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node-red/packages/node_modules/@node-red/runtime/lib/hooks.js
2020-09-29 12:19:27 +01:00

165 lines
4.5 KiB
JavaScript

const Log = require("@node-red/util").log;
// Flags for what hooks have handlers registered
let states = { }
// Hooks by id
let hooks = { }
// Hooks by label
let labelledHooks = { }
/**
* Runtime hooks engine
* @mixin @node-red/runtime_hooks
*/
/**
* Register a handler to a named hook
* @memberof @node-red/runtime_hooks
* @param {String} hookId - the name of the hook to attach to
* @param {Function} callback - the callback function for the hook
*/
function add(hookId, callback) {
let [id, label] = hookId.split(".");
if (label) {
if (labelledHooks[label] && labelledHooks[label][id]) {
throw new Error("Hook "+hookId+" already registered")
}
labelledHooks[label] = labelledHooks[label]||{};
labelledHooks[label][id] = callback;
}
// Get location of calling code
const stack = new Error().stack;
const callModule = stack.split("\n")[2].split("(")[1].slice(0,-1);
Log.debug(`Adding hook '${hookId}' from ${callModule}`);
hooks[id] = hooks[id] || [];
hooks[id].push({cb:callback,location:callModule});
states[id] = true;
}
/**
* Remove a handled from a named hook
* @memberof @node-red/runtime_hooks
* @param {String} hookId - the name of the hook event to remove - must be `name.label`
*/
function remove(hookId) {
let [id,label] = hookId.split(".");
if ( !label) {
throw new Error("Cannot remove hook without label: ",hookId)
}
Log.debug(`Removing hook '${hookId}'`);
if (labelledHooks[label]) {
if (id === "*") {
// Remove all hooks for this label
let hookList = Object.keys(labelledHooks[label]);
for (let i=0;i<hookList.length;i++) {
removeHook(hookList[i],labelledHooks[label][hookList[i]])
}
delete labelledHooks[label];
} else if (labelledHooks[label][id]) {
removeHook(id,labelledHooks[label][id])
delete labelledHooks[label][id];
if (Object.keys(labelledHooks[label]).length === 0){
delete labelledHooks[label];
}
}
}
}
function removeHook(id,callback) {
let i = hooks[id].findIndex(hook => hook.cb === callback);
if (i !== -1) {
hooks[id].splice(i,1);
if (hooks[id].length === 0) {
delete hooks[id];
delete states[id];
}
}
}
function trigger(hookId, payload, done) {
const hookStack = hooks[hookId];
if (!hookStack || hookStack.length === 0) {
done();
return;
}
let i = 0;
function callNextHook(err) {
if (i === hookStack.length || err) {
done(err);
return;
}
const hook = hookStack[i++];
const callback = hook.cb;
if (callback.length === 1) {
try {
let result = callback(payload);
if (result === false) {
// Halting the flow
done(false);
return
}
if (result && typeof result.then === 'function') {
result.then(handleResolve, callNextHook)
return;
}
callNextHook();
} catch(err) {
done(err);
return;
}
} else {
try {
callback(payload,handleResolve)
} catch(err) {
done(err);
return;
}
}
}
callNextHook();
function handleResolve(result) {
if (result === undefined) {
callNextHook();
} else {
done(result);
}
}
}
// add("preSend", function(sendEvents) {
// console.log("preSend",JSON.stringify(sendEvents));
// })
// add("preRoute", function(sendEvent) {
// console.log("preRoute",JSON.stringify(sendEvent.msg));
// })
// add("onSend", function(sendEvent) {
// console.log("onSend",JSON.stringify(sendEvent.msg));
// })
// add("postSend", function(sendEvent) {
// console.log("postSend",JSON.stringify(sendEvent.msg));
// })
// add("onReceive", function(recEvent) {
// console.log("onReceive",recEvent.destination.id,JSON.stringify(recEvent.msg))
// })
// add("postReceive", function(recEvent) {
// console.log("postReceive",recEvent.destination.id,JSON.stringify(recEvent.msg))
// })
function clear() {
hooks = {}
labelledHooks = {}
states = {}
}
module.exports = {
get states() { return states },
clear,
add,
remove,
trigger
}