Fix 'new manifest created with non 0 lock' error

Fix dropping and creating the same database on dolt sql-server. We were caching doltdb's using a singleton
and at the manifest cache level which lead to problems.

go/libraries/doltcore/dbfactory/file.go

@@ -65,6 +65,13 @@ func CloseAllLocalDatabases() (err error) {
 	return
 }
 
+func DeleteFromSingletonCache(path string) error {
+	singletonLock.Lock()
+	defer singletonLock.Unlock()
+	delete(singletons, path)
+	return nil
+}
+
 // PrepareDB creates the directory for the DB if it doesn't exist, and returns an error if a file or symlink is at the
 // path given
 func (fact FileFactory) PrepareDB(ctx context.Context, nbf *types.NomsBinFormat, u *url.URL, params map[string]interface{}) error {

go/libraries/doltcore/doltdb/doltdb.go

@@ -215,6 +215,10 @@ func (ddb *DoltDB) WriteEmptyRepoWithCommitTimeAndDefaultBranch(
 	return err
 }
 
+func (ddb *DoltDB) Close() error {
+	return ddb.db.Close()
+}
+
 func getCommitValForRefStr(ctx context.Context, db datas.Database, vrw types.ValueReadWriter, ref string) (*datas.Commit, error) {
 	if err := datas.ValidateDatasetId(ref); err != nil {
 		return nil, fmt.Errorf("invalid ref format: %s", ref)

go/libraries/doltcore/sqle/database_provider.go

@@ -592,15 +592,29 @@ func (p DoltDatabaseProvider) DropDatabase(ctx *sql.Context, name string) error
 	dbKey := formatDbMapKeyName(name)
 	db := p.databases[dbKey]
 
+	ddb := db.(Database).ddb
+	err = ddb.Close()
+	if err != nil {
+		return err
+	}
+
 	// get location of database that's being dropped
 	dbLoc := p.dbLocations[dbKey]
 	if dbLoc == nil {
 		return sql.ErrDatabaseNotFound.New(db.Name())
 	}
+
 	dropDbLoc, err := dbLoc.Abs("")
 	if err != nil {
 		return err
 	}
+
+	// If this database is re-created, we don't want to return any cached results.
+	err = dbfactory.DeleteFromSingletonCache("file://" + dropDbLoc + "/.dolt/noms")
+	if err != nil {
+		return err
+	}
+
 	rootDbLoc, err := p.fs.Abs("")
 	if err != nil {
 		return err

go/store/nbs/manifest.go

@@ -427,6 +427,11 @@ func (mm manifestManager) UpdateGCGen(ctx context.Context, lastLock addr, newCon
 	return
 }
 
+func (mm manifestManager) Close() error {
+	mm.cache.Delete(mm.Name())
+	return nil
+}
+
 func (mm manifestManager) Name() string {
 	return mm.m.Name()
 }

go/store/nbs/manifest_cache.go

@@ -114,3 +114,17 @@ func (mc *manifestCache) Put(db string, contents manifestContents, t time.Time)
 
 	return nil
 }
+
+// Delete removes a key from the cache.
+func (mc *manifestCache) Delete(db string) {
+	mc.mu.Lock()
+	defer mc.mu.Unlock()
+
+	if entry, ok := mc.entry(db); ok {
+		mc.totalSize -= entry.contents.size()
+		mc.lru.Remove(entry.lruEntry)
+		delete(mc.cache, db)
+	}
+
+	return
+}

go/store/nbs/manifest_cache_test.go

@@ -128,4 +128,15 @@ func TestSizeCache(t *testing.T) {
 		assert.False(t, ok)
 	})
 
+	t.Run("Delete", func(t *testing.T) {
+		c := newManifestCache(1 * defSize)
+		err := c.Put("db", manifestContents{}, time.Now())
+		require.NoError(t, err)
+		_, _, ok := c.Get("db")
+		assert.True(t, ok)
+		c.Delete("db")
+		_, _, ok = c.Get("db")
+		assert.False(t, ok)
+	})
+
 }

go/store/nbs/store.go

@@ -1111,6 +1111,9 @@ func (nbs *NomsBlockStore) Close() (err error) {
 	if cerr := nbs.tables.close(); cerr != nil {
 		err = cerr
 	}
+	if cerr := nbs.mm.Close(); cerr != nil {
+		err = cerr
+	}
 	return
 }
 

integration-tests/bats/sql-server.bats

@@ -1798,6 +1798,29 @@ s.close()
     [[ ! "$output" =~ "mydb" ]] || false
 }
 
+@test "sql-server: create database, drop it, and then create it again" {
+    skiponwindows "Missing dependencies"
+
+    mkdir mydbs
+    cd mydbs
+
+    start_sql_server >> server_log.txt 2>&1
+    dolt sql-client -P $PORT -u dolt --use-db '' -q "CREATE DATABASE mydb1;"
+    [ -d mydb1 ]
+
+    run dolt sql-client -P $PORT -u dolt --use-db '' -q "DROP DATABASE mydb1;"
+    [ $status -eq 0 ]
+    [ ! -d mydb1 ]
+
+    run dolt sql-client -P $PORT -u dolt --use-db '' -q "CREATE DATABASE mydb1;"
+    [ $status -eq 0 ]
+    [ -d mydb1 ]
+
+    run dolt sql-client -P $PORT -u dolt --use-db '' -q "SHOW DATABASES;"
+    [ $status -eq 0 ]
+    [[ "$output" =~ "mydb1" ]] || false
+}
+
 @test "sql-server: dropping database with '-' in it" {
     skiponwindows "Missing dependencies"