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bikeshed

Lock free hierarchical work scheduler Builds with MSVC, Clang and GCC, header only, C99 compliant, MIT license.

See github for latest version: https://github.com/DanEngelbrecht/bikeshed

See design blogs at: https://danengelbrecht.github.io

Version history

Version v1.0 29/5 2019

Release 1.0

Fixes

• Use explicit int32_t for instead of long to ensure 32-bit values on GCC/Clang x64-builds
• Corrected URL to blog in README.md
• Added sample code for performance tests (in examples folder)

Version v0.4 18/5 2019

Pre-release 4

API changes

• Bikeshed_AddDependencies to take array of parent task task_ids
• Bikeshed_ReadyCallback now gets called per channel range

API additions

• Bikeshed_FreeTasks
• BIKESHED_L1CACHE_SIZE to control ready head alignement - no padding/alignement added by default
• BIKESHED_CPU_YIELD to control yielding in high-contention scenarios

Fixes

• Added default (non-atomic) implementations for helper for unsupported platforms/compilers
• Codacy analisys and badge
• More input validation on public apis when BIKESHED_ASSERTS is enabled
• Batch allocation of task indexes
• Batch allocation of dependency indexes
• Batch free of task indexes
• Batch free of dependency indexes
• Fixed broken channel range detection when resolving dependencies

Version v0.3 1/5 2019

Pre-release 3

Fixes

• Ready callback is now called when a task is readied via dependency resolve
• Tasks are readied in batch when possible

Version v0.2 29/4 2019

Pre-release 2

Fixes

• Internal cleanups
• Fixed warnings and removed clang warning suppressions
  • -Wno-sign-conversion
  • -Wno-unused-macros
  • -Wno-c++98-compat
  • -Wno-implicit-fallthrough
• Made it compile cleanly with clang++ on Windows

Version v0.1 26/4 2019

Pre-release 1

Features

• Generic tasks scheduling with dependecies between tasks
  • Each task has zero or many dependecies (as defined by user)
  • User should Ready any tasks that can execute (has zero dependencies)
  • Automatic ready of tasks that reaches zero dependecies
  • Automatic free of tasks that has completed
• A task can have many parents and many child dependecies
• Task channels - execute tasks based on task channel
• No memory allocations once shed is created
• Minimal dependencies
• Memory allocation and threading are users responsability
• Lifetime of data associated with tasks is users responsability
• Configurable and optional assert (fatal error) behavior
• Configurable platform dependant functions with default implementation provided
• Header only - define BIKESHED_IMPLEMENTATION in one compilation unit and include bikeshed.h

Non-features

• Cyclic dependency detection and resolving
  • API is designed to help user avoid cyclic dependecies but does not do any analisys
• Built in threading or syncronization code - API to add it is available
• Unlimited number of active tasks - currently limited to 8 388 607 active tasks
• Cancelling of tasks
• Tagging of tasks

Dependencies

Minimal dependecies with default overridable method for atomic operations.

• <stdint.h>
• <string.h>
• The default (optional) MSVC implementation depends on <Windows.h>.

Optional default methods

The default implementations for the atomic and CPU yield functions can be overridden with your own implementation by overriding the macros:

• BIKESHED_ATOMICADD Atomically adds a 32-bit signed integer to another 32-bit signed integer and returns the result
• BIKESHED_ATOMICCAS Atomically exchange a 32-bit signed integer with another 32-bit signed integer if the value to be swapped matches the provided compare value, returns the old value.
• BIKESHED_CPU_YIELD Yield CPU (mm_pause() / YieldProcessor()).

Test code dependecies

Test code has dependencies added as drop-in headers from

• https://github.com/JCash/jctest for unit test validation

Test code has dependencies added as git sub-modules from

• https://github.com/DanEngelbrecht/nadir for threading and syncronization