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Technical Specifications
๐Ÿ“Š Platform Observability
๐Ÿ”ง Implementation Specification

Platform Observability Implementation Specification

This technical specification provides the detailed implementation design for the Platform Observability Service (sindhan-observability) Rust crate, showcasing a comprehensive observability framework with type-safe instrumentation and high-performance async design.

Design Patterns Applied

The implementation leverages multiple software design patterns optimized for observability:

  • Builder Pattern: For configuration builders and instrumentation setup
  • Factory Pattern: For exporter creation and format detection
  • Observer Pattern: For metric collection and event notifications
  • Strategy Pattern: For sampling strategies and export formats
  • Decorator Pattern: For instrumentation wrapping and enhancement
  • Registry Pattern: For metric and tracer management
  • Pipeline Pattern: For export processing and batching
  • Context Pattern: For correlation and trace propagation

Core Type System and Traits

Base Observability Traits

use std::collections::HashMap;
use std::sync::Arc;
use tokio::sync::RwLock;
use anyhow::{Result, Context};
use serde::{Deserialize, Serialize};
use async_trait::async_trait;
use opentelemetry::trace::{TraceId, SpanId};
use uuid::Uuid;
 
/// Core trait defining observability provider behavior
/// **Pattern Applied: Strategy Pattern**
#[async_trait]
pub trait ObservabilityProvider: Send + Sync + 'static {
    type MetricsType: MetricsCollector + Send + Sync;
    type LoggingType: StructuredLogger + Send + Sync;
    type TracingType: DistributedTracer + Send + Sync;
    
    async fn metrics(&self) -> &Self::MetricsType;
    async fn logging(&self) -> &Self::LoggingType;
    async fn tracing(&self) -> &Self::TracingType;
    
    async fn shutdown(&self) -> Result<()>;
    async fn flush(&self) -> Result<()>;
}
 
/// Trait for metrics collection with type safety
/// **Pattern Applied: Registry Pattern**
pub trait MetricsCollector: Send + Sync {
    fn create_counter(&self, name: &str, description: &str, labels: Labels) -> Counter;
    fn create_gauge(&self, name: &str, description: &str, labels: Labels) -> Gauge;
    fn create_histogram(&self, name: &str, description: &str, labels: Labels) -> Histogram;
    fn create_summary(&self, name: &str, description: &str, labels: Labels) -> Summary;
    
    fn register_metric<T: Metric>(&self, metric: T) -> Result<()>;
    fn export_metrics(&self) -> Result<Vec<MetricFamily>>;
}
 
/// Trait for structured logging with correlation
/// **Pattern Applied: Context Pattern**
pub trait StructuredLogger: Send + Sync {
    fn log(&self, level: LogLevel, message: &str, context: LogContext);
    fn info(&self, message: &str, context: LogContext);
    fn warn(&self, message: &str, context: LogContext);
    fn error(&self, message: &str, context: LogContext);
    fn debug(&self, message: &str, context: LogContext);
    fn trace(&self, message: &str, context: LogContext);
    
    fn with_correlation_id(&self, correlation_id: CorrelationId) -> Box<dyn StructuredLogger>;
    fn with_trace_context(&self, trace_id: TraceId, span_id: SpanId) -> Box<dyn StructuredLogger>;
}
 
/// Trait for distributed tracing
/// **Pattern Applied: Decorator Pattern**
pub trait DistributedTracer: Send + Sync {
    fn start_span(&self, name: &str) -> Span;
    fn start_span_with_parent(&self, name: &str, parent: &SpanContext) -> Span;
    fn current_span(&self) -> Option<Span>;
    fn with_span<F, R>(&self, span: Span, f: F) -> R
    where
        F: FnOnce() -> R;
    
    async fn flush(&self) -> Result<()>;
}

Core Configuration System

/// Comprehensive observability configuration
/// **Pattern Applied: Builder Pattern**
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ObservabilityConfig {
    pub service_name: String,
    pub service_version: String,
    pub environment: String,
    pub metrics: MetricsConfig,
    pub logging: LoggingConfig,
    pub tracing: TracingConfig,
    pub export: ExportConfig,
}
 
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct MetricsConfig {
    pub enabled: bool,
    pub collection_interval: std::time::Duration,
    pub prometheus_endpoint: Option<String>,
    pub custom_metrics: Vec<CustomMetricConfig>,
    pub sampling_rate: f64,
}
 
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct LoggingConfig {
    pub enabled: bool,
    pub level: LogLevel,
    pub format: LogFormat,
    pub structured: bool,
    pub correlation_tracking: bool,
    pub outputs: Vec<LogOutput>,
}
 
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct TracingConfig {
    pub enabled: bool,
    pub sampling_strategy: SamplingStrategy,
    pub jaeger_endpoint: Option<String>,
    pub otlp_endpoint: Option<String>,
    pub batch_export: bool,
    pub max_export_batch_size: usize,
}
 
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ExportConfig {
    pub prometheus: PrometheusExportConfig,
    pub jaeger: JaegerExportConfig,
    pub otlp: OtlpExportConfig,
    pub custom: Vec<CustomExportConfig>,
}
 
/// Builder for observability configuration
/// **Pattern Applied: Builder Pattern**
pub struct ObservabilityConfigBuilder {
    service_name: Option<String>,
    service_version: Option<String>,
    environment: Option<String>,
    metrics_config: Option<MetricsConfig>,
    logging_config: Option<LoggingConfig>,
    tracing_config: Option<TracingConfig>,
    export_config: Option<ExportConfig>,
}
 
impl ObservabilityConfigBuilder {
    pub fn new() -> Self {
        Self {
            service_name: None,
            service_version: None,
            environment: None,
            metrics_config: None,
            logging_config: None,
            tracing_config: None,
            export_config: None,
        }
    }
    
    pub fn with_service_name(mut self, name: impl Into<String>) -> Self {
        self.service_name = Some(name.into());
        self
    }
    
    pub fn with_service_version(mut self, version: impl Into<String>) -> Self {
        self.service_version = Some(version.into());
        self
    }
    
    pub fn with_environment(mut self, env: impl Into<String>) -> Self {
        self.environment = Some(env.into());
        self
    }
    
    pub fn with_metrics(mut self, config: MetricsConfig) -> Self {
        self.metrics_config = Some(config);
        self
    }
    
    pub fn with_logging(mut self, config: LoggingConfig) -> Self {
        self.logging_config = Some(config);
        self
    }
    
    pub fn with_tracing(mut self, config: TracingConfig) -> Self {
        self.tracing_config = Some(config);
        self
    }
    
    pub fn with_export(mut self, config: ExportConfig) -> Self {
        self.export_config = Some(config);
        self
    }
    
    pub fn build(self) -> Result<ObservabilityConfig> {
        Ok(ObservabilityConfig {
            service_name: self.service_name.ok_or_else(|| anyhow::anyhow!("Service name is required"))?,
            service_version: self.service_version.unwrap_or_else(|| "unknown".to_string()),
            environment: self.environment.unwrap_or_else(|| "development".to_string()),
            metrics: self.metrics_config.unwrap_or_default(),
            logging: self.logging_config.unwrap_or_default(),
            tracing: self.tracing_config.unwrap_or_default(),
            export: self.export_config.unwrap_or_default(),
        })
    }
}
 
impl Default for MetricsConfig {
    fn default() -> Self {
        Self {
            enabled: true,
            collection_interval: std::time::Duration::from_secs(15),
            prometheus_endpoint: Some("0.0.0.0:9090".to_string()),
            custom_metrics: Vec::new(),
            sampling_rate: 1.0,
        }
    }
}
 
impl Default for LoggingConfig {
    fn default() -> Self {
        Self {
            enabled: true,
            level: LogLevel::Info,
            format: LogFormat::Json,
            structured: true,
            correlation_tracking: true,
            outputs: vec![LogOutput::Stdout],
        }
    }
}
 
impl Default for TracingConfig {
    fn default() -> Self {
        Self {
            enabled: true,
            sampling_strategy: SamplingStrategy::Probabilistic(1.0),
            jaeger_endpoint: None,
            otlp_endpoint: None,
            batch_export: true,
            max_export_batch_size: 512,
        }
    }
}
 
impl Default for ExportConfig {
    fn default() -> Self {
        Self {
            prometheus: PrometheusExportConfig::default(),
            jaeger: JaegerExportConfig::default(),
            otlp: OtlpExportConfig::default(),
            custom: Vec::new(),
        }
    }
}

