTPBatchStoreForTest(bpcs)
 	defer bs.Close()
 	defer bpcs.Close()
 

go/datas/pull_test.go

@@ -85,7 +85,7 @@ func (suite *RemoteToRemoteSuite) SetupTest() {
 }
 
 func makeRemoteDb(cs chunks.ChunkStore) Database {
-	hbs := newHTTPBatchStoreForTest(cs)
+	hbs := NewHTTPBatchStoreForTest(cs)
 	return &RemoteDatabaseClient{newDatabaseCommon(newCachingChunkHaver(hbs), types.NewValueStore(hbs), hbs)}
 }
 

go/datas/remote_database_client.go

@@ -15,7 +15,7 @@ type RemoteDatabaseClient struct {
 }
 
 func NewRemoteDatabase(baseURL, auth string) *RemoteDatabaseClient {
-	httpBS := newHTTPBatchStore(baseURL, auth)
+	httpBS := NewHTTPBatchStore(baseURL, auth)
 	return &RemoteDatabaseClient{newDatabaseCommon(newCachingChunkHaver(httpBS), types.NewValueStore(httpBS), httpBS)}
 }
 

go/types/map.go

@@ -247,6 +247,18 @@ func (m Map) Iter(cb mapIterCallback) {
 	})
 }
 
+// Any returns true if cb() return true for any of the items in the map.
+func (m Map) Any(cb func(k, v Value) bool) (yep bool) {
+	m.Iter(func(k, v Value) bool {
+		if cb(k, v) {
+			yep = true
+			return true
+		}
+		return false
+	})
+	return
+}
+
 type mapIterAllCallback func(key, value Value)
 
 func (m Map) IterAll(cb mapIterAllCallback) {

go/types/map_test.go

@@ -808,6 +808,18 @@ func TestMapIter2(t *testing.T) {
 	doTest(getTestRefToValueOrderMap(2, NewTestValueStore()))
 }
 
+func TestMapAny(t *testing.T) {
+	assert := assert.New(t)
+
+	p := func(k, v Value) bool {
+		return k.Equals(String("foo")) && v.Equals(String("bar"))
+	}
+
+	assert.False(NewMap().Any(p))
+	assert.False(NewMap(String("foo"), String("baz")).Any(p))
+	assert.True(NewMap(String("foo"), String("bar")).Any(p))
+}
+
 func TestMapIterAll(t *testing.T) {
 	if testing.Short() {
 		t.Skip("Skipping test in short mode.")