[GitHub] [arrow] yaqi-zhao commented on a diff in pull request #14585: ARROW-17884: [C++] Add Intel®-IAA/QPL-based Parquet RLE Decode

Tue, 13 Dec 2022 23:41:13 -0800 


yaqi-zhao commented on code in PR #14585:
URL: https://github.com/apache/arrow/pull/14585#discussion_r1048109312


##########
cpp/src/arrow/util/bit_stream_utils.h:
##########
@@ -398,6 +412,27 @@ inline int BitReader::GetBatch(int num_bits, T* v, int 
batch_size) {
   return batch_size;
 }
 
+#ifdef ARROW_WITH_QPL
+inline bool BitReader::GetBatchWithQpl(int batch_size, qpl_job* job) {
+  if (!job) {
+    return false;
+  }
+  job->param_low = value_offset_;
+  job->param_high = batch_size + value_offset_;
+  job->num_input_elements = batch_size + value_offset_;
+
+  job->next_in_ptr = const_cast<uint8_t*>(buffer_ - 1);

Review Comment:
   It will not touch invlalid memory since in function  
[DictDecoderImpl::SetData](https://github.com/apache/arrow/blob/f6685371032e933e31d7ae2b156a6385c00d1673/cpp/src/parquet/encoding.cc#L1491),
 bit reader buffer was set to<encoded-data> and skip <bit_width>
   
![image](https://user-images.githubusercontent.com/100556669/207534289-0ebf8d42-dccc-4d3e-9131-24efc9c32ed6.png)
   
   IAA need a full parquet rle buffer so I `-1` here



##########
cpp/src/arrow/util/bit_stream_utils.h:
##########
@@ -398,6 +412,27 @@ inline int BitReader::GetBatch(int num_bits, T* v, int 
batch_size) {
   return batch_size;
 }
 
+#ifdef ARROW_WITH_QPL
+inline bool BitReader::GetBatchWithQpl(int batch_size, qpl_job* job) {
+  if (!job) {
+    return false;
+  }
+  job->param_low = value_offset_;
+  job->param_high = batch_size + value_offset_;
+  job->num_input_elements = batch_size + value_offset_;
+
+  job->next_in_ptr = const_cast<uint8_t*>(buffer_ - 1);

Review Comment:
   It will not touch invlalid memory since in function  
[DictDecoderImpl::SetData](https://github.com/apache/arrow/blob/f6685371032e933e31d7ae2b156a6385c00d1673/cpp/src/parquet/encoding.cc#L1491),
 bit reader buffer was set to      <encoded-data> and skip <bit_width>
   
   
![image](https://user-images.githubusercontent.com/100556669/207534289-0ebf8d42-dccc-4d3e-9131-24efc9c32ed6.png)
   
   IAA need a full parquet rle buffer so I `-1` here



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