Preload the visited link db on the file thread if the file exists.

Otherwise, just load like normal on the UI thread.

BUG=24163

Review URL: http://codereview.chromium.org/502005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@34874 0039d316-1c4b-4281-b951-d872f2087c98

6 files changed, 180 insertions, 88 deletions

diff --git a/chrome/browser/browser_main.cc b/chrome/browser/browser_main.cc
index 6ca2b4b..fd0f7fb 100644
--- a/chrome/browser/browser_main.cc
+++ b/chrome/browser/browser_main.cc
@@ -44,6 +44,7 @@
 #include "chrome/browser/plugin_service.h"
 #include "chrome/browser/process_singleton.h"
 #include "chrome/browser/profile_manager.h"
+#include "chrome/browser/profile.h"
 #include "chrome/browser/renderer_host/resource_dispatcher_host.h"
 #include "chrome/browser/shell_integration.h"
 #include "chrome/browser/user_data_manager.h"
@@ -100,7 +101,6 @@
 #include "chrome/browser/browser_trial.h"
 #include "chrome/browser/metrics/user_metrics.h"
 #include "chrome/browser/net/url_fixer_upper.h"
-#include "chrome/browser/profile.h"
 #include "chrome/browser/rlz/rlz.h"
 #include "chrome/browser/views/user_data_dir_dialog.h"
 #include "chrome/common/env_vars.h"
@@ -682,6 +682,10 @@ int BrowserMain(const MainFunctionParams& parameters) {
   CHECK(profile) << "Cannot get default profile.";
 #endif
 
+  // Now that we have a profile, try to load the visited link master on a
+  // background thread.  We want to start this as soon as we can.
+  profile->PreloadVisitedLinkMaster();
+
   PrefService* user_prefs = profile->GetPrefs();
   DCHECK(user_prefs);
 
diff --git a/chrome/browser/profile.cc b/chrome/browser/profile.cc
index 111029b..e61ae5a 100644
--- a/chrome/browser/profile.cc
+++ b/chrome/browser/profile.cc
@@ -125,6 +125,87 @@ bool HasACacheSubdir(const FilePath &dir) {
 
 }  // namespace
 
+// This helper class owns the VisitedLinkMaster and exposes a way to load it
+// from on the file thread.
+class VisitedLinkCreator
+    : public base::RefCountedThreadSafe<VisitedLinkCreator> {
+ public:
+  enum LoadState {
+    NOT_LOADED,
+    FILE_LOAD_FAILED,
+    LOAD_FINISHED
+  };
+
+  explicit VisitedLinkCreator(Profile* profile)
+      : listener_(new VisitedLinkEventListener()),
+        profile_(profile),
+        load_state_(NOT_LOADED) {
+    visited_link_master_.reset(new VisitedLinkMaster(listener_.get(),
+                                                     profile_));
+  }
+
+  // Preload the visited link master on the file thread.
+  void Preload() {
+    DCHECK(ChromeThread::CurrentlyOn(ChromeThread::UI));
+    ChromeThread::PostTask(ChromeThread::FILE, FROM_HERE, NewRunnableMethod(
+        this, &VisitedLinkCreator::LoadBackground));
+  }
+
+  // This method can return NULL if for some reason we can't initialize the
+  // visited link master.
+  VisitedLinkMaster* GetMaster() {
+    DCHECK(ChromeThread::CurrentlyOn(ChromeThread::UI));
+    // Go ahead and try to load the VisitedLink table.  If the data was
+    // preloaded, Load() does nothing.
+    AutoLock l(lock_);
+    if (LOAD_FINISHED != load_state_) {
+      bool success = false;
+      if (FILE_LOAD_FAILED == load_state_) {
+        success = visited_link_master_->InitFromScratch();
+      } else if (NOT_LOADED == load_state_) {
+        // We haven't tried to load from file yet, so go ahead and do that.
+        success = visited_link_master_->Init();
+      }
+
+      if (!success) {
+        NOTREACHED() << "Failed to init visited link master.";
+        visited_link_master_.reset();
+      }
+      load_state_ = LOAD_FINISHED;
+    }
+
+    // We don't need to lock here because after Load() has been called, we
+    // never change vistied_link_master_.
+    return visited_link_master_.get();
+  }
+
+ private:
+  // Tries to load the visited link database from the UI thread.
+  void LoadBackground() {
+    DCHECK(ChromeThread::CurrentlyOn(ChromeThread::FILE));
+    AutoLock l(lock_);
+    if (NOT_LOADED != load_state_)
+      return;
+
+    // We only want to try to load the data from a file (it's not thread safe
+    // to InitFromScratch on the file thread).
+    load_state_ = visited_link_master_->InitFromFile() ? LOAD_FINISHED
+                                                       : FILE_LOAD_FAILED;
+  }
+
+  scoped_ptr<VisitedLinkMaster::Listener> listener_;
+  Profile* profile_;
+
+  // This lock protects visited_link_master_ and load_state_.
+  Lock lock_;
+  scoped_ptr<VisitedLinkMaster> visited_link_master_;
+  // Once created_ is true, we can stop trying to create and init the
+  // VisitedLinkMaster.
+  LoadState load_state_;
+
+  DISALLOW_COPY_AND_ASSIGN(VisitedLinkCreator);
+};
+
 // A pointer to the request context for the default profile.  See comments on
 // Profile::GetDefaultRequestContext.
 URLRequestContextGetter* Profile::default_request_context_;
@@ -214,7 +295,9 @@ class OffTheRecordProfileImpl : public Profile,
     return reinterpret_cast<ProfileId>(this);
   }
 
