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ORC-2164: [C++] Add external-buffer support in DataBuffer lifecycle management #2617

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lucasfang wants to merge 2 commits into from
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ORC-2164: [C++] Add external-buffer support in DataBuffer lifecycle management #2617

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c263d11
[C++] Add external-buffer support in DataBuffer lifecycle management
lucasfang May 7, 2026
bcf1679
fix clang format
lucasfang May 11, 2026
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7 changes: 6 additions & 1 deletion c++/include/orc/MemoryPool.hh
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Original file line number Diff line number Diff line change
Expand Up @@ -42,13 +42,15 @@ namespace orc {
uint64_t currentSize_;
// maximal capacity (actual allocated memory)
uint64_t currentCapacity_;
// whether this buffer owns memory lifecycle
bool ownBuffer_;

// not implemented
DataBuffer(DataBuffer& buffer);
DataBuffer& operator=(DataBuffer& buffer);

public:
DataBuffer(MemoryPool& pool, uint64_t size = 0);
DataBuffer(MemoryPool& pool, uint64_t size = 0, bool ownBuf = true);

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DataBuffer(DataBuffer<T>&& buffer) noexcept;

Expand Down Expand Up @@ -81,6 +83,9 @@ namespace orc {
void reserve(uint64_t size);
void resize(uint64_t size);
void zeroOut();

// Attach to an external raw buffer. bufSize is in bytes.
void setData(T* buf, size_t bufSize);
};

// Specializations for char
Expand Down
88 changes: 73 additions & 15 deletions c++/src/MemoryPool.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@
#include <string.h>
#include <cstdlib>
#include <iostream>
#include <type_traits>

namespace orc {

Expand Down Expand Up @@ -52,35 +53,47 @@ namespace orc {
}

template <class T>
DataBuffer<T>::DataBuffer(MemoryPool& pool, uint64_t newSize)
: memoryPool_(pool), buf_(nullptr), currentSize_(0), currentCapacity_(0) {
reserve(newSize);
currentSize_ = newSize;
DataBuffer<T>::DataBuffer(MemoryPool& pool, uint64_t newSize, bool ownBuf)
: memoryPool_(pool), buf_(nullptr), currentSize_(0), currentCapacity_(0), ownBuffer_(ownBuf) {
if (ownBuffer_) {
reserve(newSize);
currentSize_ = newSize;
}
}

template <class T>
DataBuffer<T>::DataBuffer(DataBuffer<T>&& buffer) noexcept
: memoryPool_(buffer.memoryPool_),
buf_(buffer.buf_),
currentSize_(buffer.currentSize_),
currentCapacity_(buffer.currentCapacity_) {
currentCapacity_(buffer.currentCapacity_),
ownBuffer_(buffer.ownBuffer_) {
buffer.buf_ = nullptr;
buffer.currentSize_ = 0;
buffer.currentCapacity_ = 0;
buffer.ownBuffer_ = true;
}

template <class T>
DataBuffer<T>::~DataBuffer() {
if (!ownBuffer_) {
return;
}
for (uint64_t i = currentSize_; i > 0; --i) {
(buf_ + i - 1)->~T();
}
if (buf_) {
static_assert(std::is_trivially_copyable<T>::value,
"Only trivially copyable type is supported for DataBuffer reserve");
memoryPool_.free(reinterpret_cast<char*>(buf_));
}
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}

template <class T>
void DataBuffer<T>::resize(uint64_t newSize) {
if (!ownBuffer_) {
return;
}
reserve(newSize);
if (currentSize_ > newSize) {
for (uint64_t i = currentSize_; i > newSize; --i) {
Expand All @@ -96,6 +109,9 @@ namespace orc {

template <class T>
void DataBuffer<T>::reserve(uint64_t newCapacity) {
if (!ownBuffer_) {
return;
}
if (newCapacity > currentCapacity_ || !buf_) {
if (buf_) {
T* buf_old = buf_;
Expand All @@ -114,6 +130,18 @@ namespace orc {
memset(buf_, 0, sizeof(T) * currentCapacity_);
}

