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https://issues.apache.org/jira/browse/THRIFT-146?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13184549#comment-13184549
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Peter Sanford commented on THRIFT-146:
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I'd like to get the above patch stream committed. What needs to be done to make
that happen?
> Make Thrift EventMachine Compatible
> -----------------------------------
>
> Key: THRIFT-146
> URL: https://issues.apache.org/jira/browse/THRIFT-146
> Project: Thrift
> Issue Type: Improvement
> Components: Ruby - Library
> Environment: Ruby and EventMachine
> Reporter: Ben Taitelbaum
> Priority: Trivial
> Fix For: 0.9
>
> Attachments: 0001-Ruby-client-increments-sequence-ids.patch,
> 0002-Added-rb-eventmachine-option-to-the-compiler.patch,
> 0003-Added-ruby-eventmachine-compatible-client-code.patch,
> 0004-Added-EventMachineTransport-class.patch,
> 0005-rb-eventmachine-can-have-a-separate-namespace-than-r.patch,
> 0006-Added-eventmachine-as-a-dev-dependency.patch,
> 0007-Generate-eventmachine-bindings-for-tests.patch,
> 0008-Initial-event-machine-test.patch,
> 0009-Added-an-asnyc-test-for-EventMachine.patch,
> 0010-Added-test-for-oneway-functions-with-eventmachine.patch,
> 0011-Added-eventmachine-test-for-void-functions.patch,
> 0012-Eventmachine-triggers-errback-on-connect-errors.patch,
> 0013-Added-timeout-option-to-eventmachine-transport.patch,
> 0014-Eventmachine-spec-cleanup-for-ruby-1.8.patch,
> 0015-Added-EventMachine-tutorial-example.patch,
> 0016-EM-Trigger-error-callbacks-on-connection-close.patch,
> thrift_eventmachine.rb
>
>
> I wrote a prototype EventMachine client/server for Thrift (BinaryProtocol),
> and while it's not fully functional, the results are so promising, that I
> think it would be worth it to either include an EM client/server with the
> thrift distribution, or at least rework the libraries so that they can
> support EM without having to copy/paste all the code I did.
> I'm attaching my prototype as an example. It requires the eventmachine and
> statemachine gems. It's wired to support a simple echo service. It's a little
> confusing in that I reused the same statemachine for both client and server,
> doesn't handle exceptions, and has a bug where it'll handle all requests from
> one client before handling requests from another, but hey, it's a prototype.
> EM uses very different semantics from typical client/server, and this
> presents difficulty wiring it to the current thrift protocols. For example,
> while currently, you can call call prot.read(n) to read n bytes off of a
> stream, or wait until they're available, with EM, if n bytes aren't
> available, you simply don't handle the call yet. I handled this by trying to
> read as many bytes as need be, and keeping track of how much to backup in the
> stream, ultimately only transitioning to the next state in the statemachine
> if we were able to read all the bytes needed. This actually works fairly
> well, but it would be better if we had a byte count at each step so we could
> tell right away if we had enough data.
> The use of EM allows for new asynchronous semantics for thrift calls, in that
> the client returns right away from a call, and its callback is called when a
> result (or exception) is available. Backwards compatibility could still be
> achieved by blocking on a call, but at least in my experience, in most of the
> cases having callbacks would be a huge optimization. There are some cases
> where I do want to either ensure that calls happen sequentially, or are at
> least handled in the same order.
> These are the changes I believe would have to be made in order to support an
> EM thrift connection:
> 1. syntax to indicate that certain methods can be called asynchronously with
> callbacks. Since async is already a reserved keyword, and is changing to
> noreturn, what about using this?
> 2. I would propose moving all reading and writing to the same class. So
> instead of having ThriftStruct#read, we would have Protocol#read_struct. It
> seems out of place to me to have a model handle its own reading / writing.
> 3. support for byte counts in the protocols. It would be helpful to have a
> clear way to get the number of bytes that must be read to retrieve message
> headers, arguments, and results. Alternatively, the protocols could support
> read_or_backup semantics, but as you can see in my prototype, this can get
> messy.
> Please let me know what you think about this proposal, and the possibility of
> using EventMachine.
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