/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef mozilla_net_Tickler_h

#define mozilla_net_Tickler_h

// The tickler sends a regular 0 byte UDP heartbeat out to a

// particular address for a short time after it has been touched. This

// is used on some mobile wifi chipsets to mitigate Power Save Polling

// (PSP) Mode when we are anticipating a response packet

// soon. Typically PSP adds 100ms of latency to a read event because

// the packet delivery is not triggered until the 802.11 beacon is

// delivered to the host (100ms is the standard Access Point

// configuration for the beacon interval.) Requesting a frequent

// transmission and getting a CTS frame from the AP at least that

// frequently allows for low latency receives when we have reason to

// expect them (e.g a SYN-ACK).

//

// The tickler is used to allow RTT based phases of web transport to

// complete quickly when on wifi - ARP, DNS, TCP handshake, SSL

// handshake, HTTP headers, and the TCP slow start phase. The

// transaction is given up to 400 miliseconds by default to get

// through those phases before the tickler is disabled.

//

// The tickler only applies to wifi on mobile right now. Hopefully it

// can also be restricted to particular handset models in the future.

#if defined(ANDROID) && !defined(MOZ_PROXY_BYPASS_PROTECTION)

#define MOZ_USE_WIFI_TICKLER

#endif

#include "mozilla/Attributes.h"

#include "nsISupports.h"

#include <stdint.h>

#ifdef MOZ_USE_WIFI_TICKLER

#include "mozilla/Mutex.h"

#include "mozilla/TimeStamp.h"

#include "nsAutoPtr.h"

#include "nsISupports.h"

#include "nsIThread.h"

#include "nsITimer.h"

#include "nsWeakReference.h"

#include "prio.h"

class nsIPrefBranch;

#endif

namespace mozilla {

namespace net {

#ifdef MOZ_USE_WIFI_TICKLER

// 8f769ed6-207c-4af9-9f7e-9e832da3754e

#define NS_TICKLER_IID \

{ 0x8f769ed6, 0x207c, 0x4af9, \

  { 0x9f, 0x7e, 0x9e, 0x83, 0x2d, 0xa3, 0x75, 0x4e } }

class Tickler final : public nsSupportsWeakReference

{

public:

  NS_DECL_THREADSAFE_ISUPPORTS

  NS_DECLARE_STATIC_IID_ACCESSOR(NS_TICKLER_IID)

  // These methods are main thread only

  Tickler();

  void Cancel();

  nsresult Init();

  void SetIPV4Address(uint32_t address);

  void SetIPV4Port(uint16_t port);

  // Tickle the tickler to (re-)start the activity.

  // May call from any thread

  void Tickle();

private:

  ~Tickler();

  friend class TicklerTimer;

  Mutex mLock;

  nsCOMPtr<nsIThread> mThread;

  nsCOMPtr<nsITimer> mTimer;

  nsCOMPtr<nsIPrefBranch> mPrefs;

  bool mActive;

  bool mCanceled;

  bool mEnabled;

  uint32_t mDelay;

  TimeDuration mDuration;

  PRFileDesc* mFD;

  TimeStamp mLastTickle;

  PRNetAddr mAddr;

  // These functions may be called from any thread

  void PostCheckTickler();

  void MaybeStartTickler();

  void MaybeStartTicklerUnlocked();

  // Tickler thread only

  void CheckTickler();

  void StartTickler();

  void StopTickler();

};

NS_DEFINE_STATIC_IID_ACCESSOR(Tickler, NS_TICKLER_IID)

#else // not defined MOZ_USE_WIFI_TICKLER

class Tickler final : public nsISupports

{

  ~Tickler() = default;

public:

  NS_DECL_THREADSAFE_ISUPPORTS

  Tickler() = default;

  nsresult Init() { return NS_ERROR_NOT_IMPLEMENTED; }

  void Cancel() { }

  void SetIPV4Address(uint32_t) { };

  void SetIPV4Port(uint16_t) { }

  void Tickle() { }

};

#endif // defined MOZ_USE_WIFI_TICKLER

} // namespace net

} // namespace mozilla

#endif // mozilla_net_Tickler_h