michael@0: /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* vim: set ts=2 et sw=2 tw=80: */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
michael@0:  * You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #ifndef mozilla__CryptoTask_h
michael@0: #define mozilla__CryptoTask_h
michael@0: 
michael@0: #include "mozilla/Attributes.h"
michael@0: #include "nsThreadUtils.h"
michael@0: #include "nsNSSShutDown.h"
michael@0: 
michael@0: namespace mozilla {
michael@0: 
michael@0: /**
michael@0:  * Frequently we need to run a task on a background thread without blocking
michael@0:  * the main thread, and then call a callback on the main thread with the
michael@0:  * result. This class provides the framework for that. Subclasses must:
michael@0:  *
michael@0:  *   (1) Override CalculateResult for the off-the-main-thread computation.
michael@0:  *       NSS functionality may only be accessed within CalculateResult.
michael@0:  *   (2) Override ReleaseNSSResources to release references to all NSS
michael@0:  *       resources (that do implement nsNSSShutDownObject themselves).
michael@0:  *   (3) Override CallCallback() for the on-the-main-thread call of the
michael@0:  *       callback.
michael@0:  *
michael@0:  * CalculateResult, ReleaseNSSResources, and CallCallback are called in order,
michael@0:  * except CalculateResult might be skipped if NSS is shut down before it can
michael@0:  * be called; in that case ReleaseNSSResources will be called and then
michael@0:  * CallCallback will be called with an error code.
michael@0:  */
michael@0: class CryptoTask : public nsRunnable,
michael@0:                    public nsNSSShutDownObject
michael@0: {
michael@0: public:
michael@0:   template <size_t LEN>
michael@0:   nsresult Dispatch(const char (&taskThreadName)[LEN])
michael@0:   {
michael@0:     static_assert(LEN <= 15,
michael@0:                   "Thread name must be no more than 15 characters");
michael@0:     // Can't add 'this' as the event to run, since mThread may not be set yet
michael@0:     nsresult rv = NS_NewNamedThread(taskThreadName, getter_AddRefs(mThread));
michael@0:     if (NS_SUCCEEDED(rv)) {
michael@0:       // Note: event must not null out mThread!
michael@0:       rv = mThread->Dispatch(this, NS_DISPATCH_NORMAL);
michael@0:     }
michael@0:     return rv;
michael@0:   }
michael@0: 
michael@0: protected:
michael@0:   CryptoTask()
michael@0:     : mRv(NS_ERROR_NOT_INITIALIZED),
michael@0:       mReleasedNSSResources(false)
michael@0:   {
michael@0:   }
michael@0: 
michael@0:   virtual ~CryptoTask();
michael@0: 
michael@0:   /**
michael@0:    * Called on a background thread (never the main thread). If CalculateResult
michael@0:    * is called, then its result will be passed to CallCallback on the main
michael@0:    * thread.
michael@0:    */
michael@0:   virtual nsresult CalculateResult() = 0;
michael@0: 
michael@0:   /**
michael@0:    * Called on the main thread during NSS shutdown or just before CallCallback
michael@0:    * has been called. All NSS resources must be released. Usually, this just
michael@0:    * means assigning nullptr to the ScopedNSSType-based memory variables.
michael@0:    */
michael@0:   virtual void ReleaseNSSResources() = 0;
michael@0: 
michael@0:   /**
michael@0:    * Called on the main thread with the result from CalculateResult() or
michael@0:    * with an error code if NSS was shut down before CalculateResult could
michael@0:    * be called.
michael@0:    */
michael@0:   virtual void CallCallback(nsresult rv) = 0;
michael@0: 
michael@0: private:
michael@0:   NS_IMETHOD Run() MOZ_OVERRIDE MOZ_FINAL;
michael@0:   virtual void virtualDestroyNSSReference() MOZ_OVERRIDE MOZ_FINAL;
michael@0: 
michael@0:   nsresult mRv;
michael@0:   bool mReleasedNSSResources;
michael@0: 
michael@0:   nsCOMPtr<nsIThread> mThread;
michael@0: };
michael@0: 
michael@0: } // namespace mozilla
michael@0: 
michael@0: #endif // mozilla__CryptoTask_h