Metrics System Implementation

/// High-performance metrics registry with type safety
/// **Pattern Applied: Registry Pattern + Factory Pattern**
pub struct MetricsRegistry {
    counters: Arc<RwLock<HashMap<String, Arc<Counter>>>>,
    gauges: Arc<RwLock<HashMap<String, Arc<Gauge>>>>,
    histograms: Arc<RwLock<HashMap<String, Arc<Histogram>>>>,
    summaries: Arc<RwLock<HashMap<String, Arc<Summary>>>>,
    exporters: Vec<Box<dyn MetricsExporter>>,
    config: MetricsConfig,
}
 
impl MetricsRegistry {
    pub fn new(config: MetricsConfig) -> Self {
        Self {
            counters: Arc::new(RwLock::new(HashMap::new())),
            gauges: Arc::new(RwLock::new(HashMap::new())),
            histograms: Arc::new(RwLock::new(HashMap::new())),
            summaries: Arc::new(RwLock::new(HashMap::new())),
            exporters: Vec::new(),
            config,
        }
    }
    
    pub async fn create_counter(
        &self,
        name: &str,
        description: &str,
        labels: Labels,
    ) -> Counter {
        let key = format!("{}_{}", name, labels.fingerprint());
        
        {
            let counters = self.counters.read().await;
            if let Some(counter) = counters.get(&key) {
                return counter.as_ref().clone();
            }
        }
        
        let counter = Counter::new(name, description, labels);
        let arc_counter = Arc::new(counter.clone());
        
        {
            let mut counters = self.counters.write().await;
            counters.insert(key, arc_counter);
        }
        
        counter
    }
    
    pub async fn create_gauge(
        &self,
        name: &str,
        description: &str,
        labels: Labels,
    ) -> Gauge {
        let key = format!("{}_{}", name, labels.fingerprint());
        
        {
            let gauges = self.gauges.read().await;
            if let Some(gauge) = gauges.get(&key) {
                return gauge.as_ref().clone();
            }
        }
        
        let gauge = Gauge::new(name, description, labels);
        let arc_gauge = Arc::new(gauge.clone());
        
        {
            let mut gauges = self.gauges.write().await;
            gauges.insert(key, arc_gauge);
        }
        
        gauge
    }
    
    pub async fn create_histogram(
        &self,
        name: &str,
        description: &str,
        labels: Labels,
    ) -> Histogram {
        let key = format!("{}_{}", name, labels.fingerprint());
        
        {
            let histograms = self.histograms.read().await;
            if let Some(histogram) = histograms.get(&key) {
                return histogram.as_ref().clone();
            }
        }
        
        let histogram = Histogram::new(name, description, labels);
        let arc_histogram = Arc::new(histogram.clone());
        
        {
            let mut histograms = self.histograms.write().await;
            histograms.insert(key, arc_histogram);
        }
        
        histogram
    }
    
    pub async fn export_metrics(&self) -> Result<Vec<MetricFamily>> {
        let mut families = Vec::new();
        
        // Export counters
        {
            let counters = self.counters.read().await;
            for counter in counters.values() {
                families.push(counter.to_metric_family());
            }
        }
        
        // Export gauges
        {
            let gauges = self.gauges.read().await;
            for gauge in gauges.values() {
                families.push(gauge.to_metric_family());
            }
        }
        
        // Export histograms
        {
            let histograms = self.histograms.read().await;
            for histogram in histograms.values() {
                families.push(histogram.to_metric_family());
            }
        }
        
        // Export summaries
        {
            let summaries = self.summaries.read().await;
            for summary in summaries.values() {
                families.push(summary.to_metric_family());
            }
        }
        
        Ok(families)
    }
    
    pub async fn flush_to_exporters(&self) -> Result<()> {
        let metric_families = self.export_metrics().await?;
        
        for exporter in &self.exporters {
            exporter.export(&metric_families).await
                .with_context(|| "Failed to export metrics")?;
        }
        
        Ok(())
    }
}
 
/// Thread-safe counter implementation with atomic operations
#[derive(Debug, Clone)]
pub struct Counter {
    name: String,
    description: String,
    labels: Labels,
    value: Arc<std::sync::atomic::AtomicU64>,
}
 
impl Counter {
    pub fn new(name: &str, description: &str, labels: Labels) -> Self {
        Self {
            name: name.to_string(),
            description: description.to_string(),
            labels,
            value: Arc::new(std::sync::atomic::AtomicU64::new(0)),
        }
    }
    
    pub fn increment(&self, labels: Labels) {
        self.add(1, labels);
    }
    
    pub fn add(&self, value: u64, _labels: Labels) {
        self.value.fetch_add(value, std::sync::atomic::Ordering::Relaxed);
    }
    
    pub fn get(&self) -> u64 {
        self.value.load(std::sync::atomic::Ordering::Relaxed)
    }
    
    pub fn to_metric_family(&self) -> MetricFamily {
        MetricFamily {
            name: self.name.clone(),
            description: self.description.clone(),
            metric_type: MetricType::Counter,
            metrics: vec![Metric {
                labels: self.labels.clone(),
                value: MetricValue::Counter(self.get()),
            }],
        }
    }
}
 
/// Thread-safe gauge implementation
#[derive(Debug, Clone)]
pub struct Gauge {
    name: String,
    description: String,
    labels: Labels,
    value: Arc<std::sync::RwLock<f64>>,
}
 
impl Gauge {
    pub fn new(name: &str, description: &str, labels: Labels) -> Self {
        Self {
            name: name.to_string(),
            description: description.to_string(),
            labels,
            value: Arc::new(std::sync::RwLock::new(0.0)),
        }
    }
    
    pub fn set(&self, value: f64, _labels: Labels) {
        if let Ok(mut v) = self.value.write() {
            *v = value;
        }
    }
    
    pub fn increment(&self, _labels: Labels) {
        self.add(1.0, _labels);
    }
    
    pub fn decrement(&self, _labels: Labels) {
        self.add(-1.0, _labels);
    }
    
    pub fn add(&self, value: f64, _labels: Labels) {
        if let Ok(mut v) = self.value.write() {
            *v += value;
        }
    }
    
    pub fn get(&self) -> f64 {
        self.value.read().unwrap_or_else(|_| std::sync::RwLock::new(0.0).read().unwrap()).clone()
    }
    
    pub fn to_metric_family(&self) -> MetricFamily {
        MetricFamily {
            name: self.name.clone(),
            description: self.description.clone(),
            metric_type: MetricType::Gauge,
            metrics: vec![Metric {
                labels: self.labels.clone(),
                value: MetricValue::Gauge(self.get()),
            }],
        }
    }
}
 
/// Lock-free histogram implementation with configurable buckets
#[derive(Debug, Clone)]
pub struct Histogram {
    name: String,
    description: String,
    labels: Labels,
    buckets: Vec<f64>,
    bucket_counts: Vec<Arc<std::sync::atomic::AtomicU64>>,
    sum: Arc<std::sync::atomic::AtomicU64>, // Store as integer for atomic operations
    count: Arc<std::sync::atomic::AtomicU64>,
}
 
impl Histogram {
    pub fn new(name: &str, description: &str, labels: Labels) -> Self {
        let buckets = vec![
            0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1.0, 2.5, 5.0, 10.0, f64::INFINITY
        ];
        
        let bucket_counts = buckets.iter()
            .map(|_| Arc::new(std::sync::atomic::AtomicU64::new(0)))
            .collect();
        
        Self {
            name: name.to_string(),
            description: description.to_string(),
            labels,
            buckets,
            bucket_counts,
            sum: Arc::new(std::sync::atomic::AtomicU64::new(0)),
            count: Arc::new(std::sync::atomic::AtomicU64::new(0)),
        }
    }
    
    pub fn record(&self, value: f64, _labels: Labels) {
        // Convert to integer representation for atomic operations
        let value_bits = value.to_bits();
        
        // Update sum and count
        self.sum.fetch_add(value_bits, std::sync::atomic::Ordering::Relaxed);
        self.count.fetch_add(1, std::sync::atomic::Ordering::Relaxed);
        
