ooni-probe-cli/internal/engine/model/experiment.go
Simone Basso ff1c170562
feat(engine): allow runner to return many measurements (#527)
This is required to implement websteps, which is currently tracked
by https://github.com/ooni/probe/issues/1733.

We introduce the concept of async runner. An async runner will
post measurements on a channel until it is done. When it is done,
it will close the channel to notify the reader about that.

This change causes sync experiments now to strictly return either
a non-nil measurement or a non-nil error.

While this is a pretty much obvious situation in golang, we had
some parts of the codebase that were not robust to this assumption
and attempted to submit a measurement after the measure call
returned an error.

Luckily, we had enough tests to catch this change in our assumption
and this is why there are extra docs and tests changes.
2021-09-30 00:54:52 +02:00

110 lines
3.6 KiB
Go

package model
import (
"context"
"net/http"
)
// ExperimentSession is the experiment's view of a session.
type ExperimentSession interface {
GetTestHelpersByName(name string) ([]Service, bool)
DefaultHTTPClient() *http.Client
FetchPsiphonConfig(ctx context.Context) ([]byte, error)
FetchTorTargets(ctx context.Context, cc string) (map[string]TorTarget, error)
FetchURLList(ctx context.Context, config URLListConfig) ([]URLInfo, error)
Logger() Logger
ProbeCC() string
ResolverIP() string
TempDir() string
TorArgs() []string
TorBinary() string
UserAgent() string
}
// ExperimentAsyncTestKeys is the type of test keys returned by an experiment
// when running in async fashion rather than in sync fashion.
type ExperimentAsyncTestKeys struct {
// MeasurementRuntime is the total measurement runtime.
MeasurementRuntime float64
// TestKeys contains the actual test keys.
TestKeys interface{}
// Extensions contains the extensions used by this experiment.
Extensions map[string]int64
}
// ExperimentMeasurerAsync is a measurer that can run in async fashion.
//
// Currently this functionality is optional, but we will likely
// migrate all experiments to use this functionality in 2022.
type ExperimentMeasurerAsync interface {
// RunAsync runs the experiment in async fashion.
//
// Arguments:
//
// - ctx is the context for deadline/timeout/cancellation
//
// - sess is the measurement session
//
// - input is the input URL to measure
//
// - callbacks contains the experiment callbacks
//
// Returns either a channel where TestKeys are posted or an error.
//
// An error indicates that specific preconditions for running the experiment
// are not met (e.g., the input URL is invalid).
//
// On success, the experiment will post on the channel each new
// measurement until it is done and closes the channel.
RunAsync(ctx context.Context, sess ExperimentSession, input string,
callbacks ExperimentCallbacks) (<-chan *ExperimentAsyncTestKeys, error)
}
// ExperimentCallbacks contains experiment event-handling callbacks
type ExperimentCallbacks interface {
// OnProgress provides information about an experiment progress.
OnProgress(percentage float64, message string)
}
// PrinterCallbacks is the default event handler
type PrinterCallbacks struct {
Logger
}
// NewPrinterCallbacks returns a new default callback handler
func NewPrinterCallbacks(logger Logger) PrinterCallbacks {
return PrinterCallbacks{Logger: logger}
}
// OnProgress provides information about an experiment progress.
func (d PrinterCallbacks) OnProgress(percentage float64, message string) {
d.Logger.Infof("[%5.1f%%] %s", percentage*100, message)
}
// ExperimentMeasurer is the interface that allows to run a
// measurement for a specific experiment.
type ExperimentMeasurer interface {
// ExperimentName returns the experiment name.
ExperimentName() string
// ExperimentVersion returns the experiment version.
ExperimentVersion() string
// Run runs the experiment with the specified context, session,
// measurement, and experiment calbacks. This method should only
// return an error in case the experiment could not run (e.g.,
// a required input is missing). Otherwise, the code should just
// set the relevant OONI error inside of the measurement and
// return nil. This is important because the caller may not submit
// the measurement if this method returns an error.
Run(
ctx context.Context, sess ExperimentSession,
measurement *Measurement, callbacks ExperimentCallbacks,
) error
// GetSummaryKeys returns summary keys expected by ooni/probe-cli.
GetSummaryKeys(*Measurement) (interface{}, error)
}