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#pragma once
#include "defs.h"
#include <contrib/ydb/library/actors/util/rope.h>
#include <util/generic/noncopyable.h>
#include <util/stream/output.h>
#include <util/system/yassert.h>
namespace NKikimr {
namespace NMiniKQL {
class TPagedBuffer;
class TBufferPage : private TNonCopyable {
friend class TPagedBuffer;
static const size_t PageCapacity;
public:
static const size_t PageAllocSize = 128 * 1024;
TBufferPage() = default;
~TBufferPage() = default;
inline const TBufferPage* Next() const {
return Next_;
}
inline TBufferPage* Next() {
return Next_;
}
inline size_t Size() const {
return Size_;
}
inline char* Data() {
return reinterpret_cast<char*>(this + 1);
}
inline const char* Data() const {
return reinterpret_cast<const char*>(this + 1);
}
inline void Clear() {
Size_ = 0;
}
private:
TBufferPage* Next_ = nullptr;
size_t Size_ = 0;
static TBufferPage* Allocate();
static void Free(TBufferPage* page);
static inline const TBufferPage* GetPage(const char* data) {
Y_DEBUG_ABORT_UNLESS(data);
return reinterpret_cast<const TBufferPage*>(data - sizeof(TBufferPage));
}
static inline TBufferPage* GetPage(char* data) {
Y_DEBUG_ABORT_UNLESS(data);
return reinterpret_cast<TBufferPage*>(data - sizeof(TBufferPage));
}
};
class TPagedBuffer : private TNonCopyable {
public:
using TPtr = std::shared_ptr<TPagedBuffer>;
using TConstPtr = std::shared_ptr<const TPagedBuffer>;
TPagedBuffer() = default;
~TPagedBuffer() {
if (Head_) {
TBufferPage* curr = TBufferPage::GetPage(Head_);
while (curr) {
auto drop = curr;
curr = curr->Next_;
TBufferPage::Free(drop);
}
}
}
template<typename TFunc>
inline void ForEachPage(TFunc f) const {
if (!Head_) {
return;
}
const TBufferPage* head = TBufferPage::GetPage(Head_);
auto page = head;
auto end = TBufferPage::GetPage(Tail_);
while (page) {
const char* src;
size_t len;
if (page == end) {
src = Tail_;
len = TailSize_;
} else {
src = page->Data();
len = page->Size();
}
if (page == head) {
src += HeadReserve_;
len -= HeadReserve_;
}
if (len) {
f(src, len);
}
page = (page == end) ? nullptr : page->Next();
}
}
inline size_t Size() const {
// + (Tail_ ? TailSize_ : 0);
size_t sizeWithReserve = ClosedPagesSize_ + ((-size_t(Tail_ != nullptr)) & TailSize_);
Y_DEBUG_ABORT_UNLESS(sizeWithReserve >= HeadReserve_);
return sizeWithReserve - HeadReserve_;
}
template<typename TContainer>
inline void CopyTo(TContainer& out) const {
ForEachPage([&out](const char* data, size_t len) {
out.insert(out.end(), data, data + len);
});
}
inline void CopyTo(char* dst) const {
ForEachPage([&dst](const char* data, size_t len) {
std::memcpy(dst, data, len);
dst += len;
});
}
inline void CopyTo(IOutputStream& out) const {
ForEachPage([&out](const char* data, size_t len) {
out.Write(data, len);
});
}
size_t ReservedHeaderSize() const {
return HeadReserve_;
}
inline void ReserveHeader(size_t len) {
Y_DEBUG_ABORT_UNLESS(len > 0);
Y_DEBUG_ABORT_UNLESS(Head_ == Tail_);
Y_DEBUG_ABORT_UNLESS(HeadReserve_ == 0);
Advance(len);
HeadReserve_ = len;
}
char* Header(size_t len) {
if (len > HeadReserve_) {
return nullptr;
}
Y_DEBUG_ABORT_UNLESS(Head_);
HeadReserve_ -= len;
return Head_ + HeadReserve_;
}
// buffer-style operations with last page
inline char* Pos() const {
Y_DEBUG_ABORT_UNLESS(Tail_);
return Tail_ + TailSize_;
}
inline void Clear() {
Tail_ = Head_;
ClosedPagesSize_ = HeadReserve_ = 0;
// = Tail_ ? 0 : TBufferPage::PageAllocSize;
TailSize_ = (-size_t(Tail_ == nullptr)) & TBufferPage::PageCapacity;
}
inline void EraseBack(size_t len) {
Y_DEBUG_ABORT_UNLESS(Tail_ && TailSize_ >= len);
TailSize_ -= len;
}
inline void Advance(size_t len) {
if (Y_LIKELY(TailSize_ + len <= TBufferPage::PageCapacity)) {
TailSize_ += len;
return;
}
MKQL_ENSURE(len <= TBufferPage::PageCapacity, "Advance() size too big");
AppendPage();
TailSize_ = len;
}
inline void Append(char c) {
Advance(1);
*(Pos() - 1) = c;
}
inline void Append(const char* data, size_t size) {
while (size) {
if (TailSize_ == TBufferPage::PageCapacity) {
AppendPage();
}
Y_DEBUG_ABORT_UNLESS(TailSize_ < TBufferPage::PageCapacity);
size_t avail = TBufferPage::PageCapacity - TailSize_;
size_t chunk = std::min(avail, size);
std::memcpy(Pos(), data, chunk);
TailSize_ += chunk;
data += chunk;
size -= chunk;
}
}
static TRope AsRope(const TConstPtr& buf);
private:
void AppendPage();
char* Head_ = nullptr;
char* Tail_ = nullptr;
// TailSize_ is initialized as if last page is full, this way we can simplifiy check in Advance()
size_t TailSize_ = TBufferPage::PageCapacity;
size_t HeadReserve_ = 0;
size_t ClosedPagesSize_ = 0;
};
} // NMiniKQL
} // NKikimr
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