        // Update bucket counts
        for (i, &bucket) in self.buckets.iter().enumerate() {
            if value <= bucket {
                self.bucket_counts[i].fetch_add(1, std::sync::atomic::Ordering::Relaxed);
            }
        }
    }
    
    pub fn get_bucket_counts(&self) -> Vec<u64> {
        self.bucket_counts.iter()
            .map(|count| count.load(std::sync::atomic::Ordering::Relaxed))
            .collect()
    }
    
    pub fn get_sum(&self) -> f64 {
        let sum_bits = self.sum.load(std::sync::atomic::Ordering::Relaxed);
        f64::from_bits(sum_bits)
    }
    
    pub fn get_count(&self) -> u64 {
        self.count.load(std::sync::atomic::Ordering::Relaxed)
    }
    
    pub fn to_metric_family(&self) -> MetricFamily {
        let bucket_counts = self.get_bucket_counts();
        let buckets: Vec<Bucket> = self.buckets.iter()
            .zip(bucket_counts.iter())
            .map(|(&upper_bound, &count)| Bucket {
                upper_bound,
                cumulative_count: count,
            })
            .collect();
        
        MetricFamily {
            name: self.name.clone(),
            description: self.description.clone(),
            metric_type: MetricType::Histogram,
            metrics: vec![Metric {
                labels: self.labels.clone(),
                value: MetricValue::Histogram(HistogramValue {
                    sample_count: self.get_count(),
                    sample_sum: self.get_sum(),
                    buckets,
                }),
            }],
        }
    }
}

Structured Logging Implementation

/// High-performance structured logger with correlation tracking
/// **Pattern Applied: Context Pattern + Observer Pattern**
pub struct StructuredLogger {
    service_name: String,
    service_version: String,
    environment: String,
    level: LogLevel,
    format: LogFormat,
    outputs: Vec<Box<dyn LogOutput>>,
    correlation_id: Option<CorrelationId>,
    trace_context: Option<TraceContext>,
}
 
impl StructuredLogger {
    pub fn builder() -> StructuredLoggerBuilder {
        StructuredLoggerBuilder::new()
    }
    
    pub fn log(&self, level: LogLevel, message: &str, context: LogContext) {
        if level < self.level {
            return;
        }
        
        let log_entry = LogEntry::builder()
            .with_timestamp(chrono::Utc::now())
            .with_level(level)
            .with_service_name(&self.service_name)
            .with_service_version(&self.service_version)
            .with_environment(&self.environment)
            .with_message(message)
            .with_context(context)
            .with_correlation_id(self.correlation_id)
            .with_trace_context(self.trace_context)
            .build();
        
        let formatted = match self.format {
            LogFormat::Json => self.format_json(&log_entry),
            LogFormat::Text => self.format_text(&log_entry),
            LogFormat::Logfmt => self.format_logfmt(&log_entry),
        };
        
        for output in &self.outputs {
            output.write(&formatted);
        }
    }
    
    pub fn info(&self, message: &str, context: LogContext) {
        self.log(LogLevel::Info, message, context);
    }
    
    pub fn warn(&self, message: &str, context: LogContext) {
        self.log(LogLevel::Warn, message, context);
    }
    
    pub fn error(&self, message: &str, context: LogContext) {
        self.log(LogLevel::Error, message, context);
    }
    
    pub fn debug(&self, message: &str, context: LogContext) {
        self.log(LogLevel::Debug, message, context);
    }
    
    pub fn trace(&self, message: &str, context: LogContext) {
        self.log(LogLevel::Trace, message, context);
    }
    
    fn format_json(&self, entry: &LogEntry) -> String {
        serde_json::to_string(entry).unwrap_or_else(|_| {
            format!(r#"{{"error": "Failed to serialize log entry", "message": "{}"}}"#, entry.message)
        })
    }
    
    fn format_text(&self, entry: &LogEntry) -> String {
        format!(
            "{} [{}] {} - {} {}\n",
            entry.timestamp.format("%Y-%m-%dT%H:%M:%S%.3fZ"),
            entry.level,
            entry.service_name,
            entry.message,
            entry.context.to_string()
        )
    }
    
    fn format_logfmt(&self, entry: &LogEntry) -> String {
        format!(
            "ts={} level={} service={} msg=\"{}\" {}\n",
            entry.timestamp.format("%Y-%m-%dT%H:%M:%S%.3fZ"),
            entry.level,
            entry.service_name,
            entry.message,
            entry.context.to_logfmt()
        )
    }
}
 
impl StructuredLogger {
    pub fn with_correlation_id(&self, correlation_id: CorrelationId) -> Box<dyn StructuredLogger> {
        let mut logger = self.clone();
        logger.correlation_id = Some(correlation_id);
        Box::new(logger)
    }
    
    pub fn with_trace_context(&self, trace_id: TraceId, span_id: SpanId) -> Box<dyn StructuredLogger> {
        let mut logger = self.clone();
        logger.trace_context = Some(TraceContext { trace_id, span_id });
        Box::new(logger)
    }
}
 
/// Builder for structured logger configuration
/// **Pattern Applied: Builder Pattern**
pub struct StructuredLoggerBuilder {
    service_name: Option<String>,
    service_version: Option<String>,
    environment: Option<String>,
    level: LogLevel,
    format: LogFormat,
    outputs: Vec<Box<dyn LogOutput>>,
}
 
impl StructuredLoggerBuilder {
    pub fn new() -> Self {
        Self {
            service_name: None,
            service_version: None,
            environment: None,
            level: LogLevel::Info,
            format: LogFormat::Json,
            outputs: vec![Box::new(StdoutOutput::new())],
        }
    }
    
    pub fn with_service_name(mut self, name: impl Into<String>) -> Self {
        self.service_name = Some(name.into());
        self
    }
    
    pub fn with_service_version(mut self, version: impl Into<String>) -> Self {
        self.service_version = Some(version.into());
        self
    }
    
    pub fn with_environment(mut self, env: impl Into<String>) -> Self {
        self.environment = Some(env.into());
        self
    }
    
    pub fn with_level(mut self, level: LogLevel) -> Self {
        self.level = level;
        self
    }
    
    pub fn with_json_format(mut self) -> Self {
        self.format = LogFormat::Json;
        self
    }
    
    pub fn with_text_format(mut self) -> Self {
        self.format = LogFormat::Text;
        self
    }
    
    pub fn add_output(mut self, output: Box<dyn LogOutput>) -> Self {
        self.outputs.push(output);
        self
    }
    
    pub fn build(self) -> Result<StructuredLogger> {
        Ok(StructuredLogger {
            service_name: self.service_name.ok_or_else(|| anyhow::anyhow!("Service name is required"))?,
            service_version: self.service_version.unwrap_or_else(|| "unknown".to_string()),
            environment: self.environment.unwrap_or_else(|| "development".to_string()),
            level: self.level,
            format: self.format,
            outputs: self.outputs,
            correlation_id: None,
            trace_context: None,
        })
    }
}
 
/// Log context for structured fields
#[derive(Debug, Clone, Serialize)]
pub struct LogContext {
    fields: HashMap<String, serde_json::Value>,
    correlation_id: Option<CorrelationId>,
    trace_id: Option<TraceId>,
    span_id: Option<SpanId>,
    user_id: Option<String>,
    request_id: Option<String>,
}
 
impl LogContext {
    pub fn new() -> Self {
        Self {
            fields: HashMap::new(),
            correlation_id: None,
            trace_id: None,
            span_id: None,
            user_id: None,
            request_id: None,
        }
    }
    
    pub fn with_field<T: Serialize>(mut self, key: &str, value: T) -> Self {
        self.fields.insert(
            key.to_string(),
            serde_json::to_value(value).unwrap_or(serde_json::Value::Null),
        );
        self
    }
    
    pub fn with_correlation_id(mut self, correlation_id: CorrelationId) -> Self {
        self.correlation_id = Some(correlation_id);
        self
    }
    
    pub fn with_trace_id(mut self, trace_id: TraceId) -> Self {
        self.trace_id = Some(trace_id);
        self
    }
    
    pub fn with_span_id(mut self, span_id: SpanId) -> Self {
        self.span_id = Some(span_id);
        self
    }
    
    pub fn with_user_id(mut self, user_id: impl Into<String>) -> Self {
        self.user_id = Some(user_id.into());
        self
    }
    
    pub fn with_request_id(mut self, request_id: impl Into<String>) -> Self {
        self.request_id = Some(request_id.into());
        self
    }
    
    pub fn with_error(mut self, error: &dyn std::error::Error) -> Self {
        self.fields.insert(
            "error".to_string(),
            serde_json::json!({
                "type": error.type_name(),
                "message": error.to_string(),
                "chain": error.chain().map(|e| e.to_string()).collect::<Vec<_>>(),
            }),
        );
        self
    }
    
