Implementation of application cache update algorithm.

Does not include storage nor processing of pending master entries.


TEST=verify update functionality
BUG=none
Review URL: http://codereview.chromium.org/201070

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@28123 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 671 insertions, 0 deletions

diff --git a/webkit/appcache/appcache_update_job.cc b/webkit/appcache/appcache_update_job.cc
new file mode 100644
index 0000000..7732faf
--- /dev/null
+++ b/webkit/appcache/appcache_update_job.cc
@@ -0,0 +1,671 @@
+// Copyright (c) 2009 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 "webkit/appcache/appcache_update_job.h"
+
+#include "base/compiler_specific.h"
+#include "base/message_loop.h"
+#include "net/base/io_buffer.h"
+#include "net/base/load_flags.h"
+#include "webkit/appcache/appcache_group.h"
+#include "webkit/appcache/appcache_host.h"
+
+namespace appcache {
+
+static const int kBufferSize = 4096;
+static const size_t kMaxConcurrentUrlFetches = 2;
+
+// Extra info associated with requests for use during response processing.
+// This info is deleted when the URLRequest is deleted.
+struct UpdateJobInfo :  public URLRequest::UserData {
+  enum RequestType {
+    MANIFEST_FETCH,
+    URL_FETCH,
+    MANIFEST_REFETCH,
+  };
+
+  explicit UpdateJobInfo(RequestType request_type)
+      : type(request_type),
+        buffer(new net::IOBuffer(kBufferSize)) {
+  }
+
+  RequestType type;
+  scoped_refptr<net::IOBuffer> buffer;
+  // TODO(jennb): need storage info to stream response data to storage
+};
+
+// Helper class for collecting hosts per frontend when sending notifications
+// so that only one notification is sent for all hosts using the same frontend.
+class HostNotifier {
+ public:
+  typedef std::vector<int> HostIds;
+  typedef std::map<AppCacheFrontend*, HostIds> NotifyHostMap;
+
+  // Caller is responsible for ensuring there will be no duplicate hosts.
+  void AddHost(AppCacheHost* host) {
+    std::pair<NotifyHostMap::iterator , bool> ret = hosts_to_notify.insert(
+        NotifyHostMap::value_type(host->frontend(), HostIds()));
+    ret.first->second.push_back(host->host_id());
+  }
+
+  void AddHosts(const std::set<AppCacheHost*>& hosts) {
+    for (std::set<AppCacheHost*>::const_iterator it = hosts.begin();
+         it != hosts.end(); ++it) {
+      AddHost(*it);
+    }
+  }
+
+  void SendNotifications(EventID event_id) {
+    for (NotifyHostMap::iterator it = hosts_to_notify.begin();
+         it != hosts_to_notify.end(); ++it) {
+      AppCacheFrontend* frontend = it->first;
+      frontend->OnEventRaised(it->second, event_id);
+    }
+  }
+
+ private:
+  NotifyHostMap hosts_to_notify;
+};
+
+AppCacheUpdateJob::AppCacheUpdateJob(AppCacheService* service,
+                                     AppCacheGroup* group)
+    : ALLOW_THIS_IN_INITIALIZER_LIST(method_factory_(this)),
+      service_(service),
+      group_(group),
+      update_type_(UNKNOWN_TYPE),
+      internal_state_(FETCH_MANIFEST),
+      master_entries_completed_(0),
+      url_fetches_completed_(0),
+      manifest_url_request_(NULL) {
+  DCHECK(group_);
+  manifest_url_ = group_->manifest_url();
+}
+
+AppCacheUpdateJob::~AppCacheUpdateJob() {
+  Cancel();
+
+  DCHECK(!manifest_url_request_);
+  DCHECK(pending_url_fetches_.empty());
+
+  group_->SetUpdateStatus(AppCacheGroup::IDLE);
+}
+
+void AppCacheUpdateJob::StartUpdate(AppCacheHost* host,
+                                    const GURL& new_master_resource) {
+  DCHECK(group_->update_job() == this);
+
+  if (!new_master_resource.is_empty()) {
+    /* TODO(jennb): uncomment when processing master entries is implemented
+    std::pair<PendingMasters::iterator, bool> ret =
+        pending_master_entries_.insert(
+            PendingMasters::value_type(new_master_resource, PendingHosts()));
+    ret.first->second.push_back(host);
+    */
+  }
+
+  // Notify host (if any) if already checking or downloading.
