| // Protocol Buffers - Google's data interchange format |
| // Copyright 2012 Google Inc. All rights reserved. |
| // http://code.google.com/p/protobuf/ |
| // |
| // 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 Google Inc. 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 COPYRIGHT HOLDERS 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 COPYRIGHT |
| // OWNER OR 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. |
| |
| // The routines exported by this module are subtle. If you use them, even if |
| // you get the code right, it will depend on careful reasoning about atomicity |
| // and memory ordering; it will be less readable, and harder to maintain. If |
| // you plan to use these routines, you should have a good reason, such as solid |
| // evidence that performance would otherwise suffer, or there being no |
| // alternative. You should assume only properties explicitly guaranteed by the |
| // specifications in this file. You are almost certainly _not_ writing code |
| // just for the x86; if you assume x86 semantics, x86 hardware bugs and |
| // implementations on other archtectures will cause your code to break. If you |
| // do not know what you are doing, avoid these routines, and use a Mutex. |
| // |
| // It is incorrect to make direct assignments to/from an atomic variable. |
| // You should use one of the Load or Store routines. The NoBarrier |
| // versions are provided when no barriers are needed: |
| // NoBarrier_Store() |
| // NoBarrier_Load() |
| // Although there are currently no compiler enforcement, you are encouraged |
| // to use these. |
| |
| // This header and the implementations for each platform (located in |
| // atomicops_internals_*) must be kept in sync with the upstream code (V8). |
| |
| #ifndef GOOGLE_PROTOBUF_ATOMICOPS_H_ |
| #define GOOGLE_PROTOBUF_ATOMICOPS_H_ |
| |
| // Don't include this file for people not concerned about thread safety. |
| #ifndef GOOGLE_PROTOBUF_NO_THREAD_SAFETY |
| |
| #include <google/protobuf/stubs/platform_macros.h> |
| |
| namespace google { |
| namespace protobuf { |
| namespace internal { |
| |
| typedef int32 Atomic32; |
| #ifdef GOOGLE_PROTOBUF_ARCH_64_BIT |
| // We need to be able to go between Atomic64 and AtomicWord implicitly. This |
| // means Atomic64 and AtomicWord should be the same type on 64-bit. |
| #if defined(GOOGLE_PROTOBUF_OS_NACL) |
| // NaCl's intptr_t is not actually 64-bits on 64-bit! |
| // http://code.google.com/p/nativeclient/issues/detail?id=1162 |
| typedef int64 Atomic64; |
| #else |
| typedef intptr_t Atomic64; |
| #endif |
| #endif |
| |
| // Use AtomicWord for a machine-sized pointer. It will use the Atomic32 or |
| // Atomic64 routines below, depending on your architecture. |
| typedef intptr_t AtomicWord; |
| |
| // Atomically execute: |
| // result = *ptr; |
| // if (*ptr == old_value) |
| // *ptr = new_value; |
| // return result; |
| // |
| // I.e., replace "*ptr" with "new_value" if "*ptr" used to be "old_value". |
| // Always return the old value of "*ptr" |
| // |
| // This routine implies no memory barriers. |
| Atomic32 NoBarrier_CompareAndSwap(volatile Atomic32* ptr, |
| Atomic32 old_value, |
| Atomic32 new_value); |
| |
| // Atomically store new_value into *ptr, returning the previous value held in |
| // *ptr. This routine implies no memory barriers. |
| Atomic32 NoBarrier_AtomicExchange(volatile Atomic32* ptr, Atomic32 new_value); |
| |
| // Atomically increment *ptr by "increment". Returns the new value of |
| // *ptr with the increment applied. This routine implies no memory barriers. |
| Atomic32 NoBarrier_AtomicIncrement(volatile Atomic32* ptr, Atomic32 increment); |
| |
| Atomic32 Barrier_AtomicIncrement(volatile Atomic32* ptr, |
| Atomic32 increment); |
| |
| // These following lower-level operations are typically useful only to people |
| // implementing higher-level synchronization operations like spinlocks, |
| // mutexes, and condition-variables. They combine CompareAndSwap(), a load, or |
