Show off the problem with dual-writing metrics from one function call.

We might want to instead break this out into two separate functions— one that takes a label, the other that doesn't. That might allow us to then properly pass the callback and only call it once when everything is done.

Author: Yasumoto

Sources/Prometheus/MetricTypes/Histogram.swift

@@ -128,7 +128,18 @@ public class Histogram<NumType: DoubleRepresentable, Labels: HistogramLabels>: M
         prometheusQueue.async(flags: .barrier) {
             if let labels = labels, type(of: labels) != type(of: EmptySummaryLabels()) {
                 let his = self.prometheus.getOrCreateHistogram(with: labels, for: self)
-                his.observe(value)
+                his.observe(value) {
+                    self.total.inc(value)
+                    
+                    for (i, bound) in self.upperBounds.enumerated() {
+                        if bound >= value.doubleValue {
+                            self.buckets[i].inc()
+                            break
+                        }
+                    }
+                    done()
+                }
+                return
             }
             self.total.inc(value)
 

Sources/Prometheus/MetricTypes/Summary.swift

@@ -1,3 +1,5 @@
+import Dispatch
+
 /// Default quantiles used by Summaries
 public var defaultQuantiles = [0.01, 0.05, 0.5, 0.9, 0.95, 0.99, 0.999]
 
@@ -127,12 +129,19 @@ public class Summary<NumType: DoubleRepresentable, Labels: SummaryLabels>: Metri
         prometheusQueue.async(flags: .barrier) {
             if let labels = labels, type(of: labels) != type(of: EmptySummaryLabels()) {
                 let sum = self.prometheus.getOrCreateSummary(withLabels: labels, forSummary: self)
-                sum.observe(value)
+                sum.observe(value) {
+                    self.count.inc(1)
+                    self.sum.inc(value)
+                    self.values.append(value)
+                    done()
+                }
+                return
+            } else {
+                self.count.inc(1)
+                self.sum.inc(value)
+                self.values.append(value)
+                done()
             }
-            self.count.inc(1)
-            self.sum.inc(value)
-            self.values.append(value)
-            done()
         }
     }
 }