Update the Prometheus exporter to the new API. (#156)

Author: Ian Sturdy

WORKSPACE

@@ -84,19 +84,15 @@ cc_library(
 """
 )
 
-# TODO: Remove protobuf dependency and reset to head.
 http_archive(
     name = "com_github_jupp0r_prometheus_cpp",
-    strip_prefix = "prometheus-cpp-a97127c9aeec8decb76cf3bec1fb9c9a0dd4a9fc",
-    urls = ["https://github.com/jupp0r/prometheus-cpp/archive/a97127c9aeec8decb76cf3bec1fb9c9a0dd4a9fc.zip"],
+    strip_prefix = "prometheus-cpp-master",
+    urls = ["https://github.com/jupp0r/prometheus-cpp/archive/master.zip"],
 )
 
-load("@com_github_jupp0r_prometheus_cpp//:repositories.bzl",
-     "load_prometheus_client_model",
-     "load_civetweb")
+load("@com_github_jupp0r_prometheus_cpp//:repositories.bzl", "load_civetweb")
 
 # Load dependencies individually since we load some of them above.
-load_prometheus_client_model()
 load_civetweb()
 
 # Curl library - used by zipkin exporter.

opencensus/exporters/stats/prometheus/BUILD

@@ -28,7 +28,6 @@ cc_library(
         ":prometheus_utils",
         "//opencensus/stats",
         "@com_github_jupp0r_prometheus_cpp//:prometheus_cpp",
-        "@prometheus_client_model",
     ],
 )
 
@@ -42,9 +41,9 @@ cc_library(
     copts = DEFAULT_COPTS,
     deps = [
         "//opencensus/stats",
+        "@com_github_jupp0r_prometheus_cpp//:prometheus_cpp",
         "@com_google_absl//absl/strings",
         "@com_google_absl//absl/time",
-        "@prometheus_client_model",
     ],
 )
 
@@ -61,8 +60,6 @@ cc_test(
         "//opencensus/stats:test_utils",
         "@com_google_absl//absl/strings",
         "@com_google_googletest//:gtest_main",
-        "@com_google_protobuf//:protobuf",
-        "@prometheus_client_model",
     ],
 )
 

opencensus/exporters/stats/prometheus/internal/prometheus_exporter.cc

@@ -17,18 +17,17 @@
 #include <utility>
 #include <vector>
 
-#include "metrics.pb.h"
 #include "opencensus/exporters/stats/prometheus/internal/prometheus_utils.h"
 #include "opencensus/stats/stats.h"
+#include "prometheus/metric_family.h"
 
 namespace opencensus {
 namespace exporters {
 namespace stats {
 
-std::vector<io::prometheus::client::MetricFamily>
-PrometheusExporter::Collect() {
+std::vector<prometheus::MetricFamily> PrometheusExporter::Collect() {
   const auto data = opencensus::stats::StatsExporter::GetViewData();
-  std::vector<io::prometheus::client::MetricFamily> output(data.size());
+  std::vector<prometheus::MetricFamily> output(data.size());
   for (int i = 0; i < data.size(); ++i) {
     SetMetricFamily(data[i].first, data[i].second, &output[i]);
   }

opencensus/exporters/stats/prometheus/internal/prometheus_utils.cc

@@ -16,6 +16,7 @@
 
 #include <cctype>
 #include <cstdint>
+#include <limits>
 #include <string>
 #include <utility>
 #include <vector>
@@ -24,8 +25,9 @@
 #include "absl/strings/str_cat.h"
 #include "absl/strings/string_view.h"
 #include "absl/time/time.h"
-#include "metrics.pb.h"
 #include "opencensus/stats/stats.h"
+#include "prometheus/metric.h"
+#include "prometheus/metric_type.h"
 
 namespace opencensus {
 namespace exporters {
@@ -42,99 +44,100 @@ std::string SanitizeName(absl::string_view name) {
   return sanitized;
 }
 
-io::prometheus::client::MetricType MetricType(
-    opencensus::stats::Aggregation::Type type) {
+prometheus::MetricType MetricType(opencensus::stats::Aggregation::Type type) {
   switch (type) {
     case opencensus::stats::Aggregation::Type::kCount:
-      return io::prometheus::client::MetricType::COUNTER;
+      return prometheus::MetricType::Counter;
     case opencensus::stats::Aggregation::Type::kSum:
-      return io::prometheus::client::MetricType::UNTYPED;
+      return prometheus::MetricType::Untyped;
     case opencensus::stats::Aggregation::Type::kLastValue:
-      return io::prometheus::client::MetricType::GAUGE;
+      return prometheus::MetricType::Gauge;
     case opencensus::stats::Aggregation::Type::kDistribution:
-      return io::prometheus::client::MetricType::HISTOGRAM;
+      return prometheus::MetricType::Histogram;
   }
 }
 
-void SetValue(double value, io::prometheus::client::MetricType type,
-              io::prometheus::client::Metric* metric) {
-  if (type == io::prometheus::client::MetricType::UNTYPED) {
-    metric->mutable_untyped()->set_value(value);
+void SetValue(double value, prometheus::MetricType type,
+              prometheus::ClientMetric* metric) {
+  if (type == prometheus::MetricType::Untyped) {
+    metric->untyped.value = value;
   } else {
-    ABSL_ASSERT(type == io::prometheus::client::MetricType::GAUGE);
-    metric->mutable_gauge()->set_value(value);
+    ABSL_ASSERT(type == prometheus::MetricType::Gauge);
+    metric->gauge.value = value;
   }
 }
 
