Ensure consistent BLE scan behavior #2718
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wiring/src/spark_wiring_ble.cpp
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| if (!delegator->filter_.allowDuplicates() && delegator->isCachedDevice(event->peer_addr)) { | ||
| return; | ||
| } | ||
| delegator->cachedDevices_.append(event->peer_addr); |
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This should not be populated in case of allowDuplicates() to avoid uncontrollable growth of the vector, as otherwise it will continue to fill-up with duplicates.
Same can potentially happen normally depending on scan duration, although highly unlikely, but should potentially be taken care of somehow as well.
| if (delegator->isCachedDevice(event->peer_addr)) { | ||
| return; | ||
| } | ||
| delegator->cachedDevices_.append(event->peer_addr); |
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@XuGuohui Do you think it would make sense to put a hard limit here on a maximum number of results?
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I think it wouldn't make sense, cos when the vector reaches the limit the device will report a large amount of duplicates, which more looks like a bug and might make the user panic. In whichever way we go we should document the limitation.
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I'm talking specifically about the case of non-duplicates. E.g. a moving device with a long scan duration and capturing a large number of devices around.
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What about introducing an option BleScanFilter.cachedDeviceSize() so that user can explicitly notice the limitation, otherwise, the cache can be uncontrollable to grow?
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Doubt anyone would use it :) Some relatively large default (e.g. 512-1024) is probably better, but honestly up to you to leave as-is potentially as well.
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Cool. I'll leave it as-is, as you said it's highly unlikely happen and we can react on it when there is customers encounter a shortage of RAM.
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Cc. @rickkas7 Introduced an option |
Problem
BLE.scan()andBLE.scanWithFilter()filter duplicate results on Gen3, but it's not true on Gen4.Solution
Make the BLE HAL report all of the scanned results and implement a filtering mechanism in wiring layer instead.
Steps to Test
Build and run the
tests/app/ble/scannerapp.References
N/A
Completeness