From 4ed75d2c7e9c30a38bc33e552ccda4fb1f799f5e Mon Sep 17 00:00:00 2001
From: Mya Pitzeruse <j.mya.pitz@gmail.com>
Date: Thu, 6 Oct 2022 12:04:39 -0500
Subject: [PATCH] feat: periodically reload underlying repository

---
 .gitignore                  |  1 +
 internal/commands/host.go   | 16 ++++++++++++++++
 internal/git/service.go     | 12 +++++++-----
 internal/metrics/metrics.go | 23 +++++++++++++++++------
 internal/session/handler.go |  7 ++++---
 5 files changed, 45 insertions(+), 14 deletions(-)

diff --git a/.gitignore b/.gitignore
index 6936877..8f26fb1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -22,4 +22,5 @@ go.work
 
 dist/
 
+.coverprofile
 pages
diff --git a/internal/commands/host.go b/internal/commands/host.go
index d17c639..8616cef 100644
--- a/internal/commands/host.go
+++ b/internal/commands/host.go
@@ -20,6 +20,7 @@ import (
 	"context"
 	"mime"
 	"net/http"
+	"time"
 
 	"github.com/urfave/cli/v2"
 	"go.uber.org/zap"
@@ -97,6 +98,21 @@ var (
 
 			group, c := errgroup.WithContext(ctx.Context)
 			group.Go(server.ListenAndServe)
+			group.Go(func() error {
+				timer := time.NewTimer(hostConfig.Git.SyncInterval)
+				defer timer.Stop()
+
+				for {
+					select {
+					case <-c.Done():
+						return nil
+					case <-timer.C:
+						_ = gitService.Sync(ctx.Context)
+
+						timer.Reset(hostConfig.Git.SyncInterval)
+					}
+				}
+			})
 
 			<-c.Done()
 
diff --git a/internal/git/service.go b/internal/git/service.go
index 1d24a52..2ce7534 100644
--- a/internal/git/service.go
+++ b/internal/git/service.go
@@ -19,6 +19,7 @@ package git
 import (
 	"context"
 	"os"
+	"time"
 
 	"github.com/go-git/go-billy/v5"
 	"github.com/go-git/go-billy/v5/osfs"
@@ -34,11 +35,12 @@ import (
 
 // Config encapsulates the elements that can be configured about the git service.
 type Config struct {
-	URL      string `json:"url"      usage:"the git url used to clone the repository"`
-	Branch   string `json:"branch"   usage:"the name of the git branch to clone"`
-	Tag      string `json:"tag"      usage:"the name of the git tag to clone"`
-	Username string `json:"username" usage:"the username used to authenticate with the git service"`
-	Password string `json:"password" usage:"the password used to authenticate with the git service"`
+	URL          string        `json:"url"           usage:"the git url used to clone the repository"`
+	Branch       string        `json:"branch"        usage:"the name of the git branch to clone"`
+	Tag          string        `json:"tag"           usage:"the name of the git tag to clone"`
+	Username     string        `json:"username"      usage:"the username used to authenticate with the git service"`
+	Password     string        `json:"password"      usage:"the password used to authenticate with the git service"`
+	SyncInterval time.Duration `json:"sync_interval" usage:"how frequently the git repository is pulled for changes" default:"1h"`
 }
 
 // NewService constructs a Service that manages the underlying git repository.
diff --git a/internal/metrics/metrics.go b/internal/metrics/metrics.go
index df8a04c..bc170b8 100644
--- a/internal/metrics/metrics.go
+++ b/internal/metrics/metrics.go
@@ -25,6 +25,16 @@ var (
 	namespace = "pages"
 	page      = "page"
 
+	// by default, summaries give us counts and sums which we can use to compute an average (not great, but it can work)
+	// in addition to the default information, we report on the following quantiles:
+	defaultObjectives = map[float64]float64{
+		0.25: 0, // lower quartile
+		0.5:  0, // median
+		0.75: 0, // upper quartile
+		0.90: 0, // One 9
+		0.99: 0, // Two 9s
+	}
+
 	// PageViewCount tracks page views by how often they're loaded.
 	PageViewCount = promauto.NewCounterVec(
 		prometheus.CounterOpts{
@@ -37,12 +47,13 @@ var (
 	)
 
 	// PageSessionDuration tracks how long someone spends on an individual page.
-	PageSessionDuration = promauto.NewHistogramVec(
-		prometheus.HistogramOpts{
-			Namespace: namespace,
-			Subsystem: page,
-			Name:      "session_seconds",
-			Help:      "how long someone spent on a given page",
+	PageSessionDuration = promauto.NewSummaryVec(
+		prometheus.SummaryOpts{
+			Namespace:  namespace,
+			Subsystem:  page,
+			Name:       "session_seconds",
+			Help:       "how long someone spent on a given page",
+			Objectives: defaultObjectives,
 		},
 		[]string{"domain", "path", "country"},
 	)
diff --git a/internal/session/handler.go b/internal/session/handler.go
index 44fb720..aed3f95 100644
--- a/internal/session/handler.go
+++ b/internal/session/handler.go
@@ -19,7 +19,6 @@ package session
 import (
 	"net/http"
 	"net/url"
-	"time"
 
 	"github.com/gorilla/websocket"
 	"go.uber.org/zap"
@@ -27,6 +26,7 @@ import (
 	"code.pitz.tech/mya/pages/internal/geoip"
 	"code.pitz.tech/mya/pages/internal/metrics"
 
+	"github.com/mjpitz/myago/clocks"
 	"github.com/mjpitz/myago/zaputil"
 )
 
@@ -62,6 +62,7 @@ type Handle struct {
 func (h *Handle) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	ctx := r.Context()
 	log := zaputil.Extract(ctx)
+	clock := clocks.Extract(ctx)
 
 	conn, err := h.upgrader.Upgrade(w, r, nil)
 	if err != nil {
@@ -91,9 +92,9 @@ func (h *Handle) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	active.Inc()
 	defer func() { active.Dec() }()
 
-	start := time.Now()
+	start := clock.Now()
 	defer func() {
-		metrics.PageSessionDuration.WithLabelValues(domain, path, geoInfo.CountryCode).Observe(time.Since(start).Seconds())
+		metrics.PageSessionDuration.WithLabelValues(domain, path, geoInfo.CountryCode).Observe(clock.Since(start).Seconds())
 	}()
 
 	for {