Add base persistence interfaces for Prefetching Offline Pages.

BUG=701939

Review-Url: https://codereview.chromium.org/2872933003
Cr-Commit-Position: refs/heads/master@{#472166}

components/offline_pages/core/prefetch/BUILD.gn

@@ -11,6 +11,8 @@ static_library("prefetch") {
   sources = [
     "generate_page_bundle_request.cc",
     "generate_page_bundle_request.h",
+    "prefetch_item.cc",
+    "prefetch_item.h",
     "prefetch_request_fetcher.cc",
     "prefetch_request_fetcher.h",
     "prefetch_service.h",
@@ -48,6 +50,7 @@ source_set("unit_tests") {
   testonly = true
   sources = [
     "generate_page_bundle_request_unittest.cc",
+    "prefetch_item_unittest.cc",
     "prefetch_request_fetcher_unittest.cc",
     "prefetch_request_test_base.cc",
     "prefetch_request_test_base.h",

components/offline_pages/core/prefetch/prefetch_item.cc

+// 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.
+
+#include "components/offline_pages/core/prefetch/prefetch_item.h"
+
+namespace offline_pages {
+
+PrefetchItem::PrefetchItem() = default;
+
+PrefetchItem::PrefetchItem(const PrefetchItem& other) = default;
+
+PrefetchItem::~PrefetchItem(){};
+
+bool PrefetchItem::operator==(const PrefetchItem& other) const {
+  return guid == other.guid && client_name_space == other.client_name_space &&
+         client_id == other.client_id && state == other.state &&
+         url == other.url && final_archived_url == other.final_archived_url &&
+         request_archive_attempt_count == other.request_archive_attempt_count &&
+         operation_name == other.operation_name &&
+         archive_body_name == other.archive_body_name &&
+         archive_body_length == other.archive_body_length &&
+         creation_time == other.creation_time &&
+         freshness_time == other.freshness_time &&
+         error_code == other.error_code;
+}
+
+bool PrefetchItem::operator!=(const PrefetchItem& other) const {
+  return !(*this == other);
+}
+
+}  // namespace offline_pages

components/offline_pages/core/prefetch/prefetch_item.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 COMPONENTS_OFFLINE_PAGES_CORE_PREFETCH_PREFETCH_ITEM_H_
+#define COMPONENTS_OFFLINE_PAGES_CORE_PREFETCH_PREFETCH_ITEM_H_
+
+#include <string>
+
+#include "base/time/time.h"
+#include "components/offline_pages/core/prefetch/prefetch_types.h"
+#include "url/gurl.h"
+
+namespace offline_pages {
+
+// Data object representing an item progressing through the prefetching process
+// from the moment a URL is requested by a client until its processing is done,
+// successfully or not.
+// Instances of this class are in-memory representations of items in (or to be
+// inserted into) the persistent prefetching data store.
+struct PrefetchItem {
+  PrefetchItem();
+  explicit PrefetchItem(const PrefetchItem& other);
+
+  ~PrefetchItem();
+
+  bool operator==(const PrefetchItem& other) const;
+  bool operator!=(const PrefetchItem& other) const;
+
+  // Primary key/ID for this prefetch item (See |base::GenerateGUID()|). This
+  // value will be reused when communicating with other systems accepting GUID
+  // identifiers for operations linked to this item.
+  std::string guid;
+
+  // Externally provided namespace and id values so that this item can be
+  // uniquely identified by the client requesting it. It is the client's
+  // responsibility to make sure the id is unique within the context of its
+  // assigned namespace.
+  std::string client_name_space;
+  std::string client_id;
+
+  // Current prefetching progress state.
+  PrefetchItemState state = PrefetchItemState::NEW_REQUEST;
+
+  // The URL of the page the client requested to be prefetched.
+  GURL url;
+
+  // The final URL whose page was actually included in a successfully created
+  // archive after redirects, if it was different than the |url|. It will be
+  // left empty if they are the same.
+  GURL final_archived_url;
+
+  // Number of times an attempt was made to generate an archive for this item.
+  int request_archive_attempt_count = 0;
+
+  // Name used to identify the archiving operation being executed by the
+  // prefetching service for processing this item's URL. It is used as the
+  // |operation_name| reported by an incoming GCM message and in the
+  // |GetOperationRequest.name| field of the respective GetOperation RPC.
+  std::string operation_name;
+
+  // The name specific to this item's archive that can be used to build the URL
+  // to allow the downloading of that archive. Will only be set when and if an
+  // archive was successfully created for this item. It will be kept empty
+  // otherwise.
+  std::string archive_body_name;
+
+  // The final size of the generated archive that contains this item's page
+  // snapshot. The archive might also include other articles in a bundle so the
+  // length is not necessarily directly related to this item's page contents.
+  // Will only be set when and if an archive was successfully created for this
+  // item. It holds a negative value otherwise.
+  int64_t archive_body_length = -1;
+
+  // Time when this item was inserted into the store with the URL to be
+  // prefetched.
+  base::Time creation_time;
+
+  // Time used for the expiration of the item depending on the applicable policy
+  // for its current state. It is initially set with the same value as
+  // |creation_time|. Its value is "refreshed" to the current time on some state
+  // transitions considered significant for the prefetching process.
+  base::Time freshness_time;
+
+  // The reason why the item was set to the FINISHED state. Should be
+  // disregarded until reaching that state.
+  PrefetchItemErrorCode error_code = PrefetchItemErrorCode::SUCCESS;
+};
+
+}  // namespace offline_pages
+
+#endif  // COMPONENTS_OFFLINE_PAGES_CORE_PREFETCH_PREFETCH_ITEM_H_

