Provide monitoring of usage for a storage type and origin

webkit/browser/quota/storage_monitor.cc

Index: webkit/browser/quota/storage_monitor.cc
diff --git a/webkit/browser/quota/storage_monitor.cc b/webkit/browser/quota/storage_monitor.cc
new file mode 100644
index 0000000000000000000000000000000000000000..fbb015118d819c7c0380d61d6cca87e313c597f6
--- /dev/null
+++ b/webkit/browser/quota/storage_monitor.cc
@@ -0,0 +1,367 @@
+// Copyright 2014 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/browser/quota/storage_monitor.h"
+
+#include <algorithm>
+
+#include "base/stl_util.h"
+#include "net/base/net_util.h"
+#include "webkit/browser/quota/quota_manager.h"
+#include "webkit/common/quota/quota_status_code.h"
+
+namespace quota {
+
+// StorageObserverList:
+
+StorageObserverList::ObserverState::ObserverState()
+    : requires_update(false) {
+}
+
+StorageObserverList::StorageObserverList() {}
+
+StorageObserverList::~StorageObserverList() {}
+
+void StorageObserverList::AddObserver(
+    StorageObserver* observer, const StorageObserver::MonitorParams& params) {
+  ObserverState& observer_state = observers_[observer];
+  observer_state.origin = params.filter.origin;
+  observer_state.rate = params.rate;
+}
+
+void StorageObserverList::RemoveObserver(StorageObserver* observer) {
+  observers_.erase(observer);
+}
+
+int StorageObserverList::ObserverCount() const {
+  return observers_.size();
+}
+
+void StorageObserverList::OnStorageChange(const StorageObserver::Event& event) {
+  for (StorageObserverStateMap::iterator it = observers_.begin();
+       it != observers_.end(); ++it) {
+    it->second.requires_update = true;
+  }
+
+  MaybeDispatchEvent(event);
+}
+
+void StorageObserverList::MaybeDispatchEvent(
+    const StorageObserver::Event& event) {
+  notification_timer_.Stop();
+  base::TimeDelta min_delay = base::TimeDelta::Max();
+  bool all_observers_notified = true;
+
+  for (StorageObserverStateMap::iterator it = observers_.begin();
+       it != observers_.end(); ++it) {
+    if (!it->second.requires_update)
+      continue;
+
+    base::TimeTicks current_time = base::TimeTicks::Now();
+    base::TimeDelta delta = current_time - it->second.last_notification_time;
+    if (it->second.last_notification_time.is_null() ||
+        delta >= it->second.rate) {
+      it->second.requires_update = false;
+      it->second.last_notification_time = current_time;
+
+      if (it->second.origin == event.filter.origin) {
+        it->first->OnStorageEvent(event);
+      } else {
+        // When the quota and usage of an origin is requested, QuotaManager
+        // returns the quota and usage of the host. Multiple origins can map to
+        // to the same host, so ensure the |origin| field in the dispatched
+        // event matches the |origin| specified by the observer when it was
+        // registered.
+        StorageObserver::Event dispatch_event(event);
+        dispatch_event.filter.origin = it->second.origin;
+        it->first->OnStorageEvent(dispatch_event);
+      }
+    } else {
+      all_observers_notified = false;
+      base::TimeDelta delay = it->second.rate - delta;
+      if (delay < min_delay)
+        min_delay = delay;
+    }
+  }
+
+  // We need to respect the notification rate specified by observers. So if it
+  // is too soon to dispatch an event to an observer, save the event and
+  // dispatch it after a delay. If we simply drop the event, another one may
+  // not arrive anytime soon and the observer will miss the most recent event.
