ResourceMetadata for supporting StartPageToken in the header and directories.

This cl adds start_page_token to ResourceMetadataHeader and
DirectorySpecificInfo for supporting change list retrival based on
startPageToken instead of largestChangeId.

Bug: 840211
Change-Id: Ib498276b48b28dc1876fc9a70a4a1356b60ddeb9
Reviewed-on: https://chromium-review.googlesource.com/1050052Reviewed-by: Ryo Hashimoto <hashimoto@chromium.org>
Commit-Queue: Stuart Langley <slangley@chromium.org>
Cr-Commit-Position: refs/heads/master@{#557137}

components/drive/chromeos/resource_metadata.cc

@@ -103,6 +103,10 @@ FileError ResourceMetadata::Reset() {
   if (error != FILE_ERROR_OK)
     return error;
 
+  error = storage_->SetStartPageToken(std::string());
+  if (error != FILE_ERROR_OK)
+    return error;
+
   // Remove all root entries.
   std::unique_ptr<Iterator> it = GetIterator();
   for (; !it->IsAtEnd(); it->Advance()) {
@@ -245,6 +249,20 @@ FileError ResourceMetadata::SetLargestChangestamp(int64_t value) {
   return storage_->SetLargestChangestamp(value);
 }
 
+FileError ResourceMetadata::GetStartPageToken(std::string* out_value) {
+  DCHECK(blocking_task_runner_->RunsTasksInCurrentSequence());
+  return storage_->GetStartPageToken(out_value);
+}
+
+FileError ResourceMetadata::SetStartPageToken(const std::string& value) {
+  DCHECK(blocking_task_runner_->RunsTasksInCurrentSequence());
+
+  if (!EnoughDiskSpaceIsAvailableForDBOperation(storage_->directory_path()))
+    return FILE_ERROR_NO_LOCAL_SPACE;
+
+  return storage_->SetStartPageToken(value);
+}
+
 FileError ResourceMetadata::AddEntry(const ResourceEntry& entry,
                                      std::string* out_id) {
   DCHECK(blocking_task_runner_->RunsTasksInCurrentSequence());

components/drive/chromeos/resource_metadata.h

@@ -62,6 +62,12 @@ class ResourceMetadata {
   // Sets the largest changestamp.
   FileError SetLargestChangestamp(int64_t value);
 
+  // Returns the start page token for the users default corpus.
+  FileError GetStartPageToken(std::string* out_value);
+
+  // Sets the start page token for the users default corpus.
+  FileError SetStartPageToken(const std::string& value);
+
   // Adds |entry| to the metadata tree based on its parent_local_id.
   FileError AddEntry(const ResourceEntry& entry, std::string* out_id);
 

components/drive/drive.proto

@@ -79,7 +79,12 @@ message DirectorySpecificInfo {
   // changestamp of ResourceMetadata, if this directory was
   // "fast-fetched". See crbug.com/178348 for details about the "fast-fetch"
   // feature.
+  // TODO(slangley): Deprecate and remove changestamp.
   optional int64 changestamp = 1;
+
+  // The start page token of this directory. This value may not match the
+  // start_page_token of ResourceMetadata if the directory was "fast-fetched".
+  optional string start_page_token = 2;
 }
 
 // Represents metadata of a resource (file or directory) on Drive.
@@ -162,11 +167,16 @@ message ResourceMetadataHeader {
   // incompatible change is made to the DB format. kDBVersion in
   // drive_resource_metadata_storage.h defines the current version.
   optional int32 version = 1;
+
+  // TODO(slangley): Deprecate and remove changestamp.
   optional int64 largest_changestamp = 2;
 
   // The argument with ID 3 (starred_property_initialized) had been used, but
   // got deleted.
   reserved 3;
+
+  // The start_page_token for the users default corpus changelist.
+  optional string start_page_token = 4;
 }
 
 // Message to store information of an existing cache file.

components/drive/resource_metadata_storage.cc

@@ -767,6 +767,33 @@ FileError ResourceMetadataStorage::GetLargestChangestamp(
   return FILE_ERROR_OK;
 }
 
