throttling

type DialThrottler interface {
	// Block until the event associated with this Acquire can happen.
	// If [ctx] is canceled, gives up and returns an error.
	Acquire(ctx context.Context) error
}

type InboundConnThrottler interface {
	// Dispatch starts this InboundConnThrottler.
	// Must be called before [Allow].
	// Blocks until [Stop] is called (i.e. should be called in a goroutine.)
	Dispatch()
	// Stop this InboundConnThrottler and causes [Dispatch] to return.
	// Should be called when we're done with this InboundConnThrottler.
	// This InboundConnThrottler must not be used after [Stop] is called.
	Stop()
	// Returns whether we should allow an inbound connection from [ipStr].
	// Must only be called after [Dispatch] has been called.
	// Must not be called after [Stop] has been called.
	Allow(ipStr string) bool
}

type InboundConnThrottlerConfig struct {
	// Allow(ipStr) returns true if it has been at least [AllowCooldown]
	// since the last time Allow(ipStr) returned true or if
	// Allow(ipStr) has never been called.
	// If <= 0, inbound connections not rate-limited.
	AllowCooldown time.Duration
	// Maximum number of inbound connections allowed within [AllowCooldown].
	// (As implemented in inboundConnThrottler, may actually allow
	// [MaxRecentConns+1] due to a race condition but that's fine.)
	// If <= 0, inbound connections not rate-limited.
	MaxRecentConns int
}

type InboundMsgThrottler interface {
	// Blocks until node [nodeID] can put a message of
	// size [msgSize] onto the incoming message buffer.
	Acquire(msgSize uint64, nodeID ids.ShortID)

	// Mark that a message from [nodeID] of size [msgSize]
	// has been removed from the incoming message buffer.
	Release(msgSize uint64, nodeID ids.ShortID)
}

type MsgThrottlerConfig struct {
	VdrAllocSize        uint64
	AtLargeAllocSize    uint64
	NodeMaxAtLargeBytes uint64
}

type OutboundMsgThrottler interface {
	// Returns true if we can queue a message of size [msgSize] to be sent to node [nodeID].
	// Returns false if the message should be dropped (not sent to [nodeID]).
	// If this method returns true, Release([msgSize], [nodeID]) must be called (!) when
	// the message is sent (or when we give up trying to send the message, if applicable.)
	// If this method returns false, do not make a corresponding call to Release.
	Acquire(msgSize uint64, nodeID ids.ShortID) bool

	// Mark that a message of size [msgSize] has been sent to [nodeID] or we have
	// given up sending the message. Must correspond to a previous call to
	// Acquire([msgSize], [nodeID]) that returned true.
	Release(msgSize uint64, nodeID ids.ShortID)
}