Documentation
¶
Index ¶
- Variables
- type Field
- type FieldCallback
- type Flags
- func (a Flags) And(b Flags) Flags
- func (a Flags) AndNot(b Flags) Flags
- func (a Flags) Equals(b Flags) bool
- func (a Flags) HasAll(b Flags) bool
- func (a Flags) HasNone(b Flags) bool
- func (a Flags) IsEmpty() bool
- func (a Flags) Or(b Flags) Flags
- func (f Flags) String() string
- func (a Flags) Xor(b Flags) Flags
- type NodeStateMachine
- func (ns *NodeStateMachine) AddLogMetrics(requireFlags, disableFlags Flags, name string, inMeter, outMeter metrics.Meter, ...)
- func (ns *NodeStateMachine) AddTimeout(n *enode.Node, flags Flags, timeout time.Duration) error
- func (ns *NodeStateMachine) ForEach(requireFlags, disableFlags Flags, cb func(n *enode.Node, state Flags))
- func (ns *NodeStateMachine) GetField(n *enode.Node, field Field) interface{}
- func (ns *NodeStateMachine) GetNode(id enode.ID) *enode.Node
- func (ns *NodeStateMachine) Operation(fn func()) error
- func (ns *NodeStateMachine) Persist(n *enode.Node) error
- func (ns *NodeStateMachine) SetField(n *enode.Node, field Field, value interface{}) error
- func (ns *NodeStateMachine) SetFieldSub(n *enode.Node, field Field, value interface{}) error
- func (ns *NodeStateMachine) SetState(n *enode.Node, setFlags, resetFlags Flags, timeout time.Duration) error
- func (ns *NodeStateMachine) SetStateSub(n *enode.Node, setFlags, resetFlags Flags, timeout time.Duration)
- func (ns *NodeStateMachine) Start()
- func (ns *NodeStateMachine) Stop()
- func (ns *NodeStateMachine) SubscribeField(field Field, callback FieldCallback)
- func (ns *NodeStateMachine) SubscribeState(flags Flags, callback StateCallback)
- type Setup
- func (s *Setup) NewField(name string, ftype reflect.Type) Field
- func (s *Setup) NewFlag(name string) Flags
- func (s *Setup) NewPersistentField(name string, ftype reflect.Type, encode func(interface{}) ([]byte, error), ...) Field
- func (s *Setup) NewPersistentFlag(name string) Flags
- func (s *Setup) OfflineFlag() Flags
- type StateCallback
Constants ¶
This section is empty.
Variables ¶
var ( ErrInvalidField = errors.New("invalid field type") ErrClosed = errors.New("already closed") )
Functions ¶
This section is empty.
Types ¶
type Field ¶
type Field struct {
// contains filtered or unexported fields
}
Field represents a field from a certain setup
type FieldCallback ¶
FieldCallback is a subscription callback which is called when the value of a specific field is changed.
type Flags ¶
type Flags struct {
// contains filtered or unexported fields
}
Flags represents a set of flags from a certain setup
func MergeFlags ¶
MergeFlags merges multiple sets of state flags
type NodeStateMachine ¶
type NodeStateMachine struct {
// contains filtered or unexported fields
}
NodeStateMachine implements a network node-related event subscription system. It can assign binary state flags and fields of arbitrary type to each node and allows subscriptions to flag/field changes which can also modify further flags and fields, potentially triggering further subscriptions. An operation includes an initial change and all resulting subsequent changes and always ends in a consistent global state. It is initiated by a "top level" SetState/SetField call that blocks (also blocking other top-level functions) until the operation is finished. Callbacks making further changes should use the non-blocking SetStateSub/SetFieldSub functions. The tree of events resulting from the initial changes is traversed in a breadth-first order, ensuring for each subscription callback that all other callbacks caused by the same change triggering the current callback are processed before anything is triggered by the changes made in the current callback. In practice this logic ensures that all subscriptions "see" events in the logical order, callbacks are never called concurrently and "back and forth" effects are also possible. The state machine design should ensure that infinite event cycles cannot happen. The caller can also add timeouts assigned to a certain node and a subset of state flags. If the timeout elapses, the flags are reset. If all relevant flags are reset then the timer is dropped. State flags with no timeout are persisted in the database if the flag descriptor enables saving. If a node has no state flags set at any moment then it is discarded. Note: in order to avoid mutex deadlocks the callbacks should never lock a mutex that might be locked when the top level SetState/SetField functions are called. If a function potentially performs state/field changes then it is recommended to mention this fact in the function description, along with whether it should run inside an operation callback.
func NewNodeStateMachine ¶
func NewNodeStateMachine(db ethdb.KeyValueStore, dbKey []byte, clock mclock.Clock, setup *Setup) *NodeStateMachine
NewNodeStateMachine creates a new node state machine. If db is not nil then the node states, fields and active timeouts are persisted. Persistence can be enabled or disabled for each state flag and field.
