jt2594838 commented on code in PR #527:
URL: https://github.com/apache/tsfile/pull/527#discussion_r2176349259
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cpp/src/common/allocator/mem_alloc.cc:
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@@ -63,45 +63,41 @@ const char *g_mod_names[__LAST_MOD_ID] = {
/* 27 */ "HASH_TABLE",
};
-const uint32_t HEADER_SIZE_4B = 4;
-const uint32_t HEADER_SIZE_8B = 8;
+// Most modern CPUs (e.g., x86_64, Arm) support at least 8-byte alignment,
+// and C++ mandates that alignof(std::max_align_t) reflects the strictest
+// alignment requirement for built-in types (typically 8 or 16 bytes,
especially
+// with SIMD)
+
+// To ensure that the returned memory pointer from mem_alloc is properly
aligned
+// for any type, we standardize on an 8-byte header(HEADER_SIZE_8B).
+// If the actual header content is smaller, additional padding is inserted
+// automatically before the aligned payload to preserve alignment.
+// constexpr uint32_t HEADER_SIZE_4B = 4;
+constexpr size_t HEADER_PTR_SIZE = 8;
+// Default alignment is 8 bytes, sufficient for basic types.
+// If SIMD (e.g., SSE/AVX) is introduced later, increase ALIGNMENT to 16/32/64
+// as needed.
+// constexpr size_t ALIGNMENT = alignof(std::max_align_t);
+constexpr size_t ALIGNMENT = 8;
Review Comment:
Can we make them compilation options via macros?
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