Make ThumbnailStore broadcast a notification when it has finished reading thumbnails from disk.

Make DOMUIThumbnailSource wait for this notification if ThumbnailStore isn't ready yet.
Also clean up some of the code.

Review URL: http://codereview.chromium.org/155911

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@21785 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 91 insertions, 48 deletions

diff --git a/chrome/browser/thumbnail_store.cc b/chrome/browser/thumbnail_store.cc
index e6f0e99..4f30c62 100644
--- a/chrome/browser/thumbnail_store.cc
+++ b/chrome/browser/thumbnail_store.cc
@@ -26,7 +26,8 @@ ThumbnailStore::ThumbnailStore()
     : cache_(NULL),
       db_(NULL),
       hs_(NULL),
-      url_blacklist_(NULL) {
+      url_blacklist_(NULL),
+      disk_data_loaded_(false) {
 }
 
 ThumbnailStore::~ThumbnailStore() {
@@ -34,8 +35,7 @@ ThumbnailStore::~ThumbnailStore() {
   DCHECK(hs_ == NULL);
 }
 
-void ThumbnailStore::Init(const FilePath& db_name,
-                          Profile* profile) {
+void ThumbnailStore::Init(const FilePath& db_name, Profile* profile) {
   // Load thumbnails already in the database.
   g_browser_process->file_thread()->message_loop()->PostTask(FROM_HERE,
       NewRunnableMethod(this, &ThumbnailStore::InitializeFromDB,
@@ -50,7 +50,9 @@ void ThumbnailStore::Init(const FilePath& db_name,
 
   // Get the list of most visited URLs and redirect information from the
   // HistoryService.
-  seconds_to_next_update_ = kInitialUpdateIntervalSecs;
+  most_visited_urls_.reset(new MostVisitedMap);
+  timer_.Start(base::TimeDelta::FromSeconds(kUpdateIntervalSecs), this,
+      &ThumbnailStore::UpdateURLData);
   UpdateURLData();
 
   // Register to get notified when the history is cleared.
@@ -139,8 +141,7 @@ void ThumbnailStore::Shutdown() {
   // for details.
   hs_ = NULL;
 
-  // The source of notifications is the Profile. We may outlive the Profile so
-  // we unregister for notifications here.
+  // De-register for notifications.
   registrar_.RemoveAll();
 
   // Stop the timer to ensure that UpdateURLData is not called during shutdown.
@@ -161,6 +162,11 @@ void ThumbnailStore::OnRedirectsForURLAvailable(
   if (!success)
     return;
 
+  DCHECK(redirect_urls_.get());
+
+  // If A -> B -> C is a redirect chain, then this function would be called
+  // with url=C and redirects = {B, A}. This is entered into the RedirectMap as
+  // A => {B -> C}.
   if (redirects->empty()) {
     (*redirect_urls_)[url] = new RefCountedVector<GURL>;
   } else {
@@ -171,9 +177,20 @@ void ThumbnailStore::OnRedirectsForURLAvailable(
   }
 }
 
+history::RedirectMap::iterator ThumbnailStore::GetRedirectIteratorForURL(
+    const GURL& url) const {
+  for (history::RedirectMap::iterator it = redirect_urls_->begin();
+      it != redirect_urls_->end(); ++it) {
+    if (it->first == url ||
+        (!it->second->data.empty() && it->second->data.back() == url))
+      return it;
+  }
+  return redirect_urls_->end();
+}
+
 void ThumbnailStore::Observe(NotificationType type,
-                             const NotificationSource& source,
-                             const NotificationDetails& details) {
+    const NotificationSource& source,
+    const NotificationDetails& details) {
   if (type.value != NotificationType::HISTORY_URLS_DELETED) {
     NOTREACHED();
     return;
@@ -183,37 +200,58 @@ void ThumbnailStore::Observe(NotificationType type,
   // If all history was cleared, clear all of our data and reset the update
   // timer.
   if (url_details->all_history) {
-    most_visited_urls_.reset();
-    redirect_urls_.reset();
-    cache_.reset();
-
-    timer_.Stop();
-    seconds_to_next_update_ = kInitialUpdateIntervalSecs;
-    timer_.Start(base::TimeDelta::FromSeconds(seconds_to_next_update_), this,
-        &ThumbnailStore::UpdateURLData);
+    most_visited_urls_->clear();
+    redirect_urls_->clear();
+    cache_->clear();
+    timer_.Reset();
   }
 }
 
