Initial distributor implementation

common/api/dm/service/v1/quest_desc_normalize.go

Index: common/api/dm/service/v1/quest_desc_normalize.go
diff --git a/common/api/dm/service/v1/quest_desc_normalize.go b/common/api/dm/service/v1/quest_desc_normalize.go
new file mode 100644
index 0000000000000000000000000000000000000000..4e33f7d5fa8e2bf5de5a391ff0c00281ccf36e90
--- /dev/null
+++ b/common/api/dm/service/v1/quest_desc_normalize.go
@@ -0,0 +1,66 @@
+// 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 dm
+
+import (
+	"crypto/sha256"
+	"encoding/base64"
+	"fmt"
+
+	"github.com/golang/protobuf/proto"
+	"github.com/luci/luci-go/common/api/template"
+)
+
+// IsEmpty returns true if this metadata retry message only contains
+// zero-values.
+func (q *Quest_Desc_Meta_Retry) IsEmpty() bool {
+	return q.Crashed == 0 && q.Expired == 0 && q.Failed == 0 && q.TimedOut == 0
+}
+
+// IsEmpty returns true if this metadata only contains zero-values.
+func (q *Quest_Desc_Meta) IsEmpty() bool {
+	return q.AsAccount == "" && q.Retry.IsEmpty()
+}
+
+var (
+	// QuestIDLength is the number of encoded bytes to use. It removes the
+	// single padding character.
+	QuestIDLength = base64.URLEncoding.EncodedLen(sha256.Size) - 1
+)
+
+// QuestDescPayloadMaxLength is the maximum length (in bytes) of an
+// un-normalized Quest payload.
+const QuestDescPayloadMaxLength = 256 * 1024
+
+// Normalize returns an error iff the Quest_Desc is invalid.
+func (q *Quest_Desc) Normalize() error {
+	if q.Meta == nil {
+		q.Meta = &Quest_Desc_Meta{Retry: &Quest_Desc_Meta_Retry{}}
+	} else if q.Meta.Retry == nil {
+		q.Meta.Retry = &Quest_Desc_Meta_Retry{}
+	}
+
+	if len(q.JsonPayload) > QuestDescPayloadMaxLength {
+		return fmt.Errorf("quest payload is too large: %d > %d",
+			len(q.JsonPayload), QuestDescPayloadMaxLength)
+	}
+	normed, err := template.NormalizeJSON(q.JsonPayload, true)
+	if err != nil {
+		return fmt.Errorf("failed to normalize payload: %s", err)
+	}
+	q.JsonPayload = normed
+	return nil
+}
+
+// QuestID computes the DM compatible quest ID for this Quest_Desc. The
+// Quest_Desc should already be Normalize()'d.
+func (q *Quest_Desc) QuestID() string {
+	data, err := proto.Marshal(q)
+	if err != nil {
+		panic(err)
+	}
+	h := sha256.Sum256(data)
+	return base64.URLEncoding.EncodeToString(h[:])[:QuestIDLength]

[dnj (Google), 2016/06/09 18:00:57]

Note that if we ever change QuestIDLength, data could be hard to reach. TBH I'd
prefer we stick with full SHA256.

[iannucci, 2016/06/15 00:46:02]

? We do, we're just chopping off the extra, constant-length '=' padding at the
end.

+}