dom/geolocation/MLSFallback.h
author Dylan Roeh <droeh@mozilla.com>
Tue, 28 Aug 2018 11:35:46 -0500
branchGECKOVIEW_62_RELBRANCH
changeset 481113 31683bdf39d7bcacf8d9bf265fc2365024473fbe
parent 422446 4b879e41eae3aa845e77f6ce7336fb9eb4ed35fa
child 508163 6f3709b3878117466168c40affa7bca0b60cf75b
permissions -rw-r--r--
Bug 1485178 - Only migrate sharedprefs when in Fennec. r=snorp a=ritu

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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/. */

#include "nsCOMPtr.h"
#include "nsITimer.h"
#include "nsINamed.h"

class nsIGeolocationUpdate;
class nsIGeolocationProvider;

/*
 This class wraps the NetworkGeolocationProvider in a delayed startup.
 It is for providing a fallback to MLS when:
 1) using another provider as the primary provider, and
 2) that primary provider may fail to return a result (i.e. the error returned
 is indeterminate, or no error callback occurs)

 The intent is that the primary provider is started, then MLSFallback
 is started with sufficient delay that the primary provider will respond first
 if successful (in the majority of cases).

 MLS has an average response of 3s, so with the 2s default delay, a response can
 be expected in 5s.

 Telemetry is recommended to monitor that the primary provider is responding
 first when expected to do so.
*/
class MLSFallback : public nsITimerCallback
                  , public nsINamed
{
public:
  NS_DECL_ISUPPORTS
  NS_DECL_NSITIMERCALLBACK
  NS_DECL_NSINAMED

  explicit MLSFallback(uint32_t delayMs = 2000);
  nsresult Startup(nsIGeolocationUpdate* aWatcher);
  nsresult Shutdown();

private:
  nsresult CreateMLSFallbackProvider();
  virtual ~MLSFallback();
  nsCOMPtr<nsITimer> mHandoffTimer;
  nsCOMPtr<nsIGeolocationProvider> mMLSFallbackProvider;
  nsCOMPtr<nsIGeolocationUpdate> mUpdateWatcher;
  const uint32_t mDelayMs;
};