Flat Pool working on Windows

modules/common/chowdsp_data_structures/Allocators/chowdsp_FlatMemoryPool.h

@@ -1,12 +1,21 @@
 #pragma once
 
+#if ! JUCE_TEENSY
+
 #if JUCE_WINDOWS
+#define NOMINMAX
+#define WIN32_LEAN_AND_MEAN 1
+#include <windows.h>
 #else
 #include <sys/mman.h>
 #endif
 
 namespace chowdsp
 {
+/**
+ * A "flat" memory pool that reserves a ton of virtual memory,
+ * and then commits pages of that memory as needed.
+ */
 struct FlatMemoryPool
 {
     std::byte* current_pointer {};
@@ -15,8 +24,6 @@ struct FlatMemoryPool
     std::byte* address_limit {};
     size_t page_size {};
 
-    static constexpr size_t DEFAULT_VIRTUAL_MEMORY_RESERVE = 256 * 1024 * 1024;
-
     void* allocate_bytes (size_t num_bytes, size_t alignment = 8)
     {
         auto* p = juce::snapPointerToAlignment (current_pointer, alignment);
@@ -80,12 +87,13 @@ struct FlatMemoryPool
         return Frame { *this };
     }
 
-    void init()
+    void init (size_t reserve_bytes = 1 << 28)
     {
         page_size = static_cast<size_t> (juce::SystemStats::getPageSize());
-        const auto reserve_padded = page_size * ((DEFAULT_VIRTUAL_MEMORY_RESERVE + page_size - 1) / page_size);
+        const auto reserve_padded = page_size * ((reserve_bytes + page_size - 1) / page_size);
 
 #if JUCE_WINDOWS
+        memory_base = static_cast<std::byte*> (VirtualAlloc (nullptr, reserve_padded, MEM_RESERVE, PAGE_READWRITE));
 #else
         memory_base = static_cast<std::byte*> (mmap (nullptr, reserve_padded, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0));
         jassert (memory_base != nullptr);
@@ -102,6 +110,7 @@ struct FlatMemoryPool
             return;
 
 #if JUCE_WINDOWS
+        VirtualFree (memory_base, 0, MEM_RELEASE);
 #else
         munmap (memory_base, static_cast<size_t> (address_limit - memory_base));
 #endif
@@ -110,13 +119,18 @@ struct FlatMemoryPool
     }
 
 private:
-#if JUCE_WINDOWS
-#else
     void extend_committed_pages (std::byte* end)
     {
         jassert (end - first_uncommitted_page >= 0);
-        first_uncommitted_page = juce::snapPointerToAlignment (current_pointer, page_size);
-    }
+#if JUCE_WINDOWS
+        const auto size = juce::snapPointerToAlignment (end, page_size) - first_uncommitted_page;
+        VirtualAlloc(first_uncommitted_page, static_cast<size_t> (size), MEM_COMMIT, PAGE_READWRITE);
+        first_uncommitted_page += size;
+#else
+        first_uncommitted_page = juce::snapPointerToAlignment (end, page_size);
 #endif
+    }
 };
 } // namespace chowdsp
+
+#endif