storage: Scope WebStorage quota per storage type instead of per origin total
#56933
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The review process for this patch is being conducted in the Servo project.
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The new tests verify that exhausting the quota of one Web Storage area does not significantly reduce the capacity available to the other one. Each test first measures the baseline capacity of one storage type by filling it until QuotaExceededError is thrown, then clears it, exhausts the other storage type, and measures the capacity again. Independence is verified by requiring that the second measurement remains broadly comparable to the baseline rather than collapsing to near-zero capacity, which would indicate a shared quota. Two directional tests are added: - sessionStorage retains comparable quota after localStorage exhaustion - localStorage retains comparable quota after sessionStorage exhaustion Gecko currently fails these new tests. This is consistent with the fact that the existing quota exhaustion tests also currently fail in Gecko. Signed-off-by: Jan Varga <[email protected]>
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Change quota accounting for
WebStorageso that usage is tracked per storagetype instead of combining
localStorageandsessionStorageinto a single perorigin total.
The previous implementation summed the sizes of both storage types and applied
a shared quota limit. This could cause a write to
sessionStorageto fail dueto data stored in
localStorage(and vice-versa), and also resulted in origindescriptors being created even when only one storage type was in use.
This behavior is not consistent with other browsers, where quota is enforced
independently for each storage mechanism.
Testing: Existing unit and WPT tests continue to pass, a new WPT test has been
added
Reviewed in servo/servo#41531