After adopting the new thread model for safebrowsing, we will create a new
lookup cache for update so we can still check lookup cache at the same time.
Prefix set, completions will be generated when we open the new lookup cache
but it won't include cache, so we will loss cache after that.
This patch will copy cache data from old lookup cache to new lookup
cache while update.
MozReview-Commit-ID: L0WpiHOGIGm
In this patch, we will make Safebrowsing V2 caching use the same algorithm as V4.
So we remove "mMissCache" for negative caching and TableFresness check for
positive caching.
But Safebrowsing V2 doesn't contain negative/positive cache duration information in
gethash response. So we hard-code a fixed value, 15 minutes, as cache duration.
In this way, we can sync the mechanism we handle caching for V2 and V4.
An extra effort for V2 here is that we need to manually record prefixes misses
because we won't get any response for those prefixes(implemented in
nsUrlClassifierLookupCallback::CacheMisses).
In Bug 1323953, we always send 4-bytes prefix for completion and the prefix is also
used as the key to store cache result from gethash request.
Since it is always 4-bytes, we could convert it to integer for simplicity.
MozReview-Commit-ID: Lkvrg0wvX5Z
LookupCacheV4::Has implements safebrowsing v4 caching logic.
1. Check if fullhash match any prefix in local database:
- If not, the URL is safe.
2. Check if prefix is in the cache(prefix is always the first 4-byte of
the fullhash, Bug 1323953):
- If not, send fullhash request
3. Check if fullhash is in the positive cache:
- If fullhash is found and it is not expired, the URL is not safe.
- If fullhash is found and it is expired, send fullhash request.
4. If fullhash is not found, check negative cache expired time:
- If negative cache time is not expired, the URL is safe.
- If negative cache time is expired, send fullhash request.
MozReview-Commit-ID: GRX7CP8ig49
LookupCacheV4::Has implements safebrowsing v4 caching logic.
1. Check if fullhash match any prefix in local database:
- If not, the URL is safe.
2. Check if prefix is in the cache(prefix is always the first 4-byte of
the fullhash, Bug 1323953):
- If not, send fullhash request
3. Check if fullhash is in the positive cache:
- If fullhash is found and it is not expired, the URL is not safe.
- If fullhash is found and it is expired, send fullhash request.
4. If fullhash is not found, check negative cache expired time:
- If negative cache time is not expired, the URL is safe.
- If negative cache time is expired, send fullhash request.
MozReview-Commit-ID: GRX7CP8ig49
