From e35ec43ad806e9d9055bcd7c6498fc0c3e49c567 Mon Sep 17 00:00:00 2001
From: Roland Kuehn <roland.kuehn@cs.tu-dortmund.de>
Date: Sun, 10 Apr 2022 18:58:36 +0200
Subject: [PATCH] Removed atomics in metadata (lead to crashes on aarch64)

---
 include/concurrency/metadata.h  | 29 ++++++++++++++++++-----------
 include/concurrency/timestamp.h |  2 +-
 2 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/include/concurrency/metadata.h b/include/concurrency/metadata.h
index 6bb88b1..cf46e11 100644
--- a/include/concurrency/metadata.h
+++ b/include/concurrency/metadata.h
@@ -54,8 +54,8 @@ class Metadata
         : _original_record_identifier(other._original_record_identifier), _begin_timestamp(timestamp::make_infinity()),
           _end_timestamp(timestamp::make_infinity())
     {
-        _begin_timestamp.store(other._begin_timestamp.load());
-        _end_timestamp.store(other._end_timestamp.load());
+        _begin_timestamp = other._begin_timestamp;
+        _end_timestamp = other._end_timestamp;
         _next_in_version_chain = other._next_in_version_chain;
     }
 
@@ -66,7 +66,7 @@ class Metadata
      */
     [[nodiscard]] timestamp begin_timestamp() const
     {
-        return _begin_timestamp.load();
+        return _begin_timestamp;
     }
 
     /**
@@ -75,7 +75,7 @@ class Metadata
      */
     [[nodiscard]] timestamp end_timestamp() const
     {
-        return _end_timestamp.load();
+        return _end_timestamp;
     }
 
     /**
@@ -92,7 +92,7 @@ class Metadata
      */
     void begin_timestamp(const timestamp timestamp)
     {
-        _begin_timestamp.store(timestamp);
+        _begin_timestamp = timestamp;
     }
 
     /**
@@ -105,7 +105,11 @@ class Metadata
      */
     bool try_begin_timestamp(timestamp old_timestamp, const timestamp timestamp)
     {
-        return _begin_timestamp.compare_exchange_strong(old_timestamp, timestamp);
+        if (_begin_timestamp == old_timestamp){
+            _begin_timestamp = timestamp;
+            return true;
+        }
+        return false;
     }
 
     /**
@@ -114,7 +118,7 @@ class Metadata
      */
     void end_timestamp(const timestamp timestamp)
     {
-        _end_timestamp.store(timestamp);
+        _end_timestamp = timestamp;
     }
 
     /**
@@ -127,7 +131,11 @@ class Metadata
      */
     bool try_end_timestamp(timestamp old_timestamp, const timestamp timestamp)
     {
-        return _end_timestamp.compare_exchange_strong(old_timestamp, timestamp);
+        if (_end_timestamp == old_timestamp){
+            _end_timestamp = timestamp;
+            return true;
+        }
+        return false;
     }
 
     /**
@@ -147,15 +155,14 @@ class Metadata
         return _original_record_identifier;
     }
 
-  private:
     // Pointer to the record in the table space.
     storage::RecordIdentifier _original_record_identifier;
 
     // Timestamp the record begins living.
-    std::atomic<timestamp> _begin_timestamp;
+    timestamp _begin_timestamp;
 
     // Timestamp the record dies.
-    std::atomic<timestamp> _end_timestamp;
+    timestamp _end_timestamp;
 
     // Pointer to the next record in version chain.
     storage::RecordIdentifier _next_in_version_chain;
diff --git a/include/concurrency/timestamp.h b/include/concurrency/timestamp.h
index 70383d9..a64df24 100644
--- a/include/concurrency/timestamp.h
+++ b/include/concurrency/timestamp.h
@@ -35,7 +35,7 @@ namespace beedb::concurrency
  *
  * The time "0" in combination with the set committed flag indicates "infinity".
  */
-class alignas(64) timestamp
+class timestamp
 {
   public:
     using timestamp_t = std::uint64_t;