agent

type Agent interface {
	// GetCall will return a Call that is executable by the Agent, which
	// can be built via various CallOpt's provided to the method.
	GetCall(...CallOpt) (Call, error)

	// Submit will attempt to execute a call locally, a Call may store information
	// about itself in its Start and End methods, which will be called in Submit
	// immediately before and after the Call is executed, respectively. An error
	// will be returned if there is an issue executing the call or the error
	// may be from the call's execution itself (if, say, the container dies,
	// or the call times out).
	Submit(Call) error

	// Close will wait for any outstanding calls to complete and then exit.
	// Close is not safe to be called from multiple threads.
	io.Closer

	// Stats should be burned at the stake. adding so as to not ruffle feathers.
	// TODO this should be derived from our metrics
	Stats() Stats

	// Return the http.Handler used to handle Prometheus metric requests
	PromHandler() http.Handler
	AddCallListener(extensions.CallListener)
}

type Call interface {
	// Model will return the underlying models.Call configuration for this call.
	// TODO we could respond to async correctly from agent but layering, this
	// is only because the front end has different responses based on call type.
	// try to discourage use elsewhere until this gets pushed down more...
	Model() *models.Call

	// Start will be called before this call is executed, it may be used to
	// guarantee mutual exclusion, check docker permissions, update timestamps,
	// etc.
	// TODO Start and End can likely be unexported as they are only used in the agent,
	// and on a type which is constructed in a specific agent. meh.
	Start(ctx context.Context, t callTrigger) error

	// End will be called immediately after attempting a call execution,
	// regardless of whether the execution failed or not. An error will be passed
	// to End, which if nil indicates a successful execution. Any error returned
	// from End will be returned as the error from Submit.
	End(ctx context.Context, err error, t callTrigger) error
}

type CallOpt func(a *agent, c *call) error

type FunctionStats struct {
	Queue    uint64
	Running  uint64
	Complete uint64
	Failed   uint64
}

type Handle func(http.ResponseWriter, *http.Request, Params)

type Param struct {
	Key   string
	Value string
}

type Params []Param

type Stats struct {
	// statistics for all functions combined
	Queue    uint64
	Running  uint64
	Complete uint64
	Failed   uint64
	// statistics for individual functions, keyed by function path
	FunctionStatsMap map[string]*FunctionStats
}

type Token interface {
	// Close must be called by any thread that receives a token.
	io.Closer
}