1cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project/* 2cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project * Copyright (C) 2005 The Android Open Source Project 3cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project * 4cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project * Licensed under the Apache License, Version 2.0 (the "License"); 5cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project * you may not use this file except in compliance with the License. 6cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project * You may obtain a copy of the License at 7cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project * 8cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project * http://www.apache.org/licenses/LICENSE-2.0 9cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project * 10cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project * Unless required by applicable law or agreed to in writing, software 11cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project * distributed under the License is distributed on an "AS IS" BASIS, 12cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project * See the License for the specific language governing permissions and 14cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project * limitations under the License. 15cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project */ 16cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project 17cfd5b080af8de527d768f0ff7902c26af8d49307Mark Salyzyn#define LOG_TAG "sharedbuffer" 18cfd5b080af8de527d768f0ff7902c26af8d49307Mark Salyzyn 1922dbf3947fedf988e714a4703ddf85fc41413f90Mathias Agopian#include "SharedBuffer.h" 2022dbf3947fedf988e714a4703ddf85fc41413f90Mathias Agopian 21cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project#include <stdlib.h> 22cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project#include <string.h> 23cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project 2430f991f251940be3ed11566fb71139852286f68aMark Salyzyn#include <log/log.h> 25cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project 26cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project// --------------------------------------------------------------------------- 27cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project 28cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Projectnamespace android { 29cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project 30cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source ProjectSharedBuffer* SharedBuffer::alloc(size_t size) 31cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project{ 327987b83553804156aeca61b4c111c2b983c4c551Sergio Giro // Don't overflow if the combined size of the buffer / header is larger than 337987b83553804156aeca61b4c111c2b983c4c551Sergio Giro // size_max. 347987b83553804156aeca61b4c111c2b983c4c551Sergio Giro LOG_ALWAYS_FATAL_IF((size >= (SIZE_MAX - sizeof(SharedBuffer))), 357987b83553804156aeca61b4c111c2b983c4c551Sergio Giro "Invalid buffer size %zu", size); 367987b83553804156aeca61b4c111c2b983c4c551Sergio Giro 37cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project SharedBuffer* sb = static_cast<SharedBuffer *>(malloc(sizeof(SharedBuffer) + size)); 38cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project if (sb) { 393e4c076ef204c4b572d02bd1c8dbf8c599e0014dHans Boehm // Should be std::atomic_init(&sb->mRefs, 1); 403e4c076ef204c4b572d02bd1c8dbf8c599e0014dHans Boehm // But that generates a warning with some compilers. 413e4c076ef204c4b572d02bd1c8dbf8c599e0014dHans Boehm // The following is OK on Android-supported platforms. 423e4c076ef204c4b572d02bd1c8dbf8c599e0014dHans Boehm sb->mRefs.store(1, std::memory_order_relaxed); 43cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project sb->mSize = size; 44cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project } 45cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project return sb; 46cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project} 47cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project 48cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project 493e4c076ef204c4b572d02bd1c8dbf8c599e0014dHans Boehmvoid SharedBuffer::dealloc(const SharedBuffer* released) 50cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project{ 51cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project free(const_cast<SharedBuffer*>(released)); 52cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project} 53cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project 54cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source ProjectSharedBuffer* SharedBuffer::edit() const 55cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project{ 56cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project if (onlyOwner()) { 57cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project return const_cast<SharedBuffer*>(this); 58cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project } 59cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project SharedBuffer* sb = alloc(mSize); 60cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project if (sb) { 61cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project memcpy(sb->data(), data(), size()); 62cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project release(); 63cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project } 647987b83553804156aeca61b4c111c2b983c4c551Sergio Giro return sb; 65cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project} 66cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project 67cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source ProjectSharedBuffer* SharedBuffer::editResize(size_t newSize) const 68cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project{ 69cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project if (onlyOwner()) { 70cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project SharedBuffer* buf = const_cast<SharedBuffer*>(this); 71cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project if (buf->mSize == newSize) return buf; 727987b83553804156aeca61b4c111c2b983c4c551Sergio Giro // Don't overflow if the combined size of the new buffer / header is larger than 737987b83553804156aeca61b4c111c2b983c4c551Sergio Giro // size_max. 747987b83553804156aeca61b4c111c2b983c4c551Sergio Giro LOG_ALWAYS_FATAL_IF((newSize >= (SIZE_MAX - sizeof(SharedBuffer))), 757987b83553804156aeca61b4c111c2b983c4c551Sergio Giro "Invalid buffer size %zu", newSize); 767987b83553804156aeca61b4c111c2b983c4c551Sergio Giro 77cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project buf = (SharedBuffer*)realloc(buf, sizeof(SharedBuffer) + newSize); 78cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project if (buf != NULL) { 79cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project buf->mSize = newSize; 80cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project return buf; 81cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project } 82cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project } 83cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project SharedBuffer* sb = alloc(newSize); 84cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project if (sb) { 85cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project const size_t mySize = mSize; 86cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project memcpy(sb->data(), data(), newSize < mySize ? newSize : mySize); 87cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project release(); 88cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project } 89cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project return sb; 90cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project} 91cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project 92cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source ProjectSharedBuffer* SharedBuffer::attemptEdit() const 93cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project{ 94cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project if (onlyOwner()) { 95cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project return const_cast<SharedBuffer*>(this); 96cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project } 97cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project return 0; 98cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project} 99cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project 100cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source ProjectSharedBuffer* SharedBuffer::reset(size_t new_size) const 101cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project{ 102cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project // cheap-o-reset. 103cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project SharedBuffer* sb = alloc(new_size); 104cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project if (sb) { 105cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project release(); 106cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project } 107cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project return sb; 108cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project} 109cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project 110cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Projectvoid SharedBuffer::acquire() const { 1113e4c076ef204c4b572d02bd1c8dbf8c599e0014dHans Boehm mRefs.fetch_add(1, std::memory_order_relaxed); 112cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project} 113cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project 114cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Projectint32_t SharedBuffer::release(uint32_t flags) const 115cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project{ 116476dbc48daf654ececb6e02d585ea9a43ca8513bGreg Kaiser const bool useDealloc = ((flags & eKeepStorage) == 0); 117476dbc48daf654ececb6e02d585ea9a43ca8513bGreg Kaiser if (onlyOwner()) { 118476dbc48daf654ececb6e02d585ea9a43ca8513bGreg Kaiser // Since we're the only owner, our reference count goes to zero. 1193e4c076ef204c4b572d02bd1c8dbf8c599e0014dHans Boehm mRefs.store(0, std::memory_order_relaxed); 120476dbc48daf654ececb6e02d585ea9a43ca8513bGreg Kaiser if (useDealloc) { 121476dbc48daf654ececb6e02d585ea9a43ca8513bGreg Kaiser dealloc(this); 122476dbc48daf654ececb6e02d585ea9a43ca8513bGreg Kaiser } 123476dbc48daf654ececb6e02d585ea9a43ca8513bGreg Kaiser // As the only owner, our previous reference count was 1. 124476dbc48daf654ececb6e02d585ea9a43ca8513bGreg Kaiser return 1; 125476dbc48daf654ececb6e02d585ea9a43ca8513bGreg Kaiser } 126476dbc48daf654ececb6e02d585ea9a43ca8513bGreg Kaiser // There's multiple owners, we need to use an atomic decrement. 127476dbc48daf654ececb6e02d585ea9a43ca8513bGreg Kaiser int32_t prevRefCount = mRefs.fetch_sub(1, std::memory_order_release); 128476dbc48daf654ececb6e02d585ea9a43ca8513bGreg Kaiser if (prevRefCount == 1) { 129476dbc48daf654ececb6e02d585ea9a43ca8513bGreg Kaiser // We're the last reference, we need the acquire fence. 130476dbc48daf654ececb6e02d585ea9a43ca8513bGreg Kaiser atomic_thread_fence(std::memory_order_acquire); 131476dbc48daf654ececb6e02d585ea9a43ca8513bGreg Kaiser if (useDealloc) { 132476dbc48daf654ececb6e02d585ea9a43ca8513bGreg Kaiser dealloc(this); 133cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project } 134cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project } 135476dbc48daf654ececb6e02d585ea9a43ca8513bGreg Kaiser return prevRefCount; 136cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project} 137cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project 138cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project 139cbb1011c95e0c25c29e40e203a6a31bccd029da3The Android Open Source Project}; // namespace android 140