dashboard/app: add drop namespace functionality

dropNamespace drops all entities related to a single namespace.
Use with care. There is no undo.
This functionality is intentionally not connected to any handler.
To use it, first make a backup of the datastore. Then, specify the target
namespace in the ns variable, connect the function to a handler, invoke it
and double check the output. Finally, set dryRun to false and invoke again.

dashboard/app/admin.go

@@ -0,0 +1,120 @@
+// Copyright 2017 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+package dash
+
+import (
+	"fmt"
+	"net/http"
+
+	"golang.org/x/net/context"
+	"google.golang.org/appengine/datastore"
+	"google.golang.org/appengine/log"
+)
+
+// dropNamespace drops all entities related to a single namespace.
+// Use with care. There is no undo.
+// This functionality is intentionally not connected to any handler.
+// To use it, first make a backup of the datastore. Then, specify the target
+// namespace in the ns variable, connect the function to a handler, invoke it
+// and double check the output. Finally, set dryRun to false and invoke again.
+func dropNamespace(c context.Context, w http.ResponseWriter, r *http.Request) error {
+	ns := "non-existent"
+	dryRun := true
+	if !dryRun {
+		log.Criticalf(c, "dropping namespace %v", ns)
+	}
+	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
+	fmt.Fprintf(w, "dropping namespace %v\n", ns)
+	if err := dropNamespaceReportingState(c, w, ns, dryRun); err != nil {
+		return err
+	}
+	type Entity struct {
+		name  string
+		child string
+	}
+	entities := []Entity{
+		{"Patch", ""},
+		{"ReproC", ""},
+		{"ReproSyz", ""},
+		{"KernelConfig", ""},
+		{"Job", ""},
+		{"Error", ""},
+		{"CrashLog", ""},
+		{"CrashReport", ""},
+		{"Build", ""},
+		{"Manager", "ManagerStats"},
+		{"Bug", "Crash"},
+	}
+	for _, entity := range entities {
+		keys, err := datastore.NewQuery(entity.name).
+			Filter("Namespace=", ns).
+			KeysOnly().
+			GetAll(c, nil)
+		if err != nil {
+			return err
+		}
+		fmt.Fprintf(w, "%v: %v\n", entity.name, len(keys))
+		if entity.child != "" {
+			var childKeys []*datastore.Key
+			for _, key := range keys {
+				keys1, err := datastore.NewQuery(entity.child).
+					Ancestor(key).
+					KeysOnly().
+					GetAll(c, nil)
+				if err != nil {
+					return err
+				}
+				childKeys = append(childKeys, keys1...)
+			}
+			fmt.Fprintf(w, "  %v: %v\n", entity.child, len(childKeys))
+			if err := dropEntities(c, childKeys, dryRun); err != nil {
+				return err
+			}
+		}
+		if err := dropEntities(c, keys, dryRun); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func dropNamespaceReportingState(c context.Context, w http.ResponseWriter, ns string, dryRun bool) error {
+	tx := func(c context.Context) error {
+		state, err := loadReportingState(c)
+		if err != nil {
+			return err
+		}
+		newState := new(ReportingState)
+		for _, ent := range state.Entries {
+			if ent.Namespace != ns {
+				newState.Entries = append(newState.Entries, ent)
+			}
+		}
+		if !dryRun {
+			if err := saveReportingState(c, newState); err != nil {
+				return err
+			}
+		}
+		fmt.Fprintf(w, "ReportingState: %v\n", len(state.Entries)-len(newState.Entries))
+		return nil
+	}
+	return datastore.RunInTransaction(c, tx, nil)
+}
+
+func dropEntities(c context.Context, keys []*datastore.Key, dryRun bool) error {
+	if dryRun {
+		return nil
+	}
+	for len(keys) != 0 {
+		batch := 100
+		if batch > len(keys) {
+			batch = len(keys)
+		}
+		if err := datastore.DeleteMulti(c, keys[:batch]); err != nil {
+			return err
+		}
+		keys = keys[batch:]
+	}
+	return nil
+}