void IOBuf::unshareOneSlow() {
// Allocate a new buffer for the data
uint8_t* buf;
SharedInfo* sharedInfo;
uint64_t actualCapacity;
allocExtBuffer(capacity_, &buf, &sharedInfo, &actualCapacity);
// Copy the data
// Maintain the same amount of headroom. Since we maintained the same
// minimum capacity we also maintain at least the same amount of tailroom.
uint64_t headlen = headroom();
if (length_ > 0) {
assert(data_ != nullptr);
memcpy(buf + headlen, data_, length_);
}
// Release our reference on the old buffer
decrementRefcount();
// Make sure kFlagMaybeShared and kFlagFreeSharedInfo are all cleared.
setFlagsAndSharedInfo(0, sharedInfo);
// Update the buffer pointers to point to the new buffer
data_ = buf + headlen;
buf_ = buf;
}
IOBuf::IOBuf(CreateOp, uint32_t capacity)
: next_(this),
prev_(this),
data_(nullptr),
length_(0),
flags_(0),
type_(kExtAllocated) {
allocExtBuffer(capacity, &buf_, &sharedInfo_, &capacity_);
data_ = buf_;
}
IOBuf::IOBuf(CreateOp, uint64_t capacity)
: next_(this),
prev_(this),
data_(nullptr),
length_(0),
flagsAndSharedInfo_(0) {
SharedInfo* info;
allocExtBuffer(capacity, &buf_, &info, &capacity_);
setSharedInfo(info);
data_ = buf_;
}
void IOBuf::coalesceAndReallocate(size_t newHeadroom,
size_t newLength,
IOBuf* end,
size_t newTailroom) {
uint64_t newCapacity = newLength + newHeadroom + newTailroom;
if (newCapacity > UINT32_MAX) {
throw std::overflow_error("IOBuf chain too large to coalesce");
}
// Allocate space for the coalesced buffer.
// We always convert to an external buffer, even if we happened to be an
// internal buffer before.
uint8_t* newBuf;
SharedInfo* newInfo;
uint32_t actualCapacity;
allocExtBuffer(newCapacity, &newBuf, &newInfo, &actualCapacity);
// Copy the data into the new buffer
uint8_t* newData = newBuf + newHeadroom;
uint8_t* p = newData;
IOBuf* current = this;
size_t remaining = newLength;
do {
assert(current->length_ <= remaining);
remaining -= current->length_;
memcpy(p, current->data_, current->length_);
p += current->length_;
current = current->next_;
} while (current != end);
assert(remaining == 0);
// Point at the new buffer
decrementRefcount();
// Make sure kFlagUserOwned, kFlagMaybeShared, and kFlagFreeSharedInfo
// are all cleared.
flags_ = 0;
capacity_ = actualCapacity;
type_ = kExtAllocated;
buf_ = newBuf;
sharedInfo_ = newInfo;
data_ = newData;
length_ = newLength;
// Separate from the rest of our chain.
// Since we don't store the unique_ptr returned by separateChain(),
// this will immediately delete the returned subchain.
if (isChained()) {
(void)separateChain(next_, current->prev_);
}
}
void IOBuf::coalesceAndReallocate(size_t newHeadroom,
size_t newLength,
IOBuf* end,
size_t newTailroom) {
uint64_t newCapacity = newLength + newHeadroom + newTailroom;
// Allocate space for the coalesced buffer.
// We always convert to an external buffer, even if we happened to be an
// internal buffer before.
uint8_t* newBuf;
SharedInfo* newInfo;
uint64_t actualCapacity;
allocExtBuffer(newCapacity, &newBuf, &newInfo, &actualCapacity);
// Copy the data into the new buffer
uint8_t* newData = newBuf + newHeadroom;
uint8_t* p = newData;
IOBuf* current = this;
size_t remaining = newLength;
do {
if (current->length_ > 0) {
assert(current->length_ <= remaining);
assert(current->data_ != nullptr);
remaining -= current->length_;
memcpy(p, current->data_, current->length_);
p += current->length_;
}
current = current->next_;
} while (current != end);
assert(remaining == 0);
// Point at the new buffer
decrementRefcount();
// Make sure kFlagMaybeShared and kFlagFreeSharedInfo are all cleared.
setFlagsAndSharedInfo(0, newInfo);
capacity_ = actualCapacity;
buf_ = newBuf;
data_ = newData;
length_ = newLength;
// Separate from the rest of our chain.
// Since we don't store the unique_ptr returned by separateChain(),
// this will immediately delete the returned subchain.
if (isChained()) {
(void)separateChain(next_, current->prev_);
}
}
void IOBuf::unshareOneSlow() {
// Allocate a new buffer for the data
uint8_t* buf;
SharedInfo* sharedInfo;
uint32_t actualCapacity;
allocExtBuffer(capacity_, &buf, &sharedInfo, &actualCapacity);
// Copy the data
// Maintain the same amount of headroom. Since we maintained the same
// minimum capacity we also maintain at least the same amount of tailroom.
uint32_t headlen = headroom();
memcpy(buf + headlen, data_, length_);
// Release our reference on the old buffer
decrementRefcount();
// Make sure kFlagUserOwned, kFlagMaybeShared, and kFlagFreeSharedInfo
// are all cleared.
flags_ = 0;
// Update the buffer pointers to point to the new buffer
data_ = buf + headlen;
buf_ = buf;
sharedInfo_ = sharedInfo;
}