only apply for BufferInputStream

velox/common/memory/ByteStream.cpp

@@ -172,6 +172,31 @@ std::string_view BufferInputStream::nextView(int32_t size) {
       reinterpret_cast<char*>(current_->buffer) + position, viewSize);
 }
 
+std::unique_ptr<folly::IOBuf> BufferInputStream::readBytes(int32_t size) {
+  VELOX_CHECK_GE(size, 0, "Attempting to read negative number of bytes");
+  if (size == 0) {
+    return nullptr;
+  }
+  std::unique_ptr<folly::IOBuf> result;
+  for (;;) {
+    const int32_t availableBytes = current_->size - current_->position;
+    const int32_t readBytes = std::min(availableBytes, size);
+    auto newBuf = folly::IOBuf::wrapBuffer(
+        current_->buffer + current_->position, readBytes);
+    if (result) {
+      result->prev()->appendChain(std::move(newBuf));
+    } else {
+      result = std::move(newBuf);
+    }
+    size -= readBytes;
+    current_->position += readBytes;
+    if (size == 0) {
+      return result;
+    }
+    nextRange();
+  }
+}
+
 void BufferInputStream::skip(int32_t size) {
   VELOX_CHECK_GE(size, 0, "Attempting to skip negative number of bytes");
   for (;;) {

velox/common/memory/ByteStream.h

@@ -191,6 +191,8 @@ class BufferInputStream : public ByteInputStream {
 
   void readBytes(uint8_t* bytes, int32_t size) override;
 
+  std::unique_ptr<folly::IOBuf> readBytes(int32_t size);
+
   std::string_view nextView(int32_t size) override;
 
   void skip(int32_t size) override;

velox/common/memory/tests/ByteStreamTest.cpp

@@ -431,6 +431,44 @@ TEST_P(InputByteStreamTest, inputStream) {
   ASSERT_TRUE(byteStream->atEnd());
 }
 
+TEST_P(InputByteStreamTest, iobuf) {
+  if (!GetParam()) {
+    return;
+  }
+  const auto streamSize = 4096;
+  std::vector<ByteRange> byteRanges;
+  std::uint8_t buffer[streamSize];
+  for (auto i = 0; i < streamSize; ++i) {
+    buffer[i] = i % 256;
+  }
+  byteRanges.push_back(ByteRange{buffer, streamSize, 0});
+
+  std::uint8_t buffer2[streamSize];
+  for (auto i = 0; i < streamSize; ++i) {
+    buffer2[i] = i % 13;
+  }
+  byteRanges.push_back(ByteRange{buffer2, streamSize, 0});
+
+  auto byteStream = createStream(byteRanges);
+  auto bufferStream = dynamic_cast<BufferInputStream*>(byteStream.get());
+  for (int offset = 0; offset < streamSize;) {
+    auto iobuf = bufferStream->readBytes(streamSize / 8);
+    ASSERT_EQ(iobuf->computeChainDataLength(), streamSize / 8);
+    for (int i = 0; i < streamSize / 8; ++i, ++offset) {
+      ASSERT_EQ(iobuf->data()[i], offset % 256);
+    }
+  }
+
+  for (int offset = 0; offset < streamSize;) {
+    auto iobuf = bufferStream->readBytes(streamSize / 8);
+    ASSERT_EQ(iobuf->computeChainDataLength(), streamSize / 8);
+    for (int i = 0; i < streamSize / 8; ++i, ++offset) {
+      ASSERT_EQ(iobuf->data()[i], offset % 13);
+    }
+  }
+  ASSERT_TRUE(bufferStream->atEnd());
+}
+
 TEST_P(InputByteStreamTest, emptyInputStreamError) {
   if (GetParam()) {
     VELOX_ASSERT_THROW(createStream({}), "Empty BufferInputStream");

velox/serializers/PrestoSerializer.cpp

@@ -4360,28 +4360,25 @@ void readTopColumns(
       &source, childTypes, resultOffset, nullptr, 0, pool, opts, children);
 }
 
-std::unique_ptr<folly::IOBuf> uncompressBuffer(
+std::unique_ptr<folly::IOBuf> uncompressStream(
     ByteInputStream* source,
     const PrestoHeader& header,
-    common::CompressionKind compressionKind) {
+    common::CompressionKind compressionKind,
+    memory::MemoryPool& pool) {
   const auto codec = common::compressionKindToCodec(compressionKind);
-  std::unique_ptr<folly::IOBuf> iobuf;
-  int32_t readCount = 0;
-  while (readCount < header.compressedSize) {
-    const auto remaining = header.compressedSize - readCount;
-    auto view = source->nextView(remaining);
-    readCount += view.size();
-    auto newBuf = folly::IOBuf::wrapBuffer(view.data(), view.size());
-    if (iobuf) {
-      iobuf->prev()->appendChain(std::move(newBuf));
-    } else {
-      iobuf = std::move(newBuf);
-    }
-  }
-
-  VELOX_DCHECK_EQ(readCount, header.compressedSize);
+  if (dynamic_cast<BufferInputStream*>(source)) {
+    // If the source is a BufferInputStream, we can avoid copying the data
+    // by creating an IOBuf from the underlying buffer.
+    const auto bufferSource = dynamic_cast<BufferInputStream*>(source);
+    const auto iobuf = bufferSource->readBytes(header.compressedSize);
+    // Process chained uncompressed results IOBufs.
+    return codec->uncompress(iobuf.get(), header.uncompressedSize);
+  }
+  auto compressBuf = folly::IOBuf::create(header.compressedSize);
+  source->readBytes(compressBuf->writableData(), header.compressedSize);
+  compressBuf->append(header.compressedSize);
   // Process chained uncompressed results IOBufs.
-  return codec->uncompress(iobuf.get(), header.uncompressedSize);
+  return codec->uncompress(compressBuf.get(), header.uncompressedSize);
 }
 } // namespace
 
@@ -4436,7 +4433,7 @@ void PrestoVectorSerde::deserialize(
     readTopColumns(*source, type, pool, *result, resultOffset, prestoOptions);
   } else {
     auto uncompress =
-        uncompressBuffer(source, header, prestoOptions.compressionKind);
+        uncompressStream(source, header, prestoOptions.compressionKind, *pool);
     auto uncompressedSource = std::make_unique<BufferInputStream>(
         byteRangesFromIOBuf(uncompress.get()));
     readTopColumns(