Update to leveldb upstream using subtree merge

13 files changed, 272 insertions, 1024 deletions

diff --git a/src/leveldb/port/README b/src/leveldb/port/README.md
index 422563e25c..8b171532e1 100644
--- a/src/leveldb/port/README
+++ b/src/leveldb/port/README.md
@@ -5,6 +5,6 @@ Code in the rest of the package includes "port.h" from this directory.
 "port.h" in turn includes a platform specific "port_<platform>.h" file
 that provides the platform specific implementation.
 
-See port_posix.h for an example of what must be provided in a platform
+See port_stdcxx.h for an example of what must be provided in a platform
 specific header file.
 
diff --git a/src/leveldb/port/atomic_pointer.h b/src/leveldb/port/atomic_pointer.h
deleted file mode 100644
index d79a02230d..0000000000
--- a/src/leveldb/port/atomic_pointer.h
+++ /dev/null
@@ -1,245 +0,0 @@
-// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file. See the AUTHORS file for names of contributors.
-
-// AtomicPointer provides storage for a lock-free pointer.
-// Platform-dependent implementation of AtomicPointer:
-// - If the platform provides a cheap barrier, we use it with raw pointers
-// - If <atomic> is present (on newer versions of gcc, it is), we use
-//   a <atomic>-based AtomicPointer.  However we prefer the memory
-//   barrier based version, because at least on a gcc 4.4 32-bit build
-//   on linux, we have encountered a buggy <atomic> implementation.
-//   Also, some <atomic> implementations are much slower than a memory-barrier
-//   based implementation (~16ns for <atomic> based acquire-load vs. ~1ns for
-//   a barrier based acquire-load).
-// This code is based on atomicops-internals-* in Google's perftools:
-// http://code.google.com/p/google-perftools/source/browse/#svn%2Ftrunk%2Fsrc%2Fbase
-
-#ifndef PORT_ATOMIC_POINTER_H_
-#define PORT_ATOMIC_POINTER_H_
-
-#include <stdint.h>
-#ifdef LEVELDB_ATOMIC_PRESENT
-#include <atomic>
-#endif
-#ifdef OS_WIN
-#include <windows.h>
-#endif
-#ifdef OS_MACOSX
-#include <libkern/OSAtomic.h>
-#endif
-
-#if defined(_M_X64) || defined(__x86_64__)
-#define ARCH_CPU_X86_FAMILY 1
-#elif defined(_M_IX86) || defined(__i386__) || defined(__i386)
-#define ARCH_CPU_X86_FAMILY 1
-#elif defined(__ARMEL__)
-#define ARCH_CPU_ARM_FAMILY 1
-#elif defined(__aarch64__)
-#define ARCH_CPU_ARM64_FAMILY 1
-#elif defined(__ppc__) || defined(__powerpc__) || defined(__powerpc64__)
-#define ARCH_CPU_PPC_FAMILY 1
-#elif defined(__mips__)
-#define ARCH_CPU_MIPS_FAMILY 1
-#endif
-
-namespace leveldb {
-namespace port {
-
-// AtomicPointer based on <cstdatomic> if available
-#if defined(LEVELDB_ATOMIC_PRESENT)
-class AtomicPointer {
- private:
-  std::atomic<void*> rep_;
- public:
-  AtomicPointer() { }
-  explicit AtomicPointer(void* v) : rep_(v) { }
-  inline void* Acquire_Load() const {
-    return rep_.load(std::memory_order_acquire);
-  }
-  inline void Release_Store(void* v) {
-    rep_.store(v, std::memory_order_release);
-  }
-  inline void* NoBarrier_Load() const {
-    return rep_.load(std::memory_order_relaxed);
-  }
-  inline void NoBarrier_Store(void* v) {
-    rep_.store(v, std::memory_order_relaxed);
-  }
-};
-
-#else
-
-// Define MemoryBarrier() if available
-// Windows on x86
-#if defined(OS_WIN) && defined(COMPILER_MSVC) && defined(ARCH_CPU_X86_FAMILY)
-// windows.h already provides a MemoryBarrier(void) macro
-// http://msdn.microsoft.com/en-us/library/ms684208(v=vs.85).aspx
-#define LEVELDB_HAVE_MEMORY_BARRIER
-
-// Mac OS
-#elif defined(OS_MACOSX)
-inline void MemoryBarrier() {
-  OSMemoryBarrier();
-}
-#define LEVELDB_HAVE_MEMORY_BARRIER
-
-// Gcc on x86
-#elif defined(ARCH_CPU_X86_FAMILY) && defined(__GNUC__)
-inline void MemoryBarrier() {
-  // See http://gcc.gnu.org/ml/gcc/2003-04/msg01180.html for a discussion on
-  // this idiom. Also see http://en.wikipedia.org/wiki/Memory_ordering.
-  __asm__ __volatile__("" : : : "memory");
-}
-#define LEVELDB_HAVE_MEMORY_BARRIER
-
-// Sun Studio
-#elif defined(ARCH_CPU_X86_FAMILY) && defined(__SUNPRO_CC)
-inline void MemoryBarrier() {
-  // See http://gcc.gnu.org/ml/gcc/2003-04/msg01180.html for a discussion on
-  // this idiom. Also see http://en.wikipedia.org/wiki/Memory_ordering.
-  asm volatile("" : : : "memory");
-}
-#define LEVELDB_HAVE_MEMORY_BARRIER
-
-// ARM Linux
-#elif defined(ARCH_CPU_ARM_FAMILY) && defined(__linux__)
-typedef void (*LinuxKernelMemoryBarrierFunc)(void);
-// The Linux ARM kernel provides a highly optimized device-specific memory
-// barrier function at a fixed memory address that is mapped in every
-// user-level process.
-//
-// This beats using CPU-specific instructions which are, on single-core
-// devices, un-necessary and very costly (e.g. ARMv7-A "dmb" takes more
-// than 180ns on a Cortex-A8 like the one on a Nexus One). Benchmarking
-// shows that the extra function call cost is completely negligible on
-// multi-core devices.
-//
-inline void MemoryBarrier() {
-  (*(LinuxKernelMemoryBarrierFunc)0xffff0fa0)();
-}
-#define LEVELDB_HAVE_MEMORY_BARRIER
-
-// ARM64
-#elif defined(ARCH_CPU_ARM64_FAMILY)
-inline void MemoryBarrier() {
-  asm volatile("dmb sy" : : : "memory");
-}
-#define LEVELDB_HAVE_MEMORY_BARRIER
-
-// PPC
-#elif defined(ARCH_CPU_PPC_FAMILY) && defined(__GNUC__)
-inline void MemoryBarrier() {
-  // TODO for some powerpc expert: is there a cheaper suitable variant?
-  // Perhaps by having separate barriers for acquire and release ops.
-  asm volatile("sync" : : : "memory");
-}
-#define LEVELDB_HAVE_MEMORY_BARRIER
-
-// MIPS
-#elif defined(ARCH_CPU_MIPS_FAMILY) && defined(__GNUC__)
-inline void MemoryBarrier() {
-  __asm__ __volatile__("sync" : : : "memory");
-}
-#define LEVELDB_HAVE_MEMORY_BARRIER
-
-#endif
-
-// AtomicPointer built using platform-specific MemoryBarrier()
-#if defined(LEVELDB_HAVE_MEMORY_BARRIER)
-class AtomicPointer {
- private:
-  void* rep_;
- public:
-  AtomicPointer() { }
-  explicit AtomicPointer(void* p) : rep_(p) {}
-  inline void* NoBarrier_Load() const { return rep_; }
-  inline void NoBarrier_Store(void* v) { rep_ = v; }
-  inline void* Acquire_Load() const {
-    void* result = rep_;
-    MemoryBarrier();
-    return result;
-  }
-  inline void Release_Store(void* v) {
-    MemoryBarrier();
-    rep_ = v;
-  }
-};
-
-// Atomic pointer based on sparc memory barriers
-#elif defined(__sparcv9) && defined(__GNUC__)
-class AtomicPointer {
- private:
-  void* rep_;
- public:
-  AtomicPointer() { }
-  explicit AtomicPointer(void* v) : rep_(v) { }
-  inline void* Acquire_Load() const {
-    void* val;
-    __asm__ __volatile__ (
-        "ldx [%[rep_]], %[val] \n\t"
-         "membar #LoadLoad|#LoadStore \n\t"
-        : [val] "=r" (val)
-        : [rep_] "r" (&rep_)
-        : "memory");
-    return val;
-  }
-  inline void Release_Store(void* v) {
-    __asm__ __volatile__ (
-        "membar #LoadStore|#StoreStore \n\t"
-        "stx %[v], [%[rep_]] \n\t"
-        :
-        : [rep_] "r" (&rep_), [v] "r" (v)
-        : "memory");
-  }
-  inline void* NoBarrier_Load() const { return rep_; }
-  inline void NoBarrier_Store(void* v) { rep_ = v; }
-};
-
-// Atomic pointer based on ia64 acq/rel
-#elif defined(__ia64) && defined(__GNUC__)
-class AtomicPointer {
- private:
-  void* rep_;
- public:
-  AtomicPointer() { }
-  explicit AtomicPointer(void* v) : rep_(v) { }
-  inline void* Acquire_Load() const {
-    void* val    ;
-    __asm__ __volatile__ (
-        "ld8.acq %[val] = [%[rep_]] \n\t"
-        : [val] "=r" (val)
-        : [rep_] "r" (&rep_)
-        : "memory"
-        );
-    return val;
-  }
-  inline void Release_Store(void* v) {
-    __asm__ __volatile__ (
-        "st8.rel [%[rep_]] = %[v]  \n\t"
-        :
-        : [rep_] "r" (&rep_), [v] "r" (v)
-        : "memory"
-        );
-  }
-  inline void* NoBarrier_Load() const { return rep_; }
-  inline void NoBarrier_Store(void* v) { rep_ = v; }
-};
-
-// We have neither MemoryBarrier(), nor <atomic>
-#else
-#error Please implement AtomicPointer for this platform.
-
-#endif
-#endif
-
-#undef LEVELDB_HAVE_MEMORY_BARRIER
-#undef ARCH_CPU_X86_FAMILY
-#undef ARCH_CPU_ARM_FAMILY
-#undef ARCH_CPU_ARM64_FAMILY
-#undef ARCH_CPU_PPC_FAMILY
-
-}  // namespace port
-}  // namespace leveldb
-
-#endif  // PORT_ATOMIC_POINTER_H_
diff --git a/src/leveldb/port/port.h b/src/leveldb/port/port.h
index 4baafa8e22..4b247f74f9 100644
--- a/src/leveldb/port/port.h
+++ b/src/leveldb/port/port.h
@@ -10,12 +10,10 @@
 // Include the appropriate platform specific file below.  If you are
 // porting to a new platform, see "port_example.h" for documentation
 // of what the new port_<platform>.h file must provide.
-#if defined(LEVELDB_PLATFORM_POSIX)
-#  include "port/port_posix.h"
+#if defined(LEVELDB_PLATFORM_POSIX) || defined(LEVELDB_PLATFORM_WINDOWS)
+#include "port/port_stdcxx.h"
 #elif defined(LEVELDB_PLATFORM_CHROMIUM)
-#  include "port/port_chromium.h"
-#elif defined(LEVELDB_PLATFORM_WINDOWS)
-#  include "port/port_win.h"
+#include "port/port_chromium.h"
 #endif
 