+  appcache::AppCacheGroup::UpdateStatus update_status = group_->update_status();
+  if (update_status == AppCacheGroup::CHECKING ||
+      update_status == AppCacheGroup::DOWNLOADING) {
+    if (host) {
+      NotifySingleHost(host, CHECKING_EVENT);
+      if (update_status == AppCacheGroup::DOWNLOADING)
+        NotifySingleHost(host, DOWNLOADING_EVENT);
+    }
+    return;
+  }
+
+  // Begin update process for the group.
+  group_->SetUpdateStatus(AppCacheGroup::CHECKING);
+  if (group_->HasCache()) {
+    update_type_ = UPGRADE_ATTEMPT;
+    NotifyAllAssociatedHosts(CHECKING_EVENT);
+  } else {
+    update_type_ = CACHE_ATTEMPT;
+    DCHECK(host);
+    NotifySingleHost(host, CHECKING_EVENT);
+  }
+
+  FetchManifest(true);
+}
+
+void AppCacheUpdateJob::FetchManifest(bool is_first_fetch) {
+  DCHECK(!manifest_url_request_);
+  manifest_url_request_ = new URLRequest(manifest_url_, this);
+  UpdateJobInfo::RequestType fetch_type = is_first_fetch ?
+      UpdateJobInfo::MANIFEST_FETCH : UpdateJobInfo::MANIFEST_REFETCH;
+  manifest_url_request_->SetUserData(this, new UpdateJobInfo(fetch_type));
+  manifest_url_request_->set_context(service_->request_context());
+  // TODO(jennb): add "If-Modified-Since" if have previous date
+  manifest_url_request_->set_load_flags(
+      manifest_url_request_->load_flags() | net::LOAD_DISABLE_INTERCEPT);
+  manifest_url_request_->Start();
+}
+
+void AppCacheUpdateJob::OnResponseStarted(URLRequest *request) {
+  if (request->status().is_success())
+    ReadResponseData(request);
+  else
+    OnResponseCompleted(request);
+}
+
+void AppCacheUpdateJob::ReadResponseData(URLRequest* request) {
+  if (internal_state_ == CACHE_FAILURE)
+    return;
+
+  int bytes_read = 0;
+  UpdateJobInfo* info =
+      static_cast<UpdateJobInfo*>(request->GetUserData(this));
+  request->Read(info->buffer, kBufferSize, &bytes_read);
+  OnReadCompleted(request, bytes_read);
+}
+
+void AppCacheUpdateJob::OnReadCompleted(URLRequest* request, int bytes_read) {
+  bool data_consumed = true;
+  if (request->status().is_success() && bytes_read > 0) {
+    UpdateJobInfo* info =
+        static_cast<UpdateJobInfo*>(request->GetUserData(this));
+
+    data_consumed = ConsumeResponseData(request, info, bytes_read);
+    if (data_consumed) {
+      bytes_read = 0;
+      while (request->Read(info->buffer, kBufferSize, &bytes_read)) {
+        if (bytes_read > 0) {
+          data_consumed = ConsumeResponseData(request, info, bytes_read);
+          if (!data_consumed)
+            break;  // wait for async data processing, then read more
+        } else {
+          break;
+        }
+      }
+    }
+  }
+
+  if (data_consumed && !request->status().is_io_pending())
+    OnResponseCompleted(request);
+}
+
+bool AppCacheUpdateJob::ConsumeResponseData(URLRequest* request,
+                                            UpdateJobInfo* info,
+                                            int bytes_read) {
+  switch (info->type) {
+    case UpdateJobInfo::MANIFEST_FETCH:
+      manifest_data_.append(info->buffer->data(), bytes_read);
+      break;
+    case UpdateJobInfo::URL_FETCH:
+      // TODO(jennb): stream data to storage. will be async so need to wait
+      // for callback before reading next chunk.