+FileError ResourceMetadataStorage::GetStartPageToken(
+    std::string* start_page_token) {
+  base::AssertBlockingAllowed();
+  ResourceMetadataHeader header;
+  FileError error = GetHeader(&header);
+  if (error != FILE_ERROR_OK) {
+    DLOG(ERROR) << "Failed to get the header.";
+    return error;
+  }
+  *start_page_token = header.start_page_token();
+  return FILE_ERROR_OK;
+}
+
+FileError ResourceMetadataStorage::SetStartPageToken(
+    const std::string& start_page_token) {
+  base::AssertBlockingAllowed();
+
+  ResourceMetadataHeader header;
+  FileError error = GetHeader(&header);
+  if (error != FILE_ERROR_OK) {
+    DLOG(ERROR) << "Failed to get the header.";
+    return error;
+  }
+  header.set_start_page_token(start_page_token);
+  return PutHeader(header);
+}
+
 FileError ResourceMetadataStorage::PutEntry(const ResourceEntry& entry) {
   base::AssertBlockingAllowed();
 

components/drive/resource_metadata_storage.h

@@ -109,6 +109,10 @@ class ResourceMetadataStorage {
   // Gets the largest changestamp.
   FileError GetLargestChangestamp(int64_t* largest_changestamp);
 
+  FileError GetStartPageToken(std::string* out_value);
+
+  FileError SetStartPageToken(const std::string& value);
+
   // Puts the entry to this storage.
   FileError PutEntry(const ResourceEntry& entry);
 

components/drive/resource_metadata_unittest.cc

@@ -27,9 +27,8 @@ namespace drive {
 namespace internal {
 namespace {
 
-// The changestamp of the resource metadata used in
-// ResourceMetadataTest.
-const int64_t kTestChangestamp = 100;
+// The start page token of the resource metadata used in ResourceMetadataTest.
+constexpr char kTestStartPageToken[] = "a token";
 
 // Returns the sorted base names from |entries|.
 std::vector<std::string> GetSortedBaseNames(
@@ -52,7 +51,8 @@ ResourceEntry CreateDirectoryEntryWithResourceId(
   entry.set_resource_id(resource_id);
   entry.set_parent_local_id(parent_local_id);
   entry.mutable_file_info()->set_is_directory(true);
-  entry.mutable_directory_specific_info()->set_changestamp(kTestChangestamp);
+  entry.mutable_directory_specific_info()->set_start_page_token(
+      kTestStartPageToken);
   return entry;
 }
 
@@ -131,7 +131,7 @@ void SetUpEntries(ResourceMetadata* resource_metadata) {
       CreateFileEntry("file10", local_id_dir3), &local_id));
 
   ASSERT_EQ(FILE_ERROR_OK,
-            resource_metadata->SetLargestChangestamp(kTestChangestamp));
+            resource_metadata->SetStartPageToken(kTestStartPageToken));
 }
 
 }  // namespace
@@ -181,6 +181,16 @@ TEST_F(ResourceMetadataTest, LargestChangestamp) {
   EXPECT_EQ(kChangestamp, changestamp);
 }
 
+TEST_F(ResourceMetadataTest, StartPageToken) {
+  constexpr char kStartPageToken[] = "a different token";
+  EXPECT_EQ(FILE_ERROR_OK,
+            resource_metadata_->SetStartPageToken(kStartPageToken));
+  std::string start_page_token;
+  EXPECT_EQ(FILE_ERROR_OK,
+            resource_metadata_->GetStartPageToken(&start_page_token));
+  EXPECT_EQ(kStartPageToken, start_page_token);
+}
+
 TEST_F(ResourceMetadataTest, GetResourceEntryByPath) {
   // Confirm that an existing file is found.
   ResourceEntry entry;
@@ -675,10 +685,10 @@ TEST_F(ResourceMetadataTest, Reset) {
   EXPECT_EQ(FILE_ERROR_OK, resource_metadata_->Reset());
 
   // change stamp should be reset.
-  int64_t changestamp = 0;
+  std::string start_page_token;
   EXPECT_EQ(FILE_ERROR_OK,
-            resource_metadata_->GetLargestChangestamp(&changestamp));
-  EXPECT_EQ(0, changestamp);
+            resource_metadata_->GetStartPageToken(&start_page_token));
+  EXPECT_TRUE(start_page_token.empty());
 
   // root should continue to exist.
   ResourceEntry entry;