Fix for select read+write and spurious wakeup #552
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Codecov Report
@@ Coverage Diff @@
## master #552 +/- ##
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+ Coverage 46% 46% +<1%
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Files 81 81
Lines 7978 7987 +9
Branches 1364 1365 +1
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+ Hits 3722 3735 +13
+ Misses 3999 3996 -3
+ Partials 257 256 -1
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Can we please merge and release this as soon as possible? |
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RQ users also, via redis-py |
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Addresses #551
The green select function relies on removing the listeners in the "finally" block to ensure that no other callbacks will be issued. But in some hubs (poll and epolls, but not selects), callbacks are queued up in a local variable (called "callbacks"), so will not be prevented even if we remove the corresponding listeners. So in the case where both read and write are applicable, one of those callbacks gets issued after the select call returns, causing a spurious wakeup.
This addresses the issue by scheduling another callback to call current.switch, so that Hub.wait has a chance to finish issuing all callbacks.
This also has the benefit that select will now return both the read and write flags if they both apply, which is more consistent with the behavior of the original select function.