Translate: language list smart updater

chrome/browser/translate/translate_language_list.cc

Index: chrome/browser/translate/translate_language_list.cc
diff --git a/chrome/browser/translate/translate_language_list.cc b/chrome/browser/translate/translate_language_list.cc
index 7056f6dc739d32f41c196c49f3607657e87eaa3d..081303e3ffda19deddf37480119d236effb599df 100644
--- a/chrome/browser/translate/translate_language_list.cc
+++ b/chrome/browser/translate/translate_language_list.cc
@@ -105,7 +105,10 @@ const char kAlphaLanguageQueryName[] = "alpha";
 const char kAlphaLanguageQueryValue[] = "1";
 
 // Retry parameter for fetching supporting language list.
-const int kMaxRetryLanguageListFetch = 5;
+const int kMaxRetryLanguageListFetchOn5xx = 5;
+
+// Retry parameter for LanguageListFetcher.
+const int kMaxRetryLanguageListFetcher = 16;
 
 // Assign following IDs to URLFetchers so that tests can distinguish each
 // request in order to simiulate respectively.
@@ -184,7 +187,8 @@ void SetSupportedLanguages(const std::string& language_list,
 TranslateLanguageList::LanguageListFetcher::LanguageListFetcher(
     bool include_alpha_languages)
   : include_alpha_languages_(include_alpha_languages),
-    state_(IDLE) {
+    state_(IDLE),
+    retry_count_(0) {
 }
 
 TranslateLanguageList::LanguageListFetcher::~LanguageListFetcher() {
@@ -192,13 +196,20 @@ TranslateLanguageList::LanguageListFetcher::~LanguageListFetcher() {
 
 bool TranslateLanguageList::LanguageListFetcher::Request(
     const TranslateLanguageList::LanguageListFetcher::Callback& callback) {
-  // This function is not supporsed to be called before previous operaion is not
+  // This function is not supposed to be called before previous operaion is not
   // finished.
   if (state_ == REQUESTING) {
     NOTREACHED();
     return false;
   }
 
+  // Limits LanguageListFetcher level retry to kMaxRetryLanguageListFetcher

[Alexei Svitkine (slow), 2013/06/13 14:46:02]

Nit: I don't think the comment is needed, the code below is clear enough.

[Takashi Toyoshima, 2013/06/14 09:10:48]

Done.

+  if (retry_count_ >= kMaxRetryLanguageListFetcher) {
+    NotifyEvent(__LINE__, "Request is omitted due to retry limitation");

[Alexei Svitkine (slow), 2013/06/13 14:46:02]

Nit: limitation -> limit

(The two have slightly different meanings.)

[Takashi Toyoshima, 2013/06/14 09:10:48]

Wow, thank you:)
I didn't know.

Done!

+    return false;
+  }
+  retry_count_++;
+
   state_ = REQUESTING;
   callback_ = callback;
 
@@ -226,7 +237,10 @@ bool TranslateLanguageList::LanguageListFetcher::Request(
   fetcher_->SetLoadFlags(net::LOAD_DO_NOT_SEND_COOKIES |
                          net::LOAD_DO_NOT_SAVE_COOKIES);
   fetcher_->SetRequestContext(g_browser_process->system_request_context());
-  fetcher_->SetMaxRetriesOn5xx(kMaxRetryLanguageListFetch);
+  // Set retry parameter for HTTP status code 5xx. This doesn't work against
+  // 106 (net::ERR_INTERNET_DISCONNECTED) and so on.
+  // TranslateLanguageList handles network status, and implements retry.
+  fetcher_->SetMaxRetriesOn5xx(kMaxRetryLanguageListFetchOn5xx);
   fetcher_->Start();
 
   return true;
@@ -257,6 +271,7 @@ void TranslateLanguageList::LanguageListFetcher::OnURLFetchComplete(
   callback_.Run(include_alpha_languages_, state_ == COMPLETED, data);
 }
 
+// Transfer URLFetcher's ownership before invoking a callback.

[Alexei Svitkine (slow), 2013/06/13 14:46:02]

This comment seems out of place...

[Takashi Toyoshima, 2013/06/14 09:10:48]

Oops. Sorry, it looks like that I made wrong rebase to move this line here.
I fix to move it to proper place.

 // This must be kept in sync with the &cb= value in the kLanguageListFetchURL.
 const char TranslateLanguageList::kLanguageListCallbackName[] = "sl(";
 const char TranslateLanguageList::kTargetLanguagesKey[] = "tl";
@@ -271,6 +286,8 @@ TranslateLanguageList::TranslateLanguageList() {
 
   language_list_fetcher_.reset(new LanguageListFetcher(false));
   alpha_language_list_fetcher_.reset(new LanguageListFetcher(true));
+
+  resource_request_allowed_notifier_.Init(this);
 }
 
 TranslateLanguageList::~TranslateLanguageList() {
@@ -282,6 +299,11 @@ void TranslateLanguageList::GetSupportedLanguages(
   std::set<std::string>::const_iterator iter = all_supported_languages_.begin();
   for (; iter != all_supported_languages_.end(); ++iter)
     languages->push_back(*iter);
+
+  // Update language lists if they are not updated after Chrome was launched
+  // for later requests.
+  if (language_list_fetcher_.get() || alpha_language_list_fetcher_.get())
+    RequestLanguageList();
 }
 
 std::string TranslateLanguageList::GetLanguageCode(
@@ -308,6 +330,12 @@ bool TranslateLanguageList::IsAlphaLanguage(const std::string& language) {
 }
 
 void TranslateLanguageList::RequestLanguageList() {
+  // If resource requests are not allowed, we'll get a callback when they are.
+  if (resource_request_allowed_notifier_.ResourceRequestsAllowed())
+    OnResourceRequestsAllowed();
+}
+
+void TranslateLanguageList::OnResourceRequestsAllowed() {
   if (language_list_fetcher_.get() &&
       (language_list_fetcher_->state() == LanguageListFetcher::IDLE ||
        language_list_fetcher_->state() == LanguageListFetcher::FAILED)) {
@@ -329,8 +357,13 @@ void TranslateLanguageList::OnLanguageListFetchComplete(
     bool include_alpha_languages,
     bool success,
     const std::string& data) {
-  if (!success)
+  if (!success) {
+    resource_request_allowed_notifier_.ResourceRequestsAllowed();
+    // Since it fails just now, omit to schedule resource requests if
+    // ResourceRequestAllowedNotifier think it's ready. Otherwise, a callback
+    // will be invoked later to reuest resources again.

[Alexei Svitkine (slow), 2013/06/13 14:46:02]

Can you expand this comment to mention that fetcher is responsible for aborting
re-tries if it's asked to re-try too many times?

Else, just from the block of code it looks like you could get into an infinite
retry/fail cycle.

[Takashi Toyoshima, 2013/06/14 09:10:48]

Done.

     return;
+  }
 
   if (!include_alpha_languages) {
     SetSupportedLanguages(data, &supported_languages_);