components/offline_pages/core/prefetch/prefetch_item_unittest.cc

+// 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.
+
+#include "components/offline_pages/core/prefetch/prefetch_item.h"
+
+#include "base/time/time.h"
+#include "components/offline_pages/core/prefetch/prefetch_types.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "url/gurl.h"
+
+namespace offline_pages {
+
+TEST(PrefetchItemTest, OperatorEqualsAndCopyConstructor) {
+  PrefetchItem item1;
+  EXPECT_EQ(item1, PrefetchItem());
+  EXPECT_EQ(item1, PrefetchItem(item1));
+
+  item1.guid = "A";
+  EXPECT_NE(item1, PrefetchItem());
+  EXPECT_EQ(item1, PrefetchItem(item1));
+  item1 = PrefetchItem();
+
+  item1.client_name_space = "B";
+  EXPECT_NE(item1, PrefetchItem());
+  EXPECT_EQ(item1, PrefetchItem(item1));
+  item1 = PrefetchItem();
+
+  item1.client_id = "C";
+  EXPECT_NE(item1, PrefetchItem());
+  EXPECT_EQ(item1, PrefetchItem(item1));
+  item1 = PrefetchItem();
+
+  item1.state = PrefetchItemState::AWAITING_GCM;
+  EXPECT_NE(item1, PrefetchItem());
+  EXPECT_EQ(item1, PrefetchItem(item1));
+  item1 = PrefetchItem();
+
+  item1.url = GURL("http://test.com");
+  EXPECT_NE(item1, PrefetchItem());
+  EXPECT_EQ(item1, PrefetchItem(item1));
+  item1 = PrefetchItem();
+
+  item1.final_archived_url = GURL("http://test.com/final");
+  EXPECT_NE(item1, PrefetchItem());
+  EXPECT_EQ(item1, PrefetchItem(item1));
+  item1 = PrefetchItem();
+
+  item1.request_archive_attempt_count = 10;
+  EXPECT_NE(item1, PrefetchItem());
+  EXPECT_EQ(item1, PrefetchItem(item1));
+  item1 = PrefetchItem();
+
+  item1.operation_name = "D";
+  EXPECT_NE(item1, PrefetchItem());
+  EXPECT_EQ(item1, PrefetchItem(item1));
+  item1 = PrefetchItem();
+
+  item1.archive_body_name = "E";
+  EXPECT_NE(item1, PrefetchItem());
+  EXPECT_EQ(item1, PrefetchItem(item1));
+  item1 = PrefetchItem();
+
+  item1.archive_body_length = 20;
+  EXPECT_NE(item1, PrefetchItem());
+  EXPECT_EQ(item1, PrefetchItem(item1));
+  item1 = PrefetchItem();
+
+  item1.creation_time = base::Time::FromJavaTime(1000L);
+  EXPECT_NE(item1, PrefetchItem());
+  EXPECT_EQ(item1, PrefetchItem(item1));
+  item1 = PrefetchItem();
+
+  item1.freshness_time = base::Time::FromJavaTime(2000L);
+  EXPECT_NE(item1, PrefetchItem());
+  EXPECT_EQ(item1, PrefetchItem(item1));
+  item1 = PrefetchItem();
+
+  item1.error_code = PrefetchItemErrorCode::EXPIRED;
+  EXPECT_NE(item1, PrefetchItem());
+  EXPECT_EQ(item1, PrefetchItem(item1));
+}
+
+}  // namespace offline_pages

components/offline_pages/core/prefetch/prefetch_types.h

@@ -59,6 +59,46 @@ struct RenderPageInfo {
   base::Time render_time;
 };
 
+// List of states a prefetch item can be at during its progress through the
+// prefetching process. They follow somewhat the order below, but some states
+// might be skipped.
+enum class PrefetchItemState {
+  // New request just received from the client.
+  NEW_REQUEST,
+  // The item has been included in a GeneratePageBundle RPC requesting the
+  // creation of an archive for its URL.
+  SENT_GENERATE_PAGE_BUNDLE,
+  // The archive was not immediately available (cached) upon the request and
+  // is now waiting for a GCM message notifying of its archiving operation
+  // completion.
+  AWAITING_GCM,
+  // The GCM message notifying of the archiving operation completion was
+  // received for this item.
+  RECEIVED_GCM,
+  // A GetOperation RPC was sent for this item to query for the final results
+  // of its archiving request.
+  SENT_GET_OPERATION,
+  // Information was received about a successfully created archive for this
+  // item that can now be downloaded.
+  RECEIVED_BUNDLE,
+  // This item's archive is currently being downloaded.
+  DOWNLOADING,
+  // Item has finished processing, successfully or otherwise, and is waiting to
+  // be processed for stats reporting to UMA.
+  FINISHED,
+  // UMA stats have been reported and the item is being kept just long enough
+  // to confirm that the same URL is not being repeatedly requested by its
+  // client.
+  ZOMBIE,
+};
+
+// Error codes used to identify the reason why a prefetch item has finished
+// processing.
+enum class PrefetchItemErrorCode {
+  SUCCESS,
+  EXPIRED,
+};
+
 }  // namespace offline_pages
 
 #endif  // COMPONENTS_OFFLINE_PAGES_CORE_PREFETCH_PREFETCH_TYPES_H_