Terms and Conventions

This chapter describes Argobots terms, conventions, and data types used throughout this document.

• Glossary
• Conventions
  • Naming Convention
  • API Convention
• Data Types
  • Object Types
  • Scalar Types
  • Other Types
• Null Objects
• Constants
• Error Classes

Glossary

• Condition Variable: a condition on which ULTs are waiting until it is signaled.
• Execution Stream (ES): a sequential instruction stream that contains one or more work units.
• Future: a mechanism for passing a value between work units, allowing a work unit to wait for a value that is set asynchronously.
• Handle: an opaque reference to an Argobots object.
• Mutex: a synchronization method to support mutual exclusion between work units.
• Object: abstract representation of resources that are manipulated by the Argobots API. For example, there are ES objects, ULT objects, tasklet objects, etc.
• Pool: a data structure that contains scheduling units.
• Scheduler: an object that controls execution order of scheduling units in the ES. A scheduler is associated with an ES.
• Scheduling Unit (SU): an object handled by a scheduler with a scheduling policy. It includes work units, such as ULTs or tasklets, and schedulers.
• Tasklet: an indivisible unit of work, with dependence only on its input data, and typically providing output data upon completion. Tasklet is associated with a function but it does not have its own stack. It is not allowed to make blocking calls and does not explicitly yield control.
• User-level Thread (ULT): an independent execution unit in user space. It is associated with a function and its own stack. ULTs provide standard thread semantics at a very low context-switching cost. ULTs can make blocking calls and explicitly yield control.
• Work Unit (WU): a lightweight execution unit, such as ULT or tasklet.

Conventions

Naming Convention

In Argobots, all names including data types, constants, and APIs begin with ABT_ prefix. Following name after ABT_ prefix for data types and APIs is all lower-case, but constants use all capital letters.

API Convention

int ABT_xxx()

All public APIs begin with ABT_ prefix and return an error code of int type. xxx is lower-case. The arguments of Argobots APIs in this document are marked as [in], [out], [in,out] to indicate how they are used during execution of the routine. Their meanings are:

• [in]: the argument is used as the input and it is not updated during execution of the routine.
• [out]: the argument is used as the output and it is updated in the routine.
• [in,out]: the argument is used as both the input and the output.

Data Types

Object Types

All Argobots objects are opaque to users and can only be accessed via handles. All public APIs use handles or pointers to handles.

Scalar Types

Other Types

Null Objects

The following constants are defined to indicate handles to null objects for some public data types.

Constants

Error Classes