Revert removal of external producers

opentelemetry-sdk/CHANGELOG.md

@@ -4,6 +4,8 @@
 
 - TODO: Placeholder for Span processor related things
   - *Fix* SpanProcessor::on_start is no longer called on non recording spans
+- Revert removal of `MetricProducer` which allowed metrics from
+  external sources to be sent through OpenTelemetry.
 
 ## 0.30.0
 

opentelemetry-sdk/src/metrics/manual_reader.rs

@@ -13,7 +13,7 @@
 use super::{
     data::ResourceMetrics,
     pipeline::Pipeline,
-    reader::{MetricReader, SdkProducer},
+    reader::{MetricProducer, MetricReader, SdkProducer},
 };
 
 /// A simple [MetricReader] that allows an application to read metrics on demand.
@@ -50,6 +50,7 @@
 struct ManualReaderInner {
     sdk_producer: Option<Weak<dyn SdkProducer>>,
     is_shutdown: bool,
+    external_producers: Vec<Box<dyn MetricProducer>>,
 }
 
 impl ManualReader {
@@ -59,11 +60,15 @@
     }
 
     /// A [MetricReader] which is directly called to collect metrics.
-    pub(crate) fn new(temporality: Temporality) -> Self {
+    pub(crate) fn new(
+        temporality: Temporality,
+        external_producers: Vec<Box<dyn MetricProducer>>,
+    ) -> Self {
         ManualReader {
             inner: Mutex::new(ManualReaderInner {
                 sdk_producer: None,
                 is_shutdown: false,
+                external_producers,
             }),
             temporality,
         }
@@ -86,7 +91,7 @@
         });
     }
 
-    /// Gathers all metrics from the SDK, calling any
+    /// Gathers all metrics from the SDK and other [MetricProducer]s, calling any
     /// callbacks necessary and returning the results.
     ///
     /// Returns an error if called after shutdown.
@@ -105,7 +110,19 @@
             }
         };
 
-        Ok(())
+        let mut errs = vec![];
+        for producer in &inner.external_producers {
+            match producer.produce() {
+                Ok(metrics) => rm.scope_metrics.push(metrics),
+                Err(err) => errs.push(err),
+            }
+        }
+
+        if errs.is_empty() {
+            Ok(())
+        } else {
+            Err(OTelSdkError::InternalFailure(format!("{:?}", errs)))
+        }
     }
 
     /// ForceFlush is a no-op, it always returns nil.
@@ -123,6 +140,7 @@
         // Any future call to collect will now return an error.
         inner.sdk_producer = None;
         inner.is_shutdown = true;
+        inner.external_producers = Vec::new();
 
         Ok(())
     }
@@ -136,6 +154,7 @@
 #[derive(Default)]
 pub struct ManualReaderBuilder {
     temporality: Temporality,
+    producers: Vec<Box<dyn MetricProducer>>,
 }
 
 impl fmt::Debug for ManualReaderBuilder {
@@ -156,8 +175,17 @@
         self
     }
 
+    /// Registers a an external [MetricProducer] with this reader.
+    ///
+    /// The producer is used as a source of aggregated metric data which is
+    /// incorporated into metrics collected from the SDK.
+    pub fn with_producer(mut self, producer: impl MetricProducer + 'static) -> Self {
+        self.producers.push(Box::new(producer));
+        self
+    }
+
     /// Create a new [ManualReader] from this configuration.
     pub fn build(self) -> ManualReader {
-        ManualReader::new(self.temporality)
+        ManualReader::new(self.temporality, self.producers)
     }
 }

opentelemetry-sdk/src/metrics/periodic_reader.rs

@@ -12,7 +12,7 @@
 
 use crate::{
     error::{OTelSdkError, OTelSdkResult},
-    metrics::{exporter::PushMetricExporter, reader::SdkProducer},
+    metrics::{exporter::PushMetricExporter, reader::MetricProducer, reader::SdkProducer},
     Resource,
 };
 
@@ -30,6 +30,7 @@
 pub struct PeriodicReaderBuilder<E> {
     interval: Duration,
     exporter: E,
+    producers: Vec<Box<dyn MetricProducer>>,
 }
 
 impl<E> PeriodicReaderBuilder<E>
@@ -42,7 +43,11 @@
             .and_then(|v| v.parse().map(Duration::from_millis).ok())
             .unwrap_or(DEFAULT_INTERVAL);
 