+  if (!all_observers_notified) {
+    pending_event_ = event;
+    notification_timer_.Start(
+        FROM_HERE,
+        min_delay,
+        this,
+        &StorageObserverList::DispatchPendingEvent);
+  }
+}
+
+void StorageObserverList::ScheduleUpdateForObserver(StorageObserver* observer) {
+  DCHECK(ContainsKey(observers_, observer));
+  observers_[observer].requires_update = true;
+}
+
+void StorageObserverList::DispatchPendingEvent() {
+  MaybeDispatchEvent(pending_event_);
+}
+
+
+// HostStorageObservers:
+
+HostStorageObservers::HostStorageObservers(QuotaManager* quota_manager)
+    : quota_manager_(quota_manager),
+      initialized_(false),
+      initializing_(false),
+      event_occurred_before_init_(false),
+      cached_usage_(0),
+      cached_quota_(0),
+      weak_factory_(this) {
+}
+
+HostStorageObservers::~HostStorageObservers() {}
+
+void HostStorageObservers::AddObserver(
+    StorageObserver* observer,
+    const StorageObserver::MonitorParams& params) {
+  observers_.AddObserver(observer, params);
+
+  if (!params.dispatch_initial_state)
+    return;
+
+  if (initialized_) {
+    StorageObserver::Event event(params.filter,
+                                 std::max<int64>(cached_usage_, 0),
+                                 std::max<int64>(cached_quota_, 0));
+    observer->OnStorageEvent(event);
+    return;
+  }
+
+  // Ensure the observer receives the initial storage state once initialization
+  // is complete.
+  observers_.ScheduleUpdateForObserver(observer);
+  StartInitialization(params.filter);
+}
+
+void HostStorageObservers::RemoveObserver(StorageObserver* observer) {
+  observers_.RemoveObserver(observer);
+}
+
+bool HostStorageObservers::ContainsObservers() const {
+  return observers_.ObserverCount() > 0;
+}
+
+void HostStorageObservers::NotifyUsageChange(
+    const StorageObserver::Filter& filter, int64 delta) {
+  if (initialized_) {
+    cached_usage_ += delta;
+    DispatchEvent(filter, true);
+    return;
+  }
+
+  // If a storage change occurs before initialization, ensure all observers will
+  // receive an event once initialization is complete.
+  event_occurred_before_init_ = true;
+  StartInitialization(filter);
+}
+
+void HostStorageObservers::StartInitialization(
+    const StorageObserver::Filter& filter) {
+  if (initialized_ || initializing_)
+    return;
+
+  initializing_ = true;
+  quota_manager_->GetUsageAndQuotaForWebApps(
+      filter.origin,
+      filter.storage_type,
+      base::Bind(&HostStorageObservers::GotHostUsageAndQuota,
+                 weak_factory_.GetWeakPtr(),
+                 filter));
+}
+
+void HostStorageObservers::GotHostUsageAndQuota(
+    const StorageObserver::Filter& filter,
+    QuotaStatusCode status,
+    int64 usage,
+    int64 quota) {
+  initializing_ = false;
+  if (status != kQuotaStatusOk)
+    return;
+
+  initialized_ = true;
+  cached_quota_ = quota;
+  cached_usage_ = usage;
+  DispatchEvent(filter, event_occurred_before_init_);
+}
+
+void HostStorageObservers::DispatchEvent(
+    const StorageObserver::Filter& filter, bool is_update) {
+  StorageObserver::Event event(filter,
+                               std::max<int64>(cached_usage_, 0),
+                               std::max<int64>(cached_quota_, 0));
+  if (is_update)
+    observers_.OnStorageChange(event);
+  else
+    observers_.MaybeDispatchEvent(event);
+}
+
+
+// StorageTypeObservers:
+
+StorageTypeObservers::StorageTypeObservers(QuotaManager* quota_manager)
+    : quota_manager_(quota_manager) {
+}
+
+StorageTypeObservers::~StorageTypeObservers() {
+  STLDeleteValues(&host_observers_map_);
+}
+
+void StorageTypeObservers::AddObserver(
+    StorageObserver* observer, const StorageObserver::MonitorParams& params) {
+  std::string host = net::GetHostOrSpecFromURL(params.filter.origin);
+  if (host.empty())
+    return;
+
+  HostStorageObservers* host_observers = NULL;
+  HostObserversMap::iterator it = host_observers_map_.find(host);
+  if (it == host_observers_map_.end()) {
+    host_observers = new HostStorageObservers(quota_manager_);
+    host_observers_map_[host] = host_observers;
