This is a hash table that is optimized for architectures that
implement total store ordering and workloads that are read-heavy
involving a single writer and multiple readers. Unlike traditional
non-blocking multi-producer/multi-consumer hash table
implementations this version allows for immediate re-use of deleted
buckets (no need for explicit reclamation cycles) and is more
conducive to traditional safe memory reclamation schemes used in
unmanaged languages (otherwise, we would require key duplication).
It is relatively heavy-weight for MPMC workloads on architectures
which do not implement TSO in comparison to Click's MPMC hash
table. However, it still has better performance characteristics
than a blocking hash table.
The committed version currently only provides x86_64 support. This is
being committed for review by peers and for a silent release that will
allow us to test ck_ht_spmc under high production workloads.
Next public release will include additional documentation as well as
support for other architectures.
In the mean time, please see the unit tests for example usage. Included in
this commit: Dropped -Wbad-function-cast from GCC port.
We shouldn't offload the responsibility of the read_begin flush
for shared data mutations to the user. read_end requires a load
barrier at the least, not a store barrier.
Writer-side synchronization is still necessary. My current use-cases call for
SLIST and LIST implementations, and as such, I've only implemented support
for these. TAILQ facilities will be developed when the time comes that I require
them or if there is sufficient user-demand.
Several users in the past have noted it was difficult for them
to decide what spinlock implementation to use. In light of this,
a light-weight greedy default is chosen (currently ck_spinlock_fas).
Samy Al Bahra
Samy Al Bahra
David Joseph
Samy Al Bahra
William Irwin