The Tor Browser: security/manager/ssl/src/CryptoTask.h@141e0f1194b1

     1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

     2 /* vim: set ts=2 et sw=2 tw=80: */

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

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

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

     7 #ifndef mozilla__CryptoTask_h

     8 #define mozilla__CryptoTask_h

    10 #include "mozilla/Attributes.h"

    11 #include "nsThreadUtils.h"

    12 #include "nsNSSShutDown.h"

    14 namespace mozilla {

    16 /**

    17  * Frequently we need to run a task on a background thread without blocking

    18  * the main thread, and then call a callback on the main thread with the

    19  * result. This class provides the framework for that. Subclasses must:

    20  *

    21  *   (1) Override CalculateResult for the off-the-main-thread computation.

    22  *       NSS functionality may only be accessed within CalculateResult.

    23  *   (2) Override ReleaseNSSResources to release references to all NSS

    24  *       resources (that do implement nsNSSShutDownObject themselves).

    25  *   (3) Override CallCallback() for the on-the-main-thread call of the

    26  *       callback.

    27  *

    28  * CalculateResult, ReleaseNSSResources, and CallCallback are called in order,

    29  * except CalculateResult might be skipped if NSS is shut down before it can

    30  * be called; in that case ReleaseNSSResources will be called and then

    31  * CallCallback will be called with an error code.

    32  */

    33 class CryptoTask : public nsRunnable,

    34                    public nsNSSShutDownObject

    35 {

    36 public:

    37   template <size_t LEN>

    38   nsresult Dispatch(const char (&taskThreadName)[LEN])

    39   {

    40     static_assert(LEN <= 15,

    41                   "Thread name must be no more than 15 characters");

    42     // Can't add 'this' as the event to run, since mThread may not be set yet

    43     nsresult rv = NS_NewNamedThread(taskThreadName, getter_AddRefs(mThread));

    44     if (NS_SUCCEEDED(rv)) {

    45       // Note: event must not null out mThread!

    46       rv = mThread->Dispatch(this, NS_DISPATCH_NORMAL);

    47     }

    48     return rv;

    49   }

    51 protected:

    52   CryptoTask()

    53     : mRv(NS_ERROR_NOT_INITIALIZED),

    54       mReleasedNSSResources(false)

    55   {

    56   }

    58   virtual ~CryptoTask();

    60   /**

    61    * Called on a background thread (never the main thread). If CalculateResult

    62    * is called, then its result will be passed to CallCallback on the main

    63    * thread.

    64    */

    65   virtual nsresult CalculateResult() = 0;

    67   /**

    68    * Called on the main thread during NSS shutdown or just before CallCallback

    69    * has been called. All NSS resources must be released. Usually, this just

    70    * means assigning nullptr to the ScopedNSSType-based memory variables.

    71    */

    72   virtual void ReleaseNSSResources() = 0;

    74   /**

    75    * Called on the main thread with the result from CalculateResult() or

    76    * with an error code if NSS was shut down before CalculateResult could

    77    * be called.

    78    */

    79   virtual void CallCallback(nsresult rv) = 0;

    81 private:

    82   NS_IMETHOD Run() MOZ_OVERRIDE MOZ_FINAL;

    83   virtual void virtualDestroyNSSReference() MOZ_OVERRIDE MOZ_FINAL;

    85   nsresult mRv;

    86   bool mReleasedNSSResources;

    88   nsCOMPtr<nsIThread> mThread;

    89 };

    91 } // namespace mozilla

    93 #endif // mozilla__CryptoTask_h

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