Documentation
¶
Index ¶
- Variables
- func WriteComponent(cn *ComponentNode, debugInfo bool) *hclwrite.Block
- type ComponentGlobals
- type ComponentID
- type ComponentNode
- func (cn *ComponentNode) Arguments() component.Arguments
- func (cn *ComponentNode) CurrentHealth() component.Health
- func (cn *ComponentNode) DebugInfo() interface{}
- func (cn *ComponentNode) Evaluate(ectx *hcl.EvalContext) error
- func (cn *ComponentNode) Exports() component.Exports
- func (cn *ComponentNode) ID() ComponentID
- func (cn *ComponentNode) NodeID() string
- func (cn *ComponentNode) Run(ctx context.Context) error
- func (cn *ComponentNode) UpdateBlock(b *hcl.Block)
- type Loader
- func (l *Loader) Apply(parentContext *hcl.EvalContext, blocks hcl.Blocks) hcl.Diagnostics
- func (l *Loader) Components() []*ComponentNode
- func (l *Loader) EvaluateDependencies(parentContext *hcl.EvalContext, c *ComponentNode)
- func (l *Loader) Graph() *dag.Graph
- func (l *Loader) WriteBlocks(debugInfo bool) []*hclwrite.Block
- type Queue
- type Reference
- type RunnableNode
- type Scheduler
Constants ¶
This section is empty.
Variables ¶
var ErrUnevaluated = errors.New("managed component not built")
ErrUnevaluated is returned if ComponentNode.Run is called before a managed component is built.
Functions ¶
func WriteComponent ¶
func WriteComponent(cn *ComponentNode, debugInfo bool) *hclwrite.Block
WriteComponent generates an hclwrite Block from a component. Health and debug info will be included if debugInfo is true.
Types ¶
type ComponentGlobals ¶
type ComponentGlobals struct {
Logger log.Logger // Logger shared between all managed components.
DataPath string // Shared directory where component data may be stored
OnExportsChange func(cn *ComponentNode) // Invoked when the managed component updated its exports
}
ComponentGlobals are used by ComponentNodes to build managed components. All ComponentNodes should use the same ComponentGlobals.
type ComponentID ¶
type ComponentID []string
ComponentID is a fully-qualified name of a component. Each element in ComponentID corresponds to a fragment of the period-delimited string; "remote.http.example" is ComponentID{"remote", "http", "example"}.
func BlockComponentID ¶
func BlockComponentID(b *hcl.Block) ComponentID
BlockComponentID returns the ComponentID specified by an HCL block.
func (ComponentID) Equals ¶
func (id ComponentID) Equals(other ComponentID) bool
Equals returns true if id == other.
func (ComponentID) String ¶
func (id ComponentID) String() string
String returns the string representation of a component ID.
type ComponentNode ¶
type ComponentNode struct {
// contains filtered or unexported fields
}
ComponentNode is a controller node which manages a user-defined component.
ComponentNode manages the underlying component and caches its current arguments and exports. ComponentNode manages the arguments for the component from an HCL block.
func NewComponentNode ¶
func NewComponentNode(globals ComponentGlobals, b *hcl.Block) *ComponentNode
NewComponentNode creates a new ComponentNode from an initial hcl.Block. The underlying managed component isn't created until Evaluate is called.
func (*ComponentNode) Arguments ¶
func (cn *ComponentNode) Arguments() component.Arguments
Arguments returns the current arguments of the managed component.
func (*ComponentNode) CurrentHealth ¶
func (cn *ComponentNode) CurrentHealth() component.Health
CurrentHealth returns the current health of the ComponentNode.
The health of a ComponentNode is tracked from three parts, in descending precedence order:
- Exited health from a call to Run()
- Unhealthy status from last call to Evaluate
- Health reported by the managed component (if any)
- Latest health from Run() or Evaluate(), if the managed component does not report health.
func (*ComponentNode) DebugInfo ¶
func (cn *ComponentNode) DebugInfo() interface{}
DebugInfo returns debugging information from the managed component (if any).
func (*ComponentNode) Evaluate ¶
func (cn *ComponentNode) Evaluate(ectx *hcl.EvalContext) error
Evaluate updates the arguments for the managed component by re-evaluating its HCL block with the provided evaluation context. The managed component will be built the first time Evaluate is called.