| // a store with appropriate memory-ordering instructions. "Acquire" operations |
| // ensure that no later memory access can be reordered ahead of the operation. |
| // "Release" operations ensure that no previous memory access can be reordered |
| // after the operation. "Barrier" operations have both "Acquire" and "Release" |
| // semantics. A MemoryBarrier() has "Barrier" semantics, but does no memory |
| // access. |
| Atomic32 Acquire_CompareAndSwap(volatile Atomic32* ptr, |
| Atomic32 old_value, |
| Atomic32 new_value); |
| Atomic32 Release_CompareAndSwap(volatile Atomic32* ptr, |
| Atomic32 old_value, |
| Atomic32 new_value); |
| |
| void MemoryBarrier(); |
| void NoBarrier_Store(volatile Atomic32* ptr, Atomic32 value); |
| void Acquire_Store(volatile Atomic32* ptr, Atomic32 value); |
| void Release_Store(volatile Atomic32* ptr, Atomic32 value); |
| |
| Atomic32 NoBarrier_Load(volatile const Atomic32* ptr); |
| Atomic32 Acquire_Load(volatile const Atomic32* ptr); |
| Atomic32 Release_Load(volatile const Atomic32* ptr); |
| |
| // 64-bit atomic operations (only available on 64-bit processors). |
| #ifdef GOOGLE_PROTOBUF_ARCH_64_BIT |
| Atomic64 NoBarrier_CompareAndSwap(volatile Atomic64* ptr, |
| Atomic64 old_value, |
| Atomic64 new_value); |
| Atomic64 NoBarrier_AtomicExchange(volatile Atomic64* ptr, Atomic64 new_value); |
| Atomic64 NoBarrier_AtomicIncrement(volatile Atomic64* ptr, Atomic64 increment); |
| Atomic64 Barrier_AtomicIncrement(volatile Atomic64* ptr, Atomic64 increment); |
| |
| Atomic64 Acquire_CompareAndSwap(volatile Atomic64* ptr, |
| Atomic64 old_value, |
| Atomic64 new_value); |
| Atomic64 Release_CompareAndSwap(volatile Atomic64* ptr, |
| Atomic64 old_value, |
| Atomic64 new_value); |
| void NoBarrier_Store(volatile Atomic64* ptr, Atomic64 value); |
| void Acquire_Store(volatile Atomic64* ptr, Atomic64 value); |
| void Release_Store(volatile Atomic64* ptr, Atomic64 value); |
| Atomic64 NoBarrier_Load(volatile const Atomic64* ptr); |
| Atomic64 Acquire_Load(volatile const Atomic64* ptr); |
| Atomic64 Release_Load(volatile const Atomic64* ptr); |
| #endif // GOOGLE_PROTOBUF_ARCH_64_BIT |
| |
| } // namespace internal |
| } // namespace protobuf |
| } // namespace google |
| |
| // Include our platform specific implementation. |
| #define GOOGLE_PROTOBUF_ATOMICOPS_ERROR \ |
| #error "Atomic operations are not supported on your platform" |
| |
| // MSVC. |
| #if defined(_MSC_VER) |
| #if defined(GOOGLE_PROTOBUF_ARCH_IA32) || defined(GOOGLE_PROTOBUF_ARCH_X64) |
| #include <google/protobuf/stubs/atomicops_internals_x86_msvc.h> |
| #else |
| GOOGLE_PROTOBUF_ATOMICOPS_ERROR |
| #endif |
| |
| // Apple. |
| #elif defined(GOOGLE_PROTOBUF_OS_APPLE) |
| #include <google/protobuf/stubs/atomicops_internals_macosx.h> |
| |
| // GCC. |
| #elif defined(__GNUC__) |
| #if defined(GOOGLE_PROTOBUF_ARCH_IA32) || defined(GOOGLE_PROTOBUF_ARCH_X64) |
| #include <google/protobuf/stubs/atomicops_internals_x86_gcc.h> |
| #elif defined(GOOGLE_PROTOBUF_ARCH_ARM) |
| #include <google/protobuf/stubs/atomicops_internals_arm_gcc.h> |
| #elif defined(GOOGLE_PROTOBUF_ARCH_ARM_QNX) |
| #include <google/protobuf/stubs/atomicops_internals_arm_qnx.h> |
| #elif defined(GOOGLE_PROTOBUF_ARCH_MIPS) |
| #include <google/protobuf/stubs/atomicops_internals_mips_gcc.h> |
| #elif defined(__pnacl__) |
| #include <google/protobuf/stubs/atomicops_internals_pnacl.h> |
| #else |
| GOOGLE_PROTOBUF_ATOMICOPS_ERROR |
| #endif |
| |
| // Unknown. |
| #else |
| GOOGLE_PROTOBUF_ATOMICOPS_ERROR |
| #endif |
| |
| // On some platforms we need additional declarations to make AtomicWord |
| // compatible with our other Atomic* types. |
| #if defined(GOOGLE_PROTOBUF_OS_APPLE) |
| #include <google/protobuf/stubs/atomicops_internals_atomicword_compat.h> |
| #endif |
| |
| #undef GOOGLE_PROTOBUF_ATOMICOPS_ERROR |
| |
| #endif // GOOGLE_PROTOBUF_NO_THREAD_SAFETY |
| |
| #endif // GOOGLE_PROTOBUF_ATOMICOPS_H_ |