-        PeriodicReaderBuilder { interval, exporter }
+        PeriodicReaderBuilder {
+            interval,
+            exporter,
+            producers: Vec::new(),
+        }
     }
 
     /// Configures the intervening time between exports for a [PeriodicReader].
@@ -59,6 +64,15 @@
         self
     }
 
+    /// Registers a an external [MetricProducer] with this reader.
+    ///
+    /// The producer is used as a source of aggregated metric data which is
+    /// incorporated into metrics collected from the SDK.
+    pub fn with_producer(mut self, producer: impl MetricProducer + 'static) -> Self {
+        self.producers.push(Box::new(producer));
+        self
+    }
+
     /// Create a [PeriodicReader] with the given config.
     pub fn build(self) -> PeriodicReader<E> {
         PeriodicReader::new(self.exporter, self.interval)
@@ -152,6 +166,7 @@
                 message_sender,
                 producer: Mutex::new(None),
                 exporter: exporter_arc.clone(),
+                external_producers: Vec::new(),
             }),
         };
         let cloned_reader = reader.clone();
@@ -351,6 +366,7 @@
     exporter: Arc<E>,
     message_sender: mpsc::Sender<Message>,
     producer: Mutex<Option<Weak<dyn SdkProducer>>>,
+    external_producers: Vec<Box<dyn MetricProducer>>,
 }
 
 impl<E: PushMetricExporter> PeriodicReaderInner<E> {
@@ -364,23 +380,36 @@
     }
 
     fn collect(&self, rm: &mut ResourceMetrics) -> OTelSdkResult {
+        let mut errs = vec![];
         let producer = self.producer.lock().expect("lock poisoned");
         if let Some(p) = producer.as_ref() {
             p.upgrade()
                 .ok_or(OTelSdkError::AlreadyShutdown)?
                 .produce(rm)?;
-            Ok(())
         } else {
             otel_warn!(
             name: "PeriodReader.MeterProviderNotRegistered",
             message = "PeriodicReader is not registered with MeterProvider. Metrics will not be collected. \
                    This occurs when a periodic reader is created but not associated with a MeterProvider \
                    by calling `.with_reader(reader)` on MeterProviderBuilder."
             );
-            Err(OTelSdkError::InternalFailure(
+            errs.push(OTelSdkError::InternalFailure(
                 "MeterProvider is not registered".into(),
             ))
         }
+
+        for producer in &self.external_producers {
+            match producer.produce() {
+                Ok(metrics) => rm.scope_metrics.push(metrics),
+                Err(err) => errs.push(err),
+            }
+        }
+
+        if errs.is_empty() {
+            Ok(())
+        } else {
+            Err(OTelSdkError::InternalFailure(format!("{:?}", errs)))
+        }
     }
 
     fn collect_and_export(&self, rm: &mut ResourceMetrics) -> OTelSdkResult {

opentelemetry-sdk/src/metrics/reader.rs

@@ -1,9 +1,14 @@
 //! Interfaces for reading and producing metrics
-use crate::error::OTelSdkResult;
+use crate::error::{OTelSdkError, OTelSdkResult};
 use std::time::Duration;
 use std::{fmt, sync::Weak};
 
-use super::{data::ResourceMetrics, instrument::InstrumentKind, pipeline::Pipeline, Temporality};
+use super::{
+    data::{ResourceMetrics, ScopeMetrics},
+    instrument::InstrumentKind,
+    pipeline::Pipeline,
+    Temporality,
+};
 
 /// The interface used between the SDK and an exporter.
 ///
@@ -65,3 +70,9 @@ pub(crate) trait SdkProducer: fmt::Debug + Send + Sync {
     /// Returns aggregated metrics from a single collection.
     fn produce(&self, rm: &mut ResourceMetrics) -> OTelSdkResult;
 }
+
+/// Produces metrics for a [MetricReader] from an external source.
+pub trait MetricProducer: fmt::Debug + Send + Sync {
+    /// Returns aggregated metrics from an external source.
+    fn produce(&self) -> Result<ScopeMetrics, OTelSdkError>;
+}