[now dev] Memoize the getNowConfig() promise
#2561
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The `getNowConfig()` function gets invoked frequently, and it is also async and makes mutations to the cached now config object. This ends up being a race condition when `getNowConfig()` is invoked concurrently, since one of the invocations may end up with an incomplete `NowConfig` object (namely, with missing `builds`/`routes` arrays due to the zero-config processing). This change makes it so that there's only one `getNowConfig()` invocation being executed at a time, and other concurrent executions will await the same promise that the original invocation is responsible for.
Codecov Report
@@ Coverage Diff @@
## canary #2561 +/- ##
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+ Coverage 13.65% 13.68% +0.03%
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Files 256 256
Lines 9435 9439 +4
Branches 1078 1078
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+ Hits 1288 1292 +4
+ Misses 8023 8022 -1
- Partials 124 125 +1
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AndyBitz
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Jul 16, 2019
AndyBitz
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Jul 17, 2019
The `getNowConfig()` function gets invoked frequently, and it is also async and makes mutations to the cached now config object. This ends up being a race condition when `getNowConfig()` is invoked concurrently, since one of the invocations may end up with an incomplete `NowConfig` object (namely, with missing `builds`/`routes` arrays due to the zero-config processing). This change makes it so that there's only one `getNowConfig()` invocation being executed at a time, and other concurrent executions will await the same promise that the original invocation is responsible for.
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The
getNowConfig()function gets invoked frequently, and it is also async and makes mutations to the cached now config object. This ends up being a race condition whengetNowConfig()is invoked concurrently, since one of the invocations may end up with an incompleteNowConfigobject (namely, with missingbuilds/routesarrays due to the zero-config processing).This change makes it so that there's only one
getNowConfig()invocation being executed at a time, and other concurrent executions will await the same promise that the original invocation is responsible for.