 #endif  // STORAGE_LEVELDB_PORT_PORT_H_
diff --git a/src/leveldb/port/port_config.h.in b/src/leveldb/port/port_config.h.in
new file mode 100644
index 0000000000..21273153a3
--- /dev/null
+++ b/src/leveldb/port/port_config.h.in
@@ -0,0 +1,39 @@
+// Copyright 2017 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#ifndef STORAGE_LEVELDB_PORT_PORT_CONFIG_H_
+#define STORAGE_LEVELDB_PORT_PORT_CONFIG_H_
+
+// Define to 1 if you have a definition for fdatasync() in <unistd.h>.
+#if !defined(HAVE_FDATASYNC)
+#cmakedefine01 HAVE_FDATASYNC
+#endif  // !defined(HAVE_FDATASYNC)
+
+// Define to 1 if you have a definition for F_FULLFSYNC in <fcntl.h>.
+#if !defined(HAVE_FULLFSYNC)
+#cmakedefine01 HAVE_FULLFSYNC
+#endif  // !defined(HAVE_FULLFSYNC)
+
+// Define to 1 if you have a definition for O_CLOEXEC in <fcntl.h>.
+#if !defined(HAVE_O_CLOEXEC)
+#cmakedefine01 HAVE_O_CLOEXEC
+#endif  // !defined(HAVE_O_CLOEXEC)
+
+// Define to 1 if you have Google CRC32C.
+#if !defined(HAVE_CRC32C)
+#cmakedefine01 HAVE_CRC32C
+#endif  // !defined(HAVE_CRC32C)
+
+// Define to 1 if you have Google Snappy.
+#if !defined(HAVE_SNAPPY)
+#cmakedefine01 HAVE_SNAPPY
+#endif  // !defined(HAVE_SNAPPY)
+
+// Define to 1 if your processor stores words with the most significant byte
+// first (like Motorola and SPARC, unlike Intel and VAX).
+#if !defined(LEVELDB_IS_BIG_ENDIAN)
+#cmakedefine01 LEVELDB_IS_BIG_ENDIAN
+#endif  // !defined(LEVELDB_IS_BIG_ENDIAN)
+
+#endif  // STORAGE_LEVELDB_PORT_PORT_CONFIG_H_
\ No newline at end of file
diff --git a/src/leveldb/port/port_example.h b/src/leveldb/port/port_example.h
index 5b1d027de5..1a8fca24b3 100644
--- a/src/leveldb/port/port_example.h
+++ b/src/leveldb/port/port_example.h
@@ -10,6 +10,8 @@
 #ifndef STORAGE_LEVELDB_PORT_PORT_EXAMPLE_H_
 #define STORAGE_LEVELDB_PORT_PORT_EXAMPLE_H_
 
