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xacrimon / dashmap

Blazing fast concurrent HashMap for Rust.
MIT License
2.84k stars 140 forks source link

Implements get_or_insert for write once workloads. #293

Open geekbeast opened 4 months ago

geekbeast commented 4 months ago

This change allows retrieving values from the map without having to acquire a write lock, unless the value is missing. For read once (or mostly read) workloads this is superior to taking a write lock everytime the entry is read. It also saves having to allocate value if it is not inserted and having to compute the usize hash / shard index twice versus the approach of calling get then using entry to insert (as there is not try_insert yet)

Unfortunately, it doesn't seem like it is possible to avoid the second read without changing the behavior of HashMap.

geekbeast commented 4 months ago

I didn't touch dependencies so not sure why home package all of sudden is requiring a newer rustc.

ryoqun commented 1 month ago

@xacrimon I wonder this pr could ever be merged soonish? if more efforts are needed, i can work on. cc: @geekbeast

ryoqun commented 1 week ago

@xacrimon I wonder this pr could ever be merged soonish? if more efforts are needed, i can work on. cc: @geekbeast

@xacrimon (thanks for recent release with perf increase!) friendly reminder. if this api sounds okay, I'm available to work on this pr. cc: @geekbeast