+void ThumbnailStore::NotifyThumbnailStoreReady() {
+  NotificationService::current()->Notify(
+      NotificationType::THUMBNAIL_STORE_READY,
+      Source<ThumbnailStore>(this),
+      NotificationService::NoDetails());
+}
+
 void ThumbnailStore::UpdateURLData() {
+  DCHECK(url_blacklist_);
+
   int result_count = ThumbnailStore::kMaxCacheSize + url_blacklist_->GetSize();
   hs_->QueryTopURLsAndRedirects(result_count, &consumer_,
       NewCallback(this, &ThumbnailStore::OnURLDataAvailable));
 }
 
-void ThumbnailStore::OnURLDataAvailable(std::vector<GURL>* urls,
+void ThumbnailStore::OnURLDataAvailable(HistoryService::Handle handle,
+                                        bool success,
+                                        std::vector<GURL>* urls,
                                         history::RedirectMap* redirects) {
+  if (!success)
+    return;
+
   DCHECK(urls);
   DCHECK(redirects);
 
-  most_visited_urls_.reset(new std::vector<GURL>(*urls));
+  // Each element of |urls| is the start of a redirect chain. When thumbnails
+  // are stored from TabContents, the tails of the redirect chains are
+  // associated with the image. Since SetPageThumbnail is called frequently, we
+  // look up the tail end of each element in |urls| and insert that into the
+  // MostVisitedMap. This way SetPageThumbnail can more quickly check if a
+  // given url is in the most visited list.
+  most_visited_urls_->clear();
+  for (size_t i = 0; i < urls->size(); ++i) {
+    history::RedirectMap::iterator it = redirects->find(urls->at(i));
+    if (it->second->data.empty())
+      (*most_visited_urls_)[urls->at(i)] = GURL();
+    else
+      (*most_visited_urls_)[it->second->data.back()] = urls->at(i);
+  }
   redirect_urls_.reset(new history::RedirectMap(*redirects));
-  CleanCacheData();
 
-  // Schedule the next update.
-  if (seconds_to_next_update_ < kMaxUpdateIntervalSecs)
-    seconds_to_next_update_ *= 2;
-  timer_.Start(base::TimeDelta::FromSeconds(seconds_to_next_update_), this,
-      &ThumbnailStore::UpdateURLData);
+  if (IsReady())
+    NotifyThumbnailStoreReady();
+
+  CleanCacheData();
 }
 
 void ThumbnailStore::CleanCacheData() {
@@ -228,26 +266,15 @@ void ThumbnailStore::CleanCacheData() {
   // be written to disk.
   for (Cache::iterator cache_it = cache_->begin();
        cache_it != cache_->end();) {
-    const GURL* url = NULL;
-    // For each URL in the cache, search the RedirectMap for the originating
-    // URL.
-    for (history::RedirectMap::iterator it = redirect_urls_->begin();
-         it != redirect_urls_->end(); ++it) {
-      if (cache_it->first == it->first ||
-          (it->second->data.size() &&
-          cache_it->first == it->second->data.back())) {
-        url = &it->first;
-        break;
-      }
-    }
+    history::RedirectMap::iterator redirect_it =
+        GetRedirectIteratorForURL(cache_it->first);
+    const GURL* url = redirect_it == redirect_urls_->end() ?
+                          NULL : &redirect_it->first;
 
     // If this URL is blacklisted or not in the most visited list, mark it for
     // deletion. Otherwise, if the cache entry is dirty, mark it to be written
     // to disk.
     if (url == NULL || IsURLBlacklisted(*url) || !IsPopular(*url)) {
-      // Note that we don't check whether the cache entry is dirty or not. If
-      // it is not dirty, then the thumbnail exists on disk and must be
-      // deleted. If it is dirty, it may exist on disk so we delete it anyways.
       urls_to_delete->data.push_back(cache_it->first);
       cache_->erase(cache_it++);
     } else {
@@ -271,6 +298,8 @@ void ThumbnailStore::CommitCacheToDB(
   if (!db_)
     return;
 