+#include "port/thread_annotations.h"
+
 namespace leveldb {
 namespace port {
 
@@ -23,23 +25,23 @@ static const bool kLittleEndian = true /* or some other expression */;
 // ------------------ Threading -------------------
 
 // A Mutex represents an exclusive lock.
-class Mutex {
+class LOCKABLE Mutex {
  public:
   Mutex();
   ~Mutex();
 
   // Lock the mutex.  Waits until other lockers have exited.
   // Will deadlock if the mutex is already locked by this thread.
-  void Lock();
+  void Lock() EXCLUSIVE_LOCK_FUNCTION();
 
   // Unlock the mutex.
   // REQUIRES: This mutex was locked by this thread.
-  void Unlock();
+  void Unlock() UNLOCK_FUNCTION();
 
   // Optionally crash if this thread does not hold this mutex.
   // The implementation must be fast, especially if NDEBUG is
   // defined.  The implementation is allowed to skip all checks.
-  void AssertHeld();
+  void AssertHeld() ASSERT_EXCLUSIVE_LOCK();
 };
 
 class CondVar {
@@ -60,57 +62,18 @@ class CondVar {
   void SignallAll();
 };
 
-// Thread-safe initialization.
-// Used as follows:
-//      static port::OnceType init_control = LEVELDB_ONCE_INIT;
-//      static void Initializer() { ... do something ...; }
-//      ...
-//      port::InitOnce(&init_control, &Initializer);
-typedef intptr_t OnceType;
-#define LEVELDB_ONCE_INIT 0
-extern void InitOnce(port::OnceType*, void (*initializer)());
-
-// A type that holds a pointer that can be read or written atomically
-// (i.e., without word-tearing.)
-class AtomicPointer {
- private:
-  intptr_t rep_;
- public:
-  // Initialize to arbitrary value
-  AtomicPointer();
-
-  // Initialize to hold v
-  explicit AtomicPointer(void* v) : rep_(v) { }
-
-  // Read and return the stored pointer with the guarantee that no
-  // later memory access (read or write) by this thread can be
-  // reordered ahead of this read.
-  void* Acquire_Load() const;
-
-  // Set v as the stored pointer with the guarantee that no earlier
-  // memory access (read or write) by this thread can be reordered
-  // after this store.
-  void Release_Store(void* v);
-
-  // Read the stored pointer with no ordering guarantees.
-  void* NoBarrier_Load() const;
-
-  // Set va as the stored pointer with no ordering guarantees.
-  void NoBarrier_Store(void* v);
-};
-
 // ------------------ Compression -------------------
 
 // Store the snappy compression of "input[0,input_length-1]" in *output.
 // Returns false if snappy is not supported by this port.
-extern bool Snappy_Compress(const char* input, size_t input_length,
-                            std::string* output);
+bool Snappy_Compress(const char* input, size_t input_length,
+                     std::string* output);
 
 // If input[0,input_length-1] looks like a valid snappy compressed
 // buffer, store the size of the uncompressed data in *result and
 // return true.  Else return false.
-extern bool Snappy_GetUncompressedLength(const char* input, size_t length,
-                                         size_t* result);
+bool Snappy_GetUncompressedLength(const char* input, size_t length,
+                                  size_t* result);
 
 // Attempt to snappy uncompress input[0,input_length-1] into *output.
 // Returns true if successful, false if the input is invalid lightweight
@@ -119,19 +82,15 @@ extern bool Snappy_GetUncompressedLength(const char* input, size_t length,
 // REQUIRES: at least the first "n" bytes of output[] must be writable
 // where "n" is the result of a successful call to
 // Snappy_GetUncompressedLength.
-extern bool Snappy_Uncompress(const char* input_data, size_t input_length,
-                              char* output);
+bool Snappy_Uncompress(const char* input_data, size_t input_length,
+                       char* output);
 
 // ------------------ Miscellaneous -------------------
 
 // If heap profiling is not supported, returns false.
 // Else repeatedly calls (*func)(arg, data, n) and then returns true.
 // The concatenation of all "data[0,n-1]" fragments is the heap profile.
-extern bool GetHeapProfile(void (*func)(void*, const char*, int), void* arg);
-
-// Determine whether a working accelerated crc32 implementation exists
-// Returns true if AcceleratedCRC32C is safe to call
-bool HasAcceleratedCRC32C();
+bool GetHeapProfile(void (*func)(void*, const char*, int), void* arg);
 