+      // For now, schedule a task to continue reading to simulate async-ness.
+      MessageLoop::current()->PostTask(FROM_HERE,
+          method_factory_.NewRunnableMethod(
+              &AppCacheUpdateJob::ReadResponseData, request));
+      return false;
+    case UpdateJobInfo::MANIFEST_REFETCH:
+      manifest_refetch_data_.append(info->buffer->data(), bytes_read);
+      break;
+    default:
+      NOTREACHED();
+  }
+  return true;
+}
+
+void AppCacheUpdateJob::OnReceivedRedirect(URLRequest* request,
+                                           const GURL& new_url,
+                                           bool* defer_redirect) {
+  // Redirect is not allowed by the update process.
+  request->Cancel();
+  OnResponseCompleted(request);
+}
+
+void AppCacheUpdateJob::OnResponseCompleted(URLRequest* request) {
+  // TODO(jennb): think about retrying for 503s where retry-after is 0
+  UpdateJobInfo* info =
+      static_cast<UpdateJobInfo*>(request->GetUserData(this));
+  switch (info->type) {
+    case UpdateJobInfo::MANIFEST_FETCH:
+      HandleManifestFetchCompleted(request);
+      break;
+    case UpdateJobInfo::URL_FETCH:
+      HandleUrlFetchCompleted(request);
+      break;
+    case UpdateJobInfo::MANIFEST_REFETCH:
+      HandleManifestRefetchCompleted(request);
+      break;
+    default:
+      NOTREACHED();
+  }
+
+  delete request;
+}
+
+void AppCacheUpdateJob::HandleManifestFetchCompleted(URLRequest* request) {
+  DCHECK(internal_state_ == FETCH_MANIFEST);
+  manifest_url_request_ = NULL;
+
+  if (!request->status().is_success()) {
+    LOG(INFO) << "Request non-success, status: " << request->status().status()
+        << " os_error: " << request->status().os_error();
+    internal_state_ = CACHE_FAILURE;
+    MaybeCompleteUpdate();  // if not done, run async cache failure steps
+    return;
+  }
+
+  int response_code = request->GetResponseCode();
+  std::string mime_type;
+  request->GetMimeType(&mime_type);
+
+  if (response_code == 200 && mime_type == kManifestMimeType) {
+    if (update_type_ == UPGRADE_ATTEMPT)
+      CheckIfManifestChanged();  // continues asynchronously
+    else
+      ContinueHandleManifestFetchCompleted(true);
+  } else if (response_code == 304 && update_type_ == UPGRADE_ATTEMPT) {
+    ContinueHandleManifestFetchCompleted(false);
+  } else if (response_code == 404 || response_code == 410) {
+    group_->set_obsolete(true);
+    NotifyAllAssociatedHosts(OBSOLETE_EVENT);
+    NotifyAllPendingMasterHosts(ERROR_EVENT);
+    DeleteSoon();
+  } else {
+    LOG(INFO) << "Cache failure, response code: " << response_code;
+    internal_state_ = CACHE_FAILURE;
+    MaybeCompleteUpdate();  // if not done, run async cache failure steps
+  }
+}
+
+void AppCacheUpdateJob::ContinueHandleManifestFetchCompleted(bool changed) {
+  DCHECK(internal_state_ == FETCH_MANIFEST);
+
+  if (!changed) {
+    DCHECK(update_type_ == UPGRADE_ATTEMPT);
+    internal_state_ = NO_UPDATE;
+    MaybeCompleteUpdate();  // if not done, run async 6.9.4 step 7 substeps
+    return;
+  }
+
+  Manifest manifest;
+  if (!ParseManifest(manifest_url_, manifest_data_.data(),
+                     manifest_data_.length(), manifest)) {
+    LOG(INFO) << "Failed to parse manifest: " << manifest_url_;
+    internal_state_ = CACHE_FAILURE;
+    MaybeCompleteUpdate();  // if not done, run async cache failure steps
+    return;
+  }
+
+  // Proceed with update process. Section 6.9.4 steps 8-20.
