58 lines
2.7 KiB
Nim
58 lines
2.7 KiB
Nim
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# nim-raft
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# Copyright (c) 2023 Status Research & Development GmbH
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# Licensed under either of
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# * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
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# * MIT license ([LICENSE-MIT](LICENSE-MIT))
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# at your option.
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# This file may not be copied, modified, or distributed except according to
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# those terms.
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import std/tables
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import std/rlocks
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type
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# Define callback to use with Terminals
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ConsensusFSMCallbackType*[NodeType] = proc(node: NodeType) {.gcsafe.}
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# Define Non-Terminals as a (unique) tuples of the internal state and a sequence of callbacks
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NonTerminalSymbol*[NodeType, NodeStates] = (NodeStates, seq[ConsensusFSMCallbackType[NodeType]])
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# Define loose conditions computed from our NodeType
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Condition*[NodeType] = proc(node: NodeType): bool
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# Define Terminals as a tuple of a Event and (Hash) Table of sequences of (loose) conditions and their respective values computed from NodeType (Truth Table)
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TerminalSymbol*[NodeType, EventType] = (Table[EventType, (seq[Condition[NodeType]], seq[bool])])
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# Define State Transition Rules LUT of the form ( NonTerminal -> Terminal ) -> NonTerminal )
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StateTransitionsRulesLUT*[NodeType, EventType, NodeStates] = Table[
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(NonTerminalSymbol[NodeType, NodeStates], TerminalSymbol[NodeType, EventType]),
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NonTerminalSymbol[NodeType, NodeStates]]
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# FSM type definition
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ConsensusFSM*[NodeType, EventType, NodeStates] = ref object
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mtx: RLock
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state: NonTerminalSymbol[NodeType, NodeStates]
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stateTransitionsLUT: StateTransitionsRulesLUT[NodeType, EventType, NodeStates]
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# FSM type constructor
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proc new*[NodeType, EventType, NodeStates](T: type ConsensusFSM[NodeType, EventType, NodeStates],
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lut: StateTransitionsRulesLUT[NodeType, EventType, NodeStates],
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startSymbol: NonTerminalSymbol[NodeType, NodeStates]
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): T =
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result = new(ConsensusFSM[NodeType, EventType, NodeStates])
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initRLock(result.mtx)
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result.state = startSymbol
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result.stateTransitionsLUT = lut
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proc computeFSMInputRobustLogic[NodeType, EventType](node: NodeType, event: EventType, rawInput: TerminalSymbol[NodeType, EventType]):
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TerminalSymbol[NodeType, EventType] =
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var
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robustLogicEventTerminal = rawInput[event]
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for f, v in robustLogicEventTerminal:
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v = f(node)
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rawInput[event] = robustLogicEventTerminal
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result = rawInput
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proc consensusFSMAdvance[NodeType, EventType, NodeStates](fsm: ConsensusFSM[NodeType, EventType, NodeStates], node: NodeType, event: EventType,
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rawInput: TerminalSymbol[NodeType, EventType]): NonTerminalSymbol[NodeType, NodeStates] =
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withRLock():
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var
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input = computeFSMInputRobustLogic(node, event, rawInput)
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fsm.state = fsm.stateTransitionsLUT[fsm.state, input]
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result = fsm.state
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