1 files changed, 543 insertions, 0 deletions
diff --git a/gfx/layers/PersistentBufferProvider.cpp b/gfx/layers/PersistentBufferProvider.cpp
new file mode 100644
index 0000000000..72dbcd9468
--- /dev/null
+++ b/gfx/layers/PersistentBufferProvider.cpp
@@ -0,0 +1,543 @@
+/* -*- 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 "PersistentBufferProvider.h"
+
+#include "Layers.h"
+#include "mozilla/layers/ShadowLayers.h"
+#include "mozilla/layers/TextureClient.h"
+#include "mozilla/gfx/gfxVars.h"
+#include "mozilla/gfx/Logging.h"
+#include "mozilla/StaticPrefs_layers.h"
+#include "pratom.h"
+#include "gfxPlatform.h"
+
+namespace mozilla {
+
+using namespace gfx;
+
+namespace layers {
+
+PersistentBufferProviderBasic::PersistentBufferProviderBasic(DrawTarget* aDt)
+    : mDrawTarget(aDt) {
+  MOZ_COUNT_CTOR(PersistentBufferProviderBasic);
+}
+
+PersistentBufferProviderBasic::~PersistentBufferProviderBasic() {
+  MOZ_COUNT_DTOR(PersistentBufferProviderBasic);
+  Destroy();
+}
+
+already_AddRefed<gfx::DrawTarget>
+PersistentBufferProviderBasic::BorrowDrawTarget(
+    const gfx::IntRect& aPersistedRect) {
+  MOZ_ASSERT(!mSnapshot);
+  RefPtr<gfx::DrawTarget> dt(mDrawTarget);
+  return dt.forget();
+}
+
+bool PersistentBufferProviderBasic::ReturnDrawTarget(
+    already_AddRefed<gfx::DrawTarget> aDT) {
+  RefPtr<gfx::DrawTarget> dt(aDT);
+  MOZ_ASSERT(mDrawTarget == dt);
+  if (dt) {
+    // Since SkiaGL default to storing drawing command until flush
+    // we have to flush it before present.
+    dt->Flush();
+  }
+  return true;
+}
+
+already_AddRefed<gfx::SourceSurface>
+PersistentBufferProviderBasic::BorrowSnapshot() {
+  mSnapshot = mDrawTarget->Snapshot();
+  RefPtr<SourceSurface> snapshot = mSnapshot;
+  return snapshot.forget();
+}
+
+void PersistentBufferProviderBasic::ReturnSnapshot(
+    already_AddRefed<gfx::SourceSurface> aSnapshot) {
+  RefPtr<SourceSurface> snapshot = aSnapshot;
+  MOZ_ASSERT(!snapshot || snapshot == mSnapshot);
+  mSnapshot = nullptr;
+}
+
+void PersistentBufferProviderBasic::Destroy() {
+  mSnapshot = nullptr;
+  mDrawTarget = nullptr;
+}
+
+// static
+already_AddRefed<PersistentBufferProviderBasic>
+PersistentBufferProviderBasic::Create(gfx::IntSize aSize,
+                                      gfx::SurfaceFormat aFormat,
+                                      gfx::BackendType aBackend) {
+  RefPtr<DrawTarget> dt =
+      gfxPlatform::GetPlatform()->CreateDrawTargetForBackend(aBackend, aSize,
+                                                             aFormat);
+
+  if (dt) {
+    // This is simply to ensure the DrawTarget gets initialized, and will detect
+    // a device reset, even if we're on the main thread.
