client/isolate: add skeleton exparchive command

client/cmd/isolate/exp_archive.go

+// Copyright 2015 The LUCI Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+package main
+
+import (
+        "encoding/json"
+        "errors"
+        "fmt"
+        "io/ioutil"
+        "log"
+        "os"
+        "path/filepath"
+
+        "github.com/luci/luci-go/client/isolate"
+        "github.com/luci/luci-go/common/isolated"
+        "github.com/maruel/subcommands"
+)
+
+var cmdExpArchive = &subcommands.Command{
+        UsageLine: "exparchive <options>",
+        ShortDesc: "EXPERIMENTAL parses a .isolate file to creates a .isolated file, and uploads it and all referenced files to an isolate server",

[mcgreevy, 2016/11/22 23:43:35]

s/to creates/to create/

[djd-OOO-Apr2017, 2016/11/23 00:12:11]

Done.

+        LongDesc:  "All the files listed in the .isolated file are put in the isolate server cache. Small files are combined together in a tar archive before uploading.",
+        CommandRun: func() subcommands.CommandRun {
+                c := expArchiveRun{}
+                c.commonServerFlags.Init()
+                c.isolateFlags.Init(&c.Flags)
+                return &c
+        },
+}
+
+// expArchiveRun contains the logic for the experimental archive subcommand.
+// It implements subcommand.CommandRun
+type expArchiveRun struct {
+        commonServerFlags // Provides the GetFlags method.
+        isolateFlags      isolateFlags
+}
+
+// main contains the core logic for experimental archive.
+func (c *expArchiveRun) main() error {
+        // Parse the incoming isolate file.
+        deps, rootDir, isol, err := isolate.ProcessIsolate(&c.isolateFlags.ArchiveOptions)

[mcgreevy, 2016/11/22 23:43:35]

before this, can you do:

archiveOpts := &c.isolateFlags.ArchiveOptions

and use throughout?

It's be nice if we didn't hang on to isolateFlags at all -- just stored
ArchiveOptions, but as written it needs to be a field of expArchiveRun so that
it can be initialized on line 28, and then parsed on line 76.

Could you just create and Init isolateFlags as a temporary before line 76, and
then return ArchiveOptions from parseFlags, then pass it as an argument to main
(maybe call main something else)?  

[djd-OOO-Apr2017, 2016/11/23 00:12:11]

I would like to be able to do that, but I don't think I can: the initialisation
of the flags needs to happen before we return the CommandRun. This is because
GetFlags needs the full list of flags to support help (./isolate help
exparchive). If I do it only in Main then that help text is missed.

I agree this is gross as it stands, but making it more einsteinian will invole
multiple package's clean up. (tandrii already has a cleanup TODO for the
isolateFlags struct too – so I guess this is a known smell)

PTAL what I did to try to make this a bit friendlier.

+        if err != nil {
+                return fmt.Errorf("failed to process isolate: %v", err)
+        }
+        log.Printf("Isolate referenced %d deps", len(deps))
+
+        // TODO(djd): actually do something with the isolated.
+        _ = rootDir
+
+        // Marshal the isolated file into JSON.
+        isolJSON, err := json.Marshal(isol)
+        if err != nil {
+                return err
+        }
+        // TODO(djd): actually check/upload the isolated.
+
+        // Write the isolated file, and emit its digest to stdout.
+        if err := ioutil.WriteFile(c.isolateFlags.ArchiveOptions.Isolated, isolJSON, 0644); err != nil {
+                return err
+        }
+        fmt.Printf("%s\t%s\n", isolated.HashBytes(isolJSON), filepath.Base(c.isolateFlags.ArchiveOptions.Isolated))
+
+        return errors.New("experimental archive is not implemented")
+}
+
+func (c *expArchiveRun) parseFlags(a subcommands.Application, args []string) error {

[mcgreevy, 2016/11/22 23:54:38]

The "a" parameter does not seem to be used.

[djd-OOO-Apr2017, 2016/11/23 00:12:11]

Done.

+        if err := c.commonServerFlags.Parse(); err != nil {
+                return err
+        }
+        cwd, err := os.Getwd()
+        if err != nil {
+                return err
+        }
+        if err := c.isolateFlags.Parse(cwd, RequireIsolateFile&RequireIsolatedFile); err != nil {
+                return err
+        }
+        if len(args) != 0 {

[mcgreevy, 2016/11/22 23:54:38]

This seems like something you could do up-front before doing all of the other
parsing work.

[djd-OOO-Apr2017, 2016/11/23 00:12:11]

Done.

+                return errors.New("position arguments not expected")
+        }
+        return nil
+}
+
+func (c *expArchiveRun) Run(a subcommands.Application, args []string) int {
+        fmt.Fprintln(a.GetErr(), "WARNING: this command is experimental")
+        if err := c.parseFlags(a, args); err != nil {
+                fmt.Fprintf(a.GetErr(), "%s: %s\n", a.GetName(), err)
+                return 1
+        }
+        if len(c.isolateFlags.ArchiveOptions.Blacklist) != 0 {
+                fmt.Fprintf(a.GetErr(), "%s: blacklist is not supported\n", a.GetName())
+                return 1
+        }
+        if err := c.main(); err != nil {
+                fmt.Fprintf(a.GetErr(), "%s: %s\n", a.GetName(), err)
+                return 1
+        }
+        return 0
+}