Fix wrong Tell() result from BufferedOutputStream in an edge case (ap…

…ache#73) (apache#74) Co-authored-by: Hongze Zhang <[email protected]>
zhouyuan · Jan 9, 2022 · 21698d7 · 21698d7
1 parent b0044c5
commit 21698d7
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diff --git a/cpp/src/arrow/io/buffered.cc b/cpp/src/arrow/io/buffered.cc
@@ -144,6 +144,8 @@ class BufferedOutputStream::Impl : public BufferedBase {
       RETURN_NOT_OK(FlushUnlocked());
       DCHECK_EQ(buffer_pos_, 0);
       if (nbytes >= buffer_size_) {
+        // Invalidate cached raw pos
+        raw_pos_ = -1;
         // Direct write
         if (buffer) {
           return raw_->Write(buffer);

diff --git a/cpp/src/arrow/io/buffered_test.cc b/cpp/src/arrow/io/buffered_test.cc
@@ -296,6 +296,19 @@ TEST_F(TestBufferedOutputStream, Tell) {
   AssertTell(0);
 }
 
+TEST_F(TestBufferedOutputStream, Tell2) {
+  OpenBuffered();
+  AssertTell(0);
+
+  const std::string datastr = GenerateRandomData(10000);
+  const char* d = datastr.data();
+
+  ASSERT_OK(buffered_->Write(d, 5000));
+  AssertTell(5000);
+
+  ASSERT_OK(buffered_->Close());
+}
+
 TEST_F(TestBufferedOutputStream, TruncatesFile) {
   OpenBuffered();