+  base::TimeTicks db_start = base::TimeTicks::Now();
+
   int rv = sqlite3_exec(db_, "BEGIN TRANSACTION", NULL, NULL, NULL);
   DCHECK(rv == SQLITE_OK) << "Failed to begin transaction";
 
@@ -292,7 +321,8 @@ void ThumbnailStore::CommitCacheToDB(
          it != data_to_save->end(); ++it) {
       SQLITE_UNIQUE_STATEMENT(statement, *statement_cache_,
           "INSERT OR REPLACE INTO thumbnails "
-          "(url, boring_score, good_clipping, at_top, time_taken, data) "
+          "(url, boring_score, good_clipping, "
+          "at_top, time_taken, data) "
           "VALUES (?,?,?,?,?,?)");
       statement->bind_string(0, it->first.spec());
       statement->bind_double(1, it->second.score_.boring_score);
@@ -309,6 +339,9 @@ void ThumbnailStore::CommitCacheToDB(
 
   rv = sqlite3_exec(db_, "COMMIT", NULL, NULL, NULL);
   DCHECK(rv == SQLITE_OK) << "Failed to commit transaction";
+
+  base::TimeDelta delta = base::TimeTicks::Now() - db_start;
+  HISTOGRAM_TIMES("ThumbnailStore.WriteDBToDisk", delta);
 }
 
 void ThumbnailStore::InitializeFromDB(const FilePath& db_name,
@@ -351,18 +384,23 @@ void ThumbnailStore::InitializeFromDB(const FilePath& db_name,
 }
 
 void ThumbnailStore::GetAllThumbnailsFromDisk(MessageLoop* cb_loop) {
-  ThumbnailStore::Cache* cache = new ThumbnailStore::Cache;
+  Cache* cache = new Cache;
 
   SQLITE_UNIQUE_STATEMENT(statement, *statement_cache_,
       "SELECT * FROM thumbnails");
 
   while (statement->step() == SQLITE_ROW) {
+    // The URL
     GURL url(statement->column_string(0));
+
+    // The score.
     ThumbnailScore score(statement->column_double(1),      // Boring score
                          statement->column_bool(2),        // Good clipping
                          statement->column_bool(3),        // At top
                          base::Time::FromInternalValue(
                             statement->column_int64(4)));  // Time taken
+
+    // The image.
     scoped_refptr<RefCountedBytes> data = new RefCountedBytes;
     if (statement->column_blob_as_vector(5, &data->data))
       (*cache)[url] = CacheEntry(data, score, false);
@@ -372,17 +410,23 @@ void ThumbnailStore::GetAllThumbnailsFromDisk(MessageLoop* cb_loop) {
       NewRunnableMethod(this, &ThumbnailStore::OnDiskDataAvailable, cache));
 }
 
-void ThumbnailStore::OnDiskDataAvailable(ThumbnailStore::Cache* cache) {
+void ThumbnailStore::OnDiskDataAvailable(Cache* cache) {
   if (cache)
     cache_.reset(cache);
+
+  disk_data_loaded_ = true;
+  if (IsReady())
+    NotifyThumbnailStoreReady();
 }
 
 bool ThumbnailStore::ShouldStoreThumbnailForURL(const GURL& url) const {
-  if (IsURLBlacklisted(url) || cache_->size() >= ThumbnailStore::kMaxCacheSize)
+  if (!cache_.get())
+    return false;
+
+  if (IsURLBlacklisted(url) || cache_->size() >= kMaxCacheSize)
     return false;
 
-  return most_visited_urls_->size() < ThumbnailStore::kMaxCacheSize ||
-         IsPopular(url);
+  return IsPopular(url);
 }
 
 bool ThumbnailStore::IsURLBlacklisted(const GURL& url) const {
@@ -397,7 +441,6 @@ std::wstring ThumbnailStore::GetDictionaryKeyForURL(
 }
 
 bool ThumbnailStore::IsPopular(const GURL& url) const {
-  return most_visited_urls_->end() != find(most_visited_urls_->begin(),
-                                           most_visited_urls_->end(),
-                                           url);
+  return most_visited_urls_->size() < kMaxCacheSize ||
+         most_visited_urls_->find(url) != most_visited_urls_->end();
 }