    pub fn with_structured_data<T: Serialize>(mut self, data: &T) -> Self {
        if let Ok(value) = serde_json::to_value(data) {
            if let serde_json::Value::Object(map) = value {
                for (key, value) in map {
                    self.fields.insert(key, value);
                }
            }
        }
        self
    }
    
    pub fn to_logfmt(&self) -> String {
        let mut parts = Vec::new();
        
        if let Some(correlation_id) = &self.correlation_id {
            parts.push(format!("correlation_id={}", correlation_id));
        }
        
        if let Some(trace_id) = &self.trace_id {
            parts.push(format!("trace_id={}", trace_id));
        }
        
        if let Some(span_id) = &self.span_id {
            parts.push(format!("span_id={}", span_id));
        }
        
        if let Some(user_id) = &self.user_id {
            parts.push(format!("user_id=\"{}\"", user_id));
        }
        
        if let Some(request_id) = &self.request_id {
            parts.push(format!("request_id=\"{}\"", request_id));
        }
        
        for (key, value) in &self.fields {
            match value {
                serde_json::Value::String(s) => parts.push(format!("{}=\"{}\"", key, s)),
                serde_json::Value::Number(n) => parts.push(format!("{}={}", key, n)),
                serde_json::Value::Bool(b) => parts.push(format!("{}={}", key, b)),
                _ => parts.push(format!("{}=\"{}\"", key, value)),
            }
        }
        
        parts.join(" ")
    }
}
 
impl Default for LogContext {
    fn default() -> Self {
        Self::new()
    }
}
 
impl std::fmt::Display for LogContext {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "{}", self.to_logfmt())
    }
}

Distributed Tracing Implementation

/// High-performance distributed tracer with OpenTelemetry compatibility
/// **Pattern Applied: Decorator Pattern + Context Pattern**
pub struct DistributedTracer {
    service_name: String,
    service_version: String,
    tracer_provider: Arc<TracerProvider>,
    span_processor: Arc<dyn SpanProcessor>,
    sampler: Box<dyn Sampler>,
    resource: Arc<Resource>,
}
 
impl DistributedTracer {
    pub fn builder() -> DistributedTracerBuilder {
        DistributedTracerBuilder::new()
    }
    
    pub fn start_span(&self, name: &str) -> Span {
        self.start_span_with_builder(SpanBuilder::new(name))
    }
    
    pub fn start_span_with_parent(&self, name: &str, parent: &SpanContext) -> Span {
        self.start_span_with_builder(
            SpanBuilder::new(name).with_parent_context(parent.clone())
        )
    }
    
    pub fn start_span_with_builder(&self, builder: SpanBuilder) -> Span {
        let span_context = SpanContext::new(
            TraceId::generate(),
            SpanId::generate(),
            TraceFlags::default(),
            false,
            TraceState::default(),
        );
        
        let span = Span::new(
            span_context,
            builder.name,
            builder.attributes,
            builder.links,
            builder.start_time.unwrap_or_else(|| SystemTime::now()),
            self.span_processor.clone(),
        );
        
        // Apply sampling decision
        if let SamplingResult::NotSampled = self.sampler.should_sample(&span) {
            return Span::non_recording();
        }
        
        span
    }
    
    pub fn current_span(&self) -> Option<Span> {
        CURRENT_SPAN.with(|span| span.borrow().clone())
    }
    
    pub fn with_span<F, R>(&self, span: Span, f: F) -> R
    where
        F: FnOnce() -> R,
    {
        CURRENT_SPAN.with(|current| {
            let _guard = SpanGuard::new(current, Some(span));
            f()
        })
    }
    
    pub async fn flush(&self) -> Result<()> {
        self.span_processor.force_flush().await
    }
}
 
/// Span implementation with automatic lifecycle management
#[derive(Debug, Clone)]
pub struct Span {
    context: SpanContext,
    name: String,
    attributes: HashMap<String, AttributeValue>,
    events: Vec<Event>,
    status: SpanStatus,
    start_time: SystemTime,
    end_time: Option<SystemTime>,
    span_processor: Arc<dyn SpanProcessor>,
    recording: bool,
}
 
impl Span {
    pub fn new(
        context: SpanContext,
        name: String,
        attributes: HashMap<String, AttributeValue>,
        _links: Vec<Link>,
        start_time: SystemTime,
        span_processor: Arc<dyn SpanProcessor>,
    ) -> Self {
        Self {
            context,
            name,
            attributes,
            events: Vec::new(),
            status: SpanStatus::Unset,
            start_time,
            end_time: None,
            span_processor,
            recording: true,
        }
    }
    
    pub fn non_recording() -> Self {
        Self {
            context: SpanContext::empty_context(),
            name: String::new(),
            attributes: HashMap::new(),
            events: Vec::new(),
            status: SpanStatus::Unset,
            start_time: SystemTime::now(),
            end_time: None,
            span_processor: Arc::new(NoopSpanProcessor),
            recording: false,
        }
    }
    
    pub fn set_attribute<T: Into<AttributeValue>>(&mut self, key: &str, value: T) {
        if self.recording {
            self.attributes.insert(key.to_string(), value.into());
        }
    }
    
    pub fn add_event(&mut self, name: &str, attributes: HashMap<String, AttributeValue>) {
        if self.recording {
            self.events.push(Event {
                name: name.to_string(),
                timestamp: SystemTime::now(),
                attributes,
            });
        }
    }
    
    pub fn record_exception(&mut self, exception: &dyn std::error::Error) {
        if self.recording {
            let mut attributes = HashMap::new();
            attributes.insert("exception.type".to_string(), exception.type_name().into());
            attributes.insert("exception.message".to_string(), exception.to_string().into());
            
            if let Some(source) = exception.source() {
                attributes.insert("exception.cause".to_string(), source.to_string().into());
            }
            
            self.add_event("exception", attributes);
        }
    }
    
    pub fn set_status(&mut self, status: SpanStatus) {
        if self.recording {
            self.status = status;
        }
    }
    
    pub fn end(&mut self) {
        if self.recording && self.end_time.is_none() {
            self.end_time = Some(SystemTime::now());
            self.span_processor.on_end(self.clone());
        }
    }
    
    pub fn enter(&self) -> SpanGuard {
        CURRENT_SPAN.with(|current| {
            SpanGuard::new(current, Some(self.clone()))
        })
    }
    
    pub fn context(&self) -> &SpanContext {
        &self.context
    }
    
    pub fn is_recording(&self) -> bool {
        self.recording
    }
}
 
impl Drop for Span {
    fn drop(&mut self) {
        self.end();
    }
}
 
/// Automatic span lifecycle management
pub struct SpanGuard {
    previous: Option<Span>,
    current_slot: *const std::cell::RefCell<Option<Span>>,
}
 
impl SpanGuard {
    fn new(
        current_slot: &std::cell::RefCell<Option<Span>>,
        span: Option<Span>,
    ) -> Self {
        let previous = current_slot.borrow().clone();
        *current_slot.borrow_mut() = span;
        
        Self {
            previous,
            current_slot: current_slot as *const _,
        }
    }
}
 
impl Drop for SpanGuard {
    fn drop(&mut self) {
        unsafe {
            *(*self.current_slot).borrow_mut() = self.previous.take();
        }
    }
}
 
thread_local! {
    static CURRENT_SPAN: std::cell::RefCell<Option<Span>> = std::cell::RefCell::new(None);
}
 
/// Span builder for flexible span creation
/// **Pattern Applied: Builder Pattern**
#[derive(Debug, Clone)]
pub struct SpanBuilder {
    name: String,
    parent_context: Option<SpanContext>,
    span_kind: SpanKind,
    attributes: HashMap<String, AttributeValue>,
    links: Vec<Link>,
    start_time: Option<SystemTime>,
}
 
impl SpanBuilder {
    pub fn new(name: &str) -> Self {
        Self {
            name: name.to_string(),
            parent_context: None,
            span_kind: SpanKind::Internal,
            attributes: HashMap::new(),
            links: Vec::new(),
            start_time: None,
        }
    }
    
    pub fn with_parent_context(mut self, context: SpanContext) -> Self {
        self.parent_context = Some(context);
        self
    }
    
    pub fn with_kind(mut self, kind: SpanKind) -> Self {
        self.span_kind = kind;
        self
    }
    
    pub fn with_attribute<T: Into<AttributeValue>>(mut self, key: &str, value: T) -> Self {
        self.attributes.insert(key.to_string(), value.into());
        self
    }
    
    pub fn with_start_time(mut self, start_time: SystemTime) -> Self {
        self.start_time = Some(start_time);
        self
    }
    
    pub fn start(self, tracer: &DistributedTracer) -> Span {
        tracer.start_span_with_builder(self)
    }
}

