[#CuckooCache-bit_packed_atomic_flags]
= xref:CuckooCache.adoc[CuckooCache]::bit_packed_atomic_flags
:relfileprefix: ../
:mrdocs:

xref:CuckooCache/bit_packed_atomic_flags/2constructor-0e.adoc[`bit_packed_atomic_flags`] implements a container for garbage collection flags that is only thread unsafe on calls to setup. This class bit‐packs collection flags for memory efficiency.

== Synopsis

Declared in `<cuckoocache.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
class bit_packed_atomic_flags;
----

== Description

All operations are `std::memory_order_relaxed` so external mechanisms must ensure that writes and reads are properly synchronized.

On setup(n), all bits up to `n` are marked as collected.

Under the hood, because it is an 8‐bit type, it makes sense to use a multiple of 8 for setup, but it will be safe if that is not the case as well.

== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:CuckooCache/bit_packed_atomic_flags/2constructor-0e.adoc[`bit_packed_atomic_flags`]         [.small]#[constructor]#
| Constructors
| xref:CuckooCache/bit_packed_atomic_flags/bit_is_set.adoc[`bit_is_set`] 
| bit_is_set queries the table for discardability at `s`.
| xref:CuckooCache/bit_packed_atomic_flags/bit_set.adoc[`bit_set`] 
| bit_set sets an entry as discardable.
| xref:CuckooCache/bit_packed_atomic_flags/bit_unset.adoc[`bit_unset`] 
| bit_unset marks an entry as something that should not be overwritten.
| xref:CuckooCache/bit_packed_atomic_flags/setup.adoc[`setup`] 
| setup marks all entries and ensures that bit_packed_atomic_flags can store at least `b` entries.
|===



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