Battery Status API: implementation for Mac OS.

content/browser/battery_status/battery_status_manager_mac.cc

Index: content/browser/battery_status/battery_status_manager_mac.cc
diff --git a/content/browser/battery_status/battery_status_manager_mac.cc b/content/browser/battery_status/battery_status_manager_mac.cc
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+// 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 "content/browser/battery_status/battery_status_manager.h"
+
+#include <CoreFoundation/CoreFoundation.h>
+#include <IOKit/ps/IOPowerSources.h>
+#include <IOKit/ps/IOPSKeys.h>
+
+#include "base/mac/foundation_util.h"
+#include "base/mac/scoped_cftyperef.h"
+#include "base/memory/ref_counted.h"
+#include "base/time/time.h"
+#include "content/public/browser/browser_thread.h"
+#include "third_party/WebKit/public/platform/WebBatteryStatus.h"
+
+namespace content {
+
+namespace {
+
+typedef BatteryStatusService::BatteryUpdateCallback BatteryCallback;
+
+// Returns the value corresponding to |key| in the dictionary |description|.
+// Returns |default_value| if the dictionary does not contain |key|, the
+// corresponding value is NULL or it could not be converted to SInt64.
+SInt64 GetValueAsSInt64(CFDictionaryRef description,
+                        CFStringRef key,
+                        SInt64 default_value) {
+  CFNumberRef number =
+      base::mac::GetValueFromDictionary<CFNumberRef>(description, key);
+  SInt64 value;
+
+  if (number && CFNumberGetValue(number, kCFNumberSInt64Type, &value))
+    return value;
+
+  return default_value;
+}
+
+bool GetValueAsBoolean(CFDictionaryRef description,
+                       CFStringRef key,
+                       bool default_value) {
+  CFBooleanRef boolean =
+      base::mac::GetValueFromDictionary<CFBooleanRef>(description, key);
+
+  return boolean ? CFBooleanGetValue(boolean) : default_value;
+}
+
+bool CFStringsAreEqual(CFStringRef string1, CFStringRef string2) {
+  if (!string1 || !string2)
+    return false;
+  return CFStringCompare(string1, string2, 0) == kCFCompareEqualTo;
+}
+
+void FetchBatteryStatus(CFDictionaryRef description,
+                        blink::WebBatteryStatus& status) {
+  CFStringRef current_state =
+      base::mac::GetValueFromDictionary<CFStringRef>(description,
+          CFSTR(kIOPSPowerSourceStateKey));
+
+  bool on_battery_power =
+      CFStringsAreEqual(current_state, CFSTR(kIOPSBatteryPowerValue));
+  bool is_charging =
+      GetValueAsBoolean(description, CFSTR(kIOPSIsChargingKey), true);

[Robert Sesek, 2014/07/25 14:48:44]

Why assume charging?

[timvolodine, 2014/07/25 18:17:51]

kIOPSIsChargingKey is a required key so this should normally never happen, but I
chose true to be in sync with the spec, which says that the default is
charging=true.

+  bool is_charged =
+      GetValueAsBoolean(description, CFSTR(kIOPSIsChargedKey), false);
+
+  status.charging = !on_battery_power || is_charging;
+
+  SInt64 current_capacity =
+      GetValueAsSInt64(description, CFSTR(kIOPSCurrentCapacityKey), -1);
+  SInt64 max_capacity =
+      GetValueAsSInt64(description, CFSTR(kIOPSMaxCapacityKey), -1);
+
+  // Set level if it is available and valid. Otherwise leave the default value,
+  // which is 1.
+  if (current_capacity != -1 && max_capacity != -1 &&
+      current_capacity <= max_capacity && max_capacity != 0)
+    status.level = current_capacity / static_cast<double>(max_capacity);

[Robert Sesek, 2014/07/25 14:48:44]

nit: this body requires braces since the condition is multiple lines

[timvolodine, 2014/07/25 18:17:51]

Done.

+
+  if (is_charging) {
+    SInt64 charging_time =
+        GetValueAsSInt64(description, CFSTR(kIOPSTimeToFullChargeKey), -1);
+
+    // Battery is charging: set the charging time if it's available, otherwise
+    // set to +infinity.
+    status.chargingTime = (charging_time != -1)
+        ? base::TimeDelta::FromMinutes(charging_time).InSeconds()
+        : std::numeric_limits<double>::infinity();
+  } else {
+    // Battery is not charging.
+    // Set chargingTime to +infinity if the battery is not charged. Otherwise
+    // leave the default value, which is 0.
+    if (!is_charged)
+      status.chargingTime = std::numeric_limits<double>::infinity();
+
+    // Set dischargingTime if it's available and valid, i.e. when on battery
+    // power. Otherwise leave the default value, which is +infinity.
+    if (on_battery_power) {
+      SInt64 discharging_time =
+          GetValueAsSInt64(description, CFSTR(kIOPSTimeToEmptyKey), -1);
+      if (discharging_time != -1) {
+        status.dischargingTime =
+            base::TimeDelta::FromMinutes(discharging_time).InSeconds();
+      }
+    }
+  }
+}
+
+void OnBatteryStatusChanged(const BatteryCallback& callback) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  blink::WebBatteryStatus status;
+  base::ScopedCFTypeRef<CFTypeRef> info(IOPSCopyPowerSourcesInfo());
+  base::ScopedCFTypeRef<CFArrayRef> power_sources_list(
+      IOPSCopyPowerSourcesList(info));
+  CFIndex count = CFArrayGetCount(power_sources_list);
+
+  bool internal_source_found = false;
+
+  for (CFIndex i = 0; i < count; ++i) {
+    CFDictionaryRef description = IOPSGetPowerSourceDescription(info,
+        CFArrayGetValueAtIndex(power_sources_list, i));
+
+    if (!description)
+      continue;
+
+    CFStringRef transport_type =
+        base::mac::GetValueFromDictionary<CFStringRef>(description,
+            CFSTR(kIOPSTransportTypeKey));
+
+    bool internal_source =
+        CFStringsAreEqual(transport_type, CFSTR(kIOPSInternalType));
+    bool source_present =
+        GetValueAsBoolean(description, CFSTR(kIOPSIsPresentKey), false);
+
+    if (internal_source && source_present) {
+      // FIXME: the case when there are multiple internal sources, e.g. when

