assert() is traditionally disabled in release builds, but not in
scylladb. This hasn't caused problems so far, but the latest abseil
release includes a commit [1] that causes a 1000 insn/op regression when
NDEBUG is not defined.
Clearly, we must move towards a build system where NDEBUG is defined in
release builds. But we can't just define it blindly without vetting
all the assert() calls, as some were written with the expectation that
they are enabled in release mode.
To solve the conundrum, change all assert() calls to a new SCYLLA_ASSERT()
macro in utils/assert.hh. This macro is always defined and is not conditional
on NDEBUG, so we can later (after vetting Seastar) enable NDEBUG in release
mode.
[1] 66ef711d68Closesscylladb/scylladb#20006
Adds a configurable upper limit to memory usage by index caches.
See the source code comments added in this patch for more details.
This patch shouldn't change visible behaviour, because the limit is set to 1.0
by default, so it is never triggerred. We will change the default in a future
patch.
Before the patch, fixing list links is done manually in the move constructor of
`evictable`. After the patch, it is done by the move constructors of the links
themselves.
This makes for slightly cleaner code, especially after we add more links in an
upcoming patch.
Will be used by MVCC tests which don't want (can't) deal with the
row_cache as the container but work with the partition_entry directly.
Currently, rows_entry::on_evicted() assumes that it's embedded in
row_cache and would segfault when trying to evict the contining
partition entry which is not embedded in row_cache. The solution is to
call evict_shallow() from mvcc_tests, which does not attempt to evict
the containing partition_entry.
Previous patches introduce the assumption that evictables are manually unlinked
before destruction, to allow for correct bookkeeping within the cache.
This assert assures that this assumptions is correct.
This is particularly important because the switch from automatic to explicit
unlinking had to be done manually. Destructor calls are invisible, so it's
possible that we have missed some automatic destruction site.
unlink_from_lru() allows for unlinking elements from cache without notifying
the cache. This messes up any potential cache bookkeeping.
Improved that by replacing all uses of unlink_from_lru() with calls to
lru::remove(), which does have access to cache's metadata.
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
In preparation for tracking different kinds of objects, not just
rows_entry, in the LRU, switch to the LRU implementation form
utils/lru.hh which can hold arbitrary element type.
The LRU can link objects of different types, which is achieved by
having a virtual base class called "evictable" from which the linked
objects should inherit. Whe the object is removed from the LRU,
evictable::on_evicted() is called.
The container is non-owning.
