Adding a request counter to the snippets fetcher.

components/ntp_snippets/ntp_snippets_fetcher.cc

 // Copyright 2016 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/ntp_snippets/ntp_snippets_fetcher.h"
 
 #include <stdlib.h>
 
 #include "base/command_line.h"
 #include "base/files/file_path.h"
@@ skipping 58 matching lines @@
 
 // Constants for possible values of the "fetching_personalization" parameter.
 const char kPersonalizationPersonalString[] = "personal";
 const char kPersonalizationNonPersonalString[] = "non_personal";
 const char kPersonalizationBothString[] = "both";  // the default value
 
 // Constants for possible values of the "fetching_host_restrict" parameter.
 const char kHostRestrictionOnString[] = "on";  // the default value
 const char kHostRestrictionOffString[] = "off";
 
+const int kArticlesQuotaPerDay = 20;

[Marc Treib, 2016/07/22 13:52:52]

This sounds like "number of articles per day", but it's actually the number of
fetches.

Also, should we build in the option to override this via variation params?

[jkrcal, 2016/07/25 10:05:38]

Done.

Overriding by variation params is built in the RequestThrottler :) This is just
the default quota value if no variation param is given.

[Marc Treib, 2016/07/25 10:11:55]

I see... this is surprising to me. Since everything else related to the quota is
defined in the RequestThrottler, should we maybe move the default quota
definition there too?
If not, please at least add a "Default" somewhere in the name, to make it clear
to the reader that it might be overridden.

[jkrcal, 2016/07/25 10:26:59]

Makes sense. Done.

+
 std::string FetchResultToString(NTPSnippetsFetcher::FetchResult result) {
   switch (result) {
     case NTPSnippetsFetcher::FetchResult::SUCCESS:
       return "OK";
     case NTPSnippetsFetcher::FetchResult::EMPTY_HOSTS:
       return "Cannot fetch for empty hosts list.";
     case NTPSnippetsFetcher::FetchResult::URL_REQUEST_STATUS_ERROR:
       return "URLRequestStatus error";
     case NTPSnippetsFetcher::FetchResult::HTTP_ERROR:
       return "HTTP error";
@@ skipping 62 matching lines @@
       << "Error in translating language code to a locale string: " << error;
   return locale;
 }
 
 }  // namespace
 
 NTPSnippetsFetcher::NTPSnippetsFetcher(
     SigninManagerBase* signin_manager,
     OAuth2TokenService* token_service,
     scoped_refptr<URLRequestContextGetter> url_request_context_getter,
+    PrefService* pref_service,
     const ParseJSONCallback& parse_json_callback,
     bool is_stable_channel)
     : OAuth2TokenService::Consumer("ntp_snippets"),
       signin_manager_(signin_manager),
       token_service_(token_service),
       waiting_for_refresh_token_(false),
       url_request_context_getter_(url_request_context_getter),
       parse_json_callback_(parse_json_callback),
       fetch_url_(GetFetchEndpoint()),
       fetch_api_(UsesChromeContentSuggestionsAPI(fetch_url_)
                      ? CHROME_CONTENT_SUGGESTIONS_API
                      : CHROME_READER_API),
       is_stable_channel_(is_stable_channel),
       tick_clock_(new base::DefaultTickClock()),
+      request_throttler_(
+          pref_service,
+          RequestThrottler::RequestType::CONTENT_SUGGESTION_FETCHER,
+          kArticlesQuotaPerDay),
       weak_ptr_factory_(this) {
   // Parse the variation parameters and set the defaults if missing.
   std::string personalization = variations::GetVariationParamValue(
       ntp_snippets::kStudyName, kPersonalizationName);
   if (personalization == kPersonalizationNonPersonalString) {
     personalization_ = Personalization::kNonPersonal;
   } else if (personalization == kPersonalizationPersonalString) {
     personalization_ = Personalization::kPersonal;
   } else {
     personalization_ = Personalization::kBoth;
@@ skipping 22 matching lines @@
 }
 
 void NTPSnippetsFetcher::SetCallback(
     const SnippetsAvailableCallback& callback) {
   snippets_available_callback_ = callback;
 }
 
 void NTPSnippetsFetcher::FetchSnippetsFromHosts(
     const std::set<std::string>& hosts,
     const std::string& language_code,
-    int count) {
+    int count,
+    bool force_request) {
+  if (!request_throttler_.DemandQuotaForRequest(force_request))
+    return;
+
   hosts_ = hosts;
   fetch_start_time_ = tick_clock_->NowTicks();
 
   if (UsesHostRestrictions() && hosts_.empty()) {
     FetchFinished(OptionalSnippets(), FetchResult::EMPTY_HOSTS,
                   /*extra_message=*/std::string());
     return;
   }
 
   locale_ = PosixLocaleFromBCP47Language(language_code);
@@ skipping 296 matching lines @@
                       tick_clock_->NowTicks() - fetch_start_time_);
   UMA_HISTOGRAM_ENUMERATION("NewTabPage.Snippets.FetchResult",
                             static_cast<int>(result),
                             static_cast<int>(FetchResult::RESULT_MAX));
 
   if (!snippets_available_callback_.is_null())
     snippets_available_callback_.Run(std::move(snippets));
 }
 
 }  // namespace ntp_snippets