Export Pipeline Implementation

Multi-Format Exporters

/// Export pipeline with multiple format support
/// **Pattern Applied: Strategy Pattern + Pipeline Pattern**
use serde::{Serialize, Deserialize};
use async_trait::async_trait;
use std::sync::Arc;
use tokio::sync::mpsc;
 
#[async_trait]
pub trait MetricsExporter: Send + Sync {
    async fn export(&self, metrics: &[MetricFamily]) -> Result<()>;
    fn name(&self) -> &'static str;
}
 
#[async_trait]
pub trait TracingExporter: Send + Sync {
    async fn export(&self, spans: &[SpanData]) -> Result<()>;
    fn name(&self) -> &'static str;
}
 
/// Prometheus metrics exporter
pub struct PrometheusExporter {
    endpoint: String,
    push_gateway: Option<String>,
    job_name: String,
    client: reqwest::Client,
}
 
impl PrometheusExporter {
    pub fn new(config: &PrometheusExportConfig) -> Self {
        Self {
            endpoint: config.endpoint.clone(),
            push_gateway: config.push_gateway.clone(),
            job_name: config.job_name.clone(),
            client: reqwest::Client::new(),
        }
    }
}
 
#[async_trait]
impl MetricsExporter for PrometheusExporter {
    async fn export(&self, metrics: &[MetricFamily]) -> Result<()> {
        let formatted = self.format_prometheus_metrics(metrics)?;
        
        if let Some(push_gateway) = &self.push_gateway {
            // Push to Prometheus Push Gateway
            let url = format!("{}/metrics/job/{}", push_gateway, self.job_name);
            self.client
                .post(&url)
                .header("Content-Type", "text/plain")
                .body(formatted)
                .send()
                .await?;
        } else {
            // Serve metrics endpoint
            // Implementation would involve setting up HTTP server
        }
        
        Ok(())
    }
    
    fn name(&self) -> &'static str {
        "prometheus"
    }
}
 
impl PrometheusExporter {
    fn format_prometheus_metrics(&self, metrics: &[MetricFamily]) -> Result<String> {
        let mut output = String::new();
        
        for family in metrics {
            // HELP line
            output.push_str(&format!("# HELP {} {}\n", family.name, family.description));
            
            // TYPE line
            let type_str = match family.metric_type {
                MetricType::Counter => "counter",
                MetricType::Gauge => "gauge",
                MetricType::Histogram => "histogram",
                MetricType::Summary => "summary",
            };
            output.push_str(&format!("# TYPE {} {}\n", family.name, type_str));
            
            // Metrics
            for metric in &family.metrics {
                match &metric.value {
                    MetricValue::Counter(value) => {
                        output.push_str(&format!(
                            "{}{} {}\n",
                            family.name,
                            self.format_labels(&metric.labels),
                            value
                        ));
                    }
                    MetricValue::Gauge(value) => {
                        output.push_str(&format!(
                            "{}{} {}\n",
                            family.name,
                            self.format_labels(&metric.labels),
                            value
                        ));
                    }
                    MetricValue::Histogram(hist) => {
                        // Histogram buckets
                        for bucket in &hist.buckets {
                            output.push_str(&format!(
                                "{}_bucket{{le=\"{}\"{} {}\n",
                                family.name,
                                bucket.upper_bound,
                                self.format_labels_suffix(&metric.labels),
                                bucket.cumulative_count
                            ));
                        }
                        // +Inf bucket
                        output.push_str(&format!(
                            "{}_bucket{{le=\"+Inf\"{} {}\n",
                            family.name,
                            self.format_labels_suffix(&metric.labels),
                            hist.sample_count
                        ));
                        // Count and sum
                        output.push_str(&format!(
                            "{}_count{} {}\n",
                            family.name,
                            self.format_labels(&metric.labels),
                            hist.sample_count
                        ));
                        output.push_str(&format!(
                            "{}_sum{} {}\n",
                            family.name,
                            self.format_labels(&metric.labels),
                            hist.sample_sum
                        ));
                    }
                    MetricValue::Summary(_) => {
                        // Summary implementation
                        // Similar to histogram but with quantiles
                    }
                }
            }
        }
        
        Ok(output)
    }
    
    fn format_labels(&self, labels: &Labels) -> String {
        if labels.is_empty() {
            String::new()
        } else {
            format!("{{{}}}", 
                labels.iter()
                    .map(|(k, v)| format!("{}=\"{}\"", k, v))
                    .collect::<Vec<_>>()
                    .join(",")
            )
        }
    }
    
    fn format_labels_suffix(&self, labels: &Labels) -> String {
        if labels.is_empty() {
            "}".to_string()
        } else {
            format!(",{}}}", 
                labels.iter()
                    .map(|(k, v)| format!("{}=\"{}\"", k, v))
                    .collect::<Vec<_>>()
                    .join(",")
            )
        }
    }
}
 
/// Jaeger tracing exporter
pub struct JaegerExporter {
    collector_endpoint: String,
    agent_endpoint: String,
    client: reqwest::Client,
    batch_processor: Arc<BatchSpanProcessor>,
}
 
impl JaegerExporter {
    pub fn new(config: &JaegerExportConfig) -> Self {
        Self {
            collector_endpoint: config.collector_endpoint.clone(),
            agent_endpoint: config.agent_endpoint.clone(),
            client: reqwest::Client::new(),
            batch_processor: Arc::new(BatchSpanProcessor::new(512, Duration::from_secs(1))),
        }
    }
}
 
#[async_trait]
impl TracingExporter for JaegerExporter {
    async fn export(&self, spans: &[SpanData]) -> Result<()> {
        let jaeger_spans = self.convert_to_jaeger_spans(spans)?;
        let batch = JaegerBatch {
            process: JaegerProcess {
                service_name: "sindhan-service".to_string(),
                tags: vec![],
            },
            spans: jaeger_spans,
        };
        
        let json_payload = serde_json::to_string(&batch)?;
        
        self.client
            .post(&format!("{}/api/traces", self.collector_endpoint))
            .header("Content-Type", "application/json")
            .body(json_payload)
            .send()
            .await?;
        
        Ok(())
    }
    
    fn name(&self) -> &'static str {
        "jaeger"
    }
}
 
impl JaegerExporter {
    fn convert_to_jaeger_spans(&self, spans: &[SpanData]) -> Result<Vec<JaegerSpan>> {
        spans.iter()
            .map(|span| Ok(JaegerSpan {
                trace_id: span.context.trace_id().to_string(),
                span_id: span.context.span_id().to_string(),
                parent_span_id: span.parent_span_id.map(|id| id.to_string()),
                operation_name: span.name.clone(),
                start_time: span.start_time.duration_since(UNIX_EPOCH)?.as_micros() as u64,
                duration: span.end_time
                    .unwrap_or_else(|| SystemTime::now())
                    .duration_since(span.start_time)?
                    .as_micros() as u64,
                tags: self.convert_attributes_to_tags(&span.attributes)?,
                logs: self.convert_events_to_logs(&span.events)?,
                process: None,
            }))
            .collect()
    }
    
    fn convert_attributes_to_tags(&self, attributes: &HashMap<String, AttributeValue>) -> Result<Vec<JaegerTag>> {
        attributes.iter()
            .map(|(key, value)| Ok(JaegerTag {
                key: key.clone(),
                value: self.attribute_value_to_string(value),
                tag_type: self.get_jaeger_tag_type(value),
            }))
            .collect()
    }
    
    fn convert_events_to_logs(&self, events: &[Event]) -> Result<Vec<JaegerLog>> {
        events.iter()
            .map(|event| Ok(JaegerLog {
                timestamp: event.timestamp.duration_since(UNIX_EPOCH)?.as_micros() as u64,
                fields: vec![
                    JaegerTag {
                        key: "event".to_string(),
                        value: event.name.clone(),
                        tag_type: "string".to_string(),
                    }
                ],
            }))
            .collect()
    }
    
    fn attribute_value_to_string(&self, value: &AttributeValue) -> String {
        match value {
            AttributeValue::String(s) => s.clone(),
            AttributeValue::Bool(b) => b.to_string(),
            AttributeValue::I64(i) => i.to_string(),
            AttributeValue::F64(f) => f.to_string(),
            AttributeValue::Array(arr) => format!("{:?}", arr),
        }
    }
    
    fn get_jaeger_tag_type(&self, value: &AttributeValue) -> String {
        match value {
            AttributeValue::String(_) => "string",
            AttributeValue::Bool(_) => "bool",
            AttributeValue::I64(_) => "number",
            AttributeValue::F64(_) => "number",
            AttributeValue::Array(_) => "string",
        }.to_string()
    }
}
 
