After documenting the semantics, I noticed an arguable hole in them,
which is that you could Freeze() a dirty container, and then Repair()
wouldn't work on it. On further study, I added a roaringparanoia
check for attempts to access the N of dirty containers.
It turns out there's several such. But also, it turns out, there's
circumstances where unionInPlace is relying on the assumption that
N is valid, which it isn't always for dirty containers. Also, there's
at least one case where we rely on the assumption that forcibly
thawing a container, then calling unionInPlace on it, always modifies
that container. But that's not supposed to be true for an empty
container -- an empty container might be better handled by just
returning the container it's being unioned with. So, we drop the
unnecessary thaw (all the *InPlace ops are already thawing if/when
they need to), but we use the return from unionInPlace.
If you just stash the results of the function when defining the test cases, the
outcome is in part that you are reusing the same slices for multiple things. So,
for instance, if you perform a union on the OddBitsSet slice, with the EvenBitsSet
slice, the result is to overwrite the first entry in that slice with the 0-ffff
run... But the original slice still exists, and then we reuse it and get a slice
with a bit count of around 98,000. The underlying issue is that doContainer()
is calling NewContainerRun(), which is simply using the provided slice, not
copying it -- which is intentional, but the test has to be careful about it.
We call repair on the one we think should be a bitmap. Theoretically
maybe we should also repair the other one in case unionRunRun some day
starts returning unrepaired bitmaps, which in principle it's allowed to
do...
The copy-on-write semantics were previously documented only in
the 125-line commit log from the patch which introduced them. Add
documentation for them in a few likely places.
This commit adds the ability to start a transaction with an exclusive
lock for the entire database. This ensures no other read or write
transactions can run at the same time. Writes in this mode write
directly to the database and skip the WAL entirely.
- introduce Query Context (Qcx) for managing database-per-shard.
- replaces the MultiTx, so mtx.go is retired and removed.
- introduces the HolderConfig struct and all Holders now have
a path from birth.
- rbf speedups on bitwise writes
- badgerdb is removed due to unresolvable write conflicts.
fixes#703#676
