feat: DTail fork — server/client feature development

Squashed development of the snonux/dtail fork's product code (internal/, cmd/)
since diverging from mimecast/dtail. Major areas:

- Read/output path: the former "turbo" channel-less path is now the single,
  default server-side read/output path for cat/grep/tail and MapReduce; the old
  channel-based path and its config/env toggles were removed.
- MapReduce: single aggregate implementation (server + serverless) fed directly
  by a processor pipeline, with input-exhausted finalization via the shutdown
  coordinator; high-concurrency and data-race fixes.
- Journal source reads (journal:unit.service) via journalctl, Linux-gated behind
  a journal-v1 capability.
- Auth-key fast reconnect: in-memory per-user public-key cache with TTL/max-keys,
  registered over an authenticated session (AUTHKEY), checked before
  authorized_keys.
- Interactive query reload (--interactive-query) with SESSION START/UPDATE
  generation boundaries and capability negotiation.
- Client-side deadlines: --timeout / --shutdownAfter as context deadlines;
  follow shutdown handling.
- Client logging: diagnostics-only daily log by default, opt-in payload tee via
  --log-payload.
- Numerous correctness fixes (buffer-pool double-recycle races, EOF-sentinel
  leaks, glob-expansion cap, TOCTOU in CSV parsing) with accompanying unit tests.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

1 files changed, 71 insertions, 0 deletions

diff --git a/internal/cli/runtime_test.go b/internal/cli/runtime_test.go
new file mode 100644
index 0000000..e024a4e
--- /dev/null
+++ b/internal/cli/runtime_test.go
@@ -0,0 +1,71 @@
+package cli
+
+import (
+	"context"
+	"net/http"
+	"testing"
+	"time"
+
+	"github.com/mimecast/dtail/internal/io/dlog"
+	"github.com/mimecast/dtail/internal/profiling"
+)
+
+func TestClientRuntimeStopShutsDownPProf(t *testing.T) {
+	prevClient := dlog.Client
+	dlog.Client = &dlog.DLog{}
+	t.Cleanup(func() {
+		dlog.Client = prevClient
+	})
+
+	ctx, cancel := context.WithCancel(context.Background())
+	runtime := &ClientRuntime{
+		ctx:      ctx,
+		cancel:   cancel,
+		profiler: profiling.NewProfiler(profiling.Config{}),
+	}
+
+	runtime.StartPProf("127.0.0.1:0")
+	if runtime.pprofServer == nil {
+		t.Fatal("expected pprof server to start")
+	}
+
+	url := "http://" + runtime.pprofServer.Address() + "/debug/pprof/"
+	waitForHTTPStatus(t, url, http.StatusOK)
+
+	runtime.Stop()
+	waitForHTTPError(t, url)
+}
+
+func waitForHTTPStatus(t *testing.T, url string, want int) {
+	t.Helper()
+
+	deadline := time.Now().Add(3 * time.Second)
+	for time.Now().Before(deadline) {
+		resp, err := http.Get(url)
+		if err == nil {
+			resp.Body.Close()
+			if resp.StatusCode == want {
+				return
+			}
+		}
+		time.Sleep(10 * time.Millisecond)
+	}
+
+	t.Fatalf("timed out waiting for %s to return %d", url, want)
+}
+
+func waitForHTTPError(t *testing.T, url string) {
+	t.Helper()
+
+	deadline := time.Now().Add(3 * time.Second)
+	for time.Now().Before(deadline) {
+		resp, err := http.Get(url)
+		if err != nil {
+			return
+		}
+		resp.Body.Close()
+		time.Sleep(10 * time.Millisecond)
+	}
+
+	t.Fatalf("timed out waiting for %s to stop serving", url)
+}