From ce48a373dd691b6db7f655d0911b0847fd57222f Mon Sep 17 00:00:00 2001
From: chinaxing <chen.yack@gmail.com>
Date: Fri, 22 Dec 2023 11:48:02 +0000
Subject: [PATCH] add interface refresh_read_snaphost_tx_state for read latest

---
 src/storage/tx/ob_tx_api.cpp | 38 ++++++++++++++++++++++++++++++++++++
 src/storage/tx/ob_tx_api.h   | 16 +++++++++++++++
 2 files changed, 54 insertions(+)

diff --git a/src/storage/tx/ob_tx_api.cpp b/src/storage/tx/ob_tx_api.cpp
index 2bace002e..d962fa7db 100644
--- a/src/storage/tx/ob_tx_api.cpp
+++ b/src/storage/tx/ob_tx_api.cpp
@@ -2141,6 +2141,44 @@ bool ObTransService::tx_need_reset_(const int error_code) const
   }
   return ret;
 }
+
+int ObTransService::refresh_read_snapshot_tx_state(ObTxReadSnapshot &snapshot, const ObTxDesc &tx)
+{
+  int ret = OB_SUCCESS;
+  if (snapshot.is_weak_read()) {
+  } else {
+    ObSpinLockGuard guard(tx.lock_);
+    if (tx.is_in_tx()) {
+      snapshot.core_.scn_ = tx.get_tx_seq();
+      if (tx.is_tx_active()) {
+        if (snapshot.is_ls_snapshot() && (snapshot.parts_.count() == 1 && snapshot.parts_.at(0).left_ == snapshot.snapshot_lsid_)) {
+          // skip refresh
+        } else if (snapshot.parts_.count() == tx.parts_.count()) {
+          // skip refresh, tx.parts_ will never be reduced
+        } else { // slow path
+          if (!snapshot.core_.tx_id_.is_valid()) {
+            snapshot.core_.tx_id_ = tx.tx_id_;
+          }
+          snapshot.parts_.reuse();
+          if (OB_FAIL(snapshot.parts_.reserve(tx.parts_.count()))) {
+            TRANS_LOG(WARN, "reserve space for snapshot's parts fail", K(ret), K(snapshot), K(tx));
+          } else {
+            ARRAY_FOREACH(tx.parts_, i) {
+              const ObTxPart &it = tx.parts_.at(i);
+              ret = snapshot.parts_.push_back(ObTxLSEpochPair(it.id_, it.epoch_));
+            }
+          }
+          if (TC_REACH_TIME_INTERVAL(100_ms)) {
+            TRANS_LOG(INFO, "[TxReadSnapshot] refresh tx state", K(snapshot), "tx_id", tx.tx_id_);
+          }
+        }
+      } else {
+        ret = OB_TRANS_HAS_DECIDED;
+      }
+    }
+  }
+  return ret;
+}
 } // transaction
 } // namespace
 #undef TXN_API_SANITY_CHECK_FOR_TXN_FREE_ROUTE
diff --git a/src/storage/tx/ob_tx_api.h b/src/storage/tx/ob_tx_api.h
index 9fd5b3462..38052ade8 100644
--- a/src/storage/tx/ob_tx_api.h
+++ b/src/storage/tx/ob_tx_api.h
@@ -237,6 +237,22 @@ int get_ls_read_snapshot_version(const share::ObLSID &local_ls_id,
 int get_weak_read_snapshot_version(const int64_t max_read_stale_time,
                                    const bool local_single_ls,
                                    share::SCN &snapshot_version);
+/**
+ * refresh_read_snapshot_tx_state - update snapshot's tx state part
+ *
+ * @snapshot:                       the snapshot to refresh
+ * @tx:                             the target tx descriptor
+ *
+ * this interface try to update snapshot's tx state part by tx descriptor
+ * it was used by conflict checker which need read latest state of current
+ * transaction (while other read only read the data of before current stmt)
+ *
+ * Return:
+ * OB_SUCCESS              - OK
+ * OB_HAS_DECIDED          - transaction has terminated
+ * OB_XXX                  - unexpected error
+ */
+int refresh_read_snapshot_tx_state(ObTxReadSnapshot &snapshot, const ObTxDesc &tx);
 /*
  * release_snapshot - release snapshot
  *