LogicGrowsOnTrees.Parallel.ExplorationMode

There are several tasks for which a user may wish to use LogicGrowsOnTrees, such as gathering up all the results in a tree or stopping as soon as the first result is found. Because almost all of the infrastructure required for these different modes is the same, rather than creating a different system for each mode we instead re-use the same system but pass around a mode parameter that dictates its behavior at various points as well as some of the types in the system.

ExplorationMode is defined using a GADT where each constructor has a different argument for ExplorationMode's type parameter; this was done so that type families can be used to specialized types depending on the constructor.

Types

data ExplorationMode exploration_mode where

A type indicating the mode of the exploration. Note that this is a GADT for which the type parameter is unique to each constructor in order to allow associated types to be specialized based on the value.

Unfortunately Haddock does not seem to support documenting the constructors of a GADT, so the documentation for each constructor is located at the type it is tagged with, all of which are defined after the ExplorationMode type.

Constructors

AllMode :: Monoid result => ExplorationMode (AllMode result)

FirstMode :: ExplorationMode (FirstMode result)

FoundModeUsingPull :: Monoid result => (result -> Bool) -> ExplorationMode (FoundModeUsingPull result)

FoundModeUsingPush :: Monoid result => (result -> Bool) -> ExplorationMode (FoundModeUsingPush result)

data AllMode result

Explore the entire tree and sum the results in all of the leaves.

data FirstMode result

Explore the tree until a result is found, and if so then stop.

data FoundModeUsingPull result

Explore the tree, summing the results, until a condition has been met; Pull means that each worker's results will be kept and summed locally until a request for them has been received from the supervisor, which means that there might be a period of time where the collectively found results meet the condition but the system is unaware of this as they are scattered amongst the workers.

NOTE: If you use this mode then you are responsible for ensuring that a global progress update happens on a regular basis in order to pull the results in from the workers and check to see if the condition has been met; if you do not do this then the run will not terminate until the tree has been fully explored.

data FoundModeUsingPush result

Same as FoundModeUsingPull, but pushes each result to the supervisor as it is found rather than summing them in the worker until they are requested by the supervisor, which guarantees that the system will recognize when the condition has been met as soon as final result needed was found but has the downside that if there are a large number of results needed then sending each one could be much more costly then summing them locally and sending the current total on a regular basis to the supervisor.

Type-classes

class HasExplorationMode monad

This class indicates that a monad has information about the current exploration mode tag type that can be extracted from it.

Associated Types

type ExplorationModeFor monad :: *

Instances

HasExplorationMode (ThreadsControllerMonad exploration_mode)

HasExplorationMode (WorkgroupControllerMonad inner_state exploration_mode)

HasExplorationMode (RequestQueueReader exploration_mode worker_id m)

Type families

type family ResultFor exploration_mode :: *

The result type of the tree, i.e. the type of values at the leaves.

type family ProgressFor exploration_mode :: *

The type of progress, which keeps track of how much of the tree has already been explored.

type family FinalResultFor exploration_mode :: *

The type of the final result of exploring the tree.

type family WorkerIntermediateValueFor exploration_mode :: *

The type of the intermediate value being maintained internally by the worker.

type family WorkerFinishedProgressFor exploration_mode :: *

The progress type returned by a worker that has finished.

Functions

checkpointFromIntermediateProgress :: ExplorationMode exploration_mode -> ProgressFor exploration_mode -> Checkpoint

Extracts the Checkpoint component from a progress value.

initialProgress :: ExplorationMode exploration_mode -> ProgressFor exploration_mode

The initial progress at the start of the exploration.

initialWorkerIntermediateValue :: ExplorationMode exploration_mode -> WorkerIntermediateValueFor exploration_mode

The initial intermediate value for the worker.