BLI: improve various C++ data structures

The changes come from the `functions` branch, where I'm using
these structures a lot.

This also includes a new `BLI::Optional<T>` type, which is similar
to `std::Optional<T>` which can be used when Blender starts using
C++17.

2 files changed, 2 insertions, 117 deletions

diff --git a/source/blender/blenlib/intern/BLI_index_range.cc b/source/blender/blenlib/intern/BLI_index_range.cc
index fde4dcf6d41..6421eb0794b 100644
--- a/source/blender/blenlib/intern/BLI_index_range.cc
+++ b/source/blender/blenlib/intern/BLI_index_range.cc
@@ -24,7 +24,7 @@
 
 namespace BLI {
 
-static Vector<Array<uint, RawAllocator>, 1, RawAllocator> arrays;
+static Vector<Array<uint, 0, RawAllocator>, 1, RawAllocator> arrays;
 static uint current_array_size = 0;
 static uint *current_array = nullptr;
 static std::mutex current_array_mutex;
@@ -44,7 +44,7 @@ ArrayRef<uint> IndexRange::as_array_ref() const
   }
 
   uint new_size = std::max<uint>(1000, power_of_2_max_u(min_required_size));
-  Array<uint, RawAllocator> new_array(new_size);
+  Array<uint, 0, RawAllocator> new_array(new_size);
   for (uint i = 0; i < new_size; i++) {
     new_array[i] = i;
   }
diff --git a/source/blender/blenlib/intern/BLI_temporary_allocator.cc b/source/blender/blenlib/intern/BLI_temporary_allocator.cc
deleted file mode 100644
index b145e65530d..00000000000
--- a/source/blender/blenlib/intern/BLI_temporary_allocator.cc
+++ /dev/null
@@ -1,115 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- */
-
-#include <mutex>
-#include <stack>
-
-#include "BLI_temporary_allocator.h"
-#include "BLI_stack_cxx.h"
-
-using namespace BLI;
-
-constexpr uint ALIGNMENT = BLI_TEMPORARY_BUFFER_ALIGNMENT;
-constexpr uint SMALL_BUFFER_SIZE = 64 * 1024;
-constexpr uintptr_t ALIGNMENT_MASK = ~(uintptr_t)(ALIGNMENT - 1);
-
-enum TemporaryBufferType {
-  Small,
-  Large,
-};
-
-struct MemHead {
-  void *raw_ptr;
-  TemporaryBufferType type;
-};
-
-static MemHead &get_memhead(void *aligned_ptr)
-{
-  return *((MemHead *)aligned_ptr - 1);
-}
-
-static void *raw_allocate(uint size)
-{
-  uint total_allocation_size = size + ALIGNMENT + sizeof(MemHead);
-
-  uintptr_t raw_ptr = (uintptr_t)malloc(total_allocation_size);
-  uintptr_t aligned_ptr = (raw_ptr + ALIGNMENT + sizeof(MemHead)) & ALIGNMENT_MASK;
-
-  MemHead &memhead = get_memhead((void *)aligned_ptr);
-  memhead.raw_ptr = (void *)raw_ptr;
-  return (void *)aligned_ptr;
-}
-
-static void raw_deallocate(void *ptr)
-{
-  BLI_assert(((uintptr_t)ptr & ~ALIGNMENT_MASK) == 0);
-  MemHead &memhead = get_memhead(ptr);
-  void *raw_ptr = memhead.raw_ptr;
-  free(raw_ptr);
-}
-
-struct ThreadLocalBuffers {
-  uint allocated_amount = 0;
-  Stack<void *, 32, RawAllocator> buffers;
-
-  ~ThreadLocalBuffers()
-  {
-    for (void *ptr : buffers) {
-      raw_deallocate(ptr);
-    }
-  }
-};
-
-static thread_local ThreadLocalBuffers local_storage;
-
-void *BLI_temporary_allocate(uint size)
-{
-  /* The total amount of allocated buffers using this allocator should be limited by a constant. If
-   * it grows unbounded, there is likely a memory leak somewhere. */
-  BLI_assert(local_storage.allocated_amount < 100);
-
-  if (size <= SMALL_BUFFER_SIZE) {
-    auto &buffers = local_storage.buffers;
-    if (buffers.empty()) {
-      void *ptr = raw_allocate(SMALL_BUFFER_SIZE);
-      MemHead &memhead = get_memhead(ptr);
-      memhead.type = TemporaryBufferType::Small;
-      local_storage.allocated_amount++;
-      return ptr;
-    }
-    else {
-      return buffers.pop();
-    }
-  }
-  else {
-    void *ptr = raw_allocate(size);
-    MemHead &memhead = get_memhead(ptr);
-    memhead.type = TemporaryBufferType::Large;
-    return ptr;
-  }
-}
-
-void BLI_temporary_deallocate(void *buffer)
-{
-  MemHead &memhead = get_memhead(buffer);
-  if (memhead.type == TemporaryBufferType::Small) {
-    auto &buffers = local_storage.buffers;
-    buffers.push(buffer);
-  }
-  else {
-    raw_deallocate(buffer);
-  }
-}