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https://issues.apache.org/jira/browse/HDFS-9326?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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James Clampffer resolved HDFS-9326.
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Resolution: Won't Fix
Assignee: James Clampffer
Fix Version/s: HDFS-8707
Closing this bug without a fix. It's not required and there doesn't seem to be
a good solution that works on compilers more than a year or so old.
> Create a generic function to synchronize async functions and methods.
> ----------------------------------------------------------------------
>
> Key: HDFS-9326
> URL: https://issues.apache.org/jira/browse/HDFS-9326
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: hdfs-client
> Reporter: James Clampffer
> Assignee: James Clampffer
> Fix For: HDFS-8707
>
>
> The majority of the functionality in libhdfs++ is asynchronous, but some
> applications need synchronous operations. At the time of filing this only
> happens in 3 places in the C API, however that number is going to grow a lot
> once the C and high level C++ APIs expose all of the namenode functions.
> This synchronization is typically implemented like this:
> auto promise = std::make_shared<std::promise<T>>()
> std::future<T> = future(promise->get_future());
> auto async_callback = [promise] () {promise->set_value(val);};
> SomeClass::AsyncMethod(async_callback);
> auto result = future.get()
> Ideally this could all be pushed into a templated function so that the
> promise and future don't need to be defined at the call site. This would
> probably take the form of doing a std::bind to get all the arguments in place
> at the call site and then passing that to the synchronize function.
> This appears to require some template magic that isn't always well supported;
> see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=51979.
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