+    dt->ClearRect(Rect(0, 0, 0, 0));
+  }
+
+  if (!dt || !dt->IsValid()) {
+    return nullptr;
+  }
+
+  RefPtr<PersistentBufferProviderBasic> provider =
+      new PersistentBufferProviderBasic(dt);
+
+  return provider.forget();
+}
+
+// static
+already_AddRefed<PersistentBufferProviderShared>
+PersistentBufferProviderShared::Create(gfx::IntSize aSize,
+                                       gfx::SurfaceFormat aFormat,
+                                       KnowsCompositor* aKnowsCompositor) {
+  if (!aKnowsCompositor || !aKnowsCompositor->GetTextureForwarder() ||
+      !aKnowsCompositor->GetTextureForwarder()->IPCOpen() ||
+      // Bug 1556433 - shared buffer provider and direct texture mapping do not
+      // synchronize properly
+      aKnowsCompositor->SupportsTextureDirectMapping()) {
+    return nullptr;
+  }
+
+  if (!StaticPrefs::layers_shared_buffer_provider_enabled()) {
+    return nullptr;
+  }
+
+#ifdef XP_WIN
+  // Bug 1285271 - Disable shared buffer provider on Windows with D2D due to
+  // instability, unless we are remoting the canvas drawing to the GPU process.
+  if (gfxPlatform::GetPlatform()->GetPreferredCanvasBackend() ==
+          BackendType::DIRECT2D1_1 &&
+      !TextureData::IsRemote(aKnowsCompositor, BackendSelector::Canvas)) {
+    return nullptr;
+  }
+#endif
+
+  RefPtr<TextureClient> texture = TextureClient::CreateForDrawing(
+      aKnowsCompositor, aFormat, aSize, BackendSelector::Canvas,
+      TextureFlags::DEFAULT | TextureFlags::NON_BLOCKING_READ_LOCK,
+      TextureAllocationFlags::ALLOC_DEFAULT);
+
+  if (!texture) {
+    return nullptr;
+  }
+
+  RefPtr<PersistentBufferProviderShared> provider =
+      new PersistentBufferProviderShared(aSize, aFormat, aKnowsCompositor,
+                                         texture);
+  return provider.forget();
+}
+
+PersistentBufferProviderShared::PersistentBufferProviderShared(
+    gfx::IntSize aSize, gfx::SurfaceFormat aFormat,
+    KnowsCompositor* aKnowsCompositor, RefPtr<TextureClient>& aTexture)
+
+    : mSize(aSize),
+      mFormat(aFormat),
+      mKnowsCompositor(aKnowsCompositor),
+      mFront(Nothing()) {
+  MOZ_ASSERT(aKnowsCompositor);
+  if (mTextures.append(aTexture)) {
+    mBack = Some<uint32_t>(0);
+  }
+
+  // If we are using webrender and our textures don't have an intermediate
+  // buffer, then we have to hold onto the textures for longer to make sure that
+  // the GPU has finished using them. So, we need to allow more TextureClients
+  // to be created.
+  if (!aTexture->HasIntermediateBuffer() && gfxVars::UseWebRender()) {
+    ++mMaxAllowedTextures;
+    if (gfxVars::UseWebRenderTripleBufferingWin()) {
+      ++mMaxAllowedTextures;
+    }
+  }
+
+  MOZ_COUNT_CTOR(PersistentBufferProviderShared);
+}
+
+PersistentBufferProviderShared::~PersistentBufferProviderShared() {
+  MOZ_COUNT_DTOR(PersistentBufferProviderShared);
+
+  if (IsActivityTracked()) {
+    mKnowsCompositor->GetActiveResourceTracker()->RemoveObject(this);
+  }
+
+  Destroy();
+}
+
+LayersBackend PersistentBufferProviderShared::GetType() {
+  if (mKnowsCompositor->GetCompositorBackendType() ==
+      LayersBackend::LAYERS_WR) {
+    return LayersBackend::LAYERS_WR;
+  } else {
+    return LayersBackend::LAYERS_CLIENT;
+  }
+}
+
+bool PersistentBufferProviderShared::SetKnowsCompositor(
+    KnowsCompositor* aKnowsCompositor) {
+  MOZ_ASSERT(aKnowsCompositor);
+  if (!aKnowsCompositor) {
+    return false;
+  }
+
+  if (mKnowsCompositor == aKnowsCompositor) {
+    // The forwarder should not change most of the time.
