Periodically print simulator progress. (ServiceWeaver#620)

With this PR, a simulator periodically prints out its progress, just
like with Go's fuzz testing. This is important to make sure the user
knows the simulation isn't stuck.

```
$ go test -run=Passing/NoCallsNoGen -v
=== RUN   TestPassingSimulations
=== RUN   TestPassingSimulations/NoCallsNoGen
    simulator.go:390: Simulating *sim.noCallsNoGenWorkload for 10s with 1280 executors...
    simulator.go:405: [1s] 60,520 execs (60,064 execs/s), 4,207,853 ops (4,176,166 ops/s)
    simulator.go:405: [2s] 91,122 execs (45,390 execs/s), 9,494,404 ops (4,729,368 ops/s)
    simulator.go:405: [3s] 116,070 execs (38,594 execs/s), 15,377,846 ops (5,113,218 ops/s)
    simulator.go:405: [4s] 136,944 execs (34,175 execs/s), 21,386,940 ops (5,337,185 ops/s)
    simulator.go:405: [5s] 155,343 execs (31,024 execs/s), 27,506,001 ops (5,493,331 ops/s)
    simulator.go:405: [6s] 172,306 execs (28,681 execs/s), 33,831,171 ops (5,631,418 ops/s)
    simulator.go:405: [7s] 187,752 execs (26,794 execs/s), 40,157,529 ops (5,730,931 ops/s)
    simulator.go:405: [8s] 201,803 execs (25,203 execs/s), 46,384,348 ops (5,792,803 ops/s)
    simulator.go:405: [9s] 215,544 execs (23,930 execs/s), 52,909,102 ops (5,874,082 ops/s)
```

go.mod

@@ -26,6 +26,7 @@ require (
  golang.org/x/image v0.5.0
  golang.org/x/sync v0.3.0
  golang.org/x/term v0.10.0
+ golang.org/x/text v0.9.0
  golang.org/x/tools v0.11.0
  google.golang.org/genproto/googleapis/api v0.0.0-20230717213848-3f92550aa753
  google.golang.org/protobuf v1.31.0
@@ -48,7 +49,6 @@ require (
  go.opentelemetry.io/otel/metric v1.16.0 // indirect
  golang.org/x/mod v0.12.0 // indirect
  golang.org/x/sys v0.10.0 // indirect
- golang.org/x/text v0.9.0 // indirect
  google.golang.org/genproto/googleapis/rpc v0.0.0-20230706204954-ccb25ca9f130 // indirect
  lukechampine.com/uint128 v1.2.0 // indirect
  modernc.org/cc/v3 v3.40.0 // indirect

godeps.txt

@@ -283,6 +283,8 @@ github.com/ServiceWeaver/weaver/internal/sim
  go.opentelemetry.io/otel/trace
  golang.org/x/exp/maps
  golang.org/x/sync/errgroup
+ golang.org/x/text/language
+ golang.org/x/text/message
  log/slog
  math/bits
  math/rand

internal/sim/simulator.go

@@ -43,6 +43,8 @@ import (
  "github.com/ServiceWeaver/weaver/runtime/logging"
  "github.com/ServiceWeaver/weaver/runtime/protos"
  "golang.org/x/exp/maps"
+ "golang.org/x/text/language"
+ "golang.org/x/text/message"
 )
 
 // FakeComponent is a copy of weavertest.FakeComponent. It's needed to access
@@ -381,6 +383,30 @@ func (s *Simulator) Run(duration time.Duration) Results {
  }
  }()
 
+ // Spawn a goroutine to periodically print progress.
+ done.Add(1)
+ go func() {
+ defer done.Done()
+ s.t.Logf("Simulating %v for %v with %d executors...", s.w, duration, n)
+ printer := message.NewPrinter(language.AmericanEnglish)
+ ticker := time.NewTicker(time.Second)
+ for {
+ select {
+ case <-ctx.Done():
+ ticker.Stop()
+ return
+ case <-ticker.C:
+ execs := atomic.LoadInt64(&numExecutions)
+ ops := atomic.LoadInt64(&numOps)
+ elapsed := time.Since(start)
+ truncated := elapsed.Truncate(time.Second)
+ execRate := printer.Sprintf("%0.0f", float64(execs)/elapsed.Seconds())
+ opRate := printer.Sprintf("%0.0f", float64(ops)/elapsed.Seconds())
+ s.t.Logf("[%v] %s execs (%s execs/s), %s ops (%s ops/s)", truncated, printer.Sprint(execs), execRate, printer.Sprint(ops), opRate)
+ }
+ }
+ }()
+
  select {
  case err := <-errs:
  // An execution failed to execute properly.
@@ -411,13 +437,15 @@ func (s *Simulator) Run(duration time.Duration) Results {
 // Summary returns a human readable summary of the results.
 func (r *Results) Summary() string {
  duration := r.Duration.Truncate(time.Millisecond)
- simRate := float64(r.NumExecutions) / r.Duration.Seconds()
- opRate := float64(r.NumOps) / r.Duration.Seconds()
+ printer := message.NewPrinter(language.AmericanEnglish)
+ execRate := printer.Sprintf("%0.2f", float64(r.NumExecutions)/r.Duration.Seconds())
+ opRate := printer.Sprintf("%0.2f", float64(r.NumOps)/r.Duration.Seconds())
  prefix := "✅ No errors"
  if r.Err != nil {
  prefix = "❌ Error"
  }
- return fmt.Sprintf("%s found after %d ops across %d executions in %v (%0.2f execs/s, %0.2f ops/s).", prefix, r.NumOps, r.NumExecutions, duration, simRate, opRate)
+ return fmt.Sprintf("%s found after %s ops across %s executions in %v (%s execs/s, %s ops/s).",
+ prefix, printer.Sprint(r.NumOps), printer.Sprint(r.NumExecutions), duration, execRate, opRate)
 }
 
 // Mermaid returns a [mermaid] diagram that illustrates an execution history.