From a2dcc642c1737721bafe54605c7826fa08d18f47 Mon Sep 17 00:00:00 2001
From: ReinUsesLisp <reinuseslisp@airmail.cc>
Date: Thu, 21 May 2020 01:06:40 -0300
Subject: map_interval: Add interval allocator and drop hack

Drop the std::list hack to allocate memory indefinitely.

Instead use a custom allocator that keeps references valid until
destruction. This allocates fixed chunks of memory and puts pointers in
a free list. When an allocation is no longer used put it back to the
free list, this doesn't heap allocate because std::vector doesn't change
the capacity. If the free list is empty, allocate a new chunk.
---
 src/video_core/buffer_cache/map_interval.h | 41 ++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

(limited to 'src/video_core/buffer_cache/map_interval.h')

diff --git a/src/video_core/buffer_cache/map_interval.h b/src/video_core/buffer_cache/map_interval.h
index 45705cccf..fe0bcd1d8 100644
--- a/src/video_core/buffer_cache/map_interval.h
+++ b/src/video_core/buffer_cache/map_interval.h
@@ -4,6 +4,11 @@
 
 #pragma once
 
+#include <array>
+#include <cstddef>
+#include <memory>
+#include <vector>
+
 #include <boost/intrusive/set_hook.hpp>
 
 #include "common/common_types.h"
@@ -12,6 +17,8 @@
 namespace VideoCommon {
 
 struct MapInterval : public boost::intrusive::set_base_hook<boost::intrusive::optimize_size<true>> {
+    MapInterval() = default;
+
     /*implicit*/ MapInterval(VAddr start_) noexcept : start{start_} {}
 
     explicit MapInterval(VAddr start_, VAddr end_, GPUVAddr gpu_addr_) noexcept
@@ -48,4 +55,38 @@ struct MapIntervalCompare {
     }
 };
 
+class MapIntervalAllocator {
+public:
+    MapIntervalAllocator();
+    ~MapIntervalAllocator();
+
+    MapInterval* Allocate() {
+        if (free_list.empty()) {
+            AllocateNewChunk();
+        }
+        MapInterval* const interval = free_list.back();
+        free_list.pop_back();
+        return interval;
+    }
+
+    void Release(MapInterval* interval) {
+        free_list.push_back(interval);
+    }
+
+private:
+    struct Chunk {
+        std::unique_ptr<Chunk> next;
+        std::array<MapInterval, 0x8000> data;
+    };
+
+    void AllocateNewChunk();
+
+    void FillFreeList(Chunk& chunk);
+
+    std::vector<MapInterval*> free_list;
+    std::unique_ptr<Chunk>* new_chunk = &first_chunk.next;
+
+    Chunk first_chunk;
+};
+
 } // namespace VideoCommon
-- 
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