-  virtual FilePath GetPath() { return profile_->GetPath(); }
+  virtual FilePath GetPath() {
+    return profile_->GetPath();
+  }
 
   virtual bool IsOffTheRecord() {
     return true;
@@ -245,6 +328,8 @@ class OffTheRecordProfileImpl : public Profile,
     return NULL;
   }
 
+  virtual void PreloadVisitedLinkMaster() {}
+
   virtual ExtensionsService* GetExtensionsService() {
     return NULL;
   }
@@ -567,7 +652,6 @@ class OffTheRecordProfileImpl : public Profile,
 
 ProfileImpl::ProfileImpl(const FilePath& path)
     : path_(path),
-      visited_link_event_listener_(new VisitedLinkEventListener()),
       extension_devtools_manager_(NULL),
       request_context_(NULL),
       media_request_context_(NULL),
@@ -814,15 +898,16 @@ webkit_database::DatabaseTracker* ProfileImpl::GetDatabaseTracker() {
 }
 
 VisitedLinkMaster* ProfileImpl::GetVisitedLinkMaster() {
-  if (!visited_link_master_.get()) {
-    scoped_ptr<VisitedLinkMaster> visited_links(
-      new VisitedLinkMaster(visited_link_event_listener_.get(), this));
-    if (!visited_links->Init())
-      return NULL;
-    visited_link_master_.swap(visited_links);
-  }
+  if (!visited_link_creator_.get())
+    visited_link_creator_ = new VisitedLinkCreator(this);
+  return visited_link_creator_->GetMaster();
+}
 
-  return visited_link_master_.get();
+void ProfileImpl::PreloadVisitedLinkMaster() {
+  if (!visited_link_creator_.get()) {
+    visited_link_creator_ = new VisitedLinkCreator(this);
+    visited_link_creator_->Preload();
+  }
 }
 
 ExtensionsService* ProfileImpl::GetExtensionsService() {
diff --git a/chrome/browser/profile.h b/chrome/browser/profile.h
index 815dc22..e72dbd7 100644
--- a/chrome/browser/profile.h
+++ b/chrome/browser/profile.h
@@ -64,8 +64,8 @@ class ThemeProvider;
 class ThumbnailStore;
 class URLRequestContextGetter;
 class UserScriptMaster;
+class VisitedLinkCreator;
 class VisitedLinkMaster;
-class VisitedLinkEventListener;
 class WebDataService;
 class WebKitContext;
 class WebResourceService;
@@ -148,6 +148,10 @@ class Profile {
   // that this method is called.
   virtual VisitedLinkMaster* GetVisitedLinkMaster() = 0;
 
+  // Loads the visited link master on the file thread.  It's safe to call
+  // GetVisitedLinkMaster without calling this in advance.
+  virtual void PreloadVisitedLinkMaster() = 0;
+
   // Retrieves a pointer to the ExtensionsService associated with this
   // profile. The ExtensionsService is created at startup.
   virtual ExtensionsService* GetExtensionsService() = 0;
@@ -406,6 +410,7 @@ class ProfileImpl : public Profile,
   virtual Profile* GetOriginalProfile();
   virtual webkit_database::DatabaseTracker* GetDatabaseTracker();
   virtual VisitedLinkMaster* GetVisitedLinkMaster();
+  virtual void PreloadVisitedLinkMaster();
   virtual UserScriptMaster* GetUserScriptMaster();
   virtual SSLHostState* GetSSLHostState();
   virtual net::TransportSecurityState* GetTransportSecurityState();
@@ -491,8 +496,7 @@ class ProfileImpl : public Profile,
 
