Internal Change.

PiperOrigin-RevId: 175307445

1 files changed, 84 insertions, 0 deletions

diff --git a/tensorflow/contrib/lite/simple_memory_arena.h b/tensorflow/contrib/lite/simple_memory_arena.h
new file mode 100644
index 0000000000..0d0b7f9ff7
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+++ b/tensorflow/contrib/lite/simple_memory_arena.h
@@ -0,0 +1,84 @@
+/* Copyright 2017 The TensorFlow Authors. All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+==============================================================================*/
+#ifndef THIRD_PARTY_TENSORFLOW_CONTRIB_LITE_SIMPLE_MEMORY_ARENA_H_
+#define THIRD_PARTY_TENSORFLOW_CONTRIB_LITE_SIMPLE_MEMORY_ARENA_H_
+
+#include <list>
+#include <memory>
+#include "tensorflow/contrib/lite/context.h"
+
+namespace tflite {
+
+// This little structure holds the offset and the size for a dynamic memory
+// allocation in the memory arena. When the arena is commited and the
+// underlying buffer is set, the alloc can be resolved into an actual memory
+// pointer.
+struct ArenaAlloc {
+  ArenaAlloc() : offset(0), size(0) {}
+
+  size_t offset;
+  size_t size;
+
+  inline bool operator<(const ArenaAlloc& other) const {
+    return offset < other.offset;
+  }
+};
+
+// This small class is responsible for allocating, dealocating and reusing
+// dynamic memory from a common underlying buffer. The arena can be used in
+// scenarios when the pattern of memory allocations and dealocations is
+// repetitive, e.g. running NN inference in multiple iterations.
+class SimpleMemoryArena {
+ public:
+  explicit SimpleMemoryArena(size_t arena_alignment)
+      : commited_(false),
+        arena_alignment_(arena_alignment),
+        high_water_mark_(0),
+        underlying_buffer_size_(0),
+        allocs_() {}
+
+  TfLiteStatus Allocate(TfLiteContext* context, size_t alignment, size_t size,
+                        ArenaAlloc* new_alloc);
+
+  TfLiteStatus Deallocate(TfLiteContext* context, const ArenaAlloc& alloc);
+
+  inline size_t RequiredBufferSize() {
+    // Add in a small amount of padding to reduce the chance of resize events
+    // for small allocations.
+    size_t padding = arena_alignment_;
+    return arena_alignment_ + high_water_mark_ + padding;
+  }
+
+  TfLiteStatus Commit(TfLiteContext* context);
+
+  TfLiteStatus ResolveAlloc(TfLiteContext* context, const ArenaAlloc& alloc,
+                            char** output_ptr);
+
+  TfLiteStatus Clear();
+
+ private:
+  bool commited_;
+  size_t arena_alignment_;
+  size_t high_water_mark_;
+  std::unique_ptr<char[]> underlying_buffer_;
+  size_t underlying_buffer_size_;
+  char* underlying_buffer_aligned_ptr_;
+  // TODO(maciekc): add list iterator to the ArenaAlloc to lookup quickly.
+  std::list<ArenaAlloc> allocs_;
+};
+
+}  // namespace tflite
+
+#endif  // THIRD_PARTY_TENSORFLOW_CONTRIB_LITE_SIMPLE_MEMORY_ARENA_H_