Unsubscribe by RegExp about hemera HOT 9 CLOSED

Hi @vdakalov

There wrote "if topic is string then take sid by its topic" but "else unsubscribe by topic which does not is string". And if topic is not a string, then it is a RegExp object. Result:

Where did you read it?

RegExp aren't supported only the topic or the subscription-id.

from hemera.

Here! And keep in mind topic is /^[a-zA-Z0-9-.]+$/i, because my topic (in hemera.add) is wildcard >

    // when sid was passed
    if (typeof topic === 'string') {
      // when topic name was passed
      const subId = self._topics.get(topic)

      if (subId) {
        self._transport.unsubscribe(subId, maxMessages)
        // we remove all subscription related to this topic
        this.cleanTopic(topic)
        return true
      }
    } else {
      self._transport.unsubscribe(topic, maxMessages)
      return true
    }

typeof topic === 'string' is false and execute else-branch. Then nats.unsubscribe(/^[a-zA-Z0-9-.]+$/i). And finally I see it in gnatsd output

[11605] 2018/11/20 14:02:39.579853 [TRC] 127.0.0.1:50742 - cid:1 - ->> [UNSUB /^[a-zA-Z0-9-.]+$/i]

from hemera.

Maybe You meant it:

    if (typeof topic === 'string' || topic instanceof RegExp) {

?

from hemera.

@vdakalov forget what I said. We can't use a RegexExp as a NATS subject. Here you can find all possible variants https://nats.io/documentation/internals/nats-protocol/.

Would you mind to create a PR which throws an error when no string or number was passed?

from hemera.

Let me describe steps for reproduce the problem here (PR will be unnecessary)

First, you need start nats server with trace option

gnatsd --trace

Next just execute follow script

import * as nats from 'nats';
import * as Hemera from 'nats-hemera';

const hemera = new Hemera(nats.connect(), {});
hemera.ready(() => {
 // add new subscription
  hemera.add({
    topic: '>' // <--- full wildcard topic
  }, (request, callback) => callback(null, 'Cut the Rope'));
  // send request
  hemera.act({
    topic: 'UndefinedTopic' // <--- this topic does not exist
  }, (error, response) => {
    console.log('Who are you: ' + response)
    hemera.close(); // <-- REQUIRED!
  });
});

Now look trace logs

...
[923] 2018/11/21 08:19:42.207369 [TRC] 127.0.0.1:55560 - cid:1 - ->> [UNSUB /^[a-zA-Z0-9-.]+$/i]
...

What happen?

1. Since topic for add is a full-wildcard token, then it tranclated to RegExp, here:
   

   hemera/packages/hemera/lib/index.js

   Line 1104 in d13b529

   addDefinition.pattern.topic = Util.natsWildcardToRegex(patternOnly.topic)

   
   And this RegExp object set to this._topics Map registry as key, here
   

   hemera/packages/hemera/lib/index.js

   Line 1146 in d13b529

   this._topics.set(addDefinition.pattern.topic, sid)

2. When calling of hemera.close it will make removeAll subscriptions, here:
   

   hemera/packages/hemera/lib/index.js

   Line 1532 in d13b529

   for (var topic of this._topics.keys()) {

3. Finally, it call remove function with RegExp object as topic argument.
   

   hemera/packages/hemera/lib/index.js

   Line 1533 in d13b529

   this.remove(topic)

from hemera.

Hi @vdakalov thanks for the nice explanation. RegExp must be handled differently in comparison and if we want to remove it from the index. The PR is still needed. Would you like to create one?

from hemera.

You're welcome. Sorry, I have no time :( You can?

from hemera.

mcollina/bloomrun#48 (comment)

from hemera.

Closed in #236

from hemera.