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Add unsubscribe method. #2

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6fed0fa
Add unsubscribe method.
Jun 25, 2018
778cb8b
Code style, returns and tests for unsubscription.
Jun 26, 2018
7dad11c
Refactoring unsubscribe and its tests.
Jun 26, 2018
a5fd8e7
Catch errors on getHandlerRefsByProperties. No errors when serching f…
Jun 27, 2018
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35 changes: 35 additions & 0 deletions lib/latest/MQRouter.js
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Original file line number Diff line number Diff line change
Expand Up @@ -244,6 +244,41 @@ class MQRouter {
}
}

/**
* Unsubscribe from a queue
* @param {String} queue queue name
* @param {String} topic topic name
* @param {String} exchange exchange name
* @returns {Boolean} returns true if unsubscribed
* @public
*/
async unsubscribe({
queue,
topic,
exchange,
}) {
const { consumerTag, index } = this.queuesRoutingTable.getHandlerRefsByProperties({
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if this fails it will not be caught by catch and will throw a non standard error

queue,
topic,
exchange,
});
try {
if (consumerTag && index) {
await this.connector.unsubscribe({ consumerTag });
this.queuesRoutingTable.unregister({ index });
return true;
}
return false;
} catch (cause) {
debug(`error unsubscribing - ${cause.message}`);
throw Reflect.construct(IError, [{
name: 'MQ_ROUTER_UNSUBSCRIBE',
source: `${this.sourceIdentifier}.unsubscribe`,
cause,
}]);
}
}

/**
* Send request over mq
* @param {Buffer} message message to be sent
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31 changes: 31 additions & 0 deletions lib/latest/QueuesRoutingTable.js
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Original file line number Diff line number Diff line change
Expand Up @@ -140,6 +140,37 @@ class QueuesRoutingTable {
source: `${this.sourceIdentifier}.getHandlerByConsumerTag`,
}]);
}

/**
* locate refs by properties
* @param {String} queue queue name
* @param {String} topic topic name
* @param {String} exchange exchange name
* @returns {Object} index and consumerTag
* @public
*/
getHandlerRefsByProperties({
queue,
topic,
exchange,
}) {
try {
const { consumerTag } = Object.values(this.handlers)
.find(handler =>
handler.queue === queue &&
handler.topic === topic &&
handler.exchange === exchange);
return {
consumerTag,
index: this.consumerTags[consumerTag],
};
} catch (cause) {
return {
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please return here a specific error with cause as cause

in try block return null if consumerTag is undefined (not found)

element not found is a perfect response from this function. for actual case it is an error, but this is valid for the caller of getHandlerRefsByProperties. there can also be a check where you want to test if there is a handler associated for info provided and if it is not you need to do something else. by throwing error here you need to wrap it and do something on catch block.

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I can throw one error when handler not found and one when index not found by consumerTag:

getHandlerRefsByProperties({
    queue,
    topic,
    exchange,
  }) {
    const handler = Object.values(this.handlers)
      .find(el =>
        el.queue === queue &&
        el.topic === topic &&
        el.exchange === exchange);

    if (handler) {
      if (handler.consumerTag) {
        const index = this.consumerTags[handler.consumerTag];
        if (index) {
          return {
            consumerTag: handler.consumerTag,
            index,
          };
        }
        throw Reflect.construct(IError, [{
          name:   'MQ_ROUTING_TABLE_UNKNOWN_CONSUMER_TAG',
          source: `${this.sourceIdentifier}.getHandlerRefsByProperties`,
        }]);
      }

      return {
        consumerTag: null,
        index:       null,
      };
    }

    throw Reflect.construct(IError, [{
      name:   'MQ_ROUTING_TABLE_UNKNOWN_HANDLER',
      source: `${this.sourceIdentifier}.getHandlerRefsByProperties`,
    }]);
  }
}

consumerTag: null,
index: null,
};
}
}
}

module.exports = {
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