+    return true;
+  }
+
+  if (IsActivityTracked()) {
+    mKnowsCompositor->GetActiveResourceTracker()->RemoveObject(this);
+  }
+
+  if (mKnowsCompositor->GetTextureForwarder() !=
+          aKnowsCompositor->GetTextureForwarder() ||
+      mKnowsCompositor->GetCompositorBackendType() !=
+          aKnowsCompositor->GetCompositorBackendType()) {
+    // We are going to be used with an different and/or incompatible forwarder.
+    // This should be extremely rare. We have to copy the front buffer into a
+    // texture that is compatible with the new forwarder.
+
+    // Grab the current front buffer.
+    RefPtr<TextureClient> prevTexture = GetTexture(mFront);
+
+    // Get rid of everything else
+    Destroy();
+
+    if (prevTexture) {
+      RefPtr<TextureClient> newTexture = TextureClient::CreateForDrawing(
+          aKnowsCompositor, mFormat, mSize, BackendSelector::Canvas,
+          TextureFlags::DEFAULT | TextureFlags::NON_BLOCKING_READ_LOCK,
+          TextureAllocationFlags::ALLOC_DEFAULT);
+
+      MOZ_ASSERT(newTexture);
+      if (!newTexture) {
+        return false;
+      }
+
+      // If we early-return in one of the following branches, we will
+      // leave the buffer provider in an empty state, since we called
+      // Destroy. Not ideal but at least we won't try to use it with a
+      // an incompatible ipc channel.
+
+      if (!newTexture->Lock(OpenMode::OPEN_WRITE)) {
+        return false;
+      }
+
+      if (!prevTexture->Lock(OpenMode::OPEN_READ)) {
+        newTexture->Unlock();
+        return false;
+      }
+
+      bool success =
+          prevTexture->CopyToTextureClient(newTexture, nullptr, nullptr);
+
+      prevTexture->Unlock();
+      newTexture->Unlock();
+
+      if (!success) {
+        return false;
+      }
+
+      if (!mTextures.append(newTexture)) {
+        return false;
+      }
+      mFront = Some<uint32_t>(mTextures.length() - 1);
+      mBack = mFront;
+    }
+  }
+
+  mKnowsCompositor = aKnowsCompositor;
+
+  return true;
+}
+
+TextureClient* PersistentBufferProviderShared::GetTexture(
+    const Maybe<uint32_t>& aIndex) {
+  if (aIndex.isNothing() || !CheckIndex(aIndex.value())) {
+    return nullptr;
+  }
+  return mTextures[aIndex.value()];
+}
+
+already_AddRefed<gfx::DrawTarget>
+PersistentBufferProviderShared::BorrowDrawTarget(
+    const gfx::IntRect& aPersistedRect) {
+  if (!mKnowsCompositor->GetTextureForwarder() ||
+      !mKnowsCompositor->GetTextureForwarder()->IPCOpen()) {
+    return nullptr;
+  }
+
+  MOZ_ASSERT(!mSnapshot);
+
+  if (IsActivityTracked()) {
+    mKnowsCompositor->GetActiveResourceTracker()->MarkUsed(this);
+  } else {
+    mKnowsCompositor->GetActiveResourceTracker()->AddObject(this);
+  }
+
+  if (mDrawTarget) {
+    RefPtr<gfx::DrawTarget> dt(mDrawTarget);
+    return dt.forget();
+  }
+
+  auto previousBackBuffer = mBack;
+
+  TextureClient* tex = GetTexture(mBack);
+
+  // First try to reuse the current back buffer. If we can do that it means
+  // we can skip copying its content to the new back buffer.
+  if ((mTextureLockIsUnreliable.isSome() &&
+       mTextureLockIsUnreliable == mBack) ||
+      (tex && tex->IsReadLocked())) {
+    // The back buffer is currently used by the compositor, we can't draw
+    // into it.
+    tex = nullptr;
+  }
+
+  if (!tex) {
+    // Try to grab an already allocated texture if any is available.
+    for (uint32_t i = 0; i < mTextures.length(); ++i) {
+      if (!mTextures[i]->IsReadLocked() &&
+          !(mTextureLockIsUnreliable.isSome() &&
+            mTextureLockIsUnreliable.ref() == i)) {
+        mBack = Some(i);
+        tex = mTextures[i];
+        break;
+      }
+    }
+  }
+
+  if (!tex) {
+    // We have to allocate a new texture.