 // Extend the CRC to include the first n bytes of buf.
 //
diff --git a/src/leveldb/port/port_posix.cc b/src/leveldb/port/port_posix.cc
deleted file mode 100644
index ec39e92195..0000000000
--- a/src/leveldb/port/port_posix.cc
+++ /dev/null
@@ -1,67 +0,0 @@
-// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file. See the AUTHORS file for names of contributors.
-
-#include "port/port_posix.h"
-
-#include <cstdlib>
-#include <stdio.h>
-#include <string.h>
-
-#if (defined(__x86_64__) || defined(__i386__)) && defined(__GNUC__)
-#include <cpuid.h>
-#endif
-
-namespace leveldb {
-namespace port {
-
-static void PthreadCall(const char* label, int result) {
-  if (result != 0) {
-    fprintf(stderr, "pthread %s: %s\n", label, strerror(result));
-    abort();
-  }
-}
-
-Mutex::Mutex() { PthreadCall("init mutex", pthread_mutex_init(&mu_, NULL)); }
-
-Mutex::~Mutex() { PthreadCall("destroy mutex", pthread_mutex_destroy(&mu_)); }
-
-void Mutex::Lock() { PthreadCall("lock", pthread_mutex_lock(&mu_)); }
-
-void Mutex::Unlock() { PthreadCall("unlock", pthread_mutex_unlock(&mu_)); }
-
-CondVar::CondVar(Mutex* mu)
-    : mu_(mu) {
-    PthreadCall("init cv", pthread_cond_init(&cv_, NULL));
-}
-
-CondVar::~CondVar() { PthreadCall("destroy cv", pthread_cond_destroy(&cv_)); }
-
-void CondVar::Wait() {
-  PthreadCall("wait", pthread_cond_wait(&cv_, &mu_->mu_));
-}
-
-void CondVar::Signal() {
-  PthreadCall("signal", pthread_cond_signal(&cv_));
-}
-
-void CondVar::SignalAll() {
-  PthreadCall("broadcast", pthread_cond_broadcast(&cv_));
-}
-
-void InitOnce(OnceType* once, void (*initializer)()) {
-  PthreadCall("once", pthread_once(once, initializer));
-}
-
-bool HasAcceleratedCRC32C() {
-#if (defined(__x86_64__) || defined(__i386__)) && defined(__GNUC__)
-  unsigned int eax, ebx, ecx, edx;
-  __get_cpuid(1, &eax, &ebx, &ecx, &edx);
-  return (ecx & (1 << 20)) != 0;
-#else
-  return false;
-#endif
-}
-
-}  // namespace port
-}  // namespace leveldb
diff --git a/src/leveldb/port/port_posix.h b/src/leveldb/port/port_posix.h
deleted file mode 100644
index d85fa5d63f..0000000000
--- a/src/leveldb/port/port_posix.h
+++ /dev/null
@@ -1,161 +0,0 @@
-// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file. See the AUTHORS file for names of contributors.
-//
-// See port_example.h for documentation for the following types/functions.
-
-#ifndef STORAGE_LEVELDB_PORT_PORT_POSIX_H_
-#define STORAGE_LEVELDB_PORT_PORT_POSIX_H_
-
-#undef PLATFORM_IS_LITTLE_ENDIAN
-#if defined(OS_MACOSX)
-  #include <machine/endian.h>
-  #if defined(__DARWIN_LITTLE_ENDIAN) && defined(__DARWIN_BYTE_ORDER)
-    #define PLATFORM_IS_LITTLE_ENDIAN \
-        (__DARWIN_BYTE_ORDER == __DARWIN_LITTLE_ENDIAN)
-  #endif
-#elif defined(OS_SOLARIS)
-  #include <sys/isa_defs.h>
-  #ifdef _LITTLE_ENDIAN
-    #define PLATFORM_IS_LITTLE_ENDIAN true
-  #else
-    #define PLATFORM_IS_LITTLE_ENDIAN false
-  #endif
-#elif defined(OS_FREEBSD) || defined(OS_OPENBSD) ||\
-      defined(OS_NETBSD) || defined(OS_DRAGONFLYBSD)
-  #include <sys/types.h>
-  #include <sys/endian.h>
-  #define PLATFORM_IS_LITTLE_ENDIAN (_BYTE_ORDER == _LITTLE_ENDIAN)
-#elif defined(OS_HPUX)
-  #define PLATFORM_IS_LITTLE_ENDIAN false
-#elif defined(OS_ANDROID)
-  // Due to a bug in the NDK x86 <sys/endian.h> definition,
-  // _BYTE_ORDER must be used instead of __BYTE_ORDER on Android.
-  // See http://code.google.com/p/android/issues/detail?id=39824
-  #include <endian.h>
-  #define PLATFORM_IS_LITTLE_ENDIAN  (_BYTE_ORDER == _LITTLE_ENDIAN)
-#else
-  #include <endian.h>
-#endif
-
-#include <pthread.h>
-#ifdef SNAPPY
-#include <snappy.h>
-#endif
-#include <stdint.h>
-#include <string>
-#include "port/atomic_pointer.h"
-
-#ifndef PLATFORM_IS_LITTLE_ENDIAN
-#define PLATFORM_IS_LITTLE_ENDIAN (__BYTE_ORDER == __LITTLE_ENDIAN)
-#endif
-
-#if defined(OS_MACOSX) || defined(OS_SOLARIS) || defined(OS_FREEBSD) ||\
-    defined(OS_NETBSD) || defined(OS_OPENBSD) || defined(OS_DRAGONFLYBSD) ||\
-    defined(OS_ANDROID) || defined(OS_HPUX) || defined(CYGWIN)
-// Use fread/fwrite/fflush on platforms without _unlocked variants
-#define fread_unlocked fread
-#define fwrite_unlocked fwrite
-#define fflush_unlocked fflush
-#endif
-
-#if defined(OS_FREEBSD) ||\
-    defined(OS_OPENBSD) || defined(OS_DRAGONFLYBSD)
-// Use fsync() on platforms without fdatasync()
-#define fdatasync fsync
-#endif
-
-#if defined(OS_MACOSX)
-#define fdatasync(fd) fcntl(fd, F_FULLFSYNC, 0)
-#endif
-
-#if defined(OS_ANDROID) && __ANDROID_API__ < 9
-// fdatasync() was only introduced in API level 9 on Android. Use fsync()
-// when targetting older platforms.
-#define fdatasync fsync
-#endif
-
-namespace leveldb {
-namespace port {
-
-static const bool kLittleEndian = PLATFORM_IS_LITTLE_ENDIAN;
-#undef PLATFORM_IS_LITTLE_ENDIAN
-
-class CondVar;
-
-class Mutex {
- public:
-  Mutex();
-  ~Mutex();
-
-  void Lock();
-  void Unlock();
-  void AssertHeld() { }
-
- private:
-  friend class CondVar;
-  pthread_mutex_t mu_;
-
-  // No copying
-  Mutex(const Mutex&);
-  void operator=(const Mutex&);
-};
-
-class CondVar {
- public:
-  explicit CondVar(Mutex* mu);
-  ~CondVar();
-  void Wait();
-  void Signal();
-  void SignalAll();
- private:
-  pthread_cond_t cv_;
-  Mutex* mu_;
-};
-
-typedef pthread_once_t OnceType;
-#define LEVELDB_ONCE_INIT PTHREAD_ONCE_INIT
-extern void InitOnce(OnceType* once, void (*initializer)());
-
-inline bool Snappy_Compress(const char* input, size_t length,
-                            ::std::string* output) {
-#ifdef SNAPPY
-  output->resize(snappy::MaxCompressedLength(length));
-  size_t outlen;
-  snappy::RawCompress(input, length, &(*output)[0], &outlen);
-  output->resize(outlen);
-  return true;
-#endif
-
-  return false;
-}
-
-inline bool Snappy_GetUncompressedLength(const char* input, size_t length,
-                                         size_t* result) {
-#ifdef SNAPPY
-  return snappy::GetUncompressedLength(input, length, result);
-#else
-  return false;
-#endif
-}
-
-inline bool Snappy_Uncompress(const char* input, size_t length,
-                              char* output) {
-#ifdef SNAPPY
-  return snappy::RawUncompress(input, length, output);
-#else
-  return false;
-#endif
-}
-
-inline bool GetHeapProfile(void (*func)(void*, const char*, int), void* arg) {
-  return false;
-}
-
-bool HasAcceleratedCRC32C();
-uint32_t AcceleratedCRC32C(uint32_t crc, const char* buf, size_t size);
-
-} // namespace port
-} // namespace leveldb
-
-#endif  // STORAGE_LEVELDB_PORT_PORT_POSIX_H_
diff --git a/src/leveldb/port/port_posix_sse.cc b/src/leveldb/port/port_posix_sse.cc
deleted file mode 100644
index 2d49c21dd8..0000000000
--- a/src/leveldb/port/port_posix_sse.cc
+++ /dev/null
@@ -1,110 +0,0 @@
-// Copyright 2016 The LevelDB Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file. See the AUTHORS file for names of contributors.
-//
-// A portable implementation of crc32c, optimized to handle
-// four bytes at a time.
-//
-// In a separate source file to allow this accelerated CRC32C function to be
-// compiled with the appropriate compiler flags to enable x86 SSE 4.2
-// instructions.
-
-#include <stdint.h>
-#include <string.h>
-#include "port/port.h"
-
-#if defined(LEVELDB_PLATFORM_POSIX_SSE)
-
-#if defined(_MSC_VER)
-#include <intrin.h>
-#elif defined(__GNUC__) && defined(__SSE4_2__)
-#include <nmmintrin.h>
-#endif
-
-#endif  // defined(LEVELDB_PLATFORM_POSIX_SSE)
-
-namespace leveldb {
-namespace port {
-
-#if defined(LEVELDB_PLATFORM_POSIX_SSE)
-
-// Used to fetch a naturally-aligned 32-bit word in little endian byte-order
-static inline uint32_t LE_LOAD32(const uint8_t *p) {
-  // SSE is x86 only, so ensured that |p| is always little-endian.
-  uint32_t word;
-  memcpy(&word, p, sizeof(word));
-  return word;
-}
-
-#if defined(_M_X64) || defined(__x86_64__)  // LE_LOAD64 is only used on x64.
