stats: add built-in log linear histogram support

bazel/external/libcircllhist.BUILD

@@ -0,0 +1,17 @@
+cc_library(
+    name = "libcircllhist",
+    srcs = ["src/circllhist.c"],
+    hdrs = [
+        "src/circllhist.h",
+        "src/circllhist_config.h",  # Generated.
+    ],
+    includes = ["src"],
+    visibility = ["//visibility:public"],
+)
+
+genrule(
+    name = "circllhist_config",
+    srcs = ["src/circllhist_config.h.in"],
+    outs = ["src/circllhist_config.h"],
+    cmd = "cp $< $@",
+)

bazel/repositories.bzl

@@ -177,6 +177,7 @@ def envoy_dependencies(path = "@envoy_deps//", skip_targets = []):
     _boringssl()
     _com_google_absl()
     _com_github_bombela_backward()
+    _com_github_circonus_labs_libcircllhist()
     _com_github_cyan4973_xxhash()
     _com_github_eile_tclap()
     _com_github_fmtlib_fmt()
@@ -215,6 +216,16 @@ def _com_github_bombela_backward():
         actual = "@com_github_bombela_backward//:backward",
     )
 
+def _com_github_circonus_labs_libcircllhist():
+    _repository_impl(
+        name = "com_github_circonus_labs_libcircllhist",
+        build_file = "@envoy//bazel/external:libcircllhist.BUILD",
+    )
+    native.bind(
+        name = "libcircllhist",
+        actual = "@com_github_circonus_labs_libcircllhist//:libcircllhist",
+    )
+
 def _com_github_cyan4973_xxhash():
     _repository_impl(
         name = "com_github_cyan4973_xxhash",

bazel/repository_locations.bzl

@@ -12,6 +12,10 @@ REPOSITORY_LOCATIONS = dict(
         commit = "44ae9609e860e3428cd057f7052e505b4819eb84",  # 2018-02-06
         remote = "https://github.com/bombela/backward-cpp",
     ),
+    com_github_circonus_labs_libcircllhist = dict(
+        commit = "bb73e93ba23b5746ea15d95c21ee8536168c486c",  # 2018-03-18
+        remote = "https://github.com/circonus-labs/libcircllhist",
+    ),
     com_github_cyan4973_xxhash = dict(
         commit = "7caf8bd76440c75dfe1070d3acfbd7891aea8fca",  # v0.6.4
         remote = "https://github.com/Cyan4973/xxHash",

include/envoy/stats/stats.h

@@ -114,6 +114,11 @@ class Metric {
    * Returns the name of the Metric with the portions designated as tags removed.
    */
   virtual const std::string& tagExtractedName() const PURE;
+
+  /**
+   * Indicates whether a metric has been used.
+   */
+  virtual bool used() const PURE;
 };
 
 /**
@@ -128,7 +133,6 @@ class Counter : public virtual Metric {
   virtual void inc() PURE;
   virtual uint64_t latch() PURE;
   virtual void reset() PURE;
-  virtual bool used() const PURE;
   virtual uint64_t value() const PURE;
 };
 
@@ -146,12 +150,13 @@ class Gauge : public virtual Metric {
   virtual void inc() PURE;
   virtual void set(uint64_t value) PURE;
   virtual void sub(uint64_t amount) PURE;
-  virtual bool used() const PURE;
   virtual uint64_t value() const PURE;
 };
 
 typedef std::shared_ptr<Gauge> GaugeSharedPtr;
 
+struct HistogramStatistics;
+
 /**
  * A histogram that records values one at a time.
  * Note: Histograms now incorporate what used to be timers because the only difference between the
@@ -167,6 +172,21 @@ class Histogram : public virtual Metric {
    * Records an unsigned value. If a timer, values are in units of milliseconds.
    */
   virtual void recordValue(uint64_t value) PURE;
+
+  /**
+   * Merges the histogram values collected during the flush interval.
+   */
+  virtual void merge() PURE;
+
+  /**
+   * Returns the Histogram Summary Statistics for the flush interval.
+   */
+  virtual HistogramStatistics intervalStatistics() const PURE;
+
+  /**
+   * Returns the Cumulative Histogram Summary Statistics.
+   */
+  virtual HistogramStatistics cumulativeStatistics() const PURE;
 };
 
 typedef std::shared_ptr<Histogram> HistogramSharedPtr;
@@ -194,6 +214,11 @@ class Sink {
    */
   virtual void flushGauge(const Gauge& gauge, uint64_t value) PURE;
 
+  /**
+   * Flush a histogram.
+   */
+  virtual void flushHistogram(const Histogram&) PURE;
+
   /**
    * This will be called after beginFlush(), some number of flushCounter(), and some number of
    * flushGauge(). Sinks can use this to optimize writing if desired.
@@ -263,6 +288,11 @@ class Store : public Scope {
    * @return a list of all known gauges.
    */
   virtual std::list<GaugeSharedPtr> gauges() const PURE;
+
+  /**
+   * @return a list of all known histograms.
+   */
+  virtual std::list<HistogramSharedPtr> histograms() const PURE;
 };
 
 typedef std::unique_ptr<Store> StorePtr;
@@ -294,6 +324,11 @@ class StoreRoot : public Store {
    * down.
    */
   virtual void shutdownThreading() PURE;
+
+  /**
+   * Called during the flush process to merge all the thread local histograms.
+   */
+  virtual void mergeHistograms() PURE;
 };
 
 typedef std::unique_ptr<StoreRoot> StoreRootPtr;

include/envoy/thread_local/thread_local.h

@@ -46,6 +46,13 @@ class Slot {
    */
   virtual void runOnAllThreads(Event::PostCb cb) PURE;
 