/// OTLP (OpenTelemetry Protocol) exporter
pub struct OtlpExporter {
    endpoint: String,
    headers: HashMap<String, String>,
    client: reqwest::Client,
    timeout: Duration,
}
 
impl OtlpExporter {
    pub fn new(config: &OtlpExportConfig) -> Self {
        Self {
            endpoint: config.endpoint.clone(),
            headers: config.headers.clone(),
            client: reqwest::Client::new(),
            timeout: config.timeout,
        }
    }
}
 
#[async_trait]
impl TracingExporter for OtlpExporter {
    async fn export(&self, spans: &[SpanData]) -> Result<()> {
        let otlp_request = self.create_otlp_request(spans)?;
        let protobuf_payload = self.serialize_to_protobuf(&otlp_request)?;
        
        let mut request = self.client
            .post(&format!("{}/v1/traces", self.endpoint))
            .header("Content-Type", "application/x-protobuf")
            .timeout(self.timeout)
            .body(protobuf_payload);
        
        for (key, value) in &self.headers {
            request = request.header(key, value);
        }
        
        request.send().await?;
        Ok(())
    }
    
    fn name(&self) -> &'static str {
        "otlp"
    }
}
 
impl OtlpExporter {
    fn create_otlp_request(&self, spans: &[SpanData]) -> Result<OtlpTraceRequest> {
        // Implementation would create OTLP protobuf structures
        todo!("Implement OTLP protobuf conversion")
    }
    
    fn serialize_to_protobuf(&self, request: &OtlpTraceRequest) -> Result<Vec<u8>> {
        // Implementation would serialize to protobuf
        todo!("Implement protobuf serialization")
    }
}

Complete Configuration System

Environment-based Configuration

/// Environment-driven configuration with validation
use std::env;
use serde::{Deserialize, Serialize};
 
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct EnvironmentConfig {
    pub service_name: String,
    pub service_version: String,
    pub environment: String,
    pub metrics: MetricsConfig,
    pub logging: LoggingConfig,
    pub tracing: TracingConfig,
    pub export: ExportConfig,
}
 
impl EnvironmentConfig {
    pub fn from_env() -> Result<Self> {
        Ok(Self {
            service_name: env::var("SINDHAN_SERVICE_NAME")
                .context("SINDHAN_SERVICE_NAME environment variable is required")?,
            service_version: env::var("SINDHAN_SERVICE_VERSION")
                .unwrap_or_else(|_| "unknown".to_string()),
            environment: env::var("SINDHAN_ENVIRONMENT")
                .unwrap_or_else(|_| "development".to_string()),
            metrics: MetricsConfig::from_env()?,
            logging: LoggingConfig::from_env()?,
            tracing: TracingConfig::from_env()?,
            export: ExportConfig::from_env()?,
        })
    }
}
 
impl MetricsConfig {
    pub fn from_env() -> Result<Self> {
        Ok(Self {
            enabled: env::var("SINDHAN_METRICS_ENABLED")
                .unwrap_or_else(|_| "true".to_string())
                .parse()
                .unwrap_or(true),
            collection_interval: env::var("SINDHAN_METRICS_COLLECTION_INTERVAL")
                .unwrap_or_else(|_| "15s".to_string())
                .parse()
                .map_err(|_| anyhow::anyhow!("Invalid duration format"))?,
            prometheus_endpoint: env::var("SINDHAN_METRICS_PROMETHEUS_ENDPOINT").ok(),
            custom_metrics: Vec::new(), // Would be loaded from config file
            sampling_rate: env::var("SINDHAN_METRICS_SAMPLING_RATE")
                .unwrap_or_else(|_| "1.0".to_string())
                .parse()
                .unwrap_or(1.0),
        })
    }
}
 
impl LoggingConfig {
    pub fn from_env() -> Result<Self> {
        let level_str = env::var("SINDHAN_LOGGING_LEVEL")
            .unwrap_or_else(|_| "info".to_string());
        let level = match level_str.to_lowercase().as_str() {
            "trace" => LogLevel::Trace,
            "debug" => LogLevel::Debug,
            "info" => LogLevel::Info,
            "warn" => LogLevel::Warn,
            "error" => LogLevel::Error,
            _ => LogLevel::Info,
        };
        
        let format_str = env::var("SINDHAN_LOGGING_FORMAT")
            .unwrap_or_else(|_| "json".to_string());
        let format = match format_str.to_lowercase().as_str() {
            "json" => LogFormat::Json,
            "text" => LogFormat::Text,
            "logfmt" => LogFormat::Logfmt,
            _ => LogFormat::Json,
        };
        
        Ok(Self {
            enabled: env::var("SINDHAN_LOGGING_ENABLED")
                .unwrap_or_else(|_| "true".to_string())
                .parse()
                .unwrap_or(true),
            level,
            format,
            structured: env::var("SINDHAN_LOGGING_STRUCTURED")
                .unwrap_or_else(|_| "true".to_string())
                .parse()
                .unwrap_or(true),
            correlation_tracking: env::var("SINDHAN_LOGGING_CORRELATION_TRACKING")
                .unwrap_or_else(|_| "true".to_string())
                .parse()
                .unwrap_or(true),
            outputs: vec![LogOutput::Stdout], // Default to stdout
        })
    }
}
 
impl TracingConfig {
    pub fn from_env() -> Result<Self> {
        let sampling_str = env::var("SINDHAN_TRACING_SAMPLING_STRATEGY")
            .unwrap_or_else(|_| "probabilistic:1.0".to_string());
        
        let sampling_strategy = Self::parse_sampling_strategy(&sampling_str)?;
        
        Ok(Self {
            enabled: env::var("SINDHAN_TRACING_ENABLED")
                .unwrap_or_else(|_| "true".to_string())
                .parse()
                .unwrap_or(true),
            sampling_strategy,
            jaeger_endpoint: env::var("SINDHAN_TRACING_JAEGER_ENDPOINT").ok(),
            otlp_endpoint: env::var("SINDHAN_TRACING_OTLP_ENDPOINT").ok(),
            batch_export: env::var("SINDHAN_TRACING_BATCH_EXPORT")
                .unwrap_or_else(|_| "true".to_string())
                .parse()
                .unwrap_or(true),
            max_export_batch_size: env::var("SINDHAN_TRACING_MAX_EXPORT_BATCH_SIZE")
                .unwrap_or_else(|_| "512".to_string())
                .parse()
                .unwrap_or(512),
        })
    }
    
    fn parse_sampling_strategy(strategy_str: &str) -> Result<SamplingStrategy> {
        match strategy_str {
            "always_on" => Ok(SamplingStrategy::AlwaysOn),
            "always_off" => Ok(SamplingStrategy::AlwaysOff),
            s if s.starts_with("probabilistic:") => {
                let rate_str = s.strip_prefix("probabilistic:").unwrap();
                let rate: f64 = rate_str.parse()
                    .context("Invalid probabilistic sampling rate")?;
                Ok(SamplingStrategy::Probabilistic(rate))
            }
            s if s.starts_with("rate_limiting:") => {
                let limit_str = s.strip_prefix("rate_limiting:").unwrap();
                let limit: u32 = limit_str.parse()
                    .context("Invalid rate limiting value")?;
                Ok(SamplingStrategy::RateLimiting { max_traces_per_second: limit })
            }
            _ => Err(anyhow::anyhow!("Unknown sampling strategy: {}", strategy_str)),
        }
    }
}

Complete Application Example

Full Working Example with All Components

// Complete example showing all observability features
use sindhan_observability::{
    ObservabilityProvider, ObservabilityConfig,
    metrics::{Counter, Histogram, Gauge, MetricsRegistry},
    logging::{StructuredLogger, LogLevel, LogContext},
    tracing::{Tracer, SpanBuilder},
    instrumentation::{instrument, instrument_async},
    exporters::{PrometheusExporter, JaegerExporter, OtlpExporter},
    config::{MetricsConfig, LoggingConfig, TracingConfig},
};
use anyhow::Result;
use std::time::Duration;
use tokio::time::sleep;
use serde::{Deserialize, Serialize};
 
