MINOR: [Release][C++][Python] Update versions for 21.0.0 (#380)

Updates C++ and Python cookbooks from 20.0.0 to 21.0.0. Locally I ran
`./dev/release/01-bump-versions.sh 20.0.0 21.0.0` locally.

Updates cookbook code to be compatible with 21.0.0:

- Replace removed GenericToStatus call with new ToStatus
- Use Result-returning variant of GetRecordBatchReader
- Initialize compute before running tests

Author: amoeba

cpp/code/common.h

@@ -29,9 +29,8 @@
 
 #define ARROW_ASSIGN_OR_RAISE_NAME(x, y) ARROW_CONCAT(x, y)
 
-#define ASSERT_OK(expr)                                                         \
-  for (const ::arrow::Status& _st = ::arrow::internal::GenericToStatus((expr)); \
-       !_st.ok();)                                                              \
+#define ASSERT_OK(expr)                                                   \
+  for (const ::arrow::Status _st = ::arrow::ToStatus((expr)); !_st.ok();) \
   FAIL() << "'" ARROW_STRINGIFY(expr) "' failed with " << _st.ToString()
 
 #define ASSIGN_OR_HANDLE_ERROR_IMPL(handle_error, status_name, lhs, rexpr) \

cpp/code/datasets.cc

@@ -24,11 +24,15 @@
 #include <filesystem>
 #include <memory>
 
+#include "arrow/compute/initialize.h"
 #include "common.h"
 
 class DatasetReadingTest : public ::testing::Test {
  public:
   void SetUp() override {
+    // Initialize compute functions before the test runs
+    ASSERT_OK(arrow::compute::Initialize());
+
     airquality_partitioned_dir_ =
         std::filesystem::temp_directory_path() / "cookbook_cpp_airquality";
     std::shared_ptr<arrow::fs::FileSystem> fs =

cpp/code/flight.cc

@@ -237,10 +237,9 @@ arrow::Status TestPutGetDelete() {
   metadata_reader = std::move(put_stream.reader);
 
   // Upload data
-  std::shared_ptr<arrow::RecordBatchReader> batch_reader;
   std::vector<int> row_groups(reader->num_row_groups());
   std::iota(row_groups.begin(), row_groups.end(), 0);
-  ARROW_RETURN_NOT_OK(reader->GetRecordBatchReader(row_groups, &batch_reader));
+  ARROW_ASSIGN_OR_RAISE(auto batch_reader, reader->GetRecordBatchReader(row_groups))
   int64_t batches = 0;
   while (true) {
     ARROW_ASSIGN_OR_RAISE(auto batch, batch_reader->Next());

cpp/conda-linux-64.lock

@@ -20,11 +20,11 @@ channels:
 dependencies:
   - python=3.9
   - compilers
-  - libarrow==20.0.0
-  - libarrow-flight==20.0.0
+  - libarrow==21.0.0
+  - libarrow-flight==21.0.0
   - sphinx
   - gtest
   - gmock
-  - pyarrow==20.0.0
+  - pyarrow==21.0.0
   - clang-tools
   - zlib

cpp/conda-linux-aarch64.lock

@@ -1,5 +1,5 @@
 Sphinx>=4.0.2
-pyarrow==20.0.0
+pyarrow==21.0.0
 pandas>=1.2.5
 opentelemetry-api>=1.0.0
 opentelemetry-sdk>=1.0.0