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, 147 insertions, 0 deletions

diff --git a/internal/mapr/safe_aggregateset_test.go b/internal/mapr/safe_aggregateset_test.go
new file mode 100644
index 0000000..327987a
--- /dev/null
+++ b/internal/mapr/safe_aggregateset_test.go
@@ -0,0 +1,147 @@
+package mapr
+
+import (
+	"sync"
+	"testing"
+)
+
+// TestSafeAggregateSetConcurrency tests that SafeAggregateSet handles concurrent operations correctly.
+func TestSafeAggregateSetConcurrency(t *testing.T) {
+	safeSet := NewSafeAggregateSet()
+	
+	// Number of concurrent goroutines
+	numGoroutines := 100
+	// Number of operations per goroutine
+	opsPerGoroutine := 1000
+	
+	var wg sync.WaitGroup
+	wg.Add(numGoroutines)
+	
+	// Launch concurrent goroutines
+	for i := 0; i < numGoroutines; i++ {
+		go func(id int) {
+			defer wg.Done()
+			
+			for j := 0; j < opsPerGoroutine; j++ {
+				// Test Count operation
+				err := safeSet.Aggregate("count", Count, "1", false)
+				if err != nil {
+					t.Errorf("Error in Count aggregation: %v", err)
+				}
+				
+				// Test Sum operation
+				err = safeSet.Aggregate("sum", Sum, "10.5", false)
+				if err != nil {
+					t.Errorf("Error in Sum aggregation: %v", err)
+				}
+				
+				// Test Last operation
+				err = safeSet.Aggregate("last", Last, "value", false)
+				if err != nil {
+					t.Errorf("Error in Last aggregation: %v", err)
+				}
+				
+				// Test Min operation
+				err = safeSet.Aggregate("min", Min, "5.0", false)
+				if err != nil {
+					t.Errorf("Error in Min aggregation: %v", err)
+				}
+				
+				// Test Max operation
+				err = safeSet.Aggregate("max", Max, "15.0", false)
+				if err != nil {
+					t.Errorf("Error in Max aggregation: %v", err)
+				}
+				
+				// Increment samples
+				safeSet.IncrementSamples()
+			}
+		}(i)
+	}
+	
+	// Wait for all goroutines to complete
+	wg.Wait()
+	
+	// Verify results
+	clone := safeSet.Clone()
+	
+	// Check Count
+	expectedCount := float64(numGoroutines * opsPerGoroutine)
+	if clone.FValues["count"] != expectedCount {
+		t.Errorf("Expected count %f, got %f", expectedCount, clone.FValues["count"])
+	}
+	
+	// Check Sum
+	expectedSum := float64(numGoroutines * opsPerGoroutine) * 10.5
+	if clone.FValues["sum"] != expectedSum {
+		t.Errorf("Expected sum %f, got %f", expectedSum, clone.FValues["sum"])
+	}
+	
+	// Check Min
+	if clone.FValues["min"] != 5.0 {
+		t.Errorf("Expected min 5.0, got %f", clone.FValues["min"])
+	}
+	
+	// Check Max
+	if clone.FValues["max"] != 15.0 {
+		t.Errorf("Expected max 15.0, got %f", clone.FValues["max"])
+	}
+	
+	// Check Samples
+	expectedSamples := numGoroutines * opsPerGoroutine
+	if clone.Samples != expectedSamples {
+		t.Errorf("Expected samples %d, got %d", expectedSamples, clone.Samples)
+	}
+	
+	// Check Last (should be "value")
+	if clone.SValues["last"] != "value" {
+		t.Errorf("Expected last 'value', got '%s'", clone.SValues["last"])
+	}
+}
+
+// TestSafeAggregateSetClone tests that cloning creates an independent copy.
+func TestSafeAggregateSetClone(t *testing.T) {
+	original := NewSafeAggregateSet()
+	
+	// Add some data
+	original.Aggregate("count", Count, "1", false)
+	original.Aggregate("sum", Sum, "100", false)
+	original.Aggregate("last", Last, "original", false)
+	original.IncrementSamples()
+	
+	// Clone the set
+	clone := original.Clone()
+	
+	// Modify the original
+	original.Aggregate("count", Count, "1", false)
+	original.Aggregate("sum", Sum, "50", false)
+	original.Aggregate("last", Last, "modified", false)
+	original.IncrementSamples()
+	
+	// Verify clone is unchanged
+	if clone.FValues["count"] != 1 {
+		t.Errorf("Clone count should be 1, got %f", clone.FValues["count"])
+	}
+	
+	if clone.FValues["sum"] != 100 {
+		t.Errorf("Clone sum should be 100, got %f", clone.FValues["sum"])
+	}
+	
+	if clone.SValues["last"] != "original" {
+		t.Errorf("Clone last should be 'original', got '%s'", clone.SValues["last"])
+	}
+	
+	if clone.Samples != 1 {
+		t.Errorf("Clone samples should be 1, got %d", clone.Samples)
+	}
+	
+	// Verify original has changed
+	originalClone := original.Clone()
+	if originalClone.FValues["count"] != 2 {
+		t.Errorf("Original count should be 2, got %f", originalClone.FValues["count"])
+	}
+	
+	if originalClone.FValues["sum"] != 150 {
+		t.Errorf("Original sum should be 150, got %f", originalClone.FValues["sum"])
+	}
+}
\ No newline at end of file