-
-// Used to fetch a naturally-aligned 64-bit word in little endian byte-order
-static inline uint64_t LE_LOAD64(const uint8_t *p) {
-  uint64_t dword;
-  memcpy(&dword, p, sizeof(dword));
-  return dword;
-}
-
-#endif  // defined(_M_X64) || defined(__x86_64__)
-
-#endif  // defined(LEVELDB_PLATFORM_POSIX_SSE)
-
-// For further improvements see Intel publication at:
-// http://download.intel.com/design/intarch/papers/323405.pdf
-uint32_t AcceleratedCRC32C(uint32_t crc, const char* buf, size_t size) {
-#if !defined(LEVELDB_PLATFORM_POSIX_SSE)
-  return 0;
-#else
-
-  const uint8_t *p = reinterpret_cast<const uint8_t *>(buf);
-  const uint8_t *e = p + size;
-  uint32_t l = crc ^ 0xffffffffu;
-
-#define STEP1 do {                              \
-    l = _mm_crc32_u8(l, *p++);                  \
-} while (0)
-#define STEP4 do {                              \
-    l = _mm_crc32_u32(l, LE_LOAD32(p));         \
-    p += 4;                                     \
-} while (0)
-#define STEP8 do {                              \
-    l = _mm_crc32_u64(l, LE_LOAD64(p));         \
-    p += 8;                                     \
-} while (0)
-
-  if (size > 16) {
-    // Process unaligned bytes
-    for (unsigned int i = reinterpret_cast<uintptr_t>(p) % 8; i; --i) {
-      STEP1;
-    }
-
-    // _mm_crc32_u64 is only available on x64.
-#if defined(_M_X64) || defined(__x86_64__)
-    // Process 8 bytes at a time
-    while ((e-p) >= 8) {
-      STEP8;
-    }
-    // Process 4 bytes at a time
-    if ((e-p) >= 4) {
-      STEP4;
-    }
-#else  // !(defined(_M_X64) || defined(__x86_64__))
-    // Process 4 bytes at a time
-    while ((e-p) >= 4) {
-      STEP4;
-    }
-#endif  // defined(_M_X64) || defined(__x86_64__)
-  }
-  // Process the last few bytes
-  while (p != e) {
-    STEP1;
-  }
-#undef STEP8
-#undef STEP4
-#undef STEP1
-  return l ^ 0xffffffffu;
-#endif  // defined(LEVELDB_PLATFORM_POSIX_SSE)
-}
-
-}  // namespace port
-}  // namespace leveldb
diff --git a/src/leveldb/port/port_stdcxx.h b/src/leveldb/port/port_stdcxx.h
new file mode 100644
index 0000000000..e9cb0e53af
--- /dev/null
+++ b/src/leveldb/port/port_stdcxx.h
@@ -0,0 +1,153 @@
+// Copyright (c) 2018 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#ifndef STORAGE_LEVELDB_PORT_PORT_STDCXX_H_
+#define STORAGE_LEVELDB_PORT_PORT_STDCXX_H_
+
+// port/port_config.h availability is automatically detected via __has_include
+// in newer compilers. If LEVELDB_HAS_PORT_CONFIG_H is defined, it overrides the
+// configuration detection.
+#if defined(LEVELDB_HAS_PORT_CONFIG_H)
+
+#if LEVELDB_HAS_PORT_CONFIG_H
+#include "port/port_config.h"
+#endif  // LEVELDB_HAS_PORT_CONFIG_H
+
+#elif defined(__has_include)
+
+#if __has_include("port/port_config.h")
+#include "port/port_config.h"
+#endif  // __has_include("port/port_config.h")
+
+#endif  // defined(LEVELDB_HAS_PORT_CONFIG_H)
+
+#if HAVE_CRC32C
+#include <crc32c/crc32c.h>
+#endif  // HAVE_CRC32C
+#if HAVE_SNAPPY
+#include <snappy.h>
+#endif  // HAVE_SNAPPY
+
+#include <cassert>
+#include <condition_variable>  // NOLINT
+#include <cstddef>
+#include <cstdint>
+#include <mutex>  // NOLINT
+#include <string>
+
+#include "port/thread_annotations.h"
+
+namespace leveldb {
+namespace port {
+
+static const bool kLittleEndian = !LEVELDB_IS_BIG_ENDIAN;
+
+class CondVar;
+
+// Thinly wraps std::mutex.
+class LOCKABLE Mutex {
+ public:
+  Mutex() = default;
+  ~Mutex() = default;
+
+  Mutex(const Mutex&) = delete;
+  Mutex& operator=(const Mutex&) = delete;
+
+  void Lock() EXCLUSIVE_LOCK_FUNCTION() { mu_.lock(); }
+  void Unlock() UNLOCK_FUNCTION() { mu_.unlock(); }
+  void AssertHeld() ASSERT_EXCLUSIVE_LOCK() {}
+
+ private:
+  friend class CondVar;
+  std::mutex mu_;
+};
+
+// Thinly wraps std::condition_variable.
+class CondVar {
+ public:
+  explicit CondVar(Mutex* mu) : mu_(mu) { assert(mu != nullptr); }
+  ~CondVar() = default;
+
+  CondVar(const CondVar&) = delete;
+  CondVar& operator=(const CondVar&) = delete;
+
+  void Wait() {
+    std::unique_lock<std::mutex> lock(mu_->mu_, std::adopt_lock);
+    cv_.wait(lock);
+    lock.release();
+  }
+  void Signal() { cv_.notify_one(); }
+  void SignalAll() { cv_.notify_all(); }
+
+ private:
+  std::condition_variable cv_;
+  Mutex* const mu_;
+};
+
+inline bool Snappy_Compress(const char* input, size_t length,
+                            std::string* output) {
+#if HAVE_SNAPPY
+  output->resize(snappy::MaxCompressedLength(length));
+  size_t outlen;
+  snappy::RawCompress(input, length, &(*output)[0], &outlen);
+  output->resize(outlen);
+  return true;
+#else
+  // Silence compiler warnings about unused arguments.
+  (void)input;
+  (void)length;
+  (void)output;
+#endif  // HAVE_SNAPPY
+
+  return false;
+}
+
+inline bool Snappy_GetUncompressedLength(const char* input, size_t length,
+                                         size_t* result) {
+#if HAVE_SNAPPY
+  return snappy::GetUncompressedLength(input, length, result);
+#else
+  // Silence compiler warnings about unused arguments.
+  (void)input;
+  (void)length;
+  (void)result;
+  return false;
+#endif  // HAVE_SNAPPY
+}
+
+inline bool Snappy_Uncompress(const char* input, size_t length, char* output) {
+#if HAVE_SNAPPY
+  return snappy::RawUncompress(input, length, output);
+#else
+  // Silence compiler warnings about unused arguments.
+  (void)input;
+  (void)length;
+  (void)output;
+  return false;
+#endif  // HAVE_SNAPPY
+}
+
+inline bool GetHeapProfile(void (*func)(void*, const char*, int), void* arg) {
+  // Silence compiler warnings about unused arguments.
+  (void)func;
+  (void)arg;
+  return false;
+}
+
+inline uint32_t AcceleratedCRC32C(uint32_t crc, const char* buf, size_t size) {
+#if HAVE_CRC32C
+  return ::crc32c::Extend(crc, reinterpret_cast<const uint8_t*>(buf), size);
+#else
+  // Silence compiler warnings about unused arguments.
+  (void)crc;
+  (void)buf;
+  (void)size;
+  return 0;
+#endif  // HAVE_CRC32C
+}
+
+}  // namespace port
+}  // namespace leveldb
+
+#endif  // STORAGE_LEVELDB_PORT_PORT_STDCXX_H_
diff --git a/src/leveldb/port/port_win.cc b/src/leveldb/port/port_win.cc
deleted file mode 100644
index 1be9e8d5b0..0000000000
--- a/src/leveldb/port/port_win.cc
+++ /dev/null
@@ -1,158 +0,0 @@
-// LevelDB Copyright (c) 2011 The LevelDB Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file. See the AUTHORS file for names of contributors.
-//
-// See port_example.h for documentation for the following types/functions.
-
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are met:
-// 
-//  * Redistributions of source code must retain the above copyright
-//    notice, this list of conditions and the following disclaimer.
-//  * Redistributions in binary form must reproduce the above copyright
-//    notice, this list of conditions and the following disclaimer in the
-//    documentation and/or other materials provided with the distribution.
-//  * Neither the name of the University of California, Berkeley nor the
-//    names of its contributors may be used to endorse or promote products
-//    derived from this software without specific prior written permission.
-// 
-// THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND ANY
-// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
-// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
-// DISCLAIMED. IN NO EVENT SHALL THE REGENTS AND CONTRIBUTORS BE LIABLE FOR ANY
-// DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
-// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
-// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
-// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
-// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-//
-
-#include "port/port_win.h"
-
-#include <windows.h>
-#include <cassert>
-#include <intrin.h>
-
