From a5fb18533e67beea56d8f9f66f1d7f2016c1c94e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dominik=20Tomic=CC=8Cevic=CC=81?=
<dominik.tomicevic@gmail.com>
Date: Sat, 12 Mar 2016 10:39:10 +0100
Subject: [PATCH] fixed mvcc hints bug
---
mvcc/record.hpp | 6 ++++++
mvcc/version_list.hpp | 21 +++++----------------
2 files changed, 11 insertions(+), 16 deletions(-)
diff --git a/mvcc/record.hpp b/mvcc/record.hpp
index 5395b21c9..3f63bd9d6 100644
--- a/mvcc/record.hpp
+++ b/mvcc/record.hpp
@@ -92,6 +92,12 @@ public:
template <class U>
bool committed(U& hints, const Id& id, const tx::Transaction& t)
{
+ // you certainly can't see the transaction with id greater than yours
+ // as that means it started after this transaction and if it committed,
+ // it committed after this transaction had started.
+ if(id > t.id)
+ return false;
+
auto hint_bits = hints.load();
// if hints are set, return if xid is committed
diff --git a/mvcc/version_list.hpp b/mvcc/version_list.hpp
index af7d6beb2..c0e0940fa 100644
--- a/mvcc/version_list.hpp
+++ b/mvcc/version_list.hpp
@@ -17,6 +17,7 @@ class VersionList : public LazyGC<VersionList<T>>
public:
using uptr = std::unique_ptr<VersionList<T>>;
+ using item_t = T;
class Accessor
{
@@ -72,7 +73,7 @@ public:
const Id& id() const
{
- return vlist.identifier;
+ return vlist.id;
}
private:
@@ -80,14 +81,14 @@ public:
VersionList<T>& vlist;
};
- VersionList() = default;
+ VersionList(Id id) : id(id) {}
VersionList(const VersionList&) = delete;
/* @brief Move constructs the version list
* Note: use only at the beginning of the "other's" lifecycle since this
* constructor doesn't move the RecordLock, but only the head pointer
*/
- VersionList(VersionList&& other)
+ VersionList(VersionList&& other) : id(other.id)
{
this->head = other.head.load();
this->identifier = other.id();
@@ -130,22 +131,12 @@ public:
}
- const Id& id() const
- {
- return identifier;
- }
-
- void id(const Id& identifier)
- {
- this->identifier = identifier;
- }
+ const Id id;
private:
std::atomic<T*> head {nullptr};
RecordLock lock;
- Id identifier;
-
//static Recycler recycler;
T* find(const tx::Transaction& t)
@@ -172,8 +163,6 @@ private:
{
assert(head == nullptr);
- // this->id = id;
-
// create a first version of the record
// TODO replace 'new' with something better
auto v1 = new T();