From 82e8781549a153e7ce7b7bd0e4b50e86fbc1d9ca Mon Sep 17 00:00:00 2001
From: DrChat <arkolbed@gmail.com>
Date: Fri, 2 Mar 2018 22:01:55 -0600
Subject: [PATCH] [Vulkan UI] Use an underlying queue instead of a list of
 pointers in CircularBuffer

---
 src/xenia/ui/vulkan/circular_buffer.cc | 75 ++++++++++++--------------
 src/xenia/ui/vulkan/circular_buffer.h  |  4 +-
 2 files changed, 37 insertions(+), 42 deletions(-)

diff --git a/src/xenia/ui/vulkan/circular_buffer.cc b/src/xenia/ui/vulkan/circular_buffer.cc
index 05f3f7917..46b3df9c4 100644
--- a/src/xenia/ui/vulkan/circular_buffer.cc
+++ b/src/xenia/ui/vulkan/circular_buffer.cc
@@ -177,46 +177,46 @@ CircularBuffer::Allocation* CircularBuffer::Acquire(VkDeviceSize length,
     // Write head behind read head.
     assert_true(read_head_ - write_head_ >= aligned_length);
 
-    auto alloc = new Allocation();
-    alloc->host_ptr = host_base_ + write_head_;
-    alloc->gpu_memory = gpu_memory_;
-    alloc->offset = gpu_base_ + write_head_;
-    alloc->length = length;
-    alloc->aligned_length = aligned_length;
-    alloc->fence = fence;
+    Allocation alloc;
+    alloc.host_ptr = host_base_ + write_head_;
+    alloc.gpu_memory = gpu_memory_;
+    alloc.offset = gpu_base_ + write_head_;
+    alloc.length = length;
+    alloc.aligned_length = aligned_length;
+    alloc.fence = fence;
     write_head_ += aligned_length;
-    allocations_.push_back(alloc);
+    allocations_.push(alloc);
 
-    return alloc;
+    return &allocations_.back();
   } else {
     // Write head equal to/after read head
     if (capacity_ - write_head_ >= aligned_length) {
       // Free space from write -> capacity
-      auto alloc = new Allocation();
-      alloc->host_ptr = host_base_ + write_head_;
-      alloc->gpu_memory = gpu_memory_;
-      alloc->offset = gpu_base_ + write_head_;
-      alloc->length = length;
-      alloc->aligned_length = aligned_length;
-      alloc->fence = fence;
+      Allocation alloc;
+      alloc.host_ptr = host_base_ + write_head_;
+      alloc.gpu_memory = gpu_memory_;
+      alloc.offset = gpu_base_ + write_head_;
+      alloc.length = length;
+      alloc.aligned_length = aligned_length;
+      alloc.fence = fence;
       write_head_ += aligned_length;
-      allocations_.push_back(alloc);
+      allocations_.push(alloc);
 
-      return alloc;
+      return &allocations_.back();
     } else if ((read_head_ - 0) >= aligned_length) {
       // Not enough space from write -> capacity, but there is enough free space
       // from begin -> read
-      auto alloc = new Allocation();
-      alloc->host_ptr = host_base_ + 0;
-      alloc->gpu_memory = gpu_memory_;
-      alloc->offset = gpu_base_ + 0;
-      alloc->length = length;
-      alloc->aligned_length = aligned_length;
-      alloc->fence = fence;
+      Allocation alloc;
+      alloc.host_ptr = host_base_ + 0;
+      alloc.gpu_memory = gpu_memory_;
+      alloc.offset = gpu_base_ + 0;
+      alloc.length = length;
+      alloc.aligned_length = aligned_length;
+      alloc.fence = fence;
       write_head_ = aligned_length;
-      allocations_.push_back(alloc);
+      allocations_.push(alloc);
 
-      return alloc;
+      return &allocations_.back();
     }
   }
 
@@ -244,30 +244,25 @@ void CircularBuffer::Flush(VkDeviceSize offset, VkDeviceSize length) {
 }
 
 void CircularBuffer::Clear() {
-  for (auto alloc : allocations_) {
-    delete alloc;
-  }
-  allocations_.clear();
-
+  std::swap(allocations_, std::queue<Allocation>());
   write_head_ = read_head_ = 0;
 }
 
 void CircularBuffer::Scavenge() {
-  for (auto it = allocations_.begin(); it != allocations_.end();) {
-    if (vkGetFenceStatus(*device_, (*it)->fence) != VK_SUCCESS) {
+  while (!allocations_.empty()) {
+    Allocation& alloc = allocations_.front();
+    if (vkGetFenceStatus(*device_, alloc.fence) != VK_SUCCESS) {
       // Don't bother freeing following allocations to ensure proper ordering.
       break;
     }
 
-    if (capacity_ - read_head_ < (*it)->aligned_length) {
+    allocations_.pop();
+    if (capacity_ - read_head_ < alloc.aligned_length) {
       // This allocation is stored at the beginning of the buffer.
-      read_head_ = (*it)->aligned_length;
+      read_head_ = alloc.aligned_length;
     } else {
-      read_head_ += (*it)->aligned_length;
+      read_head_ += alloc.aligned_length;
     }
-
-    delete *it;
-    it = allocations_.erase(it);
   }
 
   if (allocations_.empty()) {
diff --git a/src/xenia/ui/vulkan/circular_buffer.h b/src/xenia/ui/vulkan/circular_buffer.h
index 6940b2532..85b069aa0 100644
--- a/src/xenia/ui/vulkan/circular_buffer.h
+++ b/src/xenia/ui/vulkan/circular_buffer.h
@@ -10,7 +10,7 @@
 #ifndef XENIA_UI_VULKAN_CIRCULAR_BUFFER_H_
 #define XENIA_UI_VULKAN_CIRCULAR_BUFFER_H_
 
-#include <list>
+#include <queue>
 
 #include "xenia/ui/vulkan/vulkan.h"
 #include "xenia/ui/vulkan/vulkan_device.h"
@@ -83,7 +83,7 @@ class CircularBuffer {
   VkDeviceSize gpu_base_ = 0;
   uint8_t* host_base_ = nullptr;
 
-  std::list<Allocation*> allocations_;
+  std::queue<Allocation> allocations_;
 };
 
 }  // namespace vulkan