[jira] [Commented] (EDGENT-308) Is it possible to use poll() with FileStreams together

["Dale LaBossiere (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/EDGENT-308?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15796012#comment-15796012 ] 

Dale LaBossiere commented on EDGENT-308:
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Rui,  regarding _Currently, our requirement is to return one line in the current file content every <poll> unit (if users enable the <poll> feature). Otherwise, the default behavior is return all lines in file without any interval._

[PlumbingStreams|https://edgent.incubator.apache.org/javadoc/latest/org/apache/edgent/topology/plumbing/PlumbingStreams.html] has {{blockingThrottle()}} and {{blockingDelay()}} to throttle/delay a stream.  e.g.,
{quote}
    TStream<String> pathnames = topology.strings("/etc/passwd");
    TStream<String> lines = FileStreams.textFileReader(pathnames);
    TStream<String> throttledLines = PlumbingStreams.blockingThrottle(lines, 1, TimeUnit.SECONDS);
    throttledLines.print();  // ends up printing 1 line every second
{quote}
I'm going to close this issue.  Please reopen if that doesn't address your question.

> Is it possible to use poll() with FileStreams together
> ------------------------------------------------------
>
>                 Key: EDGENT-308
>                 URL: https://issues.apache.org/jira/browse/EDGENT-308
>             Project: Edgent
>          Issue Type: New Feature
>          Components: Connectors
>            Reporter: Rui Shen
>
> My requirement is to load data from a file and polling with a specific frequency (say every 1 second). 
> I found Topology.poll() can do this, but it requires a Supplier parameter and the get method is called periodically. With this way, I have to read the file content myself and create a Iterable instance, then a Supplier. 
> I want to use FileStreams.textFileReader() to handle the file reading. The problem is how to use it with Topology.poll() together? I could not find a way to do this. 
> Is there any way to do this? Or connectors does not support "polling" at all? 



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