template <class T>
void DataBuffer<T>::setData(T* buffer, size_t bufSize) {
if (ownBuffer_ && buf_) {
static_assert(std::is_trivially_copyable<T>::value,
"Only trivially copyable type is supported for DataBuffer reserve");
memoryPool_.free(reinterpret_cast<char*>(buf_));
}
ownBuffer_ = false;
buf_ = buffer;
currentSize_ = currentCapacity_ = static_cast<uint64_t>(bufSize / sizeof(T));
}
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// Specializations for Int128
template <>
void DataBuffer<Int128>::zeroOut() {
Expand All @@ -126,13 +154,16 @@ namespace orc {

template <>
DataBuffer<char>::~DataBuffer() {
if (buf_) {
if (ownBuffer_ && buf_) {
memoryPool_.free(reinterpret_cast<char*>(buf_));
}
}

template <>
void DataBuffer<char>::resize(uint64_t newSize) {
if (!ownBuffer_) {
return;
}
reserve(newSize);
if (newSize > currentSize_) {
memset(buf_ + currentSize_, 0, newSize - currentSize_);
Expand All @@ -144,13 +175,16 @@ namespace orc {

template <>
DataBuffer<char*>::~DataBuffer() {
if (buf_) {
if (ownBuffer_ && buf_) {
memoryPool_.free(reinterpret_cast<char*>(buf_));
}
}

template <>
void DataBuffer<char*>::resize(uint64_t newSize) {
if (!ownBuffer_) {
return;
}
reserve(newSize);
if (newSize > currentSize_) {
memset(buf_ + currentSize_, 0, (newSize - currentSize_) * sizeof(char*));
Expand All @@ -162,13 +196,16 @@ namespace orc {

template <>
DataBuffer<double>::~DataBuffer() {
if (buf_) {
if (ownBuffer_ && buf_) {
memoryPool_.free(reinterpret_cast<char*>(buf_));
}
}

template <>
void DataBuffer<double>::resize(uint64_t newSize) {
if (!ownBuffer_) {
return;
}
reserve(newSize);
if (newSize > currentSize_) {
memset(buf_ + currentSize_, 0, (newSize - currentSize_) * sizeof(double));
Expand All @@ -180,13 +217,16 @@ namespace orc {

template <>
DataBuffer<float>::~DataBuffer() {
if (buf_) {
if (ownBuffer_ && buf_) {
memoryPool_.free(reinterpret_cast<char*>(buf_));
}
}

template <>
void DataBuffer<float>::resize(uint64_t newSize) {
if (!ownBuffer_) {
return;
}
reserve(newSize);
if (newSize > currentSize_) {
memset(buf_ + currentSize_, 0, (newSize - currentSize_) * sizeof(float));
Expand All @@ -198,13 +238,16 @@ namespace orc {

template <>
DataBuffer<int64_t>::~DataBuffer() {
if (buf_) {
if (ownBuffer_ && buf_) {
memoryPool_.free(reinterpret_cast<char*>(buf_));
}
}

template <>
void DataBuffer<int64_t>::resize(uint64_t newSize) {
if (!ownBuffer_) {
return;
}
reserve(newSize);
if (newSize > currentSize_) {
memset(buf_ + currentSize_, 0, (newSize - currentSize_) * sizeof(int64_t));
Expand All @@ -216,13 +259,16 @@ namespace orc {

template <>
DataBuffer<int32_t>::~DataBuffer() {
if (buf_) {
if (ownBuffer_ && buf_) {
memoryPool_.free(reinterpret_cast<char*>(buf_));
}
}

