This revision adds two major changes: 1. build_detect_platform which generates build_config.mk with platform-dependent flags for the build process 2. /port/atomic_pointer.h with anAtomicPointerimplementation for platforms without <cstdatomic> Some of this code is loosely based on patches submitted to the LevelDB mailing list at https://groups.google.com/forum/#!forum/leveldb Tip of the hat to Dave Smith and Edouard A, who both sent patches. The presence of Snappy (http://code.google.com/p/snappy/) and cstdatomic are now both detected in the build_detect_platform script (1.) which gets executing during make. For (2.), instead of broadly importing atomicops_* from Chromium or the Google performance tools, we chose to just implement AtomicPointer and the limited atomic load and store operations it needs. This resulted in much less code and fewer files - everything is contained in atomic_pointer.h. git-svn-id: https://leveldb.googlecode.com/svn/trunk@34 62dab493-f737-651d-591e-8d6aee1b9529main
gabor@google.com
14 years ago
parent
e0cbd242cb
commit
f57e23351f
@ -0,0 +1,69 @@ |
||||
#!/bin/sh |
||||
|
||||
# Detects OS we're compiling on and generates build_config.mk, |
||||
# which in turn gets read while processing Makefile. |
||||
|
||||
# build_config.mk will set the following variables: |
||||
# - PORT_CFLAGS will either set: |
||||
# -DLEVELDB_PLATFORM_POSIX if cstatomic is present |
||||
# -DLEVELDB_PLATFORM_NOATOMIC if it is not |
||||
# - PLATFORM_CFLAGS with compiler flags for the platform |
||||
# - PLATFORM_LDFLAGS with linker flags for the platform |
||||
|
||||
# Delete existing build_config.mk |
||||
rm -f build_config.mk |
||||
|
||||
# Detect OS |
||||
case `uname -s` in |
||||
Darwin) |
||||
PLATFORM=OS_MACOSX |
||||
echo "PLATFORM_CFLAGS=-pthread -DOS_MACOSX" >> build_config.mk |
||||
echo "PLATFORM_LDFLAGS=-lpthread" >> build_config.mk |
||||
;; |
||||
Linux) |
||||
PLATFORM=OS_LINUX |
||||
echo "PLATFORM_CFLAGS=-pthread -DOS_LINUX" >> build_config.mk |
||||
echo "PLATFORM_LDFLAGS=-lpthread" >> build_config.mk |
||||
;; |
||||
SunOS) |
||||
PLATFORM=OS_SOLARIS |
||||
echo "PLATFORM_CFLAGS=-D_REENTRANT -DOS_SOLARIS" >> build_config.mk |
||||
echo "PLATFORM_LDFLAGS=-lpthread -lrt" >> build_config.mk |
||||
;; |
||||
*) |
||||
echo "Unknown platform!" |
||||
exit 1 |
||||
esac |
||||
|
||||
echo "PLATFORM=$PLATFORM" >> build_config.mk |
||||
|
||||
# On GCC, use libc's memcmp, not GCC's memcmp |
||||
PORT_CFLAGS="-fno-builtin-memcmp" |
||||
|
||||
# Detect C++0x -- this determines whether we'll use port_noatomic.h |
||||
# or port_posix.h by: |
||||
# 1. Rrying to compile with -std=c++0x and including <cstdatomic>. |
||||
# 2. If g++ returns error code, we know to use port_posix.h |
||||
