Remove XFlush call in event loop
#982
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Internally, `XFlush` calls `_XSend` to write data. It then calls `XEventsQueued(display, QueuedAfterReading)`, which reads data from the X server connection. This prevents the event loop source callback from being run, as there is no longer data waiting on the socket. Ideally, we would want to call `_XSend` directly to ensure that no output is buffered by Xlib. However, this function is not exported as part of Xlib's public API. Testing with the `XFlush` call removed does not appear to adversely affect the performance of an application. If any bugs should eventually arise from this change, perhaps another function may be used in place of `XFlush`, such as `XPending`, which writes buffered output but does not so aggressively read from the X server connection. Closes rust-windowing#865
elinorbgr
approved these changes
Jun 25, 2019
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Now that this has been merged, I think we should release an |
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There is still another flush call: |
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@aloucks That one appears to be called only when necessary. It doesn't seem to be interfering with the event loop. |
kosyak
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to kosyak/winit
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this pull request
Jul 10, 2019
Internally, `XFlush` calls `_XSend` to write data. It then calls `XEventsQueued(display, QueuedAfterReading)`, which reads data from the X server connection. This prevents the event loop source callback from being run, as there is no longer data waiting on the socket. Ideally, we would want to call `_XSend` directly to ensure that no output is buffered by Xlib. However, this function is not exported as part of Xlib's public API. Testing with the `XFlush` call removed does not appear to adversely affect the performance of an application. If any bugs should eventually arise from this change, perhaps another function may be used in place of `XFlush`, such as `XPending`, which writes buffered output but does not so aggressively read from the X server connection. Closes rust-windowing#865
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Internally,
XFlushcalls_XSendto write data. It then callsXEventsQueued(display, QueuedAfterReading), which reads data from theX server connection. This prevents the event loop source callback from
being run, as there is no longer data waiting on the socket.
Ideally, we would want to call
_XSenddirectly to ensure that nooutput is buffered by Xlib. However, this function is not exported as
part of Xlib's public API.
Testing with the
XFlushcall removed does not appear to adverselyaffect the performance of an application. If any bugs should eventually
arise from this change, perhaps another function may be used in place of
XFlush, such asXPending, which writes buffered output but does notso aggressively read from the X server connection.
Closes #865
cargo fmthas been run on this branchCHANGELOG.mdif knowledge of this change could be valuable to users