+    if (mTextures.length() >= mMaxAllowedTextures) {
+      // We should never need to buffer that many textures, something's wrong.
+      // In theory we throttle the main thread when the compositor can't keep
+      // up, so we shoud never get in a situation where we sent 4 textures to
+      // the compositor and the latter has not released any of them. In
+      // practice, though, the throttling mechanism appears to have some issues,
+      // especially when switching between layer managers (during tab-switch).
+      // To make sure we don't get too far ahead of the compositor, we send a
+      // sync ping to the compositor thread...
+      mKnowsCompositor->SyncWithCompositor();
+      // ...and try again.
+      for (uint32_t i = 0; i < mTextures.length(); ++i) {
+        if (!mTextures[i]->IsReadLocked()) {
+          gfxCriticalNote << "Managed to allocate after flush.";
+          mBack = Some(i);
+          tex = mTextures[i];
+          break;
+        }
+      }
+
+      if (!tex) {
+        gfxCriticalNote << "Unexpected BufferProvider over-production.";
+        // It would be pretty bad to keep piling textures up at this point so we
+        // call NotifyInactive to remove some of our textures.
+        NotifyInactive();
+        // Give up now. The caller can fall-back to a non-shared buffer
+        // provider.
+        return nullptr;
+      }
+    }
+
+    RefPtr<TextureClient> newTexture = TextureClient::CreateForDrawing(
+        mKnowsCompositor, mFormat, mSize, BackendSelector::Canvas,
+        TextureFlags::DEFAULT | TextureFlags::NON_BLOCKING_READ_LOCK,
+        TextureAllocationFlags::ALLOC_DEFAULT);
+
+    MOZ_ASSERT(newTexture);
+    if (newTexture) {
+      if (mTextures.append(newTexture)) {
+        tex = newTexture;
+        mBack = Some<uint32_t>(mTextures.length() - 1);
+      }
+    }
+  }
+
+  if (!tex || !tex->Lock(OpenMode::OPEN_READ_WRITE)) {
+    return nullptr;
+  }
+
+  // Clear dirty texture, since new back texture is selected.
+  mTextureLockIsUnreliable = Nothing();
+
+  mDrawTarget = tex->BorrowDrawTarget();
+  if (mBack != previousBackBuffer && !aPersistedRect.IsEmpty()) {
+    if (mPreviousSnapshot) {
+      mDrawTarget->CopySurface(mPreviousSnapshot, aPersistedRect,
+                               gfx::IntPoint(0, 0));
+    } else {
+      TextureClient* previous = GetTexture(previousBackBuffer);
+      if (previous && previous->Lock(OpenMode::OPEN_READ)) {
+        DebugOnly<bool> success =
+            previous->CopyToTextureClient(tex, &aPersistedRect, nullptr);
+        MOZ_ASSERT(success);
+
+        previous->Unlock();
+      }
+    }
+  }
+  mPreviousSnapshot = nullptr;
+
+  if (mDrawTarget) {
+    // This is simply to ensure the DrawTarget gets initialized, and will detect
+    // a device reset, even if we're on the main thread.
+    mDrawTarget->ClearRect(Rect(0, 0, 0, 0));
+
+    if (!mDrawTarget->IsValid()) {
+      mDrawTarget = nullptr;
+    }
+  }
+
+  RefPtr<gfx::DrawTarget> dt(mDrawTarget);
+  return dt.forget();
+}
+
+bool PersistentBufferProviderShared::ReturnDrawTarget(
+    already_AddRefed<gfx::DrawTarget> aDT) {
+  RefPtr<gfx::DrawTarget> dt(aDT);
+  MOZ_ASSERT(mDrawTarget == dt);
+  // Can't change the current front buffer while its snapshot is borrowed!