[Robert Sesek, 2014/07/25 14:48:44]

FIXME -> TODO(who)

[timvolodine, 2014/07/25 18:17:51]

Done.

+      // multiple batteries are present. Currently this will fail a DCHECK.
+      DCHECK(!internal_source_found);
+      FetchBatteryStatus(description, status);
+      internal_source_found = true;
+    }
+  }
+
+  callback.Run(status);
+}
+
+class BatteryStatusObserver
+    : public base::RefCountedThreadSafe<BatteryStatusObserver> {
+ public:
+  explicit BatteryStatusObserver(const BatteryCallback& callback)
+      : callback_(callback) {}
+
+  void Start() {
+    // Need to start on a thread with UI-type message loop for
+    // |notifier_run_loop_| to receive callbacks.
+    if (BrowserThread::CurrentlyOn(BrowserThread::UI)) {
+      StartOnUI();
+    } else {
+      BrowserThread::PostTask(
+          BrowserThread::UI,
+          FROM_HERE,
+          base::Bind(&BatteryStatusObserver::StartOnUI, this));
+    }
+  }
+
+  void Stop() {
+    if (BrowserThread::CurrentlyOn(BrowserThread::UI)) {
+      StopOnUI();
+    } else {
+      BrowserThread::PostTask(
+          BrowserThread::UI,
+          FROM_HERE,
+          base::Bind(&BatteryStatusObserver::StopOnUI, this));
+    }
+  }
+
+ private:
+  friend class base::RefCountedThreadSafe<BatteryStatusObserver>;
+  virtual ~BatteryStatusObserver() { DCHECK(!notifier_run_loop_); }
+
+  void StartOnUI() {
+    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+    if (notifier_run_loop_)
+      return;
+
+    notifier_run_loop_.reset(
+        IOPSNotificationCreateRunLoopSource(OnBatteryStatusChangedUI,
+                                            static_cast<void*>(&callback_)));
+    if (!notifier_run_loop_) {
+      LOG(ERROR) << "Failed to create battery status notification run loop";
+      // Make sure to execute to callback with the default values.
+      callback_.Run(blink::WebBatteryStatus());
+      return;
+    }
+
+    OnBatteryStatusChangedUI(static_cast<void*>(&callback_));
+    CFRunLoopAddSource(CFRunLoopGetCurrent(), notifier_run_loop_,
+                       kCFRunLoopDefaultMode);
+  }
+
+  void StopOnUI() {
+    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+    if (!notifier_run_loop_)
+      return;
+
+    CFRunLoopRemoveSource(CFRunLoopGetCurrent(), notifier_run_loop_,
+                          kCFRunLoopDefaultMode);
+    notifier_run_loop_.reset();
+  }
+
+  static void OnBatteryStatusChangedUI(void* callback) {
+    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+    // Offload fetching of values and callback execution to the IO thread.
+    BrowserThread::PostTask(
+        BrowserThread::IO,
+        FROM_HERE,
+        base::Bind(&OnBatteryStatusChanged,
+                   *static_cast<BatteryCallback*>(callback)));
+  }
+
+  BatteryCallback callback_;
+  base::ScopedCFTypeRef<CFRunLoopSourceRef> notifier_run_loop_;

[Robert Sesek, 2014/07/25 14:48:44]

naming: a run_loop_ indicates an object of type CFRunLoopRef, I'd call this
notifier_source_ or notifier_run_loop_source_.

[timvolodine, 2014/07/25 18:17:50]

Done.

+
+  DISALLOW_COPY_AND_ASSIGN(BatteryStatusObserver);
+};
+
+class BatteryStatusManagerMac : public BatteryStatusManager {
+ public:
+  explicit BatteryStatusManagerMac(const BatteryCallback& callback)
+      : notifier_(new BatteryStatusObserver(callback)) {}
+
+  virtual ~BatteryStatusManagerMac() {
+    notifier_->Stop();
+  }
+
+  // BatteryStatusManager:
+  virtual bool StartListeningBatteryChange() OVERRIDE {
+    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+    notifier_->Start();
+    return true;
+  }
+
+  virtual void StopListeningBatteryChange() OVERRIDE {
+    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+    notifier_->Stop();
+  }
+
+ private:
+  scoped_refptr<BatteryStatusObserver> notifier_;
+
+  DISALLOW_COPY_AND_ASSIGN(BatteryStatusManagerMac);
+};
+
+} // end namespace
+
+// static
+scoped_ptr<BatteryStatusManager> BatteryStatusManager::Create(
+    const BatteryStatusService::BatteryUpdateCallback& callback) {
+  return scoped_ptr<BatteryStatusManager>(
+      new BatteryStatusManagerMac(callback));
+}
+
+}  // namespace content