adding a new feature: corrupting MySQL by forcing it to use a lot of …

…CPU.

README.md

@@ -22,4 +22,10 @@ Corrupting MySQL and testing how the monitoring system reacts.
 ./corrupt-mysql bt -H10.186.62.63 -P25690 -uuniverse_udb -p123 100MB
 ```
 
-![example](./pics/bt.jpg)
+![example](./pics/bt.jpg)
+
+## Make MySQL's CPU usage high
+
+```bash
+./corrupt-mysql hcpu -H10.186.62.63 -P25690 -uuniverse_udb -p123
+```

backend/high_cpu_usage.go

@@ -0,0 +1,45 @@
+package backend
+
+import (
+	"fmt"
+
+	"github.com/bo-er/corrupt-mysql/pkg"
+)
+
+const prepareHighCPUUsageSQL = `
+DROP DATABASE IF EXISTS corrupt_mysql_highcpuusage_test;
+CREATE DATABASE corrupt_mysql_highcpuusage_test;
+USE corrupt_mysql_highcpuusage_test;
+DROP TABLE IF EXISTS t;
+CREATE TABLE t(x int primary key auto_increment);
+INSERT INTO t() values(),(),(),();
+`
+
+func MakeCPUUsageHigh(c pkg.Connect) error {
+	db, err := pkg.GetDB(c)
+	if err != nil {
+		return err
+	}
+	err = pkg.BatchExec(db, prepareBigTransactionSQL)
+	if err != nil {
+		return err
+	}
+	// maybe there is a better way to do this.
+	_, err = db.Exec(`USE corrupt_mysql_highcpuusage_test;`)
+	if err != nil {
+		return fmt.Errorf("use corrupt_mysql_highcpuusage_test: %s", err.Error())
+	}
+	// preparing some data
+	for i := 1; i <= 20; i++ {
+		_, err = db.Exec(quadraticGrowthSQL)
+		if err != nil {
+			return fmt.Errorf("calling(%s) for the %dth time: %s", quadraticGrowthSQL, i, err.Error())
+		}
+	}
+	// calling rand() on each entry.
+	_, err = db.Exec(`SELECT * FROM t order by rand() limit 1;`)
+	if err != nil {
+		return fmt.Errorf("calling rand() on each entry: %s", err.Error())
+	}
+	return nil
+}

cmd/high_cpu_usage.go

@@ -0,0 +1,27 @@
+package cmd
+
+import (
+	"github.com/bo-er/corrupt-mysql/backend"
+	"github.com/bo-er/corrupt-mysql/pkg"
+	"github.com/spf13/cobra"
+)
+
+// highCPUCmd increases mysql's cpu usage dramatically.
+var highCPUCmd = &cobra.Command{
+	Use:   "hcpu",
+	Short: "increasing mysql's cpu usage dramatically",
+	Long:  `./corrupt-mysql hcpu -H10.186.62.63 -P25690 -uuniverse_udb -p123`,
+	Run: func(cmd *cobra.Command, args []string) {
+		connect := pkg.Connect{
+			User:     user,
+			Host:     host,
+			Password: password,
+			DBName:   "mysql",
+			Port:     port,
+		}
+		err := backend.MakeCPUUsageHigh(connect)
+		if err != nil {
+			panic(err.Error())
+		}
+	},
+}