+  MOZ_ASSERT(!mSnapshot);
+
+  TextureClient* back = GetTexture(mBack);
+  MOZ_ASSERT(back);
+
+  // If our TextureClients have internal synchronization then, if locks are
+  // needed for reading and writing, this can cause locking issues with the
+  // compositor. To prevent this we take a snapshot when the DrawTarget is
+  // returned, so this can be used when our own BorrowSnapshot is called and
+  // also for copying to the next TextureClient. Using this snapshot outside of
+  // the locks is safe, because the TextureClient calls DetachAllSnapshots on
+  // its DrawTarget when we Unlock below.
+  if (back->HasSynchronization()) {
+    mPreviousSnapshot = back->BorrowSnapshot();
+  }
+
+  mDrawTarget = nullptr;
+  dt = nullptr;
+
+  if (back) {
+    back->Unlock();
+    mFront = mBack;
+  }
+
+  return !!back;
+}
+
+TextureClient* PersistentBufferProviderShared::GetTextureClient() {
+  // Can't access the front buffer while drawing.
+  MOZ_ASSERT(!mDrawTarget);
+  TextureClient* texture = GetTexture(mFront);
+  if (!texture) {
+    gfxCriticalNote
+        << "PersistentBufferProviderShared: front buffer unavailable";
+  }
+  return texture;
+}
+
+already_AddRefed<gfx::SourceSurface>
+PersistentBufferProviderShared::BorrowSnapshot() {
+  if (mPreviousSnapshot) {
+    mSnapshot = mPreviousSnapshot;
+    return do_AddRef(mSnapshot);
+  }
+
+  if (mDrawTarget) {
+    auto back = GetTexture(mBack);
+    MOZ_ASSERT(back && back->IsLocked());
+    mSnapshot = back->BorrowSnapshot();
+    return do_AddRef(mSnapshot);
+  }
+
+  auto front = GetTexture(mFront);
+  if (!front || front->IsLocked()) {
+    MOZ_ASSERT(false);
+    return nullptr;
+  }
+
+  if (!front->Lock(OpenMode::OPEN_READ)) {
+    return nullptr;
+  }
+
+  mSnapshot = front->BorrowSnapshot();
+
+  return do_AddRef(mSnapshot);
+}
+
+void PersistentBufferProviderShared::ReturnSnapshot(
+    already_AddRefed<gfx::SourceSurface> aSnapshot) {
+  RefPtr<SourceSurface> snapshot = aSnapshot;
+  MOZ_ASSERT(!snapshot || snapshot == mSnapshot);
+
+  mSnapshot = nullptr;
+  snapshot = nullptr;
+
+  if (mPreviousSnapshot || mDrawTarget) {
+    return;
+  }
+
+  auto front = GetTexture(mFront);
+  if (front) {
+    front->Unlock();
+  }
+}
+
+void PersistentBufferProviderShared::NotifyInactive() {
+  ClearCachedResources();
+}
+
+void PersistentBufferProviderShared::ClearCachedResources() {
+  RefPtr<TextureClient> front = GetTexture(mFront);
+  RefPtr<TextureClient> back = GetTexture(mBack);
+
+  // Clear all textures (except the front and back ones that we just kept).
+  mTextures.clear();
+
+  if (back) {
+    if (mTextures.append(back)) {
+      mBack = Some<uint32_t>(0);
+    }
+    if (front == back) {
+      mFront = mBack;
+    }
+  }
+
+  if (front && front != back) {
+    if (mTextures.append(front)) {
+      mFront = Some<uint32_t>(mTextures.length() - 1);
+    }
+  }
+  // Set front texture as dirty texture.
+  // The texture's read lock is unreliable after this function call.
+  mTextureLockIsUnreliable = mFront;
+}
+
+void PersistentBufferProviderShared::Destroy() {
+  mSnapshot = nullptr;
+  mPreviousSnapshot = nullptr;
+  mDrawTarget = nullptr;
+
+  for (auto& mTexture : mTextures) {
+    TextureClient* texture = mTexture;
+    if (texture && texture->IsLocked()) {
+      MOZ_ASSERT(false);
+      texture->Unlock();
+    }
+  }
+
+  mTextures.clear();
+}
+
+}  // namespace layers
+}  // namespace mozilla