| The Android Open Source Project | 4f6e8d7 | 2008-10-21 07:00:00 -0700 | [diff] [blame] | 1 | /* |
| 2 | * SharedBuffer.cpp |
| 3 | * Android |
| 4 | * |
| 5 | * Copyright 2005 The Android Open Source Project |
| 6 | * |
| 7 | */ |
| 8 | |
| 9 | #include <stdlib.h> |
| 10 | #include <string.h> |
| 11 | |
| 12 | #include <cutils/atomic.h> |
| 13 | |
| 14 | #include "tinyutils/SharedBuffer.h" |
| 15 | |
| 16 | // --------------------------------------------------------------------------- |
| 17 | |
| 18 | namespace android { |
| 19 | |
| 20 | SharedBuffer* SharedBuffer::alloc(size_t size) |
| 21 | { |
| 22 | SharedBuffer* sb = static_cast<SharedBuffer *>(malloc(sizeof(SharedBuffer) + size)); |
| 23 | if (sb) { |
| 24 | sb->mRefs = 1; |
| 25 | sb->mSize = size; |
| 26 | } |
| 27 | return sb; |
| 28 | } |
| 29 | |
| 30 | |
| 31 | ssize_t SharedBuffer::dealloc(const SharedBuffer* released) |
| 32 | { |
| 33 | if (released->mRefs != 0) return -1; // XXX: invalid operation |
| 34 | free(const_cast<SharedBuffer*>(released)); |
| 35 | return 0; |
| 36 | } |
| 37 | |
| 38 | SharedBuffer* SharedBuffer::edit() const |
| 39 | { |
| 40 | if (onlyOwner()) { |
| 41 | return const_cast<SharedBuffer*>(this); |
| 42 | } |
| 43 | SharedBuffer* sb = alloc(mSize); |
| 44 | if (sb) { |
| 45 | memcpy(sb->data(), data(), size()); |
| 46 | release(); |
| 47 | } |
| 48 | return sb; |
| 49 | } |
| 50 | |
| 51 | SharedBuffer* SharedBuffer::editResize(size_t newSize) const |
| 52 | { |
| 53 | if (onlyOwner()) { |
| 54 | SharedBuffer* buf = const_cast<SharedBuffer*>(this); |
| 55 | if (buf->mSize == newSize) return buf; |
| 56 | buf = (SharedBuffer*)realloc(buf, sizeof(SharedBuffer) + newSize); |
| 57 | if (buf != NULL) { |
| 58 | buf->mSize = newSize; |
| 59 | return buf; |
| 60 | } |
| 61 | } |
| 62 | SharedBuffer* sb = alloc(newSize); |
| 63 | if (sb) { |
| 64 | const size_t mySize = mSize; |
| 65 | memcpy(sb->data(), data(), newSize < mySize ? newSize : mySize); |
| 66 | release(); |
| 67 | } |
| 68 | return sb; |
| 69 | } |
| 70 | |
| 71 | SharedBuffer* SharedBuffer::attemptEdit() const |
| 72 | { |
| 73 | if (onlyOwner()) { |
| 74 | return const_cast<SharedBuffer*>(this); |
| 75 | } |
| 76 | return 0; |
| 77 | } |
| 78 | |
| 79 | SharedBuffer* SharedBuffer::reset(size_t new_size) const |
| 80 | { |
| 81 | // cheap-o-reset. |
| 82 | SharedBuffer* sb = alloc(new_size); |
| 83 | if (sb) { |
| 84 | release(); |
| 85 | } |
| 86 | return sb; |
| 87 | } |
| 88 | |
| 89 | void SharedBuffer::acquire() const { |
| 90 | android_atomic_inc(&mRefs); |
| 91 | } |
| 92 | |
| 93 | int32_t SharedBuffer::release(uint32_t flags) const |
| 94 | { |
| 95 | int32_t prev = 1; |
| 96 | if (onlyOwner() || ((prev = android_atomic_dec(&mRefs)) == 1)) { |
| 97 | mRefs = 0; |
| 98 | if ((flags & eKeepStorage) == 0) { |
| 99 | free(const_cast<SharedBuffer*>(this)); |
| 100 | } |
| 101 | } |
| 102 | return prev; |
| 103 | } |
| 104 | |
| 105 | |
| 106 | }; // namespace android |