mapleFU opened a new issue, #37434:
URL: https://github.com/apache/arrow/issues/37434
### Describe the enhancement requested
```c++
Result<int64_t> Read(int64_t nbytes, void* out) {
if (ARROW_PREDICT_FALSE(nbytes < 0)) {
return Status::Invalid("Bytes to read must be positive. Received:",
nbytes);
}
if (nbytes < buffer_size_) {
// Pre-buffer for small reads
RETURN_NOT_OK(BufferIfNeeded());
}
if (nbytes > bytes_buffered_) {
// Copy buffered bytes into out, then read rest
memcpy(out, buffer_data_ + buffer_pos_, bytes_buffered_);
int64_t bytes_to_read = nbytes - bytes_buffered_;
if (raw_read_bound_ >= 0) {
bytes_to_read = std::min(bytes_to_read, raw_read_bound_ -
raw_read_total_);
}
ARROW_ASSIGN_OR_RAISE(
int64_t bytes_read,
raw_->Read(bytes_to_read, reinterpret_cast<uint8_t*>(out) +
bytes_buffered_));
raw_read_total_ += bytes_read;
// Do not make assumptions about the raw stream position
raw_pos_ = -1;
bytes_read += bytes_buffered_;
RewindBuffer();
return bytes_read;
} else {
memcpy(out, buffer_data_ + buffer_pos_, nbytes);
ConsumeBuffer(nbytes);
return nbytes;
}
}
```
If we Set BufferSize == 100k, and read 3k bytes per IO. When we read the 34
times, the IO would be `(99k, 102k]`
In `Read`, it will read buffered `(99k, 100k]`, issue IO for `(100k, 102k]`.
Rather than `(100k, 202k]`. Is this expected?
### Component(s)
C++
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