template <>
void DataBuffer<int32_t>::resize(uint64_t newSize) {
if (!ownBuffer_) {
return;
}
reserve(newSize);
if (newSize > currentSize_) {
memset(buf_ + currentSize_, 0, (newSize - currentSize_) * sizeof(int32_t));
Expand All @@ -234,13 +280,16 @@ namespace orc {

template <>
DataBuffer<int16_t>::~DataBuffer() {
if (buf_) {
if (ownBuffer_ && buf_) {
memoryPool_.free(reinterpret_cast<char*>(buf_));
}
}

template <>
void DataBuffer<int16_t>::resize(uint64_t newSize) {
if (!ownBuffer_) {
return;
}
reserve(newSize);
if (newSize > currentSize_) {
memset(buf_ + currentSize_, 0, (newSize - currentSize_) * sizeof(int16_t));
Expand All @@ -252,13 +301,16 @@ namespace orc {

template <>
DataBuffer<int8_t>::~DataBuffer() {
if (buf_) {
if (ownBuffer_ && buf_) {
memoryPool_.free(reinterpret_cast<char*>(buf_));
}
}

template <>
void DataBuffer<int8_t>::resize(uint64_t newSize) {
if (!ownBuffer_) {
return;
}
reserve(newSize);
if (newSize > currentSize_) {
memset(buf_ + currentSize_, 0, (newSize - currentSize_) * sizeof(int8_t));
Expand All @@ -270,13 +322,16 @@ namespace orc {

template <>
DataBuffer<uint64_t>::~DataBuffer() {
if (buf_) {
if (ownBuffer_ && buf_) {
memoryPool_.free(reinterpret_cast<char*>(buf_));
}
}

template <>
void DataBuffer<uint64_t>::resize(uint64_t newSize) {
if (!ownBuffer_) {
return;
}
reserve(newSize);
if (newSize > currentSize_) {
memset(buf_ + currentSize_, 0, (newSize - currentSize_) * sizeof(uint64_t));
Expand All @@ -288,13 +343,16 @@ namespace orc {

template <>
DataBuffer<unsigned char>::~DataBuffer() {
if (buf_) {
if (ownBuffer_ && buf_) {
memoryPool_.free(reinterpret_cast<char*>(buf_));
}
}

template <>
void DataBuffer<unsigned char>::resize(uint64_t newSize) {
if (!ownBuffer_) {
return;
}
reserve(newSize);
if (newSize > currentSize_) {
memset(buf_ + currentSize_, 0, newSize - currentSize_);
Expand Down
37 changes: 37 additions & 0 deletions c++/test/TestCache.cc
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Expand Up @@ -26,6 +26,22 @@

namespace orc {

class CountingMemoryPool : public MemoryPool {
public:
uint64_t allocCount = 0;
uint64_t freeCount = 0;

char* malloc(uint64_t size) override {
++allocCount;
return static_cast<char*>(std::malloc(size));
}

void free(char* p) override {
++freeCount;
std::free(p);
}
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};

TEST(TestReadRangeCombiner, testBasics) {
ReadRangeCombiner combinator{0, 100};
/// Ranges with partial overlap and identical offsets
Expand Down Expand Up @@ -139,4 +155,25 @@ namespace orc {
slice = cache.read({20, 2});
assert_slice_equal(slice, "uv");
}

TEST(TestDataBuffer, testExternalBufferNonOwning) {
CountingMemoryPool pool;
char external[16] = {0};
uint64_t freeCountAfterSetData = 0;

{
DataBuffer<char> buffer(pool, 0);
buffer.setData(external, sizeof(external));
freeCountAfterSetData = pool.freeCount;

// Non-owning buffer should keep external size and ignore resize.
EXPECT_EQ(sizeof(external), buffer.size());
buffer.resize(8);
EXPECT_EQ(sizeof(external), buffer.size());
}

// setData may release previously owned internal memory, but destruction should not free
// external.
EXPECT_EQ(freeCountAfterSetData, pool.freeCount);
}
} // namespace orc
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