-namespace leveldb {
-namespace port {
-
-Mutex::Mutex() :
-    cs_(NULL) {
-  assert(!cs_);
-  cs_ = static_cast<void *>(new CRITICAL_SECTION());
-  ::InitializeCriticalSection(static_cast<CRITICAL_SECTION *>(cs_));
-  assert(cs_);
-}
-
-Mutex::~Mutex() {
-  assert(cs_);
-  ::DeleteCriticalSection(static_cast<CRITICAL_SECTION *>(cs_));
-  delete static_cast<CRITICAL_SECTION *>(cs_);
-  cs_ = NULL;
-  assert(!cs_);
-}
-
-void Mutex::Lock() {
-  assert(cs_);
-  ::EnterCriticalSection(static_cast<CRITICAL_SECTION *>(cs_));
-}
-
-void Mutex::Unlock() {
-  assert(cs_);
-  ::LeaveCriticalSection(static_cast<CRITICAL_SECTION *>(cs_));
-}
-
-void Mutex::AssertHeld() {
-  assert(cs_);
-  assert(1);
-}
-
-CondVar::CondVar(Mutex* mu) :
-    waiting_(0), 
-    mu_(mu), 
-    sem1_(::CreateSemaphore(NULL, 0, 10000, NULL)), 
-    sem2_(::CreateSemaphore(NULL, 0, 10000, NULL)) {
-  assert(mu_);
-}
-
-CondVar::~CondVar() {
-  ::CloseHandle(sem1_);
-  ::CloseHandle(sem2_);
-}
-
-void CondVar::Wait() {
-  mu_->AssertHeld();
-
-  wait_mtx_.Lock();
-  ++waiting_;
-  wait_mtx_.Unlock();
-
-  mu_->Unlock();
-
-  // initiate handshake
-  ::WaitForSingleObject(sem1_, INFINITE);
-  ::ReleaseSemaphore(sem2_, 1, NULL);
-  mu_->Lock();
-}
-
-void CondVar::Signal() {
-  wait_mtx_.Lock();
-  if (waiting_ > 0) {
-    --waiting_;
-
-    // finalize handshake
-    ::ReleaseSemaphore(sem1_, 1, NULL);
-    ::WaitForSingleObject(sem2_, INFINITE);
-  }
-  wait_mtx_.Unlock();
-}
-
-void CondVar::SignalAll() {
-  wait_mtx_.Lock();
-  ::ReleaseSemaphore(sem1_, waiting_, NULL);
-  while(waiting_ > 0) {
-    --waiting_;
-    ::WaitForSingleObject(sem2_, INFINITE);
-  }
-  wait_mtx_.Unlock();
-}
-
-AtomicPointer::AtomicPointer(void* v) {
-  Release_Store(v);
-}
-
-void InitOnce(OnceType* once, void (*initializer)()) {
-  once->InitOnce(initializer);
-}
-
-void* AtomicPointer::Acquire_Load() const {
-  void * p = NULL;
-  InterlockedExchangePointer(&p, rep_);
-  return p;
-}
-
-void AtomicPointer::Release_Store(void* v) {
-  InterlockedExchangePointer(&rep_, v);
-}
-
-void* AtomicPointer::NoBarrier_Load() const {
-  return rep_;
-}
-
-void AtomicPointer::NoBarrier_Store(void* v) {
-  rep_ = v;
-}
-
-bool HasAcceleratedCRC32C() {
-#if defined(__x86_64__) || defined(__i386__)
-  int cpu_info[4];
-  __cpuid(cpu_info, 1);
-  return (cpu_info[2] & (1 << 20)) != 0;
-#else
-  return false;
-#endif
-}
-
-}
-}
diff --git a/src/leveldb/port/port_win.h b/src/leveldb/port/port_win.h
deleted file mode 100644
index 989c15cd91..0000000000
--- a/src/leveldb/port/port_win.h
+++ /dev/null
@@ -1,184 +0,0 @@
-// LevelDB Copyright (c) 2011 The LevelDB Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file. See the AUTHORS file for names of contributors.
-//
-// See port_example.h for documentation for the following types/functions.
-
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are met:
-// 
-//  * Redistributions of source code must retain the above copyright
-//    notice, this list of conditions and the following disclaimer.
-//  * Redistributions in binary form must reproduce the above copyright
-//    notice, this list of conditions and the following disclaimer in the
-//    documentation and/or other materials provided with the distribution.
-//  * Neither the name of the University of California, Berkeley nor the
-//    names of its contributors may be used to endorse or promote products
-//    derived from this software without specific prior written permission.
-// 
-// THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND ANY
-// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
-// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
-// DISCLAIMED. IN NO EVENT SHALL THE REGENTS AND CONTRIBUTORS BE LIABLE FOR ANY
-// DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
-// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
-// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
-// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
-// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-//
-
-#ifndef STORAGE_LEVELDB_PORT_PORT_WIN_H_
-#define STORAGE_LEVELDB_PORT_PORT_WIN_H_
-
-#ifdef _MSC_VER
-#if !(_MSC_VER >= 1900)
-#define snprintf _snprintf
-#endif
-#define close _close
-#define fread_unlocked _fread_nolock
-#ifdef _WIN64
-#define ssize_t int64_t
-#else
-#define ssize_t int32_t
-#endif
-#endif
-
-#include <string>
-#include <stdint.h>
-#ifdef SNAPPY
-#include <snappy.h>
-#endif
-
-namespace leveldb {
-namespace port {
-
-// Windows is little endian (for now :p)
-static const bool kLittleEndian = true;
-
-class CondVar;
-
-class Mutex {
- public:
-  Mutex();
-  ~Mutex();
-
-  void Lock();
-  void Unlock();
-  void AssertHeld();
-
- private:
-  friend class CondVar;
-  // critical sections are more efficient than mutexes
-  // but they are not recursive and can only be used to synchronize threads within the same process
-  // we use opaque void * to avoid including windows.h in port_win.h
-  void * cs_;
-
-  // No copying
-  Mutex(const Mutex&);
-  void operator=(const Mutex&);
-};
-
-// the Win32 API offers a dependable condition variable mechanism, but only starting with
-// Windows 2008 and Vista
-// no matter what we will implement our own condition variable with a semaphore
-// implementation as described in a paper written by Andrew D. Birrell in 2003
-class CondVar {
- public:
-  explicit CondVar(Mutex* mu);
-  ~CondVar();
-  void Wait();
-  void Signal();
-  void SignalAll();
- private:
-  Mutex* mu_;
-  
-  Mutex wait_mtx_;
-  long waiting_;
-  
-  void * sem1_;
-  void * sem2_;
-  
-  
-};
-
-class OnceType {
-public:
-//    OnceType() : init_(false) {}
-    OnceType(const OnceType &once) : init_(once.init_) {}
-    OnceType(bool f) : init_(f) {}
-    void InitOnce(void (*initializer)()) {
-        mutex_.Lock();
-        if (!init_) {
-            init_ = true;
-            initializer();
-        }
-        mutex_.Unlock();
-    }
-
-private:
-    bool init_;
-    Mutex mutex_;
-};
-
-#define LEVELDB_ONCE_INIT false
-extern void InitOnce(port::OnceType*, void (*initializer)());
-
-// Storage for a lock-free pointer
-class AtomicPointer {
- private:
-  void * rep_;
- public:
-  AtomicPointer() : rep_(NULL) { }
-  explicit AtomicPointer(void* v); 
-  void* Acquire_Load() const;
-
-  void Release_Store(void* v);
-
-  void* NoBarrier_Load() const;
-
-  void NoBarrier_Store(void* v);
-};
-
-inline bool Snappy_Compress(const char* input, size_t length,
-                            ::std::string* output) {
-#ifdef SNAPPY
-  output->resize(snappy::MaxCompressedLength(length));
-  size_t outlen;
-  snappy::RawCompress(input, length, &(*output)[0], &outlen);
-  output->resize(outlen);
-  return true;
-#endif
-
-  return false;
-}
-
-inline bool Snappy_GetUncompressedLength(const char* input, size_t length,
-                                         size_t* result) {
-#ifdef SNAPPY
-  return snappy::GetUncompressedLength(input, length, result);
-#else
-  return false;
-#endif
-}
-
-inline bool Snappy_Uncompress(const char* input, size_t length,
-                              char* output) {
-#ifdef SNAPPY
-  return snappy::RawUncompress(input, length, output);
-#else
-  return false;
-#endif
-}
-
-inline bool GetHeapProfile(void (*func)(void*, const char*, int), void* arg) {
-  return false;
-}
-
-bool HasAcceleratedCRC32C();
-uint32_t AcceleratedCRC32C(uint32_t crc, const char* buf, size_t size);
-
-}
-}
-
-#endif  // STORAGE_LEVELDB_PORT_PORT_WIN_H_
diff --git a/src/leveldb/port/thread_annotations.h b/src/leveldb/port/thread_annotations.h
index 9470ef587c..1547df908f 100644
--- a/src/leveldb/port/thread_annotations.h
+++ b/src/leveldb/port/thread_annotations.h
@@ -5,56 +5,104 @@
 #ifndef STORAGE_LEVELDB_PORT_THREAD_ANNOTATIONS_H_
 #define STORAGE_LEVELDB_PORT_THREAD_ANNOTATIONS_H_
 