+  /**
+   * Run a callback on all registered threads with a barrier.
+   * @param cb supplies the callback to run on each thread.
+   * @param main_callback supplies the callback to run on main thread after threads are done.
+   */
+  virtual void runOnAllThreadsWithBarrier(Event::PostCb cb, Event::PostCb main_callback) PURE;
+
   /**
    * Set thread local data on all threads previously registered via registerThread().
    * @param initializeCb supplies the functor that will be called *on each thread*. The functor

source/common/stats/BUILD

@@ -12,6 +12,9 @@ envoy_cc_library(
     name = "stats_lib",
     srcs = ["stats_impl.cc"],
     hdrs = ["stats_impl.h"],
+    external_deps = [
+        "libcircllhist",
+    ],
     deps = [
         "//include/envoy/common:time_interface",
         "//include/envoy/server:options_interface",

source/common/stats/grpc_metrics_service_impl.cc

@@ -63,6 +63,41 @@ void GrpcMetricsStreamerImpl::ThreadLocalStreamer::send(
 
 MetricsServiceSink::MetricsServiceSink(const GrpcMetricsStreamerSharedPtr& grpc_metrics_streamer)
     : grpc_metrics_streamer_(grpc_metrics_streamer) {}
+
+void MetricsServiceSink::flushCounter(const Counter& counter, uint64_t) {
+  io::prometheus::client::MetricFamily* metrics_family = message_.add_envoy_metrics();
+  metrics_family->set_type(io::prometheus::client::MetricType::COUNTER);
+  metrics_family->set_name(counter.name());
+  auto* metric = metrics_family->add_metric();
+  metric->set_timestamp_ms(std::chrono::system_clock::now().time_since_epoch().count());
+  auto* counter_metric = metric->mutable_counter();
+  counter_metric->set_value(counter.value());
+}
+
+void MetricsServiceSink::flushGauge(const Gauge& gauge, uint64_t value) {
+  io::prometheus::client::MetricFamily* metrics_family = message_.add_envoy_metrics();
+  metrics_family->set_type(io::prometheus::client::MetricType::GAUGE);
+  metrics_family->set_name(gauge.name());
+  auto* metric = metrics_family->add_metric();
+  metric->set_timestamp_ms(std::chrono::system_clock::now().time_since_epoch().count());
+  auto* gauage_metric = metric->mutable_gauge();
+  gauage_metric->set_value(value);
+}
+void MetricsServiceSink::flushHistogram(const Histogram& histogram) {
+  io::prometheus::client::MetricFamily* metrics_family = message_.add_envoy_metrics();
+  metrics_family->set_type(io::prometheus::client::MetricType::SUMMARY);
+  metrics_family->set_name(histogram.name());
+  auto* metric = metrics_family->add_metric();
+  metric->set_timestamp_ms(std::chrono::system_clock::now().time_since_epoch().count());
+  auto* summary_metric = metric->mutable_summary();
+  const HistogramStatistics hist_stats = histogram.intervalStatistics();
+  for (size_t i = 0; i < ARRAY_SIZE(hist_stats.quantiles_in_); i++) {
+    auto* quantile = summary_metric->add_quantile();
+    quantile->set_quantile(hist_stats.quantiles_in_[i]);
+    quantile->set_value(hist_stats.quantiles_out_[i]);
+  }
+}
+
 } // namespace Metrics
 } // namespace Stats
 } // namespace Envoy

source/common/stats/grpc_metrics_service_impl.h

@@ -14,7 +14,7 @@
 #include "envoy/thread_local/thread_local.h"
 #include "envoy/upstream/cluster_manager.h"
 
-#include "common/buffer/buffer_impl.h"
+#include "common/stats/stats_impl.h"
 
 namespace Envoy {
 namespace Stats {
@@ -115,25 +115,9 @@ class MetricsServiceSink : public Sink {
 
   void beginFlush() override { message_.clear_envoy_metrics(); }
 
-  void flushCounter(const Counter& counter, uint64_t) override {
-    io::prometheus::client::MetricFamily* metrics_family = message_.add_envoy_metrics();
-    metrics_family->set_type(io::prometheus::client::MetricType::COUNTER);
-    metrics_family->set_name(counter.name());
-    auto* metric = metrics_family->add_metric();
-    metric->set_timestamp_ms(std::chrono::system_clock::now().time_since_epoch().count());
-    auto* counter_metric = metric->mutable_counter();
-    counter_metric->set_value(counter.value());
-  }
-
-  void flushGauge(const Gauge& gauge, uint64_t value) override {
-    io::prometheus::client::MetricFamily* metrics_family = message_.add_envoy_metrics();
-    metrics_family->set_type(io::prometheus::client::MetricType::GAUGE);
-    metrics_family->set_name(gauge.name());
-    auto* metric = metrics_family->add_metric();
-    metric->set_timestamp_ms(std::chrono::system_clock::now().time_since_epoch().count());
-    auto* gauage_metric = metric->mutable_gauge();
-    gauage_metric->set_value(value);
-  }
+  void flushCounter(const Counter& counter, uint64_t) override;
+  void flushGauge(const Gauge& gauge, uint64_t value) override;
+  void flushHistogram(const Histogram& histogram) override;
 
   void endFlush() override {
     grpc_metrics_streamer_->send(message_);
@@ -143,9 +127,7 @@ class MetricsServiceSink : public Sink {
     }
   }
 
-  void onHistogramComplete(const Histogram&, uint64_t) override {
-    // TODO : Need to figure out how to map existing histogram to Proto Model
-  }
+  void onHistogramComplete(const Histogram&, uint64_t) override {}
 
 private:
   GrpcMetricsStreamerSharedPtr grpc_metrics_streamer_;