-void SetValue(int64_t value, io::prometheus::client::MetricType type,
-              io::prometheus::client::Metric* metric) {
+void SetValue(int64_t value, prometheus::MetricType type,
+              prometheus::ClientMetric* metric) {
   switch (type) {
-    case io::prometheus::client::MetricType::COUNTER: {
-      metric->mutable_counter()->set_value(value);
+    case prometheus::MetricType::Counter: {
+      metric->counter.value = value;
       break;
     }
-    case io::prometheus::client::MetricType::GAUGE: {
-      metric->mutable_gauge()->set_value(value);
+    case prometheus::MetricType::Gauge: {
+      metric->gauge.value = value;
       break;
     }
-    case io::prometheus::client::MetricType::UNTYPED: {
-      metric->mutable_untyped()->set_value(value);
+    case prometheus::MetricType::Untyped: {
+      metric->untyped.value = value;
       break;
     }
     default:
       ABSL_ASSERT(false && "Invalid MetricType for int64 value.");
   }
 }
 void SetValue(const opencensus::stats::Distribution& value,
-              io::prometheus::client::MetricType type,
-              io::prometheus::client::Metric* metric) {
-  auto* histogram = metric->mutable_histogram();
-  histogram->set_sample_count(value.count());
-  histogram->set_sample_sum(value.count() * value.mean());
+              prometheus::MetricType type, prometheus::ClientMetric* metric) {
+  auto& histogram = metric->histogram;
+  histogram.sample_count = value.count();
+  histogram.sample_sum = value.count() * value.mean();
 
   int64_t cumulative_count = 0;
+  histogram.bucket.reserve(value.bucket_boundaries().num_buckets());
   for (int i = 0; i < value.bucket_boundaries().num_buckets(); ++i) {
     cumulative_count += value.bucket_counts()[i];
-    auto* bucket = histogram->add_bucket();
-    bucket->set_cumulative_count(cumulative_count);
+    histogram.bucket.emplace_back();
+    histogram.bucket[i].cumulative_count = cumulative_count;
     // We use lower boundaries plus an underflow bucket; Prometheus uses upper
     // boundaries, including a +Inf boundary.
-    bucket->set_upper_bound(
+    histogram.bucket[i].upper_bound =
         i < value.bucket_boundaries().lower_boundaries().size()
             ? value.bucket_boundaries().lower_boundaries()[i]
-            : std::numeric_limits<double>::infinity());
+            : std::numeric_limits<double>::infinity();
   }
 }
 
 template <typename T>
 void SetData(const opencensus::stats::ViewDescriptor& descriptor,
              const opencensus::stats::ViewData::DataMap<T>& data, int64_t time,
-             io::prometheus::client::MetricType type,
-             io::prometheus::client::MetricFamily* metric_family) {
+             prometheus::MetricType type,
+             prometheus::MetricFamily* metric_family) {
+  metric_family->metric.reserve(data.size());
   for (const auto& row : data) {
-    auto* metric = metric_family->add_metric();
-    metric->set_timestamp_ms(time);
+    metric_family->metric.emplace_back();
+    prometheus::ClientMetric& metric = metric_family->metric.back();
+    metric.timestamp_ms = time;
+    metric.label.resize(descriptor.num_columns());
     for (int i = 0; i < descriptor.num_columns(); ++i) {
-      auto* label = metric->add_label();
-      label->set_name(SanitizeName(descriptor.columns()[i].name()));
-      label->set_value(row.first[i]);
+      metric.label[i].name = SanitizeName(descriptor.columns()[i].name());
+      metric.label[i].value = row.first[i];
     }
-    SetValue(row.second, type, metric);
+    SetValue(row.second, type, &metric);
   }
 }
 
 }  // namespace
 
 void SetMetricFamily(const opencensus::stats::ViewDescriptor& descriptor,
                      const opencensus::stats::ViewData& data,
-                     io::prometheus::client::MetricFamily* metric_family) {
-  const io::prometheus::client::MetricType type =
+                     prometheus::MetricFamily* metric_family) {
+  const prometheus::MetricType type =
       MetricType(descriptor.aggregation().type());
   // TODO(sturdy): convert common units into base units (e.g. ms->s).
-  metric_family->set_name(SanitizeName(absl::StrCat(
-      descriptor.name(), "_", descriptor.measure_descriptor().units())));
-  metric_family->set_help(descriptor.description());
-  metric_family->set_type(type);
+  metric_family->name = SanitizeName(absl::StrCat(
+      descriptor.name(), "_", descriptor.measure_descriptor().units()));
+  metric_family->help = descriptor.description();
+  metric_family->type = type;
 
   const int64_t time = absl::ToUnixMillis(data.end_time());
   switch (data.type()) {

opencensus/exporters/stats/prometheus/internal/prometheus_utils.h

@@ -18,8 +18,8 @@
 #include <utility>
 #include <vector>
 
-#include "metrics.pb.h"
 #include "opencensus/stats/stats.h"
+#include "prometheus/metric_family.h"
 
 namespace opencensus {
 namespace exporters {
@@ -28,7 +28,7 @@ namespace stats {
 // Populates metric_family based on view_descriptor and view_data.
 void SetMetricFamily(const opencensus::stats::ViewDescriptor& descriptor,
                      const opencensus::stats::ViewData& data,
-                     io::prometheus::client::MetricFamily* metric_family);
+                     prometheus::MetricFamily* metric_family);
 
 }  // namespace stats
 }  // namespace exporters