Import LevelDB 1.5, it will be used for the transaction database.

src/leveldb/port/README

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+This directory contains interfaces and implementations that isolate the
+rest of the package from platform details.
+
+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
+specific header file.
+

src/leveldb/port/atomic_pointer.h

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+// 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 cstdatomic is present (on newer versions of gcc, it is), we use
+//   a cstdatomic-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 <cstdatomic>
+//   implementation.  Also, some <cstdatomic> implementations are much
+//   slower than a memory-barrier based implementation (~16ns for
+//   <cstdatomic> 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_CSTDATOMIC_PRESENT
+#include <cstdatomic>
+#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
+#endif
+
+namespace leveldb {
+namespace port {
+
+// 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
+
+// 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
+
+// Mac OS
+#elif defined(OS_MACOSX)
+inline void MemoryBarrier() {
+  OSMemoryBarrier();
+}
+#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
+
+#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;
+  }
+};
+
+// AtomicPointer based on <cstdatomic>
+#elif defined(LEVELDB_CSTDATOMIC_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);
+  }
+};
+
+// We have neither MemoryBarrier(), nor <cstdatomic>
+#else
+#error Please implement AtomicPointer for this platform.
+
+#endif
+
+#undef LEVELDB_HAVE_MEMORY_BARRIER
+#undef ARCH_CPU_X86_FAMILY
+#undef ARCH_CPU_ARM_FAMILY
+
+}  // namespace port
+}  // namespace leveldb
+
+#endif  // PORT_ATOMIC_POINTER_H_

src/leveldb/port/port.h

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+// 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.
+
+#ifndef STORAGE_LEVELDB_PORT_PORT_H_
+#define STORAGE_LEVELDB_PORT_PORT_H_
+
+#include <string.h>
+
+// 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"
+#elif defined(LEVELDB_PLATFORM_CHROMIUM)
+#  include "port/port_chromium.h"
+#endif
+
+#endif  // STORAGE_LEVELDB_PORT_PORT_H_

src/leveldb/port/port_example.h

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+// 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.
+//
+// This file contains the specification, but not the implementations,
+// of the types/operations/etc. that should be defined by a platform
+// specific port_<platform>.h file.  Use this file as a reference for
+// how to port this package to a new platform.
+
+#ifndef STORAGE_LEVELDB_PORT_PORT_EXAMPLE_H_
+#define STORAGE_LEVELDB_PORT_PORT_EXAMPLE_H_
+
+namespace leveldb {
+namespace port {
+
+// TODO(jorlow): Many of these belong more in the environment class rather than
+//               here. We should try moving them and see if it affects perf.
+
+// The following boolean constant must be true on a little-endian machine
+// and false otherwise.
+static const bool kLittleEndian = true /* or some other expression */;
+
+// ------------------ Threading -------------------
+
+// A Mutex represents an exclusive lock.
+class 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();
+
+  // Unlock the mutex.
+  // REQUIRES: This mutex was locked by this thread.
+  void Unlock();
+
+  // 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();
+};
+
+class CondVar {
+ public:
+  explicit CondVar(Mutex* mu);
+  ~CondVar();
+
+  // Atomically release *mu and block on this condition variable until
+  // either a call to SignalAll(), or a call to Signal() that picks
+  // this thread to wakeup.
+  // REQUIRES: this thread holds *mu
+  void Wait();
+
+  // If there are some threads waiting, wake up at least one of them.
+  void Signal();
+
+  // Wake up all waiting threads.
+  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);
+
+// 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);
+
+// Attempt to snappy uncompress input[0,input_length-1] into *output.
+// Returns true if successful, false if the input is invalid lightweight
+// compressed data.
+//
+// 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);
+
+// ------------------ 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);
+
+}  // namespace port
+}  // namespace leveldb
+
+#endif  // STORAGE_LEVELDB_PORT_PORT_EXAMPLE_H_

src/leveldb/port/port_posix.cc

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+// 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>
+#include "util/logging.h"
+
+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));
+}
+
+}  // namespace port
+}  // namespace leveldb

src/leveldb/port/port_posix.h

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+// 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) || defined(OS_ANDROID)
+  #include <sys/types.h>
+  #include <sys/endian.h>
+#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)
+// 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_MACOSX) || defined(OS_FREEBSD) ||\
+    defined(OS_OPENBSD) || defined(OS_DRAGONFLYBSD)
+// Use fsync() on platforms without fdatasync()
+#define fdatasync fsync
+#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;
+}
+
+} // namespace port
+} // namespace leveldb
+
+#endif  // STORAGE_LEVELDB_PORT_PORT_POSIX_H_

src/leveldb/port/win/stdint.h

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+// 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_