Add throughput1 client library (#26)

* Add handler

* Save archival data from deferred func

* Add main, fix handler

* Add script to generate local test certs

* Add build script and Dockerfile.

* Update go.mod/go.sum

* Add basic client for testing

* Swap logger

* Swap logger in measurer, too

* Remove files that don't belong to this PR

* Remove more files that don't belong here

* go mod tidy

* Change metadata length limits

* Add access_token to the knownOptions map.

* Add partial tests and prom metrics

* Duration should be milliseconds

* Increase test coverage

* Update go.mod

* Update go.mod go.sum

* Add client code

* Merge branch 'main' into sandbox-roberto-client

* Rename ndt8 -> throughput1

* Separate network-level and application-level measurements.

This commit adds application-level measurements and namespaces to better separate
the two kind of measurements in the Measurement object.

It is a breaking change and will need a schema update.

* Fix client

* Merge branch 'main' into sandbox-roberto-client

* Merge branch 'add-application-byte-counters' into sandbox-roberto-client

* Merge branch 'temp-test' into sandbox-roberto-client

* Make output more detailed, add server-side messages

* Make application-level byte counters atomic.

* Merge branch 'add-application-byte-counters' into sandbox-roberto-client

* Merge branch 'main' into sandbox-roberto-client

* Add debug flag and simplify code

* Add -debug flag, docstrings, and call Upload() in main

* Remove unused fields

* Complete rename from NDT8 to Throughput1

* Use the same version for libraryVersion and clientVersion

(and set it to version.Version, overridden by build flags)

* Rename client to msak-client-go

* Add docstrings and use the right timeout in connect() call.

* Refactor code to extract runStream().

* Add docstrings.

* Fix race condition.

* Refactor code, only output every 100ms

* Remove extra \n from OnDebug messages

* Address code review comments

- Make client name const
- Use client package consts for flags' default values
- Use log.Fatal

* Update defaults, add comments

* Include

* Add DefaultScheme const and more docstrings

* Replace fmt.Print with Emitter.OnDebug

* Panic on invalid subtests

* Remove ServiceURL

* Move client config to a dedicated struct

* Rename client.ClientConfig to client.Config

* More refactoring and more comments/docstrings.

* Add TLSClientConfig to defaultDialer.

* Add docstrings in Emitter interface.

* Merge branch 'main' into sandbox-roberto-client

* FromTCPConn -> FromTCPLikeConn

* Panic on empty clientName/Version in client.New()

* Add comments in nextURLFromLocate and remove extra printf

cmd/msak-client/client.go

@@ -0,0 +1,56 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"log"
+
+	"github.com/google/uuid"
+	"github.com/m-lab/msak/pkg/client"
+	"github.com/m-lab/msak/pkg/version"
+)
+
+const clientName = "msak-client-go"
+
+var clientVersion = version.Version
+
+var (
+	flagServer   = flag.String("server", "", "Server address")
+	flagStreams  = flag.Int("streams", client.DefaultStreams, "Number of streams")
+	flagCC       = flag.String("cc", "bbr", "Congestion control algorithm to use")
+	flagDelay    = flag.Duration("delay", 0, "Delay between each stream")
+	flagDuration = flag.Duration("duration", client.DefaultLength, "Length of the last stream")
+	flagScheme   = flag.String("scheme", client.DefaultScheme, "Websocket scheme (wss or ws)")
+	flagMID      = flag.String("mid", uuid.NewString(), "Measurement ID to use")
+	flagNoVerify = flag.Bool("no-verify", false, "Skip TLS certificate verification")
+	flagDebug    = flag.Bool("debug", false, "Enable debug logging")
+)
+
+func main() {
+	flag.Parse()
+
+	// For a given number of streams, there will be streams-1 delays. This makes
+	// sure that all the streams can at least start with the current configuration.
+	if float64(*flagStreams-1)*flagDelay.Seconds() >= flagDuration.Seconds() {
+		log.Fatal("Invalid configuration: please check streams, delay and duration and make sure they make sense.")
+	}
+
+	config := client.Config{
+		Server:            *flagServer,
+		Scheme:            *flagScheme,
+		NumStreams:        *flagStreams,
+		CongestionControl: *flagCC,
+		Delay:             *flagDelay,
+		Length:            *flagDuration,
+		MeasurementID:     *flagMID,
+		Emitter: client.HumanReadable{
+			Debug: *flagDebug,
+		},
+		NoVerify: *flagNoVerify,
+	}
+
+	cl := client.New(clientName, clientVersion, config)
+
+	cl.Download(context.Background())
+	cl.Upload(context.Background())
+}