cherry pick #25470 to release-5.1

Signed-off-by: ti-srebot <ti-srebot@pingcap.com>

config/config.go

@@ -494,7 +494,8 @@ type Binlog struct {
 // PessimisticTxn is the config for pessimistic transaction.
 type PessimisticTxn struct {
 	// The max count of retry for a single statement in a pessimistic transaction.
-	MaxRetryCount           uint `toml:"max-retry-count" json:"max-retry-count"`
+	MaxRetryCount uint `toml:"max-retry-count" json:"max-retry-count"`
+	// The max count of deadlock events that will be recorded in the information_schema.deadlocks table.
 	DeadlockHistoryCapacity uint `toml:"deadlock-history-capacity" json:"deadlock-history-capacity"`
 }
 

config/config.toml.example

@@ -440,6 +440,9 @@ strategy = "range"
 # max retry count for a statement in a pessimistic transaction.
 max-retry-count = 256
 
+# The max count of deadlock events that will be recorded in the information_schema.deadlocks table.
+deadlock-history-capacity = 10
+
 [stmt-summary]
 # enable statement summary.
 enable = true

config/config_test.go

@@ -230,6 +230,8 @@ group= "abc"
 zone= "dc-1"
 [security]
 spilled-file-encryption-method = "plaintext"
+[pessimistic-txn]
+deadlock-history-capacity = 123
 `)
 
 	c.Assert(err, IsNil)
@@ -284,6 +286,7 @@ spilled-file-encryption-method = "plaintext"
 	c.Assert(conf.EnableEnumLengthLimit, Equals, false)
 	c.Assert(conf.EnableForwarding, Equals, true)
 	c.Assert(conf.StoresRefreshInterval, Equals, uint64(30))
+	c.Assert(conf.PessimisticTxn.DeadlockHistoryCapacity, Equals, uint(123))
 
 	_, err = f.WriteString(`
 [log.file]