feat(poolCluster): add execute method

lib/pool_cluster.js

@@ -77,6 +77,32 @@ class PoolNamespace {
     return query;
   }
 
+  /**
+   * pool cluster execute
+   * @param {*} sql 
+   * @param {*} values 
+   * @param {*} cb 
+   */
+  execute(sql, values, cb) {
+    if (typeof values === 'function') {
+      cb = values;
+      values = [];
+    }
+    this.getConnection((err, conn) => {
+      if (err) {
+        return cb(err);
+      }
+      try {
+        conn.execute(sql, values, cb).once('end', () => {
+          conn.release();
+        });
+      } catch (e) {
+        conn.release();
+        throw e;
+      }
+    });
+  }
+
   _getClusterNode() {
     const foundNodeIds = this._cluster._findNodeIds(this._pattern);
     if (foundNodeIds.length === 0) {

promise.js

@@ -463,6 +463,20 @@ class PromisePoolCluster extends EventEmitter {
     });
   }
 
+  execute(sql, args) {
+    const corePoolCluster = this.poolCluster;
+    const localErr = new Error();
+    if (typeof args === 'function') {
+      throw new Error(
+        'Callback function is not available with promise clients.'
+      );
+    }
+    return new this.Promise((resolve, reject) => {
+      const done = makeDoneCb(resolve, reject, localErr);
+      corePoolCluster.execute(sql, args, done);
+    });
+  }
+
   of(pattern, selector) {
     return new PromisePoolCluster(
       this.poolCluster.of(pattern, selector),