   FilePath path_;
   FilePath base_cache_path_;
-  scoped_ptr<VisitedLinkEventListener> visited_link_event_listener_;
-  scoped_ptr<VisitedLinkMaster> visited_link_master_;
+  scoped_refptr<VisitedLinkCreator> visited_link_creator_;
   scoped_refptr<ExtensionsService> extensions_service_;
   scoped_refptr<UserScriptMaster> user_script_master_;
   scoped_refptr<ExtensionDevToolsManager> extension_devtools_manager_;
diff --git a/chrome/browser/visitedlink_master.cc b/chrome/browser/visitedlink_master.cc
index c2aa3fe..299f220 100644
--- a/chrome/browser/visitedlink_master.cc
+++ b/chrome/browser/visitedlink_master.cc
@@ -24,7 +24,6 @@
 #include "base/rand_util.h"
 #include "base/stack_container.h"
 #include "base/string_util.h"
-#include "chrome/browser/browser_process.h"
 #include "chrome/browser/chrome_thread.h"
 #include "chrome/browser/history/history.h"
 #include "chrome/browser/profile.h"
@@ -255,10 +254,70 @@ void VisitedLinkMaster::InitMembers(Listener* listener, Profile* profile) {
 
 bool VisitedLinkMaster::Init() {
   if (!InitFromFile())
-    return InitFromScratch(suppress_rebuild_);
+    return InitFromScratch();
   return true;
 }
 
+bool VisitedLinkMaster::InitFromFile() {
+  DCHECK(file_ == NULL);
+
+  FilePath filename;
+  GetDatabaseFileName(&filename);
+  ScopedFILE file_closer(OpenFile(filename, "rb+"));
+  if (!file_closer.get())
+    return false;
+
+  int32 num_entries, used_count;
+  if (!ReadFileHeader(file_closer.get(), &num_entries, &used_count, salt_))
+    return false;  // Header isn't valid.
+
+  // Allocate and read the table.
+  if (!CreateURLTable(num_entries, false))
+    return false;
+  if (!ReadFromFile(file_closer.get(), kFileHeaderSize,
+                    hash_table_, num_entries * sizeof(Fingerprint))) {
+    FreeURLTable();
+    return false;
+  }
+  used_items_ = used_count;
+
+#ifndef NDEBUG
+  DebugValidate();
+#endif
+
+  file_ = file_closer.release();
+  return true;
+}
+
+bool VisitedLinkMaster::InitFromScratch() {
+  int32 table_size = kDefaultTableSize;
+  if (table_size_override_)
+    table_size = table_size_override_;
+
+  // The salt must be generated before the table so that it can be copied to
+  // the shared memory.
+  GenerateSalt(salt_);
+  if (!CreateURLTable(table_size, true))
+    return false;
+
+#ifndef NDEBUG
+  DebugValidate();
+#endif
+
+  if (suppress_rebuild_) {
+    // When we disallow rebuilds (normally just unit tests), just use the
+    // current empty table.
+    return WriteFullTable();
+  }
+
+  // This will build the table from history. On the first run, history will
+  // be empty, so this will be correct. This will also write the new table
+  // to disk. We don't want to save explicitly here, since the rebuild may
+  // not complete, leaving us with an empty but valid visited link database.
+  // In the future, we won't know we need to try rebuilding again.
+  return RebuildTableFromHistory();
+}
+
 VisitedLinkMaster::Hash VisitedLinkMaster::TryToAddURL(const GURL& url) {
   // Extra check that we are not off the record. This should not happen.
   if (profile_ && profile_->IsOffTheRecord()) {
@@ -537,66 +596,6 @@ bool VisitedLinkMaster::WriteFullTable() {
   return true;
 }
 
