(arrow) branch main updated: GH-48799: [C++] Improve SharedExclusiveChecker error messages (#48800)

[apitrou]

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The following commit(s) were added to refs/heads/main by this push:
     new 6657a920a4 GH-48799: [C++] Improve SharedExclusiveChecker error 
messages  (#48800)
6657a920a4 is described below

commit 6657a920a4e4d0f0b3be20183b30157099132239
Author: Hyukjin Kwon <gurwls...@apache.org>
AuthorDate: Tue Jan 13 02:06:14 2026 +0900

    GH-48799: [C++] Improve SharedExclusiveChecker error messages  (#48800)
    
    ### Rationale for this change
    
    The XXX comment in `SharedExclusiveChecker` noted that error messages were 
too generic and didn't describe the actual operations involved.
    
    **Shared lock:**
    
    `ReadAt()`:
    
    
https://github.com/apache/arrow/blob/7be5a89ef083f38317fd94330127be5b5df648d8/cpp/src/arrow/io/concurrency.h#L210-L212
    
https://github.com/apache/arrow/blob/7be5a89ef083f38317fd94330127be5b5df648d8/cpp/src/arrow/io/concurrency.h#L215-L217
    
    `GetSize()`:
    
    
https://github.com/apache/arrow/blob/7be5a89ef083f38317fd94330127be5b5df648d8/cpp/src/arrow/io/concurrency.h#L199-L201
    
    **Exclusive lock:**
    
    `Read()`:
    
https://github.com/apache/arrow/blob/7be5a89ef083f38317fd94330127be5b5df648d8/cpp/src/arrow/io/concurrency.h#L109-L111
    
https://github.com/apache/arrow/blob/7be5a89ef083f38317fd94330127be5b5df648d8/cpp/src/arrow/io/concurrency.h#L114-L116
    
https://github.com/apache/arrow/blob/7be5a89ef083f38317fd94330127be5b5df648d8/cpp/src/arrow/io/concurrency.h#L179-L181
    
https://github.com/apache/arrow/blob/7be5a89ef083f38317fd94330127be5b5df648d8/cpp/src/arrow/io/concurrency.h#L184-L186
    
    `Seek()`:
    
https://github.com/apache/arrow/blob/7be5a89ef083f38317fd94330127be5b5df648d8/cpp/src/arrow/io/concurrency.h#L194-L196
    
    `Tell()`:
    
https://github.com/apache/arrow/blob/7be5a89ef083f38317fd94330127be5b5df648d8/cpp/src/arrow/io/concurrency.h#L104-L106
    
https://github.com/apache/arrow/blob/7be5a89ef083f38317fd94330127be5b5df648d8/cpp/src/arrow/io/concurrency.h#L174-L176
    
    `Peek()`:
    
https://github.com/apache/arrow/blob/7be5a89ef083f38317fd94330127be5b5df648d8/cpp/src/arrow/io/concurrency.h#L119-L121
    
https://github.com/apache/arrow/blob/7be5a89ef083f38317fd94330127be5b5df648d8/cpp/src/arrow/io/concurrency.h#L189-L191
    
    `Close()`:
    
https://github.com/apache/arrow/blob/7be5a89ef083f38317fd94330127be5b5df648d8/cpp/src/arrow/io/concurrency.h#L94-L96
    
https://github.com/apache/arrow/blob/7be5a89ef083f38317fd94330127be5b5df648d8/cpp/src/arrow/io/concurrency.h#L164-L166
    
    `Abort()`:
    
https://github.com/apache/arrow/blob/7be5a89ef083f38317fd94330127be5b5df648d8/cpp/src/arrow/io/concurrency.h#L99-L101
    
https://github.com/apache/arrow/blob/7be5a89ef083f38317fd94330127be5b5df648d8/cpp/src/arrow/io/concurrency.h#L169-L171
    
    ### What changes are included in this PR?
    
    Improved three error messages in `SharedExclusiveChecker` to explicitly 
list the I/O operations involved:
    - Shared lock operations: `ReadAt`, `GetSize`
    - Exclusive lock operations: `Read`, `Seek`, `Tell`, `Peek`, `Close`, 
`Abort`
    
    ### Are these changes tested?
    
    I manually tested all of combinations.
    
    ### Are there any user-facing changes?
    
    No.
    
    * GitHub Issue: #48799
    
    Authored-by: Hyukjin Kwon <gurwls...@apache.org>
    Signed-off-by: Antoine Pitrou <anto...@python.org>
---
 cpp/src/arrow/io/interfaces.cc | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/cpp/src/arrow/io/interfaces.cc b/cpp/src/arrow/io/interfaces.cc
index 75f3d71ae8..12c124ce21 100644
--- a/cpp/src/arrow/io/interfaces.cc
+++ b/cpp/src/arrow/io/interfaces.cc
@@ -338,10 +338,9 @@ SharedExclusiveChecker::SharedExclusiveChecker() : 
impl_(new Impl) {}
 
 void SharedExclusiveChecker::LockShared() {
   std::lock_guard<std::mutex> lock(impl_->mutex);
-  // XXX The error message doesn't really describe the actual situation
-  // (e.g. ReadAt() called while Read() call in progress)
   ARROW_CHECK_EQ(impl_->n_exclusive, 0)
-      << "Attempted to take shared lock while locked exclusive";
+      << "Cannot perform position-independent I/O (ReadAt/GetSize) while an "
+         "exclusive operation (Read/Seek/Tell/Peek/Close/Abort) is in 
progress";
   ++impl_->n_shared;
 }
 
@@ -354,9 +353,11 @@ void SharedExclusiveChecker::UnlockShared() {
 void SharedExclusiveChecker::LockExclusive() {
   std::lock_guard<std::mutex> lock(impl_->mutex);
   ARROW_CHECK_EQ(impl_->n_shared, 0)
-      << "Attempted to take exclusive lock while locked shared";
+      << "Cannot perform exclusive I/O operation 
(Read/Seek/Tell/Peek/Close/Abort) while "
+         "position-independent operations (ReadAt/GetSize) are in progress";
   ARROW_CHECK_EQ(impl_->n_exclusive, 0)
-      << "Attempted to take exclusive lock while already locked exclusive";
+      << "Cannot perform exclusive I/O operation 
(Read/Seek/Tell/Peek/Close/Abort) while "
+         "another exclusive operation is already in progress";
   ++impl_->n_exclusive;
 }