feat: add process snapshot support and update metrics parsing logic

Author: guiyumin

internal/prometheus/.gitignore

@@ -1 +1,2 @@
-metrics.txt
+metrics.txt
+process_snapshot.txt

internal/prometheus/process_exporter_parser.go

@@ -124,7 +124,9 @@ func parseProcessLine(line string, processMetrics map[string]*processData) error
 		pm.numProcs = int(value)
 
 	case "namedprocess_namegroup_cpu_seconds_total":
-		pm.cpuSecondsTotal = value
+		// Sum across all modes (user + system)
+		// process_exporter provides: mode="user" and mode="system"
+		pm.cpuSecondsTotal += value
 
 	case "namedprocess_namegroup_memory_bytes":
 		// Only use resident memory (RSS)

internal/prometheus/process_exporter_parser_test.go

@@ -0,0 +1,139 @@
+package prometheus
+
+import (
+	"testing"
+)
+
+func TestParseProcessExporterMetrics(t *testing.T) {
+	// Sample process_exporter output with mode labels (user/system)
+	input := `# HELP namedprocess_namegroup_num_procs Number of processes in this group
+# TYPE namedprocess_namegroup_num_procs gauge
+namedprocess_namegroup_num_procs{groupname="nginx"} 4
+namedprocess_namegroup_num_procs{groupname="postgres"} 1
+
+# HELP namedprocess_namegroup_cpu_seconds_total CPU time consumed by this process group
+# TYPE namedprocess_namegroup_cpu_seconds_total counter
+namedprocess_namegroup_cpu_seconds_total{groupname="nginx",mode="system"} 123.45
+namedprocess_namegroup_cpu_seconds_total{groupname="nginx",mode="user"} 456.78
+namedprocess_namegroup_cpu_seconds_total{groupname="postgres",mode="system"} 10.5
+namedprocess_namegroup_cpu_seconds_total{groupname="postgres",mode="user"} 20.3
+
+# HELP namedprocess_namegroup_memory_bytes Memory used by this process group
+# TYPE namedprocess_namegroup_memory_bytes gauge
+namedprocess_namegroup_memory_bytes{groupname="nginx",memtype="resident"} 104857600
+namedprocess_namegroup_memory_bytes{groupname="nginx",memtype="virtual"} 209715200
+namedprocess_namegroup_memory_bytes{groupname="postgres",memtype="resident"} 52428800
+namedprocess_namegroup_memory_bytes{groupname="postgres",memtype="virtual"} 104857600
+`
+
+	snapshots, err := ParseProcessExporterMetrics([]byte(input))
+	if err != nil {
+		t.Fatalf("ParseProcessExporterMetrics failed: %v", err)
+	}
+
+	// Should have 2 process groups
+	if len(snapshots) != 2 {
+		t.Fatalf("Expected 2 snapshots, got %d", len(snapshots))
+	}
+
+	// Find nginx snapshot
+	var nginx *ProcessExporterMetricSnapshot
+	for i := range snapshots {
+		if snapshots[i].Name == "nginx" {
+			nginx = &snapshots[i]
+			break
+		}
+	}
+
+	if nginx == nil {
+		t.Fatal("nginx snapshot not found")
+	}
+
+	// Verify nginx metrics
+	if nginx.NumProcs != 4 {
+		t.Errorf("Expected nginx.NumProcs=4, got %d", nginx.NumProcs)
+	}
+
+	// CPU should be sum of user + system = 123.45 + 456.78 = 580.23
+	expectedCPU := 123.45 + 456.78
+	if nginx.CPUSecondsTotal != expectedCPU {
+		t.Errorf("Expected nginx.CPUSecondsTotal=%.2f, got %.2f", expectedCPU, nginx.CPUSecondsTotal)
+	}
+
+	// Memory should be resident (RSS)
+	if nginx.MemoryBytes != 104857600 {
+		t.Errorf("Expected nginx.MemoryBytes=104857600, got %d", nginx.MemoryBytes)
+	}
+
+	// Find postgres snapshot
+	var postgres *ProcessExporterMetricSnapshot
+	for i := range snapshots {
+		if snapshots[i].Name == "postgres" {
+			postgres = &snapshots[i]
+			break
+		}
+	}
+
+	if postgres == nil {
+		t.Fatal("postgres snapshot not found")
+	}
+
+	// Verify postgres metrics
+	if postgres.NumProcs != 1 {
+		t.Errorf("Expected postgres.NumProcs=1, got %d", postgres.NumProcs)
+	}
+
+	// CPU should be sum of user + system = 10.5 + 20.3 = 30.8
+	expectedPostgresCPU := 10.5 + 20.3
+	if postgres.CPUSecondsTotal != expectedPostgresCPU {
+		t.Errorf("Expected postgres.CPUSecondsTotal=%.2f, got %.2f", expectedPostgresCPU, postgres.CPUSecondsTotal)
+	}
+
+	if postgres.MemoryBytes != 52428800 {
+		t.Errorf("Expected postgres.MemoryBytes=52428800, got %d", postgres.MemoryBytes)
+	}
+}
+
+func TestParseProcessExporterMetrics_OnlyNumProcs(t *testing.T) {
+	// Test with process that only has num_procs > 0
+	input := `namedprocess_namegroup_num_procs{groupname="test"} 2
+namedprocess_namegroup_cpu_seconds_total{groupname="test",mode="system"} 0
+namedprocess_namegroup_cpu_seconds_total{groupname="test",mode="user"} 0
+namedprocess_namegroup_memory_bytes{groupname="test",memtype="resident"} 1024
+`
+
+	snapshots, err := ParseProcessExporterMetrics([]byte(input))
+	if err != nil {
+		t.Fatalf("ParseProcessExporterMetrics failed: %v", err)
+	}
+
+	if len(snapshots) != 1 {
+		t.Fatalf("Expected 1 snapshot, got %d", len(snapshots))
+	}
+
+	if snapshots[0].Name != "test" {
+		t.Errorf("Expected name='test', got '%s'", snapshots[0].Name)
+	}
+
+	if snapshots[0].NumProcs != 2 {
+		t.Errorf("Expected NumProcs=2, got %d", snapshots[0].NumProcs)
+	}
+}
+
+func TestParseProcessExporterMetrics_ZeroProcs(t *testing.T) {
+	// Process with 0 procs should be filtered out
+	input := `namedprocess_namegroup_num_procs{groupname="dead"} 0
+namedprocess_namegroup_cpu_seconds_total{groupname="dead",mode="system"} 100
+namedprocess_namegroup_cpu_seconds_total{groupname="dead",mode="user"} 200
+`
+
+	snapshots, err := ParseProcessExporterMetrics([]byte(input))
+	if err != nil {
+		t.Fatalf("ParseProcessExporterMetrics failed: %v", err)
+	}
+
+	// Should be filtered out because numProcs == 0
+	if len(snapshots) != 0 {
+		t.Fatalf("Expected 0 snapshots (filtered), got %d", len(snapshots))
+	}
+}