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node-red/packages/node_modules/@node-red/runtime/lib/hooks.js

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const Log = require("@node-red/util").log;
const VALID_HOOKS = [
// Message Routing Path
"onSend",
"preRoute",
"preDeliver",
"postDeliver",
"onReceive",
"postReceive",
"onComplete"
]
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// Flags for what hooks have handlers registered
let states = { }
// Hooks by id
let hooks = { }
// Hooks by label
let labelledHooks = { }
/**
* Runtime hooks engine
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*
* The following hooks can be used:
*
* Message sending
* - `onSend` - passed an array of `SendEvent` objects. The messages inside these objects are exactly what the node has passed to `node.send` - meaning there could be duplicate references to the same message object.
* - `preRoute` - passed a `SendEvent`
* - `preDeliver` - passed a `SendEvent`. The local router has identified the node it is going to send to. At this point, the message has been cloned if needed.
* - `postDeliver` - passed a `SendEvent`. The message has been dispatched to be delivered asynchronously (unless the sync delivery flag is set, in which case it would be continue as synchronous delivery)
* - `onReceive` - passed a `ReceiveEvent` when a node is about to receive a message
* - `postReceive` - passed a `ReceiveEvent` when the message has been given to the node's `input` handler(s)
* - `onComplete` - passed a `CompleteEvent` when the node has completed with a message or logged an error
*
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* @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 (VALID_HOOKS.indexOf(id) === -1) {
throw new Error(`Invalid hook '${id}'`);
}
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if (label) {
if (labelledHooks[label] && labelledHooks[label][id]) {
throw new Error("Hook "+hookId+" already registered")
}
labelledHooks[label] = labelledHooks[label]||{};
labelledHooks[label][id] = callback;
}
// Get location of calling code
const stack = new Error().stack;
const callModule = stack.split("\n")[2].split("(")[1].slice(0,-1);
Log.debug(`Adding hook '${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);
}
}
}
function clear() {
hooks = {}
labelledHooks = {}
states = {}
}
function has(hookId) {
let [id, label] = hookId.split(".");
if (label) {
return !!(labelledHooks[label] && labelledHooks[label][id])
}
return !!states[id]
}
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module.exports = {
has,
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clear,
add,
remove,
trigger
}