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