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#pragma once
#include <util/generic/array_ref.h>
#include <util/generic/maybe.h>
#include <util/generic/utility.h>
#include <util/generic/vector.h>
#include <util/system/yassert.h>
template <typename T>
struct TRingBuffer {
private:
ui32 CapacityPow;
ui32 CapacityMask;
ui32 Capacity;
ui32 WritePos;
ui32 ReadPos;
TVector<T> Data;
void StateCheck() const {
Y_ASSERT(Capacity == Data.size());
Y_ASSERT(Capacity == (1u << CapacityPow));
Y_ASSERT((Capacity & CapacityMask) == 0u);
Y_ASSERT(Capacity - CapacityMask == 1u);
Y_ASSERT(WritePos < Capacity);
Y_ASSERT(ReadPos < Capacity);
}
size_t Writable() const {
return (Capacity + ReadPos - WritePos - 1) & CapacityMask;
}
void ReserveWritable(ui32 sz) {
if (sz <= Writable())
return;
ui32 newCapacityPow = CapacityPow;
while ((1u << newCapacityPow) < sz + ui32(Size()) + 1u) {
++newCapacityPow;
}
ui32 newCapacity = 1u << newCapacityPow;
ui32 newCapacityMask = newCapacity - 1u;
TVector<T> newData(newCapacity);
ui32 oldSize = Size();
// Copy old elements
for (size_t i = 0; i < oldSize; ++i) {
newData[i] = Get(i);
}
CapacityPow = newCapacityPow;
Capacity = newCapacity;
CapacityMask = newCapacityMask;
Data.swap(newData);
ReadPos = 0;
WritePos = oldSize;
StateCheck();
}
const T& Get(ui32 i) const {
return Data[(ReadPos + i) & CapacityMask];
}
public:
TRingBuffer()
: CapacityPow(0)
, CapacityMask(0)
, Capacity(1 << CapacityPow)
, WritePos(0)
, ReadPos(0)
, Data(Capacity)
{
StateCheck();
}
size_t Size() const {
return (Capacity + WritePos - ReadPos) & CapacityMask;
}
bool Empty() const {
return WritePos == ReadPos;
}
void PushAll(TArrayRef<const T> value) {
ReserveWritable(value.size());
ui32 secondSize;
ui32 firstSize;
if (WritePos + value.size() <= Capacity) {
firstSize = value.size();
secondSize = 0;
} else {
firstSize = Capacity - WritePos;
secondSize = value.size() - firstSize;
}
for (size_t i = 0; i < firstSize; ++i) {
Data[WritePos + i] = value[i];
}
for (size_t i = 0; i < secondSize; ++i) {
Data[i] = value[firstSize + i];
}
WritePos = (WritePos + value.size()) & CapacityMask;
StateCheck();
}
void Push(const T& t) {
PushAll(MakeArrayRef(&t, 1));
}
bool TryPop(T* r) {
StateCheck();
if (Empty()) {
return false;
}
*r = Data[ReadPos];
ReadPos = (ReadPos + 1) & CapacityMask;
return true;
}
TMaybe<T> TryPop() {
T tmp;
if (TryPop(&tmp)) {
return tmp;
} else {
return TMaybe<T>();
}
}
T Pop() {
return *TryPop();
}
};
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