-// Some environments provide custom macros to aid in static thread-safety
-// analysis.  Provide empty definitions of such macros unless they are already
-// defined.
+// Use Clang's thread safety analysis annotations when available. In other
+// environments, the macros receive empty definitions.
+// Usage documentation: https://clang.llvm.org/docs/ThreadSafetyAnalysis.html
+
+#if !defined(THREAD_ANNOTATION_ATTRIBUTE__)
+
+#if defined(__clang__)
+
+#define THREAD_ANNOTATION_ATTRIBUTE__(x) __attribute__((x))
+#else
+#define THREAD_ANNOTATION_ATTRIBUTE__(x)  // no-op
+#endif
+
+#endif  // !defined(THREAD_ANNOTATION_ATTRIBUTE__)
+
+#ifndef GUARDED_BY
+#define GUARDED_BY(x) THREAD_ANNOTATION_ATTRIBUTE__(guarded_by(x))
+#endif
+
+#ifndef PT_GUARDED_BY
+#define PT_GUARDED_BY(x) THREAD_ANNOTATION_ATTRIBUTE__(pt_guarded_by(x))
+#endif
+
+#ifndef ACQUIRED_AFTER
+#define ACQUIRED_AFTER(...) \
+  THREAD_ANNOTATION_ATTRIBUTE__(acquired_after(__VA_ARGS__))
+#endif
+
+#ifndef ACQUIRED_BEFORE
+#define ACQUIRED_BEFORE(...) \
+  THREAD_ANNOTATION_ATTRIBUTE__(acquired_before(__VA_ARGS__))
+#endif
 
