Initial import of pstop v0.0.10

[pstop.git] / lib / global_variables.go

diff --git a/lib/global_variables.go b/lib/global_variables.go
new file mode 100644 (file)
index 0000000..a83ec7e
--- /dev/null
+++ b/lib/global_variables.go
@@ -0,0 +1,94 @@
+package lib
+
+import (
+       "database/sql"
+       "log"
+       "strings"
+)
+
+/*
+** mysql> select VARIABLE_VALUE from information_schema.global_variables where variable_name = 'hostname';
+* +----------------+
+* | VARIABLE_VALUE |
+* +----------------+
+* | myhostname     |
+* +----------------+
+* 1 row in set (0.00 sec)
+**/
+func SelectGlobalVariableByVariableName(dbh *sql.DB, variable_name string) (error, string) {
+       sql_select := "SELECT VARIABLE_VALUE FROM INFORMATION_SCHEMA.GLOBAL_VARIABLES WHERE VARIABLE_NAME = ?"
+
+       var variable_value string
+       err := dbh.QueryRow(sql_select, variable_name).Scan(&variable_value)
+       switch {
+       case err == sql.ErrNoRows:
+               log.Println("No setting with that variable_name", variable_name)
+       case err != nil:
+               log.Fatal(err)
+       default:
+               // fmt.Println("variable_value for", variable_name, "is", variable_value)
+       }
+
+       return err, variable_value
+}
+
+// Provide a slice of string and get back a hash of variable_name to value.
+// - note the query is case insensitive for variable names.
+// - they key values are lower-cased.
+func SelectGlobalVariablesByVariableName(dbh *sql.DB, wanted []string) (error, map[string]string) {
+       hashref := make(map[string]string)
+
+       // create an IN list to make up the query
+       quoted := make([]string, 0, len(wanted))
+       sql_select := "SELECT VARIABLE_NAME, VARIABLE_VALUE FROM INFORMATION_SCHEMA.GLOBAL_VARIABLES WHERE VARIABLE_NAME IN ("
+
+       if len(wanted) == 0 {
+               log.Fatal("SelectGlobalVariablesByVariableName() needs at least one entry")
+       }
+
+       for i := range wanted {
+               quoted = append(quoted, "'"+wanted[i]+"'")
+
+       }
+       sql_select += strings.Join(quoted, ",")
+       sql_select += ")"
+
+       rows, err := dbh.Query(sql_select)
+       defer rows.Close()
+
+       for rows.Next() {
+               var variable, value string
+               if err := rows.Scan(&variable, &value); err != nil {
+                       log.Fatal(err)
+               }
+               hashref[strings.ToLower(variable)] = value
+       }
+       if err := rows.Err(); err != nil {
+               log.Fatal(err)
+       }
+
+       return err, hashref
+}
+
+// Return all global variables as a hashref
+func SelectAllGlobalVariablesByVariableName(dbh *sql.DB) (error, map[string]string) {
+       hashref := make(map[string]string)
+
+       sql_select := "SELECT VARIABLE_NAME, VARIABLE_VALUE FROM INFORMATION_SCHEMA.GLOBAL_VARIABLES"
+
+       rows, err := dbh.Query(sql_select)
+       defer rows.Close()
+
+       for rows.Next() {
+               var variable, value string
+               if err := rows.Scan(&variable, &value); err != nil {
+                       log.Fatal(err)
+               }
+               hashref[strings.ToLower(variable)] = value
+       }
+       if err := rows.Err(); err != nil {
+               log.Fatal(err)
+       }
+
+       return err, hashref
+}