Add stats API

envoyfilter/src/lib.rs

@@ -1,28 +1,47 @@
 use log::info;
+use stats::IncrementingMetric;
+use stats::Metric;
+use stats::RecordingMetric;
 use std::time::Duration;
 
 use proxy_wasm::traits::*;
 use proxy_wasm::types::*;
 
+mod stats;
+
 proxy_wasm::main! {{
     proxy_wasm::set_log_level(LogLevel::Trace);
     proxy_wasm::set_root_context(|_| -> Box<dyn RootContext> {
         Box::new(HttpHeaderRoot {
             header_content: String::new(),
+            metrics: WasmMetrics {
+                counter: stats::Counter::new(String::from("wasm_counter")),
+                gauge: stats::Gauge::new(String::from("wasm_gauge")),
+                histogram: stats::Histogram::new(String::from("wasm_histogram")),
+            }
         })
     });
 }}
 
 struct HttpHeader {
     context_id: u32,
     header_content: String,
+    metrics: WasmMetrics,
 }
 
 // HttpContext is the trait that allows the Rust code to interact with HTTP objects.
 impl HttpContext for HttpHeader {
     // Envoy's HTTP model is event driven. The WASM ABI has given implementors events to hook onto
     // the lifecycle of the http request and response.
     fn on_http_request_headers(&mut self, _num_headers: usize, _end_of_stream: bool) -> Action {
+        // Metrics
+        self.metrics.counter.increment(10);
+        info!("counter -> {}", self.metrics.counter.value());
+        self.metrics.gauge.record(20);
+        info!("gauge -> {}", self.metrics.gauge.value());
+        self.metrics.histogram.record(30);
+        info!("histogram -> {}", self.metrics.histogram.value());
+
         // Example of reading the HTTP headers on the incoming request
         for (name, value) in &self.get_http_request_headers() {
             info!("#{} -> {}: {}", self.context_id, name, value);
@@ -86,8 +105,16 @@ impl Context for HttpHeader {
     }
 }
 
+#[derive(Copy, Clone)]
+struct WasmMetrics {
+    counter: stats::Counter,
+    gauge: stats::Gauge,
+    histogram: stats::Histogram,
+}
+
 struct HttpHeaderRoot {
     header_content: String,
+    metrics: WasmMetrics,
 }
 
 impl Context for HttpHeaderRoot {}
@@ -105,6 +132,7 @@ impl RootContext for HttpHeaderRoot {
         Some(Box::new(HttpHeader {
             context_id,
             header_content: self.header_content.clone(),
+            metrics: self.metrics,
         }))
     }
 

envoyfilter/src/stats.rs

@@ -0,0 +1,98 @@
+
+use proxy_wasm::hostcalls;
+use proxy_wasm::types::*;
+
+pub trait Metric {
+    fn id(&self) -> u32;
+
+    fn value(&self) -> u64 {
+        match hostcalls::get_metric(self.id()) {
+            Ok(value) => value,
+            Err(Status::NotFound) => panic!("metric not found: {}", self.id()),
+            Err(err) => panic!("unexpected status: {:?}", err),
+        }
+    }
+}
+
+pub trait IncrementingMetric: Metric {
+    fn increment(&self, offset: i64) {
+        match hostcalls::increment_metric(self.id(), offset) {
+            Ok(_) => return,
+            Err(Status::NotFound) => panic!("metric not found: {}", self.id()),
+            Err(err) => panic!("unexpected status: {:?}", err),
+        }
+    }
+}
+
+pub trait RecordingMetric: Metric {
+    fn record(&self, value: u64) {
+        match hostcalls::record_metric(self.id(), value) {
+            Ok(_) => return,
+            Err(Status::NotFound) => panic!("metric not found: {}", self.id()),
+            Err(err) => panic!("unexpected status: {:?}", err),
+        }
+    }
+}
+
+#[derive(Copy, Clone)]
+pub struct Counter {
+    id: u32,
+}
+
+impl Counter {
+    pub fn new(name: String) -> Counter {
+        let returned_id = hostcalls::define_metric(MetricType::Counter, &name)
+            .expect("failed to define counter '{}', name");
+        Counter { id: returned_id }
+    }
+}
+
+impl Metric for Counter {
+    fn id(&self) -> u32 {
+        self.id
+    }
+}
+
+impl IncrementingMetric for Counter {}
+
+#[derive(Copy, Clone)]
+pub struct Gauge {
+    id: u32,
+}
+
+impl Gauge {
+    pub fn new(name: String) -> Gauge {
+        let returned_id = hostcalls::define_metric(MetricType::Gauge, &name)
+            .expect("failed to define gauge '{}', name");
+        Gauge { id: returned_id }
+    }
+}
+
+impl Metric for Gauge {
+    fn id(&self) -> u32 {
+        self.id
+    }
+}
+
+impl RecordingMetric for Gauge {}
+
+#[derive(Copy, Clone)]
+pub struct Histogram {
+    id: u32,
+}
+
+impl Histogram {
+    pub fn new(name: String) -> Histogram {
+        let returned_id = hostcalls::define_metric(MetricType::Histogram, &name)
+            .expect("failed to define histogram '{}', name");
+        Histogram { id: returned_id }
+    }
+}
+
+impl Metric for Histogram {
+    fn id(&self) -> u32 {
+        self.id
+    }
+}
+
+impl RecordingMetric for Histogram {}