Vulkan: Add CommandGraph class.

This also renames CommandBufferNode to CommandGraphNode. It also
renames some of the intenal members to more closely represent the
tree relationships (parents/children). This should clean up the
command graph classes and make them a bit easier to understand.

Bug: angleproject:2361
Change-Id: I024bffcc7f4157c78072ef902a3c40a07a08b18a
Reviewed-on: https://chromium-review.googlesource.com/922121
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>
diff --git a/src/libANGLE/renderer/vulkan/CommandGraph.h b/src/libANGLE/renderer/vulkan/CommandGraph.h
new file mode 100644
index 0000000..23e0226
--- /dev/null
+++ b/src/libANGLE/renderer/vulkan/CommandGraph.h
@@ -0,0 +1,147 @@
+//
+// Copyright 2017 The ANGLE Project Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+// CommandGraph:
+//    Deferred work constructed by GL calls, that will later be flushed to Vulkan.
+//
+
+#ifndef LIBANGLE_RENDERER_VULKAN_COMMAND_GRAPH_H_
+#define LIBANGLE_RENDERER_VULKAN_COMMAND_GRAPH_H_
+
+#include "libANGLE/renderer/vulkan/vk_cache_utils.h"
+
+namespace rx
+{
+
+namespace vk
+{
+
+enum class VisitedState
+{
+    Unvisited,
+    Ready,
+    Visited,
+};
+
+// Translating OpenGL commands into Vulkan and submitting them immediately loses out on some
+// of the powerful flexiblity Vulkan offers in RenderPasses. Load/Store ops can automatically
+// clear RenderPass attachments, or preserve the contents. RenderPass automatic layout transitions
+// can improve certain performance cases. Also, we can remove redundant RenderPass Begin and Ends
+// when processing interleaved draw operations on independent Framebuffers.
+//
+// ANGLE's CommandGraph (and CommandGraphNode) attempt to solve these problems using deferred
+// command submission. We also sometimes call this command re-ordering. A brief summary:
+//
+// During GL command processing, we record Vulkan commands into secondary command buffers, which
+// are stored in CommandGraphNodes, and these nodes are chained together via dependencies to
+// for a directed acyclic CommandGraph. When we need to submit the CommandGraph, say during a
+// SwapBuffers or ReadPixels call, we begin a primary Vulkan CommandBuffer, and walk the
+// CommandGraph, starting at the most senior nodes, recording secondary CommandBuffers inside
+// and outside vk::RenderPasses as necessary, filled with the right load/store operations. Once
+// the primary CommandBuffer has recorded all of the secondary CommandBuffers from all the open
+// CommandGraphNodes, we submit the primary CommandBuffer to the VkQueue on the device.
+
+class CommandGraphNode final : angle::NonCopyable
+{
+  public:
+    CommandGraphNode();
+    ~CommandGraphNode();
+
+    // Immutable queries for when we're walking the commands tree.
+    CommandBuffer *getOutsideRenderPassCommands();
+    CommandBuffer *getInsideRenderPassCommands();
+
+    // For outside the render pass (copies, transitions, etc).
+    Error beginOutsideRenderPassRecording(VkDevice device,
+                                          const CommandPool &commandPool,
+                                          CommandBuffer **commandsOut);
+
+    // For rendering commands (draws).
+    Error beginInsideRenderPassRecording(RendererVk *renderer, CommandBuffer **commandsOut);
+
+    // storeRenderPassInfo and append*RenderTarget store info relevant to the RenderPass.
+    void storeRenderPassInfo(const Framebuffer &framebuffer,
+                             const gl::Rectangle renderArea,
+                             const std::vector<VkClearValue> &clearValues);
+
+    // storeRenderPassInfo and append*RenderTarget store info relevant to the RenderPass.
+    // Note: RenderTargets must be added in order, with the depth/stencil being added last.
+    void appendColorRenderTarget(Serial serial, RenderTargetVk *colorRenderTarget);
+    void appendDepthStencilRenderTarget(Serial serial, RenderTargetVk *depthStencilRenderTarget);
+
+    // Dependency commands order node execution in the command graph.
+    // Once a node has commands that must happen after it, recording is stopped and the node is
+    // frozen forever.
+    static void SetHappensBeforeDependency(CommandGraphNode *beforeNode,
+                                           CommandGraphNode *afterNode);
+    static void SetHappensBeforeDependencies(const std::vector<CommandGraphNode *> &beforeNodes,
+                                             CommandGraphNode *afterNode);
+    bool hasParents() const;
+    bool hasChildren() const;
+
+    // Commands for traversing the node on a flush operation.
+    VisitedState visitedState() const;
+    void visitParents(std::vector<CommandGraphNode *> *stack);
+    Error visitAndExecute(VkDevice device,
+                          Serial serial,
+                          RenderPassCache *renderPassCache,
+                          CommandBuffer *primaryCommandBuffer);
+
+  private:
+    void setHasChildren();
+
+    // Used for testing only.
+    bool isChildOf(CommandGraphNode *parent);
+
+    // Only used if we need a RenderPass for these commands.
+    RenderPassDesc mRenderPassDesc;
+    Framebuffer mRenderPassFramebuffer;
+    gl::Rectangle mRenderPassRenderArea;
+    gl::AttachmentArray<VkClearValue> mRenderPassClearValues;
+
+    // Keep a separate buffers for commands inside and outside a RenderPass.
+    // TODO(jmadill): We might not need inside and outside RenderPass commands separate.
+    CommandBuffer mOutsideRenderPassCommands;
+    CommandBuffer mInsideRenderPassCommands;
+
+    // Parents are commands that must be submitted before 'this' CommandNode can be submitted.
+    std::vector<CommandGraphNode *> mParents;
+
+    // If this is true, other commands exist that must be submitted after 'this' command.
+    bool mHasChildren;
+
+    // Used when traversing the dependency graph.
+    VisitedState mVisitedState;
+};
+
+// The Command Graph consists of an array of open Command Graph Nodes. It supports allocating new
+// nodes for the graph, which are linked via dependency relation calls in CommandGraphNode, and
+// also submitting the whole command graph via submitCommands.
+class CommandGraph final : angle::NonCopyable
+{
+  public:
+    CommandGraph();
+    ~CommandGraph();
+
+    // Allocates a new CommandGraphNode and adds it to the list of current open nodes. No ordering
+    // relations exist in the node by default. Call CommandGraphNode::SetHappensBeforeDependency
+    // to set up dependency relations.
+    CommandGraphNode *allocateNode();
+
+    Error submitCommands(VkDevice device,
+                         Serial serial,
+                         RenderPassCache *renderPassCache,
+                         CommandPool *commandPool,
+                         CommandBuffer *primaryCommandBufferOut);
+    bool empty() const;
+
+  private:
+    std::vector<CommandGraphNode *> mNodes;
+};
+
+}  // namespace vk
+}  // namespace rx
+
+#endif  // LIBANGLE_RENDERER_VULKAN_COMMAND_GRAPH_H_