Reporting: Implement delivery agent.

net/reporting/reporting_delivery_agent.h

+// Copyright 2017 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.
+
+#ifndef NET_REPORTING_REPORTING_DELIVERY_AGENT_H_
+#define NET_REPORTING_REPORTING_DELIVERY_AGENT_H_
+
+#include <memory>
+#include <set>
+#include <string>
+#include <utility>
+
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "net/base/backoff_entry.h"
+#include "net/base/net_export.h"
+#include "net/reporting/reporting_endpoint_manager.h"
+#include "net/reporting/reporting_uploader.h"
+#include "url/gurl.h"
+#include "url/origin.h"
+
+namespace base {
+class TickClock;
+}  // namespace base
+
+namespace net {
+
+class ReportingCache;
+
+// Takes reports from the ReportingCache, assembles reports into deliveries to
+// endpoints, and sends those deliveries using ReportingUploader.
+//
+// Since the Reporting spec is completely silent on issues of concurrency, the
+// delivery agent handles it as so:
+//
+// 1. An individual report can only be part of one delivery at once -- if
+//    SendReports is called again while a report is being delivered, it won't
+//    be included in another delivery. (This is, in fact, made redundant by rule
+//    3, but it's included anyway in case rule 3 changes.)
+//
+// 2. An endpoint can only be the target of one delivery at once -- if
+//    SendReports is called again with reports that could be delivered to that
+//    endpoint, it won't be chosen. This may mean that the new reports are not
+//    delivered at all.
+//
+// 3. Reports for an (origin, group) tuple can only be included in one delivery
+//    at once -- if SendReports is called again with reports in that (origin,
+//    group), they won't be included in any delivery. (This prevents the agent
+//    from getting around rule 2 by using other endpoints.)
+//
+// 4. Reports for an origin *can* be included in multiple deliveries if they are
+//    in different groups.
+class NET_EXPORT ReportingDeliveryAgent {
+ public:
+  ReportingDeliveryAgent(base::TickClock* clock,
+                         ReportingCache* cache,
+                         ReportingUploader* uploader,
+                         const BackoffEntry::Policy* endpoint_backoff_policy);

[shivanisha, 2017/03/30 20:16:11]

Document lifetime assumptions for clock, cache, uploader and
endpoint_backoff_policy since raw pointers to those will be stored in this
object.

+  ~ReportingDeliveryAgent();
+
+  // Tries to deliver all of the reports in the cache. Reports that are already
+  // being delivered will not be attempted a second time, and reports that do
+  // not have a viable endpoint will be neither attempted nor removed.
+  void SendReports();
+
+ private:
+  class Delivery;
+
+  using OriginGroup = std::pair<url::Origin, std::string>;
+
+  void OnUploadComplete(const std::unique_ptr<Delivery>& delivery,
+                        ReportingUploader::Outcome outcome);
+
+  base::TickClock* clock_;
+  ReportingCache* cache_;
+  ReportingUploader* uploader_;
+
+  ReportingEndpointManager endpoint_manager_;
+  // Would be an unordered_set, but there's no hash on pair.
+  std::set<OriginGroup> pending_origin_groups_;
+
+  base::WeakPtrFactory<ReportingDeliveryAgent> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(ReportingDeliveryAgent);
+};
+
+}  // namespace net
+
+#endif  // NET_REPORTING_REPORTING_DELIVERY_AGENT_H_