Distribute the GameObjects across the ExecutionGroups

[TheElectronWill]

• At most n ExecutionGroups, where n is the number of cores.
• Start n groups when Tuubes starts OR add new groups later when needed to keep up with the increasing number of GameObjects?
• Dynamically equilibrate the groups? How?
• Use "hints" to keep tightly related objects in the same group? Hints would be provided by the objects themselves.

[TheElectronWill]

Implemented solution

• See be8c7d9
• Limited number of execution groups
• If the group's update time exceeds a given value, it can split into two groups and distribute its actors between the two groups.
• If the group's update time falls below a given value, it can merge with another group and regroup the actors.
• If the group cannot split (because the maximum number of groups has been reached), it can increase its maximum update time and executes itself less frequently.
• If the group cannot merge (because there are no other group ready for a merge operation), it can decrease its maximum update time and executes itself more frequently.

ExecutionGroup parameters

Individual parameters

These parameters apply to each group separately and may vary:

• maxUpdateTime: if the group's updateTime gets bigger than maxUpdateTime, the group will be considered "heavy". It will try to split or to increase its min and maxUpdateTime.
• minUpdateTime: if the group's updateTime gets smaller than minUpdateTime, the group will be considered "tiny". It will try to merge with another tiny group or to decrease its min and maxUpdateTime.
• increaseCount (not really a parameter) = number of increases - number of decreases

Global parameters

These parameters apply to every group:

• NbMovingStats: number of time measurements to keep for statistical calculations (mean, variance)
• MaxUpdateTime0: initial maxUpdateTime; a group's maxUpdateTime can be increased above this
• MinUpdateTime0: initial minUpdateTime; a group's minUpdateTime can be increased above this
• IncreaseFactor: defines how much the minUpdateTime and maxUpdateTime are increased and decreased.
• MaxIncreaseCount: maximum increaseCount
• MaxGroupCount: maximum number of existing ExecutionGroups

[TheElectronWill]

PS: The global parameters will be defined in the configuration (wip). Administrators must ensure that 2*MinUpdateTime0 < MaxUpdateTime0, otherwise a merge operation could result in a "heavy" group that would immediately get split.