#[derive(Debug, Serialize, Deserialize)]
pub struct UserProfile {
    pub id: String,
    pub name: String,
    pub email: String,
    pub created_at: chrono::DateTime<chrono::Utc>,
}
 
#[derive(Debug, Serialize, Deserialize)]
pub struct CreateUserRequest {
    pub name: String,
    pub email: String,
}
 
// Comprehensive service implementation
pub struct UserService {
    observability: ObservabilityProvider,
    database: DatabaseConnection,
    cache: CacheConnection,
    // Service-specific metrics
    request_count: Counter,
    request_duration: Histogram,
    active_connections: Gauge,
    error_count: Counter,
    // Business metrics
    user_registrations: Counter,
    user_logins: Counter,
    active_users: Gauge,
}
 
impl UserService {
    pub async fn new(
        observability: ObservabilityProvider,
        database: DatabaseConnection,
        cache: CacheConnection,
    ) -> Result<Self> {
        let metrics = observability.metrics();
        
        // Create service metrics
        let request_count = metrics.create_counter(
            "user_service_requests_total",
            "Total number of requests to user service",
            Labels::new().with("service", "user-service"),
        ).await;
        
        let request_duration = metrics.create_histogram(
            "user_service_request_duration_seconds",
            "Request duration in seconds",
            Labels::new().with("service", "user-service"),
        ).await;
        
        let active_connections = metrics.create_gauge(
            "user_service_active_connections",
            "Number of active database connections",
            Labels::new().with("service", "user-service"),
        ).await;
        
        let error_count = metrics.create_counter(
            "user_service_errors_total",
            "Total number of errors",
            Labels::new().with("service", "user-service"),
        ).await;
        
        // Business metrics
        let user_registrations = metrics.create_counter(
            "user_registrations_total",
            "Total number of user registrations",
            Labels::new(),
        ).await;
        
        let user_logins = metrics.create_counter(
            "user_logins_total",
            "Total number of user logins",
            Labels::new(),
        ).await;
        
        let active_users = metrics.create_gauge(
            "active_users_current",
            "Currently active users",
            Labels::new(),
        ).await;
        
        Ok(Self {
            observability,
            database,
            cache,
            request_count,
            request_duration,
            active_connections,
            error_count,
            user_registrations,
            user_logins,
            active_users,
        })
    }
    
    #[instrument_async(
        name = "create_user",
        skip(self, request),
        fields(
            user.email = %request.email,
            user.name = %request.name
        )
    )]
    pub async fn create_user(&self, request: CreateUserRequest) -> Result<UserProfile> {
        let start_time = std::time::Instant::now();
        let logger = self.observability.logging();
        let tracer = self.observability.tracing();
        
        // Log the request start
        logger.info(
            "Creating new user",
            LogContext::new()
                .with_field("email", &request.email)
                .with_field("name", &request.name),
        );
        
        // Increment request counter
        self.request_count.increment(
            Labels::new()
                .with("operation", "create_user")
                .with("method", "POST")
        );
        
        // Create operation span
        let span = tracer.start_span("user_creation")
            .with_attribute("user.email", &request.email)
            .with_attribute("operation", "create");
        let _guard = span.enter();
        
        let result = async {
            // Validate request
            self.validate_create_request(&request).await?;
            
            // Check if user already exists
            if self.user_exists_by_email(&request.email).await? {
                return Err(anyhow::anyhow!("User with email {} already exists", request.email));
            }
            
            // Create user in database
            let user = self.create_user_in_database(&request).await?;
            
            // Cache the user
            self.cache_user(&user).await?;
            
            // Update business metrics
            self.user_registrations.increment(Labels::new());
            self.active_users.increment(Labels::new());
            
            Ok(user)
        }.await;
        
        // Record metrics and logs
        let duration = start_time.elapsed();
        self.request_duration.record(
            duration.as_secs_f64(),
            Labels::new()
                .with("operation", "create_user")
                .with("status", if result.is_ok() { "success" } else { "error" })
        );
        
        match &result {
            Ok(user) => {
                logger.info(
                    "User created successfully",
                    LogContext::new()
                        .with_field("user_id", &user.id)
                        .with_field("email", &user.email)
                        .with_field("duration_ms", duration.as_millis()),
                );
                span.set_attribute("user.id", &user.id);
                span.set_status(SpanStatus::Ok);
            }
            Err(error) => {
                self.error_count.increment(
                    Labels::new()
                        .with("operation", "create_user")
                        .with("error_type", error.type_name())
                );
                
                logger.error(
                    "Failed to create user",
                    LogContext::new()
                        .with_field("email", &request.email)
                        .with_field("duration_ms", duration.as_millis())
                        .with_error(error),
                );
                
                span.record_exception(error);
                span.set_status(SpanStatus::error(error.to_string()));
            }
        }
        
        result
    }
    
    #[instrument_async(
        name = "get_user",
        skip(self),
        fields(user.id = %user_id)
    )]
    pub async fn get_user(&self, user_id: &str) -> Result<Option<UserProfile>> {
        let start_time = std::time::Instant::now();
        let logger = self.observability.logging();
        let tracer = self.observability.tracing();
        
        logger.debug(
            "Fetching user",
            LogContext::new().with_field("user_id", user_id),
        );
        
        self.request_count.increment(
            Labels::new()
                .with("operation", "get_user")
                .with("method", "GET")
        );
        
        // Try cache first
        let result = match self.get_user_from_cache(user_id).await? {
            Some(user) => {
                logger.debug(
                    "User found in cache",
                    LogContext::new().with_field("user_id", user_id),
                );
                Ok(Some(user))
            }
            None => {
                // Fallback to database
                let user = self.get_user_from_database(user_id).await?;
                
                if let Some(ref user) = user {
                    // Cache for future requests
                    self.cache_user(user).await?;
                }
                
                Ok(user)
            }
        };
        
        let duration = start_time.elapsed();
        self.request_duration.record(
            duration.as_secs_f64(),
            Labels::new()
                .with("operation", "get_user")
                .with("status", if result.is_ok() { "success" } else { "error" })
        );
        
        result
    }
    
    #[instrument_async(
        name = "authenticate_user",
        skip(self, password),
        fields(user.email = %email)
    )]
    pub async fn authenticate_user(&self, email: &str, password: &str) -> Result<bool> {
        let start_time = std::time::Instant::now();
        let logger = self.observability.logging();
        
        logger.info(
            "Authenticating user",
            LogContext::new().with_field("email", email),
        );
        
        self.request_count.increment(
            Labels::new()
                .with("operation", "authenticate")
                .with("method", "POST")
        );
        
        let result = self.verify_password(email, password).await;
        
        match &result {
            Ok(true) => {
                self.user_logins.increment(
                    Labels::new().with("status", "success")
                );
                logger.info(
                    "User authenticated successfully",
                    LogContext::new().with_field("email", email),
                );
            }
            Ok(false) => {
                self.user_logins.increment(
                    Labels::new().with("status", "failed")
                );
                logger.warn(
                    "Authentication failed - invalid credentials",
                    LogContext::new().with_field("email", email),
                );
            }
            Err(error) => {
                self.error_count.increment(
                    Labels::new()
                        .with("operation", "authenticate")
                        .with("error_type", error.type_name())
                );
                logger.error(
                    "Authentication error",
                    LogContext::new()
                        .with_field("email", email)
                        .with_error(error),
                );
            }
        }
        
        let duration = start_time.elapsed();
        self.request_duration.record(
            duration.as_secs_f64(),
            Labels::new()
                .with("operation", "authenticate")
                .with("status", match &result {
                    Ok(true) => "success",
                    Ok(false) => "failed",
                    Err(_) => "error",
                })
        );
        
        result
    }
    
    // Helper methods with instrumentation
    #[instrument_async(skip(self))]
    async fn validate_create_request(&self, request: &CreateUserRequest) -> Result<()> {
        if request.name.is_empty() {
            return Err(anyhow::anyhow!("Name cannot be empty"));
        }
        if request.email.is_empty() || !request.email.contains('@') {
            return Err(anyhow::anyhow!("Invalid email format"));
        }
        Ok(())
    }
    