+  internal_state_ = DOWNLOADING;
+  inprogress_cache_ = new AppCache(service_, service_->NewCacheId());
+  inprogress_cache_->set_owning_group(group_);
+  BuildUrlFileList(manifest);
+  inprogress_cache_->InitializeWithManifest(&manifest);
+
+  // Associate all pending master hosts with the newly created cache.
+  for (PendingMasters::iterator it = pending_master_entries_.begin();
+       it != pending_master_entries_.end(); ++it) {
+    PendingHosts hosts = it->second;
+    for (PendingHosts::iterator host_it = hosts.begin();
+         host_it != hosts.end(); ++host_it) {
+      AppCacheHost* host = *host_it;
+      host->AssociateCache(inprogress_cache_);
+    }
+  }
+
+  group_->SetUpdateStatus(AppCacheGroup::DOWNLOADING);
+  NotifyAllAssociatedHosts(DOWNLOADING_EVENT);
+  FetchUrls();
+  MaybeCompleteUpdate();  // if not done, continues when async fetches complete
+}
+
+void AppCacheUpdateJob::HandleUrlFetchCompleted(URLRequest* request) {
+  DCHECK(internal_state_ == DOWNLOADING);
+
+  const GURL& url = request->original_url();
+  pending_url_fetches_.erase(url);
+  ++url_fetches_completed_;
+
+  int response_code = request->GetResponseCode();
+  AppCacheEntry& entry = url_file_list_.find(url)->second;
+
+  if (request->status().is_success() && response_code == 200) {
+    // TODO(jennb): associate storage with the new entry
+    inprogress_cache_->AddEntry(url, entry);
+
+    // Foreign entries will be detected during cache selection.
+    // Note: 6.9.4, step 17.9 possible optimization: if resource is HTML or XML
+    // file whose root element is an html element with a manifest attribute
+    // whose value doesn't match the manifest url of the application cache
+    // being processed, mark the entry as being foreign.
+  } else {
+    LOG(INFO) << "Request status: " << request->status().status()
+        << " os_error: " << request->status().os_error()
+        << " response code: " << response_code;
+
+    // TODO(jennb): discard any stored data for this entry
+    if (entry.IsExplicit() || entry.IsFallback()) {
+      internal_state_ = CACHE_FAILURE;
+
+      // Cancel any pending URL requests.
+      for (PendingUrlFetches::iterator it = pending_url_fetches_.begin();
+           it != pending_url_fetches_.end(); ++it) {
+        it->second->Cancel();
+        delete it->second;
+      }
+
+      url_fetches_completed_ +=
+          pending_url_fetches_.size() + urls_to_fetch_.size();
+      pending_url_fetches_.clear();
+      urls_to_fetch_.clear();
+    } else if (response_code == 404 || response_code == 410) {
+      // Entry is skipped.  They are dropped from the cache.
+    } else if (update_type_ == UPGRADE_ATTEMPT) {
+      // Copy the resource and its metadata from the newest complete cache.
+      AppCache* cache = group_->newest_complete_cache();
+      AppCacheEntry* copy = cache->GetEntry(url);
+      if (copy)
+        CopyEntryToCache(url, *copy, &entry);
+    }
+  }
+
+  // Fetch another URL now that one request has completed.
+  if (internal_state_ != CACHE_FAILURE)
+    FetchUrls();
+
+  MaybeCompleteUpdate();
+}
+
+void AppCacheUpdateJob::HandleManifestRefetchCompleted(URLRequest* request) {
+  DCHECK(internal_state_ == REFETCH_MANIFEST);
+  manifest_url_request_ = NULL;
+
+  int response_code = request->GetResponseCode();
+  if (response_code == 304 || manifest_data_ == manifest_refetch_data_) {
+    AppCacheEntry entry(AppCacheEntry::MANIFEST);
+    // TODO(jennb): add manifest_data_ to storage and put storage key in entry
+    // Also store response headers from request for HTTP cache control.
