Precache tracking database

components/precache/content/precache_manager.cc

+// Copyright 2013 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/precache/content/precache_manager.h"
+
+#include "base/bind.h"
+#include "base/command_line.h"
+#include "base/files/file_path.h"
+#include "base/logging.h"
+#include "base/time/time.h"
+#include "components/precache/core/precache_database.h"
+#include "components/precache/core/precache_switches.h"
+#include "content/public/browser/browser_context.h"
+#include "content/public/browser/browser_thread.h"
+#include "sql/connection.h"
+
+using content::BrowserThread;
+
+namespace precache {
+
+namespace {

[bengr, 2013/10/23 19:03:36]

Move this anonymous namespace about the precache namespace.

[sclittle, 2013/10/24 22:11:38]

Done.

+
+const base::FilePath::CharType kPrecacheDatabaseName[] =
+    FILE_PATH_LITERAL("PrecacheDatabase");
+
+void InitPrecacheDatabaseOnDBThread(
+    base::FilePath dir_path,
+    scoped_refptr<PrecacheDatabase> precache_database) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::DB));
+
+  sql::Connection* db = new sql::Connection();
+  DCHECK(db->Open(dir_path.Append(kPrecacheDatabaseName)));
+
+  // The precache database will take ownership of the connection.
+  precache_database->Init(db);
+}
+
+}  // namespace
+
+PrecacheManager::PrecacheManager(content::BrowserContext* browser_context)
+    : browser_context_(browser_context),
+      precache_database_(new PrecacheDatabase()),
+      is_precaching_(false) {
+  BrowserThread::PostTask(
+      BrowserThread::DB, FROM_HERE,
+      base::Bind(&InitPrecacheDatabaseOnDBThread, browser_context->GetPath(),
+                 precache_database_));
+}
+
+PrecacheManager::~PrecacheManager() {}
+
+// static
+bool PrecacheManager::IsPrecachingEnabled() {
+  // TODO(sclittle): Test for Finch trial as well when it exists.
+  return CommandLine::ForCurrentProcess()->HasSwitch(switches::kEnablePrecache);

[bengr, 2013/10/23 19:03:36]

How does precache know which servers to query? Are these other flags? We will
want to add these via gyp as well.

[sclittle, 2013/10/24 22:11:38]

Those are set by flags already; see
components/precache/core/precache_switches.cc, and if the flags aren't set, the
values defined in precache_defines.gypi are used. 

The existence of these flags is documented in the PrecacheFetcher class comment
and in the code where they are used, should they be documented in
PrecacheManager as well?

+}
+
+void PrecacheManager::Shutdown() {
+  CancelPrecaching();
+}
+
+void PrecacheManager::OnDone() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  {
+    base::AutoLock lock(lock_);
+    is_precaching_ = false;
+  }
+
+  precache_fetcher_.reset();
+}
+
+void PrecacheManager::StartPrecaching(
+    InterestingURLsProvider* interesting_urls_provider) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  {
+    base::AutoLock lock(lock_);
+    if (is_precaching_) {
+      DLOG(WARNING) << "Cannot start precaching because precaching is already "
+                       "in progress.";
+      return;
+    }
+    is_precaching_ = true;
+  }
+
+  // Report any UMA of precache stats for days before the current date and
+  // delete expired precache history.
+  BrowserThread::PostTask(
+      BrowserThread::DB, FROM_HERE,
+      base::Bind(
+          &PrecacheDatabase::FlushOldStats, precache_database_,
+          base::Time::Now().LocalMidnight() - base::TimeDelta::FromHours(1)));

[bengr, 2013/10/23 19:03:36]

Why 11pm? I don't follow.

[sclittle, 2013/10/24 22:11:38]

It just has to be a time on the day before Now(). The 11PM weirdness is to
account for daylight savings. Pulled it out and added comment.

+
+  interesting_urls_provider->GetInterestingURLs(base::Bind(
+      &PrecacheManager::OnInterestingURLsReceived, base::Unretained(this)));
+}
+
+void PrecacheManager::OnInterestingURLsReceived(
+    const std::list<GURL>& interesting_urls) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  if (!is_precaching()) {
+    // Don't start precaching if it was canceled while waiting for the list of
+    // interesting URLs.
+    return;
+  }
+
+  // Start precaching.
+  precache_fetcher_.reset(new PrecacheFetcher(
+      interesting_urls, browser_context_->GetRequestContext(), this));
+  precache_fetcher_->Start();
+}
+
+void PrecacheManager::CancelPrecaching() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  {
+    base::AutoLock lock(lock_);
+    if (!is_precaching_) {
+      // Do nothing if precaching is not in progress.
+      return;
+    }
+    is_precaching_ = false;
+  }
+
+  // Destroying the |precache_fetcher_| will cancel any fetch in progress.
+  precache_fetcher_.reset();
+}
+
+bool PrecacheManager::is_precaching() {
+  base::AutoLock lock(lock_);
+  return is_precaching_;
+}
+
+scoped_refptr<PrecacheDatabase> PrecacheManager::precache_database() {
+  return precache_database_;
+}
+
+}  // namespace precache