refs #5666 perf: loggable to mixin

loopback/common/mixins/loggable.js

@@ -0,0 +1,12 @@
+const LoopBackContext = require('loopback-context');
+async function handleObserve(ctx) {
+    ctx.options.httpCtx = LoopBackContext.getCurrentContext();
+}
+module.exports = function(Self) {
+    let Mixin = {
+        'before save': handleObserve,
+        'before delete': handleObserve,
+    };
+    for (const [listener, handler] of Object.entries(Mixin))
+        Self.observe(listener, handler);
+};