Bigtable this.end() does not stop the stream?

[lukesneeringer]

From @arbesfeld on May 2, 2017 14:15

Using Bigtable 0.9.1 - I seem to be getting more than 1 result after calling this.end(). Is this expected behavior?

Copied from original issue: googleapis/google-cloud-node#2271

[lukesneeringer]

From @stephenplusplus on May 2, 2017 16:4

I recall seeing this discussed in another issue, and it might be an issue with one of our dependencies. I will look into it. Thanks for reporting.

[lukesneeringer]

From @stephenplusplus on May 2, 2017 17:17

The issue I was thinking of doesn't actually relate to the Bigtable API, so throw that theory out the window.

I tried to reproduce, but couldn't. My script and results:

var bigtable = require('@google-cloud/bigtable')()

bigtable.getInstancesStream()
  .on('data', function (instance) {
    console.log('instance')
    this.end()
  })
  .on('end', function () {
    console.log('over')
  })

// output:
instance
over

Without the this.end():

var bigtable = require('@google-cloud/bigtable')()

bigtable.getInstancesStream()
  .on('data', function (instance) {
    console.log('instance')
  })
  .on('end', function () {
    console.log('over')
  })

// output:
instance
instance
instance
over

Are you using a different method? Could there be other code interfering with when this.end() is called? Seeing your code might help.

[lukesneeringer]

From @arbesfeld on May 3, 2017 18:17

We're using table.createReadStream(). Here's what it looks like:

    await new Promise((resolve, reject) => {
      table
        .createReadStream({
          decode: true,
          start: 'foo',
          end: 'bar'
          filter: [{
            column: {
              cellLimit: 1,
            },
          }],
        })
        .on('data', function onData(row) {
          this.end();
          resolve();
        })
        .on('end', resolve)
        .on('error', reject);
    });

Other methods could be using table at the same time, if that affects something?

[lukesneeringer]

From @stephenplusplus on May 3, 2017 18:19

Would it be a problem that resolve() is called from the data handler and end? this.end() will gracefully exit the stream, which means that the end event will be called.

[lukesneeringer]

From @arbesfeld on May 3, 2017 20:4

That would be acceptable for our application. We found that onData would continued to be called even after this.end(). We're on Node 7.9.0, and we found a workaround by introducing another variable outside of the promise.

[lukesneeringer]

From @stephenplusplus on May 3, 2017 20:9

Found the issue. PR incoming.

[lukesneeringer]

From @stephenplusplus on May 4, 2017 18:54

PR sent: #2276