g++ $CFLAGS -std=c++0x -x c++ - -o /dev/null 2>/dev/null <<EOF |
||||
#include <cstdatomic> |
||||
int main() {} |
||||
EOF |
||||
if [ "$?" = 0 ]; then |
||||
PORT_CFLAGS+=" -DLEVELDB_PLATFORM_POSIX -DLEVELDB_CSTDATOMIC_PRESENT -std=c++0x" |
||||
else |
||||
PORT_CFLAGS+=" -DLEVELDB_PLATFORM_POSIX" |
||||
fi |
||||
|
||||
# Test whether Snappy library is installed |
||||
# http://code.google.com/p/snappy/ |
||||
g++ $CFLAGS -x c++ - -o /dev/null 2>/dev/null <<EOF |
||||
#include <snappy.h> |
||||
int main() {} |
||||
EOF |
||||
if [ "$?" = 0 ]; then |
||||
echo "SNAPPY=1" >> build_config.mk |
||||
else |
||||
echo "SNAPPY=0" >> build_config.mk |
||||
fi |
||||
|
||||
echo "PORT_CFLAGS=$PORT_CFLAGS" >> build_config.mk |
||||
@ -0,0 +1,213 @@ |
||||
// 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 cstdatomic is present (on newer versions of gcc, it is), we use
|
||||
// a cstdatomic-based AtomicPointer
|
||||
// - If it is not, we define processor-dependent AtomicWord operations,
|
||||
// and then use them to build AtomicPointer
|
||||
//
|
||||
// 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_ |
||||
|
||||
#ifdef LEVELDB_CSTDATOMIC_PRESENT |
||||
|
||||
///////////////////////////////////////////////////////////////////////////////
|
||||
// WE HAVE <cstdatomic>
|
||||
// Use a <cstdatomic>-based AtomicPointer
|
||||
|
||||
#include <cstdatomic> |
||||
#include <stdint.h> |
||||
|
||||
namespace leveldb { |
||||
namespace port { |
||||
|
||||
// Storage for a lock-free pointer
|
||||
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); |
||||
} |
||||
}; |
||||
|
||||
} // namespace leveldb::port
|
||||
} // namespace leveldb
|
||||
|
||||
#else |
||||
///////////////////////////////////////////////////////////////////////////////
|
||||
// NO <cstdatomic>
|
||||
// The entire rest of this file covers that case
|
||||
|
||||
#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 |
||||
#else |
||||
#warning Please add support for your architecture in atomicpointer.h |
||||
#endif |
||||
|
||||
namespace leveldb { |
||||
namespace port { |
||||
namespace internal { |
||||
|
||||
// AtomicWord is a machine-sized pointer.
|
||||
typedef intptr_t AtomicWord; |
||||
|
||||
} // namespace leveldb::port::internal
|
||||
} // namespace leveldb::port
|
||||
} // namespace leveldb
|
||||
|
||||
// Include our platform specific implementation.
|
||||
///////////////////////////////////////////////////////////////////////////////
|
||||
// Windows on x86
|
||||
#if defined(OS_WIN) && defined(COMPILER_MSVC) && defined(ARCH_CPU_X86_FAMILY) |
||||
|
||||
// void MemoryBarrier(void) macro is defined in windows.h:
|
||||
// http://msdn.microsoft.com/en-us/library/ms684208(v=vs.85).aspx
|
||||
// Including windows.h here; MemoryBarrier() gets used below.
