LogDog: Implement RegisterPrefix RPC.

appengine/logdog/coordinator/endpoints/services/registerPrefix.go

Index: appengine/logdog/coordinator/endpoints/services/registerPrefix.go
diff --git a/appengine/logdog/coordinator/endpoints/services/registerPrefix.go b/appengine/logdog/coordinator/endpoints/services/registerPrefix.go
deleted file mode 100644
index 99bcf6179fafe3d35d5cb96b7288904c81b949f6..0000000000000000000000000000000000000000
--- a/appengine/logdog/coordinator/endpoints/services/registerPrefix.go
+++ /dev/null
@@ -1,139 +0,0 @@
-// Copyright 2016 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-package services
-
-import (
-	"crypto/subtle"
-	"errors"
-
-	ds "github.com/luci/gae/service/datastore"
-	"github.com/luci/luci-go/appengine/logdog/coordinator"
-	"github.com/luci/luci-go/common/clock"
-	"github.com/luci/luci-go/common/grpcutil"
-	"github.com/luci/luci-go/common/logdog/types"
-	log "github.com/luci/luci-go/common/logging"
-	"golang.org/x/net/context"
-	"google.golang.org/grpc/codes"
-)
-
-// logStreamPrefix is a placeholder for a future "register prefix" RPC call.
-//
-// It represents an application's intent to register a log stream prefix.
-type logStreamPrefix struct {
-	prefix string
-	secret []byte
-}
-
-// registerPrefix registers a log stream's Prefix value.
-//
-// This function behaves like an RPC call, returning a gRPC error code on
-// failure. This is because it will eventually be a separate RPC call when
-// Butler prefix registration is implemented.
-func registerPrefix(c context.Context, lsp *logStreamPrefix) (*coordinator.LogPrefix, error) {
-	log.Fields{
-		"prefix": lsp.prefix,
-	}.Debugf(c, "Registering log prefix.")
-
-	prefix := types.StreamName(lsp.prefix)
-	if err := prefix.Validate(); err != nil {
-		return nil, grpcutil.Errf(codes.InvalidArgument, "Invalid prefix (%s): %s", lsp.prefix, err)
-	}
-
-	secret := types.PrefixSecret(lsp.secret)
-	if err := secret.Validate(); err != nil {
-		return nil, grpcutil.Errf(codes.InvalidArgument, "Invalid prefix secret: %s", err)
-	}
-
-	pfx := &coordinator.LogPrefix{ID: coordinator.LogPrefixID(prefix)}
-
-	// Check for existing prefix registration (non-transactional).
-	di := ds.Get(c)
-	switch err := checkRegisterPrefix(ds.Get(c), lsp, pfx); err {
-	case nil:
-		// The prefix is already compatibly registered.
-		return pfx, nil
-
-	case ds.ErrNoSuchEntity:
-		// The prefix does not exist. Proceed with transactional registration.
-		break
-
-	default:
-		log.WithError(err).Errorf(c, "Failed to register prefix (non-transactional).")
-		return nil, err
-	}
-
-	// The Prefix isn't registered. Register it transactionally.
-	now := clock.Now(c).UTC()
-	err := di.RunInTransaction(func(c context.Context) error {
-		di := ds.Get(c)
-
-		// Check if this Prefix exists (transactional).
-		switch err := checkRegisterPrefix(di, lsp, pfx); err {
-		case nil:
-			// The prefix is already compatibly registered.
-			log.Debugf(c, "Prefix is already registered.")
-			return nil
-
-		case ds.ErrNoSuchEntity:
-			// The Prefix is not registered, so let's register it.
-			pfx.Prefix = string(prefix)
-			pfx.Secret = []byte(secret)
-			pfx.Created = now
-
-			if err := di.Put(pfx); err != nil {
-				log.WithError(err).Errorf(c, "Failed to register prefix.")
-				return grpcutil.Internal
-			}
-			log.Infof(c, "The prefix was successfully registered.")
-			return nil
-
-		default:
-			// Unexpected error.
-			log.WithError(err).Errorf(c, "Failed to check prefix registration.")
-			return err
-		}
-	}, nil)
-	if err != nil {
-		log.WithError(err).Errorf(c, "Failed to register prefix (transactional).")
-		return nil, err
-	}
-
-	return pfx, nil
-}
-
-// checkRegisterPrefix is our registration logic. It will be executed once
-// non-transactionally and (if registration is needed) again transactionally.
-//
-// If the prefix is already compatibly registered, nil will be returned. If no
-// such entity exists, ds.ErrNoSuchEntity will be returned.
-//
-// gRPC errors returned by this method will be forwarded to the caller.
-func checkRegisterPrefix(di ds.Interface, lsp *logStreamPrefix, pfx *coordinator.LogPrefix) error {
-	switch err := di.Get(pfx); err {
-	case nil:
-		// Prefix registered, does it match? If so, this is an idempotent operation.
-		if err := matchesLogPrefix(lsp, pfx); err != nil {
-			return grpcutil.Errf(codes.AlreadyExists, "Log prefix is already registered: %v", err)
-		}
-
-		return nil
-
-	case ds.ErrNoSuchEntity:
-		return err
-
-	default:
-		return grpcutil.Internal
-	}
-}
-
-func matchesLogPrefix(lsp *logStreamPrefix, pfx *coordinator.LogPrefix) error {
-	if lsp.prefix != pfx.Prefix {
-		return errors.New("prefixes do not match")
-	}
-	if subtle.ConstantTimeCompare(lsp.secret, pfx.Secret) != 1 {
-		return errors.New("secrets do not match")
-	}
-	return nil
-}