mapleFU commented on code in PR #43409:
URL: https://github.com/apache/arrow/pull/43409#discussion_r1691039593
##########
cpp/src/arrow/io/buffered.cc:
##########
@@ -434,6 +434,32 @@ class BufferedInputStream::Impl : public BufferedBase {
return std::shared_ptr<Buffer>(std::move(buffer));
}
+ Status Advance(int64_t nbytes) {
+ if (nbytes < 0) {
+ return Status::Invalid("Bytes to advance must be non-negative.
Received:", nbytes);
+ }
+ if (nbytes == 0) {
+ return Status::OK();
+ }
+
+ if (nbytes < bytes_buffered_) {
+ ConsumeBuffer(nbytes);
+ return Status::OK();
+ }
+
+ // Invalidate buffered data, as with a Seek or large Read
+ int64_t remain_skip_bytes = nbytes - bytes_buffered_;
+ RewindBuffer();
+ // TODO(mwish): Considering using raw_->Advance if available,
+ // currently we don't have a way to know if the underlying stream supports
fast
+ // skipping. So we just read and discard the data.
Review Comment:
Maybe some code like:
```
/// \brief Return true if InputStream is capable of zero copy Buffer reads
///
/// Zero copy reads imply the use of Buffer-returning Read() overloads.
virtual bool supports_zero_copy() const;
```
Would help, a `supports_fast_advance` like
https://github.com/ClickHouse/ClickHouse/blob/1b2fd51e090214deb340a76833bab7b4985eecfc/src/Disks/IO/ReadBufferFromRemoteFSGather.h#L19
might work
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