+  } else {
+    host_observers = it->second;
+  }
+
+  host_observers->AddObserver(observer, params);
+}
+
+void StorageTypeObservers::RemoveObserver(StorageObserver* observer) {
+  for (HostObserversMap::iterator it = host_observers_map_.begin();
+       it != host_observers_map_.end(); ) {
+    it->second->RemoveObserver(observer);
+    if (!it->second->ContainsObservers()) {
+      delete it->second;
+      host_observers_map_.erase(it++);
+    } else {
+      ++it;
+    }
+  }
+}
+
+void StorageTypeObservers::RemoveObserverForFilter(
+    StorageObserver* observer, const StorageObserver::Filter& filter) {
+  std::string host = net::GetHostOrSpecFromURL(filter.origin);
+  HostObserversMap::iterator it = host_observers_map_.find(host);
+  if (it == host_observers_map_.end())
+    return;
+
+  it->second->RemoveObserver(observer);
+  if (!it->second->ContainsObservers()) {
+    delete it->second;
+    host_observers_map_.erase(it);
+  }
+}
+
+const HostStorageObservers* StorageTypeObservers::GetHostObservers(
+    const std::string& host) const {
+  HostObserversMap::const_iterator it = host_observers_map_.find(host);
+  if (it != host_observers_map_.end())
+    return it->second;
+
+  return NULL;
+}
+
+void StorageTypeObservers::NotifyUsageChange(
+    const StorageObserver::Filter& filter, int64 delta) {
+  std::string host = net::GetHostOrSpecFromURL(filter.origin);
+  HostObserversMap::iterator it = host_observers_map_.find(host);
+  if (it == host_observers_map_.end())
+    return;
+
+  it->second->NotifyUsageChange(filter, delta);
+}
+
+
+// StorageMonitor:
+
+StorageMonitor::StorageMonitor(QuotaManager* quota_manager)
+    : quota_manager_(quota_manager) {
+}
+
+StorageMonitor::~StorageMonitor() {
+  STLDeleteValues(&storage_type_observers_map_);
+}
+
+void StorageMonitor::AddObserver(
+    StorageObserver* observer, const StorageObserver::MonitorParams& params) {
+  DCHECK(observer);
+
+  // Check preconditions.
+  if (params.filter.storage_type == kStorageTypeUnknown ||
+      params.filter.storage_type == kStorageTypeQuotaNotManaged ||
+      params.filter.origin.is_empty()) {
+    NOTREACHED();
+    return;
+  }
+
+  StorageTypeObservers* type_observers = NULL;
+  StorageTypeObserversMap::iterator it =
+      storage_type_observers_map_.find(params.filter.storage_type);
+  if (it == storage_type_observers_map_.end()) {
+    type_observers = new StorageTypeObservers(quota_manager_);
+    storage_type_observers_map_[params.filter.storage_type] = type_observers;
+  } else {
+    type_observers = it->second;
+  }
+
+  type_observers->AddObserver(observer, params);
+}
+
+void StorageMonitor::RemoveObserver(StorageObserver* observer) {
+  for (StorageTypeObserversMap::iterator it =
+           storage_type_observers_map_.begin();
+       it != storage_type_observers_map_.end(); ++it) {
+    it->second->RemoveObserver(observer);
+  }
+}
+
+void StorageMonitor::RemoveObserverForFilter(
+    StorageObserver* observer, const StorageObserver::Filter& filter) {
+  StorageTypeObserversMap::iterator it =
+      storage_type_observers_map_.find(filter.storage_type);
+  if (it == storage_type_observers_map_.end())
+    return;
+
+  it->second->RemoveObserverForFilter(observer, filter);
+}
+
+const StorageTypeObservers* StorageMonitor::GetStorageTypeObservers(
+    StorageType storage_type) const {
+  StorageTypeObserversMap::const_iterator it =
+      storage_type_observers_map_.find(storage_type);
+  if (it != storage_type_observers_map_.end())
+    return it->second;
+
+  return NULL;
+}
+
+void StorageMonitor::NotifyUsageChange(
+    const StorageObserver::Filter& filter, int64 delta) {
+  // Check preconditions.
+  if (filter.storage_type == kStorageTypeUnknown ||
+      filter.storage_type == kStorageTypeQuotaNotManaged ||
+      filter.origin.is_empty()) {
+    NOTREACHED();
+    return;
+  }
+
+  StorageTypeObserversMap::iterator it =
+      storage_type_observers_map_.find(filter.storage_type);
+  if (it == storage_type_observers_map_.end())
+    return;
+
+  it->second->NotifyUsageChange(filter, delta);
+}
+
+}  // namespace quota