-bool VisitedLinkMaster::InitFromFile() {
-  DCHECK(file_ == NULL);
-
-  FilePath filename;
-  GetDatabaseFileName(&filename);
-  ScopedFILE file_closer(OpenFile(filename, "rb+"));
-  if (!file_closer.get())
-    return false;
-
-  int32 num_entries, used_count;
-  if (!ReadFileHeader(file_closer.get(), &num_entries, &used_count, salt_))
-    return false;  // Header isn't valid.
-
-  // Allocate and read the table.
-  if (!CreateURLTable(num_entries, false))
-    return false;
-  if (!ReadFromFile(file_closer.get(), kFileHeaderSize,
-                    hash_table_, num_entries * sizeof(Fingerprint))) {
-    FreeURLTable();
-    return false;
-  }
-  used_items_ = used_count;
-
-#ifndef NDEBUG
-  DebugValidate();
-#endif
-
-  file_ = file_closer.release();
-  return true;
-}
-
-bool VisitedLinkMaster::InitFromScratch(bool suppress_rebuild) {
-  int32 table_size = kDefaultTableSize;
-  if (table_size_override_)
-    table_size = table_size_override_;
-
-  // The salt must be generated before the table so that it can be copied to
-  // the shared memory.
-  GenerateSalt(salt_);
-  if (!CreateURLTable(table_size, true))
-    return false;
-
-#ifndef NDEBUG
-  DebugValidate();
-#endif
-
-  if (suppress_rebuild) {
-    // When we disallow rebuilds (normally just unit tests), just use the
-    // current empty table.
-    return WriteFullTable();
-  }
-
-  // This will build the table from history. On the first run, history will
-  // be empty, so this will be correct. This will also write the new table
-  // to disk. We don't want to save explicitly here, since the rebuild may
-  // not complete, leaving us with an empty but valid visited link database.
-  // In the future, we won't know we need to try rebuilding again.
-  return RebuildTableFromHistory();
-}
-
 bool VisitedLinkMaster::ReadFileHeader(FILE* file,
                                        int32* num_entries,
                                        int32* used_count,
diff --git a/chrome/browser/visitedlink_master.h b/chrome/browser/visitedlink_master.h
index fc35ff9..74be376 100644
--- a/chrome/browser/visitedlink_master.h
+++ b/chrome/browser/visitedlink_master.h
@@ -77,9 +77,19 @@ class VisitedLinkMaster : public VisitedLinkCommon {
 
   // Must be called immediately after object creation. Nothing else will work
   // until this is called. Returns true on success, false means that this
-  // object won't work.
+  // object won't work. You can also use InitFromFile() and InitFromScratch()
+  // if you need more control over loading the visited link information.
   bool Init();
 
+  // Try to load the table from the database file. If the file doesn't exist or
+  // is corrupt, this will return failure.
+  bool InitFromFile();
+
+  // Creates a new empty table, call if InitFromFile() fails. Normally, when
+  // |suppress_rebuild| is false, the table will be rebuilt from history,
+  // keeping us in sync.
+  bool InitFromScratch();
+
   base::SharedMemory* shared_memory() { return shared_memory_; }
 
   // Adds a URL to the table.
@@ -167,10 +177,6 @@ class VisitedLinkMaster : public VisitedLinkCommon {
   // the table file open and the handle to it in file_
   bool WriteFullTable();
 
-  // Try to load the table from the database file. If the file doesn't exist or
-  // is corrupt, this will return failure.
-  bool InitFromFile();
-
   // Reads the header of the link coloring database from disk. Assumes the
   // file pointer is at the beginning of the file and that there are no pending
   // asynchronous I/O operations.
@@ -222,13 +228,6 @@ class VisitedLinkMaster : public VisitedLinkCommon {
   // fingerprint was deleted, false if it was not in the table to delete.
   bool DeleteFingerprint(Fingerprint fingerprint, bool update_file);
 
-  // Creates a new empty table, call if InitFromFile() fails. Normally, when
-  // |suppress_rebuild| is false, the table will be rebuilt from history,
-  // keeping us in sync. When |suppress_rebuild| is true, the new table will be
-  // empty and we will not consult history. This is used when clearing the
-  // database and for unit tests.
-  bool InitFromScratch(bool suppress_rebuild);
-
   // Allocates the Fingerprint structure and length. When init_to_empty is set,
   // the table will be filled with 0s and used_items_ will be set to 0 as well.
   // If the flag is not set, these things are untouched and it is the
diff --git a/chrome/test/testing_profile.h b/chrome/test/testing_profile.h
index 0e6f16d..7e01ff0 100644
--- a/chrome/test/testing_profile.h
+++ b/chrome/test/testing_profile.h
@@ -77,6 +77,7 @@ class TestingProfile : public Profile {
   virtual Profile* GetOriginalProfile() { return this; }
   virtual webkit_database::DatabaseTracker* GetDatabaseTracker();
   virtual VisitedLinkMaster* GetVisitedLinkMaster() { return NULL; }
+  virtual void PreloadVisitedLinkMaster() {}
   virtual ExtensionsService* GetExtensionsService() { return NULL; }
   virtual UserScriptMaster* GetUserScriptMaster() { return NULL; }
   virtual ExtensionDevToolsManager* GetExtensionDevToolsManager() {