+    inprogress_cache_->AddOrModifyEntry(manifest_url_, entry);
+    inprogress_cache_->set_update_time(base::TimeTicks::Now());
+
+    // TODO(jennb): start of part to make async (cache storage may fail;
+    // group storage may fail)
+    inprogress_cache_->set_complete(true);
+
+    // TODO(jennb): write new cache to storage here
+    group_->AddCache(inprogress_cache_);
+    // TODO(jennb): write new group to storage here
+    inprogress_cache_ = NULL;
+
+    if (update_type_ == CACHE_ATTEMPT) {
+      NotifyAllAssociatedHosts(CACHED_EVENT);
+    } else {
+      NotifyAllAssociatedHosts(UPDATE_READY_EVENT);
+    }
+    DeleteSoon();
+    // TODO(jennb): end of part that needs to be made async.
+  } else {
+    LOG(INFO) << "Request status: " << request->status().status()
+        << " os_error: " << request->status().os_error()
+        << " response code: " << response_code;
+    ScheduleUpdateRetry(kRerunDelayMs);
+    internal_state_ = CACHE_FAILURE;
+    HandleCacheFailure();
+  }
+}
+
+void AppCacheUpdateJob::NotifySingleHost(AppCacheHost* host,
+                                         EventID event_id) {
+  std::vector<int> ids(1, host->host_id());
+  host->frontend()->OnEventRaised(ids, event_id);
+}
+
+void AppCacheUpdateJob::NotifyAllPendingMasterHosts(EventID event_id) {
+  // Collect hosts so we only send one notification per frontend.
+  // A host can only be associated with a single pending master entry
+  // so no need to worry about duplicate hosts being added to the notifier.
+  HostNotifier host_notifier;
+  for (PendingMasters::iterator it = pending_master_entries_.begin();
+       it != pending_master_entries_.end(); ++it) {
+    PendingHosts hosts = it->second;
+    for (PendingHosts::iterator host_it = hosts.begin();
+         host_it != hosts.end(); ++host_it) {
+      AppCacheHost* host = *host_it;
+      host_notifier.AddHost(host);
+    }
+  }
+
+  host_notifier.SendNotifications(event_id);
+}
+
+void AppCacheUpdateJob::NotifyAllAssociatedHosts(EventID event_id) {
+  // Collect hosts so we only send one notification per frontend.
+  // A host can only be associated with a single cache so no need to worry
+  // about duplicate hosts being added to the notifier.
+  HostNotifier host_notifier;
+  if (inprogress_cache_) {
+    DCHECK(internal_state_ == DOWNLOADING || internal_state_ == CACHE_FAILURE);
+    host_notifier.AddHosts(inprogress_cache_->associated_hosts());
+  }
+
+  AppCacheGroup::Caches old_caches = group_->old_caches();
+  for (AppCacheGroup::Caches::const_iterator it = old_caches.begin();
+       it != old_caches.end(); ++it) {
+    host_notifier.AddHosts((*it)->associated_hosts());
+  }
+
+  AppCache* newest_cache = group_->newest_complete_cache();
+  if (newest_cache)
+    host_notifier.AddHosts(newest_cache->associated_hosts());
+
+  // TODO(jennb): if progress event, also pass params lengthComputable=true,
+  // total = url_file_list_.size(), loaded=url_fetches_completed_.
