OperatorToObservableList: use LinkedList to buffer the sequence’s items #1208
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LinkedList has guaranteed constant insertion time when appending to the end of the list, whereas ArrayList takes O(1) amortized, since a reallocation might be necessary to insert further items. Since no capacity was specified for the buffer, on Hotspot this would cause the array to reallocate after the first 10 insertions, on Android after the first insertion (since Android’s ArrayList uses a default capacity of zero.) Since the buffer is copied to an ArrayList before emission, subscriber performance when working with the list should remain unaffected. Refs ReactiveX#1141
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RxJava-pull-requests #1117 SUCCESS |
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Why do we copy it to a new I agree that this change will be fine because of that, but that seems odd. Merging, and will let future performance discussions handle that case. |
OperatorToObservableList: use LinkedList to buffer the sequence’s items
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Added comments in #1218 to research this further. |
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Good question. It was copied before and I assumed it was done so as to not Copying it makes more sense now that the buffer is a LinkedList, since for
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LinkedList has guaranteed constant insertion time when appending to the end of the list, whereas ArrayList takes O(1) amortized, since a reallocation might be necessary to insert further items. Since no capacity was specified for the buffer, on Hotspot this would cause the array to reallocate after the first 10 insertions, on Android even after the first insertion (since Android’s ArrayList uses a default capacity of zero.)
Since the buffer is copied to an ArrayList before emission, subscriber performance when working with the list should remain unaffected.
Sorry for the import noise, that's IntelliJ reformatting them every time I look at the file.
Refs #1141