Applying lazy evaluation to the BTI encoding of clustering keys
was probably a bad default.
The benefits are dubious (because it's quite likely that the laziness
won't allow us to avoid that much work), but the overhead needed to
implement the laziness is large and immediate.
In this patch we get rid of the laziness.
We rewrite lazy_comparable_bytes_from_clustering_position
so that it performs the translation eagerly,
all components to a single bytes_ostream.
Note: the name *lazy*_comparable_bytes_from_clustering_position
stays, because the interface is still lazy.
perf_bti_key_translation:
Before:
test iterations median mad min max allocs tasks inst cycles
lcb_mismatch_test.lcb_mismatch 9233 109.930us 0.000ns 109.930us 109.930us 4356.000 0.000 2615394.3 614709.6
After:
test iterations median mad min max allocs tasks inst cycles
lcb_mismatch_test.lcb_mismatch 50952 19.487us 0.000ns 19.487us 19.487us 198.000 0.000 603120.1 109042.9
Some methods of managed_bytes contain the logic needed to read/write the
contents of managed_bytes, even though this logic is already present in
managed_bytes_{,mutable}_view.
Reimplementing those methods by using the views as intermediates allows us to
remove some code and makes the responsibilities cleaner -- after the change,
managed_bytes contains the logic of allocating and freeing the storage,
while views provide read/write access to the storage.
This change will simplify the next patch which changes the internals of
managed_bytes.
Instead of lengthy blurbs, switch to single-line, machine-readable
standardized (https://spdx.dev) license identifiers. The Linux kernel
switched long ago, so there is strong precedent.
Three cases are handled: AGPL-only, Apache-only, and dual licensed.
For the latter case, I chose (AGPL-3.0-or-later and Apache-2.0),
reasoning that our changes are extensive enough to apply our license.
The changes we applied mechanically with a script, except to
licenses/README.md.
Closes#9937
Replace stdx::optional and stdx::string_view with the C++ std
counterparts.
Some instances of boost::variant were also replaced with std::variant,
namely those that called seastar::visit.
Scylla now requires GCC 8 to compile.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
Message-Id: <20190108111141.5369-1-duarte@scylladb.com>