    #[instrument_async(skip(self))]
    async fn user_exists_by_email(&self, email: &str) -> Result<bool> {
        // Database query with automatic instrumentation
        let span = self.observability.tracing()
            .start_span("db_query")
            .with_attribute("db.operation", "SELECT")
            .with_attribute("db.table", "users");
        let _guard = span.enter();
        
        // Simulate database call
        sleep(Duration::from_millis(10)).await;
        Ok(false) // Simplified
    }
    
    #[instrument_async(skip(self, request))]
    async fn create_user_in_database(&self, request: &CreateUserRequest) -> Result<UserProfile> {
        let span = self.observability.tracing()
            .start_span("db_insert")
            .with_attribute("db.operation", "INSERT")
            .with_attribute("db.table", "users");
        let _guard = span.enter();
        
        self.active_connections.increment(Labels::new());
        
        // Simulate database call
        sleep(Duration::from_millis(25)).await;
        
        let user = UserProfile {
            id: uuid::Uuid::new_v4().to_string(),
            name: request.name.clone(),
            email: request.email.clone(),
            created_at: chrono::Utc::now(),
        };
        
        self.active_connections.decrement(Labels::new());
        
        Ok(user)
    }
    
    #[instrument_async(skip(self, user))]
    async fn cache_user(&self, user: &UserProfile) -> Result<()> {
        let span = self.observability.tracing()
            .start_span("cache_set")
            .with_attribute("cache.operation", "SET")
            .with_attribute("cache.key", format!("user:{}", user.id));
        let _guard = span.enter();
        
        // Simulate cache operation
        sleep(Duration::from_millis(5)).await;
        Ok(())
    }
    
    #[instrument_async(skip(self))]
    async fn get_user_from_cache(&self, user_id: &str) -> Result<Option<UserProfile>> {
        let span = self.observability.tracing()
            .start_span("cache_get")
            .with_attribute("cache.operation", "GET")
            .with_attribute("cache.key", format!("user:{}", user_id));
        let _guard = span.enter();
        
        // Simulate cache lookup
        sleep(Duration::from_millis(2)).await;
        Ok(None) // Simplified - cache miss
    }
    
    #[instrument_async(skip(self))]
    async fn get_user_from_database(&self, user_id: &str) -> Result<Option<UserProfile>> {
        let span = self.observability.tracing()
            .start_span("db_query")
            .with_attribute("db.operation", "SELECT")
            .with_attribute("db.table", "users")
            .with_attribute("user.id", user_id);
        let _guard = span.enter();
        
        self.active_connections.increment(Labels::new());
        
        // Simulate database query
        sleep(Duration::from_millis(15)).await;
        
        self.active_connections.decrement(Labels::new());
        
        // Simulate found user
        Ok(Some(UserProfile {
            id: user_id.to_string(),
            name: "Test User".to_string(),
            email: "test@example.com".to_string(),
            created_at: chrono::Utc::now(),
        }))
    }
    
    #[instrument_async(skip(self, password))]
    async fn verify_password(&self, email: &str, password: &str) -> Result<bool> {
        let span = self.observability.tracing()
            .start_span("password_verify")
            .with_attribute("user.email", email);
        let _guard = span.enter();
        
        // Simulate password verification
        sleep(Duration::from_millis(100)).await; // Intentionally slow for bcrypt simulation
        
        Ok(password == "correct_password") // Simplified
    }
}
 
// Application initialization and shutdown
#[tokio::main]
async fn main() -> Result<()> {
    // Initialize observability
    let observability = initialize_observability().await?;
    let logger = observability.logging();
    
    logger.info(
        "Starting user service",
        LogContext::new()
            .with_field("version", env!("CARGO_PKG_VERSION"))
            .with_field("environment", std::env::var("ENVIRONMENT").unwrap_or_else(|_| "development".to_string())),
    );
    
    // Initialize service
    let database = DatabaseConnection::new().await?;
    let cache = CacheConnection::new().await?;
    let user_service = UserService::new(observability.clone(), database, cache).await?;
    
    // Start background tasks
    let metrics_task = tokio::spawn(metrics_collection_task(observability.clone()));
    let health_check_task = tokio::spawn(health_check_task(observability.clone()));
    
    // Simulate some operations
    simulate_user_operations(&user_service).await?;
    
    // Graceful shutdown
    logger.info("Shutting down user service", LogContext::new());
    
    // Cancel background tasks
    metrics_task.abort();
    health_check_task.abort();
    
    // Flush all observability data
    observability.flush().await?;
    observability.shutdown().await?;
    
    Ok(())
}
 
async fn initialize_observability() -> Result<ObservabilityProvider> {
    let config = if let Ok(config_path) = std::env::var("OBSERVABILITY_CONFIG") {
        // Load from file
        let content = tokio::fs::read_to_string(config_path).await?;
        toml::from_str(&content)?
    } else {
        // Use environment variables
        ObservabilityConfig::from_env()?
    };
    
    ObservabilityProvider::from_config(config).await
}
 
async fn simulate_user_operations(service: &UserService) -> Result<()> {
    // Create a few users
    for i in 0..5 {
        let request = CreateUserRequest {
            name: format!("User {}", i),
            email: format!("user{}@example.com", i),
        };
        
        match service.create_user(request).await {
            Ok(user) => println!("Created user: {}", user.id),
            Err(e) => println!("Failed to create user: {}", e),
        }
        
        // Small delay
        sleep(Duration::from_millis(100)).await;
    }
    
    // Simulate some gets and authentications
    for i in 0..10 {
        let user_id = format!("user-{}", i % 3);
        
        // Get user
        match service.get_user(&user_id).await {
            Ok(Some(user)) => {
                // Try authentication
                let auth_result = service.authenticate_user(&user.email, "correct_password").await;
                println!("Auth result for {}: {:?}", user.email, auth_result);
            }
            Ok(None) => println!("User {} not found", user_id),
            Err(e) => println!("Error getting user {}: {}", user_id, e),
        }
        
        sleep(Duration::from_millis(50)).await;
    }
    
    Ok(())
}
 
// Background task for system metrics
async fn metrics_collection_task(observability: ObservabilityProvider) {
    let metrics = observability.metrics();
    let logger = observability.logging();
    
    let system_cpu = metrics.create_gauge(
        "system_cpu_usage_percent",
        "System CPU usage percentage",
        Labels::new(),
    ).await;
    
    let system_memory = metrics.create_gauge(
        "system_memory_usage_bytes",
        "System memory usage in bytes",
        Labels::new(),
    ).await;
    
    let mut interval = tokio::time::interval(Duration::from_secs(30));
    
    loop {
        interval.tick().await;
        
        // Simulate system metrics collection
        let cpu_usage = (rand::random::<f64>() * 100.0).min(100.0);
        let memory_usage = (rand::random::<f64>() * 8_000_000_000.0); // Up to 8GB
        
        system_cpu.set(cpu_usage, Labels::new());
        system_memory.set(memory_usage, Labels::new());
        
        logger.trace(
            "System metrics collected",
            LogContext::new()
                .with_field("cpu_usage", cpu_usage)
                .with_field("memory_usage", memory_usage),
        );
    }
}
 
// Health check task
async fn health_check_task(observability: ObservabilityProvider) {
    let metrics = observability.metrics();
    let logger = observability.logging();
    
    let health_status = metrics.create_gauge(
        "service_health_status",
        "Service health status (1=healthy, 0=unhealthy)",
        Labels::new(),
    ).await;
    
    let mut interval = tokio::time::interval(Duration::from_secs(60));
    
    loop {
        interval.tick().await;
        
        // Perform health checks
        let is_healthy = perform_health_checks().await;
        
        health_status.set(if is_healthy { 1.0 } else { 0.0 }, Labels::new());
        
        if is_healthy {
            logger.debug("Health check passed", LogContext::new());
        } else {
            logger.warn("Health check failed", LogContext::new());
        }
    }
}
 
async fn perform_health_checks() -> bool {
    // Simulate health checks
    sleep(Duration::from_millis(50)).await;
    true // Always healthy in this example
}
 
// Mock types for the example
struct DatabaseConnection;
impl DatabaseConnection {
    async fn new() -> Result<Self> { Ok(Self) }
}
 
struct CacheConnection;
impl CacheConnection {
    async fn new() -> Result<Self> { Ok(Self) }
}

This implementation provides a comprehensive, type-safe, and high-performance observability framework with async-first design principles and zero-cost abstractions. It includes complete configuration management, export pipelines, instrumentation patterns, and real-world usage examples.