+  host_notifier.SendNotifications(event_id);
+}
+
+void AppCacheUpdateJob::CheckIfManifestChanged() {
+  DCHECK(update_type_ == UPGRADE_ATTEMPT);
+  /*
+  AppCacheEntry* entry =
+      group_->newest_complete_cache()->GetEntry(manifest_url_);
+  */
+  // TODO(jennb): load manifest data from entry (async), continues in callback
+  // callback invokes ContinueCheckIfManifestChanged
+  // For now, schedule a task to continue checking with fake loaded data
+  MessageLoop::current()->PostTask(FROM_HERE,
+      method_factory_.NewRunnableMethod(
+          &AppCacheUpdateJob::ContinueCheckIfManifestChanged,
+          simulate_manifest_changed_ ? "different" : manifest_data_));
+}
+
+void AppCacheUpdateJob::ContinueCheckIfManifestChanged(
+    const std::string& loaded_manifest) {
+  ContinueHandleManifestFetchCompleted(manifest_data_ != loaded_manifest);
+}
+
+void AppCacheUpdateJob::BuildUrlFileList(const Manifest& manifest) {
+  for (base::hash_set<std::string>::const_iterator it =
+           manifest.explicit_urls.begin();
+       it != manifest.explicit_urls.end(); ++it) {
+    AddUrlToFileList(GURL(*it), AppCacheEntry::EXPLICIT);
+  }
+
+  const std::vector<FallbackNamespace>& fallbacks =
+      manifest.fallback_namespaces;
+  for (std::vector<FallbackNamespace>::const_iterator it = fallbacks.begin();
+       it != fallbacks.end(); ++it) {
+     AddUrlToFileList(it->second, AppCacheEntry::FALLBACK);
+  }
+
+  // Add all master entries from newest complete cache.
+  if (update_type_ == UPGRADE_ATTEMPT) {
+    const AppCache::EntryMap& entries =
+        group_->newest_complete_cache()->entries();
+    for (AppCache::EntryMap::const_iterator it = entries.begin();
+         it != entries.end(); ++it) {
+      const AppCacheEntry& entry = it->second;
+      if (entry.IsMaster())
+        AddUrlToFileList(it->first, AppCacheEntry::MASTER);
+    }
+  }
+}
+
+void AppCacheUpdateJob::AddUrlToFileList(const GURL& url, int type) {
+  std::pair<AppCache::EntryMap::iterator, bool> ret = url_file_list_.insert(
+      AppCache::EntryMap::value_type(url, AppCacheEntry(type)));
+
+  if (ret.second)
+    urls_to_fetch_.push_back(UrlToFetch(url, false));
+  else
+    ret.first->second.add_types(type);  // URL already exists. Merge types.
+}
+
+void AppCacheUpdateJob::FetchUrls() {
+  DCHECK(internal_state_ == DOWNLOADING);
+
+  // Fetch each URL in the list according to section 6.9.4 step 17.1-17.3.
+  // Fetch up to the concurrent limit. Other fetches will be triggered as each
+  // each fetch completes.
+  while (pending_url_fetches_.size() < kMaxConcurrentUrlFetches &&
+         !urls_to_fetch_.empty()) {
+    // Notify about progress first to ensure it starts from 0% in case any
+    // entries are skipped.
+    NotifyAllAssociatedHosts(PROGRESS_EVENT);
+
+    const GURL url = urls_to_fetch_.front().first;
+    bool storage_checked = urls_to_fetch_.front().second;
+    urls_to_fetch_.pop_front();
+
+    AppCache::EntryMap::iterator it = url_file_list_.find(url);
+    DCHECK(it != url_file_list_.end());
+    AppCacheEntry& entry = it->second;
+    if (ShouldSkipUrlFetch(entry)) {
+      ++url_fetches_completed_;
+    } else if (!storage_checked && MaybeLoadFromNewestCache(url, entry)) {
+      // Continues asynchronously after data is loaded from newest cache.
+    } else {
+      // Send URL request for the resource.
+      URLRequest* request = new URLRequest(url, this);
+      request->SetUserData(this, new UpdateJobInfo(UpdateJobInfo::URL_FETCH));
+      request->set_context(service_->request_context());
+      request->set_load_flags(
+          request->load_flags() | net::LOAD_DISABLE_INTERCEPT);
+      request->Start();
+      pending_url_fetches_.insert(PendingUrlFetches::value_type(url, request));
+    }
+  }
+}
+
+bool AppCacheUpdateJob::ShouldSkipUrlFetch(const AppCacheEntry& entry) {
+  if (entry.IsExplicit() || entry.IsFallback()) {
+    return false;
+  }
+
+  // TODO(jennb): decide if entry should be skipped to expire it from cache
+  return false;
+}
+
+bool AppCacheUpdateJob::MaybeLoadFromNewestCache(const GURL& url,
+                                                 AppCacheEntry& entry) {
+  if (update_type_ != UPGRADE_ATTEMPT)
+    return false;
+
+  AppCache* newest = group_->newest_complete_cache();
+  AppCacheEntry* copy_me = newest->GetEntry(url);
+  if (!copy_me)
+    return false;
+
+  // TODO(jennb): load HTTP headers for copy_me and wait for callback
+  // In callback:
+  // if HTTP caching semantics for entry allows its use,
+  //   CopyEntryData(url, copy_me, entry)
+  //   ++urls_fetches_completed_;
+  // Else, add url back to front of urls_to_fetch and call FetchUrls().
