ARROW-6073: [C++] Reset Decimal128Builder in Finish().

kmjung · emkornfield · commit 803dd89463cb · 2019-07-30T17:52:59.000-07:00
This change updates the FinishInternal implementation in Decimal128Builder to reset the internal state at finish time, honoring the contract for array builders. Closes apache#4970 from kmjung/arrow-6073 and squashes the following commits: 32fdb8f <Kenneth Jung> Reset Decimal128Builder in Finish(). Authored-by: Kenneth Jung <kmj@google.com> Signed-off-by: Micah Kornfield <emkornfield@gmail.com>
diff --git a/cpp/src/arrow/array-test.cc b/cpp/src/arrow/array-test.cc
@@ -1755,6 +1755,7 @@ class DecimalTest : public ::testing::TestWithParam<int> {
 
     std::shared_ptr<Array> out;
     FinishAndCheckPadding(builder.get(), &out);
+    ASSERT_EQ(builder->length(), 0);
 
     std::vector<uint8_t> raw_bytes;
 
diff --git a/cpp/src/arrow/array/builder_decimal.cc b/cpp/src/arrow/array/builder_decimal.cc
@@ -69,7 +69,7 @@ Status Decimal128Builder::FinishInternal(std::shared_ptr<ArrayData>* out) {
   RETURN_NOT_OK(null_bitmap_builder_.Finish(&null_bitmap));
 
   *out = ArrayData::Make(type_, length_, {null_bitmap, data}, null_count_);
-
+  capacity_ = length_ = null_count_ = 0;
   return Status::OK();
 }
 

Original file line number	Diff line number	Diff line change
`@@ -69,7 +69,7 @@ Status Decimal128Builder::FinishInternal(std::shared_ptr<ArrayData>* out) {`
`69`	`69`	`RETURN_NOT_OK(null_bitmap_builder_.Finish(&null_bitmap));`
`70`	`70`
`71`	`71`	`*out = ArrayData::Make(type_, length_, {null_bitmap, data}, null_count_);`
`72`		`-`
	`72`	`+ capacity_ = length_ = null_count_ = 0;`
`73`	`73`	`return Status::OK();`
`74`	`74`	`}`
`75`	`75`