LogDog: Support per-namespace expired archival.

appengine/logdog/coordinator/context.go

 // Copyright 2015 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 coordinator
 
 import (
+        "fmt"
+
+        "github.com/luci/gae/service/info"
+        "github.com/luci/luci-go/common/config"
+        log "github.com/luci/luci-go/common/logging"
         "golang.org/x/net/context"
 )
 
 type servicesKeyType int
 
 // WithServices installs the supplied Services instance into a Context.
 func WithServices(c context.Context, s Services) context.Context {
         return context.WithValue(c, servicesKeyType(0), s)
 }
 
 // GetServices gets the Services instance installed in the supplied Context.
 //
 // If no Services has been installed, it will panic.
 func GetServices(c context.Context) Services {
         s, ok := c.Value(servicesKeyType(0)).(Services)
         if !ok {
                 panic("no Services instance is installed")
         }
         return s
 }
+
+// WithProjectNamespace sets the current namespace to the project name.
+//
+// It will fail if either the project name or the project's namespace is
+// invalid. In the event of an error, the supplied Context will be not be
+// modified or invalidated.
+func WithProjectNamespace(c *context.Context, project config.ProjectName) error {
+        // TODO(dnj): REQUIRE this to be non-empty once namespacing is mandatory.
+        if project == "" {
+                log.Debugf(*c, "Using default namespace.")
+                return nil
+        }
+
+        if err := project.Validate(); err != nil {
+                log.Fields{
+                        log.ErrorKey: err,
+                        "project":    project,
+                }.Errorf(*c, "Project name is invalid.")
+                return err
+        }
+
+        pns := ProjectNamespace(project)
+        nc, err := info.Get(*c).Namespace(pns)
+        if err != nil {
+                log.Fields{
+                        log.ErrorKey: err,
+                        "project":    project,
+                        "namespace":  pns,
+                }.Errorf(*c, "Failed to set namespace.")
+                return err
+        }
+
+        log.Fields{
+                "project": project,
+        }.Debugf(*c, "Using project namespace.")
+        *c = nc
+        return nil
+}
+
+// Project returns the current project installed in the supplied Context's
+// namespace.
+//
+// This function is called with the expectation that the Context is in a
+// namespace conforming to ProjectNamespace. If this is not the case, this
+// method will panic.
+func Project(c context.Context) config.ProjectName {
+        ns, _ := info.Get(c).GetNamespace()
+
+        // TODO(dnj): Remove the empty namespace/project exception once we no longer
+        // support that.
+        if ns == "" {
+                return ""
+        }
+
+        project := ProjectFromNamespace(ns)
+        if project != "" {
+                return project
+        }
+        panic(fmt.Errorf("current namespace %q does not begin with project namespace prefix (%q)", ns, projectNamespacePrefix))
+}