Add bn::base::shared_mutex, a compact reader/writer lock - #8480
Open
bdash wants to merge 1 commit into
Open
Conversation
For MSVC this is an alias for `std::shared_mutex`, which is already an 8-byte wrapper around `SRWLOCK`. On macOS and Linux this is implemented via a 4-byte atomic that packs writer, writer-pending, contended, and reader count. Blocking is handled via `platform_wait`. A queued writer gates new readers so that writers are not starved by heavy read traffic. `std::shared_mutex` is 168 bytes on macOS with libc++ and 56 bytes on Linux with libstdc++, so this new implementation is significantly more compact than it. Performance is comparable on both platforms.
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
For MSVC this is an alias for
std::shared_mutex, which is already an 8-byte wrapper aroundSRWLOCK.On macOS and Linux this is implemented via a 4-byte atomic that packs writer, writer-pending, contended, and reader count. Blocking is handled via
platform_wait. A queued writer gates new readers so that writers are not starved by heavy read traffic.std::shared_mutexis 168 bytes on macOS with libc++ and 56 bytes on Linux with libstdc++, so this new implementation is significantly more compact than it. Performance is comparable on both platforms.