initial commit

tdutils/td/utils/StackAllocator.h

@@ -0,0 +1,95 @@
+/*
+    This file is part of TON Blockchain Library.
+
+    TON Blockchain Library is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation, either version 2 of the License, or
+    (at your option) any later version.
+
+    TON Blockchain Library 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 Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with TON Blockchain Library.  If not, see <http://www.gnu.org/licenses/>.
+
+    Copyright 2017-2019 Telegram Systems LLP
+*/
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/MovableValue.h"
+#include "td/utils/Slice.h"
+
+#include <array>
+#include <cstdlib>
+#include <memory>
+
+namespace td {
+
+class StackAllocator {
+  class Deleter {
+   public:
+    void operator()(char *ptr) {
+      free_ptr(ptr);
+    }
+  };
+
+  // TODO: alloc memory with mmap and unload unused pages
+  // memory still can be corrupted, but it is better than explicit free function
+  // TODO: use pointer that can't be even copied
+  using PtrImpl = std::unique_ptr<char, Deleter>;
+  class Ptr {
+   public:
+    Ptr(char *ptr, size_t size) : ptr_(ptr), size_(size) {
+    }
+
+    MutableSlice as_slice() const {
+      return MutableSlice(ptr_.get(), size_.get());
+    }
+
+   private:
+    PtrImpl ptr_;
+    MovableValue<size_t> size_;
+  };
+
+  static void free_ptr(char *ptr) {
+    impl().free_ptr(ptr);
+  }
+
+  struct Impl {
+    static const size_t MEM_SIZE = 1024 * 1024;
+    std::array<char, MEM_SIZE> mem;
+
+    size_t pos{0};
+    char *alloc(size_t size) {
+      if (size == 0) {
+        size = 1;
+      }
+      char *res = mem.data() + pos;
+      size = (size + 7) & -8;
+      pos += size;
+      if (pos > MEM_SIZE) {
+        std::abort();  // memory is over
+      }
+      return res;
+    }
+    void free_ptr(char *ptr) {
+      size_t new_pos = ptr - mem.data();
+      if (new_pos >= pos) {
+        std::abort();  // shouldn't happen
+      }
+      pos = new_pos;
+    }
+  };
+
+  static Impl &impl();
+
+ public:
+  static Ptr alloc(size_t size) {
+    return Ptr(impl().alloc(size), size);
+  }
+};
+
+}  // namespace td