move JemallocNodumpAllocator to folly/experimental

[folly.git] / folly / experimental / JemallocNodumpAllocator.h

diff --git a/folly/experimental/JemallocNodumpAllocator.h b/folly/experimental/JemallocNodumpAllocator.h
new file mode 100644 (file)
index 0000000..e12454c
--- /dev/null
+++ b/folly/experimental/JemallocNodumpAllocator.h
@@ -0,0 +1,102 @@
+/*
+ * Copyright 2016 Facebook, Inc.
+ *
+ * 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.
+ */
+
+// http://www.canonware.com/download/jemalloc/jemalloc-latest/doc/jemalloc.html
+
+#pragma once
+
+#include <folly/folly-config.h>
+
+#ifdef FOLLY_HAVE_LIBJEMALLOC
+
+#include <folly/portability/SysMman.h>
+#include <jemalloc/jemalloc.h>
+
+#if (JEMALLOC_VERSION_MAJOR > 3) && defined(MADV_DONTDUMP)
+#define FOLLY_JEMALLOC_NODUMP_ALLOCATOR_SUPPORTED 1
+#endif
+
+#endif // FOLLY_HAVE_LIBJEMALLOC
+
+#include <cstddef>
+
+namespace folly {
+
+/**
+ * An allocator which uses Jemalloc to create an dedicated arena to allocate
+ * memory from. The only special property set on the allocated memory is that
+ * the memory is not dump-able.
+ *
+ * This is done by setting MADV_DONTDUMP using the `madvise` system call. A
+ * custom hook installed which is called when allocating a new chunk of memory.
+ * All it does is call the original jemalloc hook to allocate the memory and
+ * then set the advise on it before returning the pointer to the allocated
+ * memory. Jemalloc does not use allocated chunks across different arenas,
+ * without `munmap`-ing them first, and the advises are not sticky i.e. they are
+ * unset if `munmap` is done. Also this arena can't be used by any other part of
+ * the code by just calling `malloc`.
+ *
+ * If target system doesn't support MADV_DONTDUMP or jemalloc doesn't support
+ * custom arena hook, JemallocNodumpAllocator would fall back to using malloc /
+ * free. Such behavior can be identified by using
+ * !defined(FOLLY_JEMALLOC_NODUMP_ALLOCATOR_SUPPORTED).
+ *
+ * Similarly, if binary isn't linked with jemalloc, the logic would fall back to
+ * malloc / free.
+ */
+class JemallocNodumpAllocator {
+ public:
+  enum class State {
+    ENABLED,
+    DISABLED,
+  };
+
+  // To be used as IOBuf::FreeFunction, userData should be set to
+  // reinterpret_cast<void*>(getFlags()).
+  static void deallocate(void* p, void* userData);
+
+  explicit JemallocNodumpAllocator(State state = State::ENABLED);
+
+  void* allocate(size_t size);
+  void* reallocate(void* p, size_t size);
+  void deallocate(void* p);
+
+  unsigned getArenaIndex() const { return arena_index_; }
+  int getFlags() const { return flags_; }
+
+ private:
+#ifdef FOLLY_JEMALLOC_NODUMP_ALLOCATOR_SUPPORTED
+  static chunk_alloc_t* original_chunk_alloc_;
+  static void* chunk_alloc(void* chunk,
+                           size_t size,
+                           size_t alignment,
+                           bool* zero,
+                           bool* commit,
+                           unsigned arena_ind);
+#endif // FOLLY_JEMALLOC_NODUMP_ALLOCATOR_SUPPORTED
+
+  bool extend_and_setup_arena();
+
+  unsigned arena_index_{0};
+  int flags_{0};
+};
+
+/**
+ * JemallocNodumpAllocator singleton.
+ */
+JemallocNodumpAllocator& globalJemallocNodumpAllocator();
+
+} // folly