func (*NodeStateMachine) AddLogMetrics ¶
func (ns *NodeStateMachine) AddLogMetrics(requireFlags, disableFlags Flags, name string, inMeter, outMeter metrics.Meter, gauge metrics.Gauge)
AddLogMetrics adds logging and/or metrics for nodes entering, exiting and currently being in a given set specified by required and disabled state flags
func (*NodeStateMachine) AddTimeout ¶
AddTimeout adds a node state timeout associated to the given state flag(s). After the specified time interval, the relevant states will be reset.
func (*NodeStateMachine) ForEach ¶
func (ns *NodeStateMachine) ForEach(requireFlags, disableFlags Flags, cb func(n *enode.Node, state Flags))
ForEach calls the callback for each node having all of the required and none of the disabled flags set. Note that this callback is not an operation callback but ForEach can be called from an Operation callback or Operation can also be called from a ForEach callback if necessary.
func (*NodeStateMachine) GetField ¶
func (ns *NodeStateMachine) GetField(n *enode.Node, field Field) interface{}
GetField retrieves the given field of the given node. Note that when used in a subscription callback the result can be out of sync with the state change represented by the callback parameters so extra safety checks might be necessary.
func (*NodeStateMachine) GetNode ¶
func (ns *NodeStateMachine) GetNode(id enode.ID) *enode.Node
GetNode returns the enode currently associated with the given ID
func (*NodeStateMachine) Operation ¶ added in v0.7.0
func (ns *NodeStateMachine) Operation(fn func()) error
Operation calls the given function as an operation callback. This allows the caller to start an operation with multiple initial changes. The same rules apply as for subscription callbacks.
func (*NodeStateMachine) Persist ¶
func (ns *NodeStateMachine) Persist(n *enode.Node) error
Persist saves the persistent state and fields of the given node immediately
func (*NodeStateMachine) SetField ¶
func (ns *NodeStateMachine) SetField(n *enode.Node, field Field, value interface{}) error
SetField sets the given field of the given node and blocks until the operation is finished
func (*NodeStateMachine) SetFieldSub ¶ added in v0.7.0
func (ns *NodeStateMachine) SetFieldSub(n *enode.Node, field Field, value interface{}) error
SetFieldSub sets the given field of the given node without blocking (should be called from a subscription/operation callback).
func (*NodeStateMachine) SetState ¶
func (ns *NodeStateMachine) SetState(n *enode.Node, setFlags, resetFlags Flags, timeout time.Duration) error
SetState updates the given node state flags and blocks until the operation is finished. If a flag with a timeout is set again, the operation removes or replaces the existing timeout.
func (*NodeStateMachine) SetStateSub ¶ added in v0.7.0
func (ns *NodeStateMachine) SetStateSub(n *enode.Node, setFlags, resetFlags Flags, timeout time.Duration)
SetStateSub updates the given node state flags without blocking (should be called from a subscription/operation callback).
func (*NodeStateMachine) Start ¶
func (ns *NodeStateMachine) Start()
Start starts the state machine, enabling state and field operations and disabling further subscriptions.
func (*NodeStateMachine) Stop ¶
func (ns *NodeStateMachine) Stop()
Stop stops the state machine and saves its state if a database was supplied
func (*NodeStateMachine) SubscribeField ¶
func (ns *NodeStateMachine) SubscribeField(field Field, callback FieldCallback)
SubscribeField adds a node field subscription. Same rules apply as for SubscribeState.
func (*NodeStateMachine) SubscribeState ¶
func (ns *NodeStateMachine) SubscribeState(flags Flags, callback StateCallback)
SubscribeState adds a node state subscription. The callback is called while the state machine mutex is not held and it is allowed to make further state updates using the non-blocking SetStateSub/SetFieldSub functions. All callbacks of an operation are running from the thread/goroutine of the initial caller and parallel operations are not permitted. Therefore the callback is never called concurrently. It is the responsibility of the implemented state logic to avoid deadlocks and to reach a stable state in a finite amount of steps. State subscriptions should be installed before loading the node database or making the first state update.
type Setup ¶
type Setup struct { Version uint // contains filtered or unexported fields }
stateSetup contains the list of flags and fields used by the application
func (*Setup) NewPersistentField ¶
func (s *Setup) NewPersistentField(name string, ftype reflect.Type, encode func(interface{}) ([]byte, error), decode func([]byte) (interface{}, error)) Field
NewPersistentField creates a new persistent node field
func (*Setup) NewPersistentFlag ¶
NewPersistentFlag creates a new persistent node state flag
func (*Setup) OfflineFlag ¶
OfflineFlag returns the system-defined offline flag belonging to the given setup
type StateCallback ¶
StateCallback is a subscription callback which is called when one of the state flags that is included in the subscription state mask is changed. Note: oldState and newState are also masked with the subscription mask so only the relevant bits are included.