westonpace commented on code in PR #35565:
URL: https://github.com/apache/arrow/pull/35565#discussion_r1205261311
##########
cpp/src/arrow/util/align_util.cc:
##########
@@ -94,12 +135,17 @@ bool CheckAlignment(const Table& table, int64_t alignment,
return all_aligned;
}
+// Most allocators require a minimum of 8-byte alignment.
+constexpr int64_t kMinimumAlignment = 8;
+
Result<std::shared_ptr<Buffer>> EnsureAlignment(std::shared_ptr<Buffer> buffer,
int64_t alignment,
MemoryPool* memory_pool) {
Review Comment:
I added a check and still want to add a test.
##########
cpp/src/arrow/util/align_util.cc:
##########
@@ -30,12 +33,50 @@ bool CheckAlignment(const Buffer& buffer, int64_t
alignment) {
return buffer.address() % alignment == 0;
}
-bool CheckAlignment(const ArrayData& array, int64_t alignment) {
- for (const auto& buffer : array.buffers) {
- if (buffer) {
- if (!CheckAlignment(*buffer, alignment)) return false;
+namespace {
+
+// Returns the type that controls how the buffers of this ArrayData (not its
children)
+// should behave
+Type::type GetTypeForBuffers(const ArrayData& array) {
+ Type::type type_id = array.type->storage_id();
+ if (type_id == Type::DICTIONARY) {
+ return ::arrow::internal::checked_pointer_cast<DictionaryType>(array.type)
+ ->index_type()
+ ->id();
+ }
+ return type_id;
+}
+
+// Checks to see if an array's own buffers are aligned but doesn't check
+// children
+bool CheckSelfAlignment(const ArrayData& array, int64_t alignment) {
+ if (alignment == kValueAlignment) {
+ Type::type type_id = GetTypeForBuffers(array);
+ for (std::size_t i = 0; i < array.buffers.size(); i++) {
+ if (array.buffers[i]) {
+ int expected_alignment =
+ RequiredValueAlignmentForBuffer(type_id, static_cast<int>(i));
+ if (!CheckAlignment(*array.buffers[i], expected_alignment)) {
+ return false;
+ }
+ }
+ }
+ } else {
+ for (const auto& buffer : array.buffers) {
+ if (buffer) {
+ if (!CheckAlignment(*buffer, alignment)) return false;
+ }
}
}
+ return true;
+}
+
+} // namespace
+
+bool CheckAlignment(const ArrayData& array, int64_t alignment) {
+ if (!CheckSelfAlignment(array, alignment)) {
+ return false;
+ }
if (array.type->id() == Type::DICTIONARY) {
Review Comment:
I changed this to `if (array.dictionary)`
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