 #ifndef EXCLUSIVE_LOCKS_REQUIRED
-#define EXCLUSIVE_LOCKS_REQUIRED(...)
+#define EXCLUSIVE_LOCKS_REQUIRED(...) \
+  THREAD_ANNOTATION_ATTRIBUTE__(exclusive_locks_required(__VA_ARGS__))
 #endif
 
 #ifndef SHARED_LOCKS_REQUIRED
-#define SHARED_LOCKS_REQUIRED(...)
+#define SHARED_LOCKS_REQUIRED(...) \
+  THREAD_ANNOTATION_ATTRIBUTE__(shared_locks_required(__VA_ARGS__))
 #endif
 
 #ifndef LOCKS_EXCLUDED
-#define LOCKS_EXCLUDED(...)
+#define LOCKS_EXCLUDED(...) \
+  THREAD_ANNOTATION_ATTRIBUTE__(locks_excluded(__VA_ARGS__))
 #endif
 
 #ifndef LOCK_RETURNED
-#define LOCK_RETURNED(x)
+#define LOCK_RETURNED(x) THREAD_ANNOTATION_ATTRIBUTE__(lock_returned(x))
 #endif
 
 #ifndef LOCKABLE
-#define LOCKABLE
+#define LOCKABLE THREAD_ANNOTATION_ATTRIBUTE__(lockable)
 #endif
 
 #ifndef SCOPED_LOCKABLE
-#define SCOPED_LOCKABLE
+#define SCOPED_LOCKABLE THREAD_ANNOTATION_ATTRIBUTE__(scoped_lockable)
 #endif
 
 #ifndef EXCLUSIVE_LOCK_FUNCTION
-#define EXCLUSIVE_LOCK_FUNCTION(...)
+#define EXCLUSIVE_LOCK_FUNCTION(...) \
+  THREAD_ANNOTATION_ATTRIBUTE__(exclusive_lock_function(__VA_ARGS__))
 #endif
 
 #ifndef SHARED_LOCK_FUNCTION
-#define SHARED_LOCK_FUNCTION(...)
+#define SHARED_LOCK_FUNCTION(...) \
+  THREAD_ANNOTATION_ATTRIBUTE__(shared_lock_function(__VA_ARGS__))
 #endif
 
 #ifndef EXCLUSIVE_TRYLOCK_FUNCTION
-#define EXCLUSIVE_TRYLOCK_FUNCTION(...)
+#define EXCLUSIVE_TRYLOCK_FUNCTION(...) \
+  THREAD_ANNOTATION_ATTRIBUTE__(exclusive_trylock_function(__VA_ARGS__))
 #endif
 
 #ifndef SHARED_TRYLOCK_FUNCTION
-#define SHARED_TRYLOCK_FUNCTION(...)
+#define SHARED_TRYLOCK_FUNCTION(...) \
+  THREAD_ANNOTATION_ATTRIBUTE__(shared_trylock_function(__VA_ARGS__))
 #endif
 
 #ifndef UNLOCK_FUNCTION
-#define UNLOCK_FUNCTION(...)
+#define UNLOCK_FUNCTION(...) \
+  THREAD_ANNOTATION_ATTRIBUTE__(unlock_function(__VA_ARGS__))
 #endif
 
 #ifndef NO_THREAD_SAFETY_ANALYSIS
-#define NO_THREAD_SAFETY_ANALYSIS
+#define NO_THREAD_SAFETY_ANALYSIS \
+  THREAD_ANNOTATION_ATTRIBUTE__(no_thread_safety_analysis)
+#endif
+
+#ifndef ASSERT_EXCLUSIVE_LOCK
+#define ASSERT_EXCLUSIVE_LOCK(...) \
+  THREAD_ANNOTATION_ATTRIBUTE__(assert_exclusive_lock(__VA_ARGS__))
+#endif
+
+#ifndef ASSERT_SHARED_LOCK
+#define ASSERT_SHARED_LOCK(...) \
+  THREAD_ANNOTATION_ATTRIBUTE__(assert_shared_lock(__VA_ARGS__))
 #endif
 
 #endif  // STORAGE_LEVELDB_PORT_THREAD_ANNOTATIONS_H_
diff --git a/src/leveldb/port/win/stdint.h b/src/leveldb/port/win/stdint.h
deleted file mode 100644
index 39edd0db13..0000000000
--- a/src/leveldb/port/win/stdint.h
+++ /dev/null
@@ -1,24 +0,0 @@
-// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file. See the AUTHORS file for names of contributors.
-
-// MSVC didn't ship with this file until the 2010 version.
-
-#ifndef STORAGE_LEVELDB_PORT_WIN_STDINT_H_
-#define STORAGE_LEVELDB_PORT_WIN_STDINT_H_
-
-#if !defined(_MSC_VER)
-#error This file should only be included when compiling with MSVC.
-#endif
-
-// Define C99 equivalent types.
-typedef signed char           int8_t;
-typedef signed short          int16_t;
-typedef signed int            int32_t;
-typedef signed long long      int64_t;
-typedef unsigned char         uint8_t;
-typedef unsigned short        uint16_t;
-typedef unsigned int          uint32_t;
-typedef unsigned long long    uint64_t;
-
-#endif  // STORAGE_LEVELDB_PORT_WIN_STDINT_H_