image/IDecodingTask.cpp

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "IDecodingTask.h"
   7
   8 #include "nsThreadUtils.h"
   9
  10 #include "Decoder.h"
  11 #include "DecodePool.h"
  12 #include "RasterImage.h"
  13 #include "SurfaceCache.h"
  14
  15 namespace mozilla {
  16
  17 using gfx::IntRect;
  18
  19 namespace image {
  20
  21 ///////////////////////////////////////////////////////////////////////////////
  22 // Helpers for sending notifications to the image associated with a decoder.
  23 ///////////////////////////////////////////////////////////////////////////////
  24
  25 void IDecodingTask::EnsureHasEventTarget(NotNull<RasterImage*> aImage) {
  26   if (!mEventTarget) {
  27     // We determine the event target as late as possible, at the first dispatch
  28     // time, because the observers bound to an imgRequest will affect it.
  29     // We cache it rather than query for the event target each time because the
  30     // event target can change. We don't want to risk events being executed in
  31     // a different order than they are dispatched, which can happen if we
  32     // selected scheduler groups which have no ordering guarantees relative to
  33     // each other (e.g. it moves from scheduler group A for doc group DA to
  34     // scheduler group B for doc group DB due to changing observers -- if we
  35     // dispatched the first event on A, and the second on B, we don't know which
  36     // will execute first.)
  37     RefPtr<ProgressTracker> tracker = aImage->GetProgressTracker();
  38     if (tracker) {
  39       mEventTarget = tracker->GetEventTarget();
  40     } else {
  41       mEventTarget = GetMainThreadSerialEventTarget();
  42     }
  43   }
  44 }
  45
  46 bool IDecodingTask::IsOnEventTarget() const {
  47   // This is essentially equivalent to NS_IsOnMainThread() because all of the
  48   // event targets are for the main thread (although perhaps with a different
  49   // label / scheduler group). The observers in ProgressTracker may have
  50   // different event targets from this, so this is just a best effort guess.
  51   bool current = false;
  52   mEventTarget->IsOnCurrentThread(&current);
  53   return current;
  54 }
  55
  56 void IDecodingTask::NotifyProgress(NotNull<RasterImage*> aImage,
  57                                    NotNull<Decoder*> aDecoder) {
  58   MOZ_ASSERT(aDecoder->HasProgress() && !aDecoder->IsMetadataDecode());
  59   EnsureHasEventTarget(aImage);
  60
  61   // Capture the decoder's state. If we need to notify asynchronously, it's
  62   // important that we don't wait until the lambda actually runs to capture the
  63   // state that we're going to notify. That would both introduce data races on
  64   // the decoder's state and cause inconsistencies between the NotifyProgress()
  65   // calls we make off-main-thread and the notifications that RasterImage
  66   // actually receives, which would cause bugs.
  67   Progress progress = aDecoder->TakeProgress();
  68   UnorientedIntRect invalidRect =
  69       UnorientedIntRect::FromUnknownRect(aDecoder->TakeInvalidRect());
  70   Maybe<uint32_t> frameCount = aDecoder->TakeCompleteFrameCount();
  71   DecoderFlags decoderFlags = aDecoder->GetDecoderFlags();
  72   SurfaceFlags surfaceFlags = aDecoder->GetSurfaceFlags();
  73
  74   // Synchronously notify if we can.
  75   if (IsOnEventTarget() && !(decoderFlags & DecoderFlags::ASYNC_NOTIFY)) {
  76     aImage->NotifyProgress(progress, invalidRect, frameCount, decoderFlags,
  77                            surfaceFlags);
  78     return;
  79   }
  80
  81   // Don't try to dispatch after shutdown, we'll just leak the runnable.
  82   if (gXPCOMThreadsShutDown) {
  83     return;
  84   }
  85
  86   // We're forced to notify asynchronously.
  87   NotNull<RefPtr<RasterImage>> image = aImage;
  88   mEventTarget->Dispatch(CreateMediumHighRunnable(NS_NewRunnableFunction(
  89                              "IDecodingTask::NotifyProgress",
  90                              [=]() -> void {
  91                                image->NotifyProgress(progress, invalidRect,
  92                                                      frameCount, decoderFlags,
  93                                                      surfaceFlags);
  94                              })),
  95                          NS_DISPATCH_NORMAL);
  96 }
  97
  98 void IDecodingTask::NotifyDecodeComplete(NotNull<RasterImage*> aImage,
  99                                          NotNull<Decoder*> aDecoder) {
 100   MOZ_ASSERT(aDecoder->HasError() || !aDecoder->InFrame(),
 101              "Decode complete in the middle of a frame?");
 102   EnsureHasEventTarget(aImage);
 103
 104   // Capture the decoder's state.