+  //   flag url somehow so that FetchUrls() doesn't end up here again.
+  // For now: post a message to pretend entry could not be copied
+  MessageLoop::current()->PostTask(FROM_HERE,
+      method_factory_.NewRunnableMethod(
+          &AppCacheUpdateJob::SimulateFailedLoadFromNewestCache, url));
+  return true;
+}
+
+// TODO(jennb): delete this after have real storage code
+void AppCacheUpdateJob::SimulateFailedLoadFromNewestCache(const GURL& url) {
+  if (internal_state_ == CACHE_FAILURE)
+    return;
+
+  // Re-insert url at front of fetch list. Indicate storage has been checked.
+  urls_to_fetch_.push_front(AppCacheUpdateJob::UrlToFetch(url, true));
+  FetchUrls();
+}
+
+void AppCacheUpdateJob::CopyEntryToCache(const GURL& url,
+                                         const AppCacheEntry& src,
+                                         AppCacheEntry* dest) {
+  DCHECK(dest);
+  // TODO(jennb): copy storage key from src to dest
+  inprogress_cache_->AddEntry(url, *dest);
+}
+
+bool AppCacheUpdateJob::MaybeCompleteUpdate() {
+  if (master_entries_completed_ != pending_master_entries_.size() ||
+      url_fetches_completed_ != url_file_list_.size() ) {
+    return false;
+  }
+
+  switch (internal_state_) {
+    case NO_UPDATE:
+      // 6.9.4 steps 7.3-7.7.
+      NotifyAllAssociatedHosts(NO_UPDATE_EVENT);
+      pending_master_entries_.clear();
+      DeleteSoon();
+      break;
+    case DOWNLOADING:
+      internal_state_ = REFETCH_MANIFEST;
+      FetchManifest(false);
+      return false;
+    case CACHE_FAILURE:
+      HandleCacheFailure();
+      break;
+    default:
+      NOTREACHED();
+  }
+  return true;
+}
+
+void AppCacheUpdateJob::HandleCacheFailure() {
+  // 6.9.4 cache failure steps 2-8.
+  NotifyAllAssociatedHosts(ERROR_EVENT);
+  pending_master_entries_.clear();
+
+  // Discard the inprogress cache.
+  // TODO(jennb): cleanup possible storage for entries in the cache
+  if (inprogress_cache_) {
+    inprogress_cache_->set_owning_group(NULL);
+    inprogress_cache_ = NULL;
+  }
+
+  // For a CACHE_ATTEMPT, group will be discarded when this update
+  // job removes its reference to the group. Nothing more to do here.
+
+  DeleteSoon();
+}
+
+void AppCacheUpdateJob::ScheduleUpdateRetry(int delay_ms) {
+  // TODO(jennb): post a delayed task with the "same parameters" as this job
+  // to retry the update at a later time. Need group, URLs of pending master
+  // entries and their hosts.
+}
+
+void AppCacheUpdateJob::Cancel() {
+  if (manifest_url_request_) {
+    delete manifest_url_request_;
+    manifest_url_request_ = NULL;
+  }
+
+  // TODO(jennb): code other cancel cleanup (pending url requests, storage)
+}
+
+void AppCacheUpdateJob::DeleteSoon() {
+  // TODO(jennb): revisit if update should be deleting itself
+  MessageLoop::current()->DeleteSoon(FROM_HERE, this);
+}
+}  // namespace appcache