|
||||
#include <windows.h> |
||||
|
||||
///////////////////////////////////////////////////////////////////////////////
|
||||
// Mac OS on x86
|
||||
#elif defined(OS_MACOSX) && defined(ARCH_CPU_X86_FAMILY) |
||||
|
||||
#include <libkern/OSAtomic.h> |
||||
|
||||
namespace leveldb { |
||||
namespace port { |
||||
namespace internal { |
||||
|
||||
inline void MemoryBarrier() { |
||||
#if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__)) |
||||
// 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"); |
||||
#else |
||||
OSMemoryBarrier(); |
||||
#endif |
||||
} |
||||
|
||||
} // namespace leveldb::port::internal
|
||||
} // namespace leveldb::port
|
||||
} // namespace leveldb
|
||||
|
||||
///////////////////////////////////////////////////////////////////////////////
|
||||
// Any x86 CPU
|
||||
#elif defined(ARCH_CPU_X86_FAMILY) |
||||
|
||||
namespace leveldb { |
||||
namespace port { |
||||
namespace internal { |
||||
|
||||
inline void MemoryBarrier() { |
||||
__asm__ __volatile__("" : : : "memory"); |
||||
} |
||||
|
||||
} // namespace leveldb::port::internal
|
||||
} // namespace leveldb::port
|
||||
} // namespace leveldb
|
||||
|
||||
#undef ATOMICOPS_COMPILER_BARRIER |
||||
|
||||
///////////////////////////////////////////////////////////////////////////////
|
||||
// ARM
|
||||
#elif defined(ARCH_CPU_ARM_FAMILY) |
||||
|
||||
namespace leveldb { |
||||
namespace port { |
||||
namespace internal { |
||||
|
||||
typedef void (*LinuxKernelMemoryBarrierFunc)(void); |
||||
LinuxKernelMemoryBarrierFunc pLinuxKernelMemoryBarrier __attribute__((weak)) = |
||||
(LinuxKernelMemoryBarrierFunc) 0xffff0fa0; |
||||
|
||||
inline void MemoryBarrier() { |
||||
pLinuxKernelMemoryBarrier(); |
||||
} |
||||
|
||||
} // namespace leveldb::port::internal
|
||||
} // namespace leveldb::port
|
||||
} // namespace leveldb
|
||||
|
||||
#else |
||||
#error "Atomic operations are not supported on your platform" |
||||
#endif |
||||
|
||||
///////////////////////////////////////////////////////////////////////////////
|
||||
// Implementation of AtomicPointer based on MemoryBarriers above
|
||||
|
||||
namespace leveldb { |
||||
namespace port { |
||||
namespace internal { |
||||
|
||||
// Atomic operations using per-system MemoryBarrier()s
|
||||
|
||||
inline AtomicWord Acquire_Load(volatile const AtomicWord* ptr) { |
||||
AtomicWord value = *ptr; |
||||
MemoryBarrier(); |
||||
return value; |
||||
} |
||||
|
||||
inline void Release_Store(volatile AtomicWord* ptr, AtomicWord value) { |
||||
MemoryBarrier(); |
||||
*ptr = value; |
||||
} |
||||
|
||||
inline AtomicWord NoBarrier_Load(volatile const AtomicWord* ptr) { |
||||
return *ptr; |
||||
} |
||||
|
||||
inline void NoBarrier_Store(volatile AtomicWord* ptr, AtomicWord value) { |
||||
*ptr = value; |
||||
} |
||||
|
||||
} // namespace leveldb::port::internal
|
||||
|
||||
// AtomicPointer definition for systems without <cstdatomic>.
|
||||
class AtomicPointer { |
||||
private: |
||||
typedef internal::AtomicWord Rep; |
||||
Rep rep_; |
||||
public: |
||||
AtomicPointer() { } |
||||
explicit AtomicPointer(void* p) : rep_(reinterpret_cast<Rep>(p)) {} |
||||
inline void* Acquire_Load() const { |
||||
return reinterpret_cast<void*>(internal::Acquire_Load(&rep_)); |
||||
} |
||||
inline void Release_Store(void* v) { |
||||
internal::Release_Store(&rep_, reinterpret_cast<Rep>(v)); |
||||
} |
||||
inline void* NoBarrier_Load() const { |
||||
return reinterpret_cast<void*>(internal::NoBarrier_Load(&rep_)); |
||||
} |
||||
inline void NoBarrier_Store(void* v) { |
||||
internal::NoBarrier_Store(&rep_, reinterpret_cast<Rep>(v)); |
||||
} |
||||
}; |
||||
|
||||
} // namespace leveldb::port
|
||||
} // namespace leveldb
|
||||
|
||||
#endif // LEVELDB_CSTDATOMIC_PRESENT
|
||||
|
||||
#endif // PORT_ATOMIC_POINTER_H_
|
||||
Loading…
Reference in new issue