 105   DecoderFinalStatus finalStatus = aDecoder->FinalStatus();
 106   ImageMetadata metadata = aDecoder->GetImageMetadata();
 107   DecoderTelemetry telemetry = aDecoder->Telemetry();
 108   Progress progress = aDecoder->TakeProgress();
 109   UnorientedIntRect invalidRect =
 110       UnorientedIntRect::FromUnknownRect(aDecoder->TakeInvalidRect());
 111   Maybe<uint32_t> frameCount = aDecoder->TakeCompleteFrameCount();
 112   DecoderFlags decoderFlags = aDecoder->GetDecoderFlags();
 113   SurfaceFlags surfaceFlags = aDecoder->GetSurfaceFlags();
 114
 115   // Synchronously notify if we can.
 116   if (IsOnEventTarget() && !(decoderFlags & DecoderFlags::ASYNC_NOTIFY)) {
 117     aImage->NotifyDecodeComplete(finalStatus, metadata, telemetry, progress,
 118                                  invalidRect, frameCount, decoderFlags,
 119                                  surfaceFlags);
 120     return;
 121   }
 122
 123   // Don't try to dispatch after shutdown, we'll just leak the runnable.
 124   if (gXPCOMThreadsShutDown) {
 125     return;
 126   }
 127
 128   // We're forced to notify asynchronously.
 129   NotNull<RefPtr<RasterImage>> image = aImage;
 130   mEventTarget->Dispatch(CreateMediumHighRunnable(NS_NewRunnableFunction(
 131                              "IDecodingTask::NotifyDecodeComplete",
 132                              [=]() -> void {
 133                                image->NotifyDecodeComplete(
 134                                    finalStatus, metadata, telemetry, progress,
 135                                    invalidRect, frameCount, decoderFlags,
 136                                    surfaceFlags);
 137                              })),
 138                          NS_DISPATCH_NORMAL);
 139 }
 140
 141 ///////////////////////////////////////////////////////////////////////////////
 142 // IDecodingTask implementation.
 143 ///////////////////////////////////////////////////////////////////////////////
 144
 145 void IDecodingTask::Resume() { DecodePool::Singleton()->AsyncRun(this); }
 146
 147 ///////////////////////////////////////////////////////////////////////////////
 148 // MetadataDecodingTask implementation.
 149 ///////////////////////////////////////////////////////////////////////////////
 150
 151 MetadataDecodingTask::MetadataDecodingTask(NotNull<Decoder*> aDecoder)
 152     : mMutex("mozilla::image::MetadataDecodingTask"), mDecoder(aDecoder) {
 153   MOZ_ASSERT(mDecoder->IsMetadataDecode(),
 154              "Use DecodingTask for non-metadata decodes");
 155 }
 156
 157 void MetadataDecodingTask::Run() {
 158   MutexAutoLock lock(mMutex);
 159
 160   LexerResult result = mDecoder->Decode(WrapNotNull(this));
 161
 162   if (result.is<TerminalState>()) {
 163     NotifyDecodeComplete(mDecoder->GetImage(), mDecoder);
 164     return;  // We're done.
 165   }
 166
 167   if (result == LexerResult(Yield::NEED_MORE_DATA)) {
 168     // We can't make any more progress right now. We also don't want to report
 169     // any progress, because it's important that metadata decode results are
 170     // delivered atomically. The decoder itself will ensure that we get
 171     // reenqueued when more data is available; just return for now.
 172     return;
 173   }
 174
 175   MOZ_ASSERT_UNREACHABLE("Metadata decode yielded for an unexpected reason");
 176 }
 177
 178 ///////////////////////////////////////////////////////////////////////////////
 179 // AnonymousDecodingTask implementation.
 180 ///////////////////////////////////////////////////////////////////////////////
 181
 182 AnonymousDecodingTask::AnonymousDecodingTask(NotNull<Decoder*> aDecoder,
 183                                              bool aResumable)
 184     : mDecoder(aDecoder), mResumable(aResumable) {}
 185
 186 void AnonymousDecodingTask::Run() {
 187   while (true) {
 188     LexerResult result = mDecoder->Decode(WrapNotNull(this));
 189
 190     if (result.is<TerminalState>()) {
 191       return;  // We're done.
 192     }
 193
 194     if (result == LexerResult(Yield::NEED_MORE_DATA)) {
 195       // We can't make any more progress right now. Let the caller decide how to
 196       // handle it.
 197       return;
 198     }
 199
 200     // Right now we don't do anything special for other kinds of yields, so just
 201     // keep working.
 202     MOZ_ASSERT(result.is<Yield>());
 203   }
 204 }
 205
 206 void AnonymousDecodingTask::Resume() {
 207   // Anonymous decoders normally get all their data at once. We have tests
 208   // where they don't; typically in these situations, the test re-runs them
 209   // manually. However some tests want to verify Resume works, so they will
 210   // explicitly request this behaviour.
 211   if (mResumable) {
 212     RefPtr<AnonymousDecodingTask> self(this);
 213     NS_DispatchToMainThread(
 214         NS_NewRunnableFunction("image::AnonymousDecodingTask::Resume",
 215                                [self]() -> void { self->Run(); }));
 216   }
 217 }
 218
 219 }  // namespace image
 220 }  // namespace mozilla