database_observability: add debug info to collectors

WIP

internal/component/database_observability/mysql/collector/connection_info.go

@@ -87,3 +87,7 @@ func (c *ConnectionInfo) Stop() {
 	c.Registry.Unregister(c.InfoMetric)
 	c.running.Store(false)
 }
+
+func (c *ConnectionInfo) DebugInfo() interface{} {
+	return map[string]string{}
+}

internal/component/database_observability/mysql/collector/query_sample.go

@@ -194,3 +194,7 @@ func (c *QuerySample) fetchQuerySamples(ctx context.Context) error {
 
 	return nil
 }
+
+func (c *QuerySample) DebugInfo() interface{} {
+	return map[string]string{}
+}

internal/component/database_observability/mysql/collector/schema_table.go

@@ -417,3 +417,10 @@ func (c *SchemaTable) fetchColumnsDefinitions(ctx context.Context, schemaName st
 
 	return tblSpec, nil
 }
+
+func (c *SchemaTable) DebugInfo() interface{} {
+	m := map[string]interface{}{
+		"cache_size": c.cache.Len(),
+	}
+	return m
+}

internal/component/database_observability/mysql/component.go

@@ -81,13 +81,15 @@ var (
 	_ component.Component       = (*Component)(nil)
 	_ http_service.Component    = (*Component)(nil)
 	_ component.HealthComponent = (*Component)(nil)
+	_ component.DebugComponent  = (*Component)(nil)
 )
 
 type Collector interface {
 	Name() string
 	Start(context.Context) error
 	Stopped() bool
 	Stop()
+	DebugInfo() interface{}
 }
 
 type Component struct {
@@ -374,3 +376,13 @@ func formatDSN(dsn string, params ...string) string {
 	}
 	return dsn + strings.Join(params, "&")
 }
+
+func (c *Component) DebugInfo() interface{} {
+	m := map[string]interface{}{
+		"collectors": c.collectors,
+	}
+	for _, collector := range c.collectors {
+		m["collector:"+collector.Name()] = collector.DebugInfo()
+	}
+	return m
+}