added hidden gc command

bats/garbage_collection.bats

@@ -0,0 +1,23 @@
+#!/usr/bin/env bats
+load $BATS_TEST_DIRNAME/helper/common.bash
+
+setup() {
+    setup_common
+}
+
+teardown() {
+    teardown_common
+}
+
+@test "dolt gc smoke test" {
+    run dolt gc
+    [ "$status" -eq "0" ]
+
+    dolt sql <<SQL
+CREATE TABLE test (pk int PRIMARY KEY);
+INSERT INTO test VALUES (1),(2),(3),(4),(5);
+SQL
+
+    run dolt gc
+    [ "$status" -eq "0" ]
+}

go/cmd/dolt/commands/gc.go

@@ -0,0 +1,96 @@
+// Copyright 2019 Liquidata, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package commands
+
+import (
+	"context"
+
+	"github.com/liquidata-inc/dolt/go/cmd/dolt/cli"
+	"github.com/liquidata-inc/dolt/go/cmd/dolt/errhand"
+	"github.com/liquidata-inc/dolt/go/libraries/doltcore/env"
+	"github.com/liquidata-inc/dolt/go/libraries/utils/argparser"
+	"github.com/liquidata-inc/dolt/go/libraries/utils/filesys"
+	"github.com/liquidata-inc/dolt/go/store/datas"
+)
+
+var gcDocs = cli.CommandDocumentationContent{
+	ShortDesc: "List tables",
+	LongDesc: `With no arguments lists the tables in the current working set but if a commit is specified it will list the tables in that commit.  If the {{.EmphasisLeft}}--verbose{{.EmphasisRight}} flag is provided a row count and a hash of the table will also be displayed.
+
+If the {{.EmphasisLeft}}--system{{.EmphasisRight}} flag is supplied this will show the dolt system tables which are queryable with SQL.  Some system tables can be queried even if they are not in the working set by specifying appropriate parameters in the SQL queries. To see these tables too you may pass the {{.EmphasisLeft}}--verbose{{.EmphasisRight}} flag.
+
+If the {{.EmphasisLeft}}--all{{.EmphasisRight}} flag is supplied both user and system tables will be printed.
+`,
+
+	Synopsis: []string{
+		"[--options] [{{.LessThan}}commit{{.GreaterThan}}]",
+	},
+}
+
+type GarbageCollectionCmd struct{}
+
+// Name is returns the name of the Dolt cli command. This is what is used on the command line to invoke the command
+func (cmd GarbageCollectionCmd) Name() string {
+	return "gc"
+}
+
+// Description returns a description of the command
+func (cmd GarbageCollectionCmd) Description() string {
+	return "Cleans up unreferenced data from the database."
+}
+
+// Hidden should return true if this command should be hidden from the help text
+func (cmd GarbageCollectionCmd) Hidden() bool {
+	return true
+}
+
+// RequiresRepo should return false if this interface is implemented, and the command does not have the requirement
+// that it be run from within a data repository directory
+func (cmd GarbageCollectionCmd) RequiresRepo() bool {
+	return true
+}
+
+// CreateMarkdown creates a markdown file containing the helptext for the command at the given path
+func (cmd GarbageCollectionCmd) CreateMarkdown(fs filesys.Filesys, path, commandStr string) error {
+	ap := cmd.createArgParser()
+	return CreateMarkdown(fs, path, cli.GetCommandDocumentation(commandStr, gcDocs, ap))
+}
+
+func (cmd GarbageCollectionCmd) createArgParser() *argparser.ArgParser {
+	ap := argparser.NewArgParser()
+	return ap
+}
+
+// Version displays the version of the running dolt client
+// Exec executes the command
+func (cmd GarbageCollectionCmd) Exec(ctx context.Context, commandStr string, args []string, dEnv *env.DoltEnv) int {
+	ap := cmd.createArgParser()
+	_, usage := cli.HelpAndUsagePrinters(cli.GetCommandDocumentation(commandStr, lsDocs, ap))
+
+	var verr errhand.VerboseError
+
+	db, ok := dEnv.DoltDB.ValueReadWriter().(datas.Database)
+	if !ok {
+		verr = errhand.BuildDError("this database does not support garbage collection").Build()
+	}
+
+	err := datas.PruneTableFiles(ctx, db)
+
+	if err != nil {
+		verr = errhand.BuildDError("an error occurred during garbage collection").AddCause(err).Build()
+	}
+
+	return HandleVErrAndExitCode(verr, usage)
+}

go/cmd/dolt/dolt.go

@@ -79,6 +79,7 @@ var doltCommand = cli.NewSubCommandHandler("dolt", "it's git for data", []cli.Co
 	commands.MigrateCmd{},
 	indexcmds.Commands,
 	commands.ReadTablesCmd{},
+	commands.GarbageCollectionCmd{},
 })
 
 func init() {
@@ -150,7 +151,7 @@ func runMain() int {
 	restoreIO := cli.InitIO()
 	defer restoreIO()
 
-	//warnIfMaxFilesTooLow()
+	warnIfMaxFilesTooLow()
 
 	ctx := context.Background()
 	dEnv := env.Load(ctx, env.GetCurrentUserHomeDir, filesys.LocalFS, doltdb.LocalDirDoltDB, Version)
@@ -199,7 +200,7 @@ func runMain() int {
 		return 1
 	}
 
-	//err = reconfigIfTempFileMoveFails(dEnv)
+	err = reconfigIfTempFileMoveFails(dEnv)
 
 	if err != nil {
 		cli.PrintErrln(color.RedString("Failed to setup the temporary directory. %v`", err))

go/store/datas/garbage_collection.go

@@ -0,0 +1,31 @@
+// Copyright 2020 Liquidata, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package datas
+
+import (
+	"context"
+
+	"github.com/liquidata-inc/dolt/go/store/nbs"
+)
+
+func PruneTableFiles(ctx context.Context, db Database) error {
+	tfs, ok := db.chunkStore().(nbs.TableFileStore)
+
+	if !ok {
+		return nbs.ErrUnsupportedOperation
+	}
+
+	return tfs.PruneTableFiles(ctx)
+}

go/store/nbs/file_table_persister.go

@@ -222,7 +222,7 @@ func (ftp *fsTablePersister) PruneTableFiles(ctx context.Context, contents manif
 	}
 
 	err = ftp.fc.ShrinkCache()
-	
+
 	if err != nil {
 		return err
 	}