Evaluate will return an error if the HCL block cannot be evaluated or if decoding to arguments fails.
func (*ComponentNode) Exports ¶
func (cn *ComponentNode) Exports() component.Exports
Exports returns the current set of exports from the managed component. Exports returns nil if the managed component does not have exports.
func (*ComponentNode) ID ¶
func (cn *ComponentNode) ID() ComponentID
ID returns the component ID of the managed component from its HCL block.
func (*ComponentNode) NodeID ¶
func (cn *ComponentNode) NodeID() string
NodeID implements dag.Node and returns the unique ID for this node. The NodeID is the string representation of the component's ID from its HCL block.
func (*ComponentNode) Run ¶
func (cn *ComponentNode) Run(ctx context.Context) error
Run runs the managed component in the calling goroutine until ctx is canceled. Evaluate must have been called at least once without retuning an error before calling Run.
Run will immediately return ErrUnevaluated if Evaluate has never been called successfully. Otherwise, Run will return nil.
func (*ComponentNode) UpdateBlock ¶
func (cn *ComponentNode) UpdateBlock(b *hcl.Block)
UpdateBlock updates the HCL block used to construct arguments for the managed component. The new block isn't used until the next time Evaluate is invoked.
UpdateBlock will panic if the block does not match the component ID of the ComponentNode.
type Loader ¶
type Loader struct {
// contains filtered or unexported fields
}
The Loader builds and evaluates ComponentNodes from HCL blocks.
func NewLoader ¶
func NewLoader(globals ComponentGlobals) *Loader
NewLoader creates a new Loader. Components built by the Loader will be built with co for their options.
func (*Loader) Apply ¶
func (l *Loader) Apply(parentContext *hcl.EvalContext, blocks hcl.Blocks) hcl.Diagnostics
Apply loads a new set of components into the Loader. Apply will drop any previously loaded component which is not described in the set of HCL blocks.
Apply will reuse existing components if there is an existing component which matches the component ID specified by any of the provided HCL blocks. Reused components will be updated to point at the new HCL block.
Apply will perform an evaluation of all loaded components before returning. The provided parentContext can be used to provide global variables and functions to components. A child context will be constructed from the parent to expose values of other components.
func (*Loader) Components ¶
func (l *Loader) Components() []*ComponentNode
Components returns the current set of loaded components.
func (*Loader) EvaluateDependencies ¶
func (l *Loader) EvaluateDependencies(parentContext *hcl.EvalContext, c *ComponentNode)
EvaluateDependencies re-evaluates components which depend directly or indirectly on c. EvaluateDependencies should be called whenever a component updates its exports.
The provided parentContext can be used to provide global variables and functions to components. A child context will be constructed from the parent to expose values of other components.
func (*Loader) WriteBlocks ¶
WriteBlocks returns a set of evaluated hclwrite blocks for each loaded component. Components are returned in the order they were supplied to Apply (i.e., the original order from the config file) and not topological order.
Blocks will include health and debug information if debugInfo is true.
type Queue ¶
type Queue struct {
// contains filtered or unexported fields
}
Queue is an unordered queue of components.
Queue is intended for tracking components that have updated their Exports for later reevaluation.
func (*Queue) Chan ¶
func (q *Queue) Chan() <-chan struct{}
Chan returns a channel which is written to when the queue is non-empty.
func (*Queue) Enqueue ¶
func (q *Queue) Enqueue(c *ComponentNode)
Enqueue inserts a new component into the Queue. Enqueue is a no-op if the component is already in the Queue.
func (*Queue) TryDequeue ¶
func (q *Queue) TryDequeue() *ComponentNode
TryDequeue dequeues a randomly queued component. TryDequeue will return nil if the queue is empty.
type Reference ¶
type Reference struct {
Target *ComponentNode // Component being referenced
// Traversal describes which field within Target is being accessed. It is
// relative to Target and not an absolute Traversal.
Traversal hcl.Traversal
}
Reference describes an HCL expression reference to a ComponentNode.
func ComponentReferences ¶
func ComponentReferences(cn *ComponentNode, g *dag.Graph) ([]Reference, hcl.Diagnostics)
ComponentReferences returns the list of references a component is making to other components.
type RunnableNode ¶
RunnableNode is any dag.Node which can also be ran.
type Scheduler ¶
type Scheduler struct {
// contains filtered or unexported fields
}
Scheduler runs components.
func NewScheduler ¶
func NewScheduler() *Scheduler
NewScheduler creates a new Scheduler. Call Synchronize to manage the set of components which are running.
Call Close to stop the Scheduler and all running components.
func (*Scheduler) Close ¶
Close stops the Scheduler and returns after all running goroutines have exited.
func (*Scheduler) Synchronize ¶
func (s *Scheduler) Synchronize(rr []RunnableNode) error
Synchronize synchronizes the running components to those defined by rr.
New RunnableNodes will be launched as new goroutines. RunnableNodes already managed by Scheduler will be kept running, while running RunnableNodes that are not in rr will be shut down and removed.
Existing components will be restarted if they stopped since the previous call to Synchronize.
Source Files