stats: Split up HTTP stats code

Split up the code which handles generation of HTTP stats into multiple
files and prefix relevant public structures with `HTTP` to make their
scope clear. This is in preparation for a new probe type for pushes,
which will add additional HTTP logic.

6 files changed, 166 insertions, 151 deletions

diff --git a/cmd/gitaly-debug/analyzehttp.go b/cmd/gitaly-debug/analyzehttp.go
index dda0cb11e..805094ac7 100644
--- a/cmd/gitaly-debug/analyzehttp.go
+++ b/cmd/gitaly-debug/analyzehttp.go
@@ -8,7 +8,7 @@ import (
 )
 
 func analyzeHTTPClone(cloneURL string) {
-	st, err := stats.PerformClone(context.Background(), cloneURL, "", "", true)
+	st, err := stats.PerformHTTPClone(context.Background(), cloneURL, "", "", true)
 	noError(err)
 
 	fmt.Println("\n--- Reference discovery metrics:")
diff --git a/internal/blackbox/blackbox.go b/internal/blackbox/blackbox.go
index dd77d60f8..bffcca8b2 100644
--- a/internal/blackbox/blackbox.go
+++ b/internal/blackbox/blackbox.go
@@ -105,7 +105,7 @@ func (b Blackbox) doProbe(probe Probe) {
 	entry := log.WithField("probe", probe.Name)
 	entry.Info("starting probe")
 
-	clone, err := stats.PerformClone(ctx, probe.URL, probe.User, probe.Password, false)
+	clone, err := stats.PerformHTTPClone(ctx, probe.URL, probe.User, probe.Password, false)
 	if err != nil {
 		entry.WithError(err).Error("probe failed")
 		return
diff --git a/internal/git/stats/http_clone.go b/internal/git/stats/http_clone.go
new file mode 100644
index 000000000..e47ecf06d
--- /dev/null
+++ b/internal/git/stats/http_clone.go
@@ -0,0 +1,49 @@
+package stats
+
+import (
+	"context"
+	"fmt"
+)
+
+// HTTPClone hosts information about a typical HTTP-based clone.
+type HTTPClone struct {
+	// ReferenceDiscovery is the reference discovery performed as part of the clone.
+	ReferenceDiscovery HTTPReferenceDiscovery
+	// FetchPack is the response to a git-fetch-pack(1) request which computes and transmits the
+	// packfile.
+	FetchPack HTTPFetchPack
+}
+
+// PerformHTTPClone does a Git HTTP clone, discarding cloned data to /dev/null.
+func PerformHTTPClone(ctx context.Context, url, user, password string, interactive bool) (HTTPClone, error) {
+	printInteractive := func(format string, a ...interface{}) {
+		if interactive {
+			// Ignore any errors returned by this given that we only use it as a
+			// debugging aid to write to stdout.
+			fmt.Printf(format, a...)
+		}
+	}
+
+	referenceDiscovery, err := performHTTPReferenceDiscovery(ctx, url, user, password, printInteractive)
+	if err != nil {
+		return HTTPClone{}, ctxErr(ctx, err)
+	}
+
+	fetchPack, err := performFetchPack(ctx, url, user, password,
+		referenceDiscovery.Refs(), printInteractive)
+	if err != nil {
+		return HTTPClone{}, ctxErr(ctx, err)
+	}
+
+	return HTTPClone{
+		ReferenceDiscovery: referenceDiscovery,
+		FetchPack:          fetchPack,
+	}, nil
+}
+
+func ctxErr(ctx context.Context, err error) error {
+	if ctx.Err() != nil {
+		return ctx.Err()
+	}
+	return err
+}
diff --git a/internal/git/stats/clone_test.go b/internal/git/stats/http_clone_test.go
index 4e25cea93..1c287fa50 100644
--- a/internal/git/stats/clone_test.go
+++ b/internal/git/stats/http_clone_test.go
@@ -24,7 +24,7 @@ func TestClone(t *testing.T) {
 		require.NoError(t, stopGitServer())
 	}()
 
-	clone, err := PerformClone(ctx, fmt.Sprintf("http://localhost:%d/%s", serverPort, filepath.Base(repoPath)), "", "", false)
+	clone, err := PerformHTTPClone(ctx, fmt.Sprintf("http://localhost:%d/%s", serverPort, filepath.Base(repoPath)), "", "", false)
 	require.NoError(t, err, "perform analysis clone")
 
 	const expectedRequests = 90 // based on contents of _support/gitlab-test.git-packed-refs
@@ -100,7 +100,7 @@ func TestCloneWithAuth(t *testing.T) {
 		require.NoError(t, stopGitServer())
 	}()
 
-	_, err := PerformClone(
+	_, err := PerformHTTPClone(
 		ctx,
 		fmt.Sprintf("http://localhost:%d/%s", serverPort, filepath.Base(repoPath)),
 		user,
diff --git a/internal/git/stats/clone.go b/internal/git/stats/http_fetch_pack.go
index 18f881e9a..a688e7c19 100644
--- a/internal/git/stats/clone.go
+++ b/internal/git/stats/http_fetch_pack.go
@@ -5,8 +5,6 @@ import (
 	"compress/gzip"
 	"context"
 	"fmt"
-	"io"
-	"io/ioutil"
 	"net/http"
 	"strings"
 	"time"
@@ -14,151 +12,6 @@ import (
 	"gitlab.com/gitlab-org/gitaly/v14/internal/git/pktline"
 )
 
-// Clone hosts information about a typical HTTP-based clone.
-type Clone struct {
-	// ReferenceDiscovery is the reference discovery performed as part of the clone.
-	ReferenceDiscovery HTTPReferenceDiscovery
-	// FetchPack is the response to a git-fetch-pack(1) request which computes transmits the
-	// packfile.
-	FetchPack HTTPFetchPack
-}
-
-// PerformClone does a Git HTTP clone, discarding cloned data to /dev/null.
-func PerformClone(ctx context.Context, url, user, password string, interactive bool) (Clone, error) {
-	printInteractive := func(format string, a ...interface{}) {
-		if interactive {
-			// Ignore any errors returned by this given that we only use it as a
-			// debugging aid to write to stdout.
-			fmt.Printf(format, a...)
-		}
-	}
-
-	referenceDiscovery, err := performReferenceDiscovery(ctx, url, user, password, printInteractive)
-	if err != nil {
-		return Clone{}, ctxErr(ctx, err)
-	}
-
-	fetchPack, err := performFetchPack(ctx, url, user, password,
-		referenceDiscovery.Refs(), printInteractive)
-	if err != nil {
-		return Clone{}, ctxErr(ctx, err)
-	}
-
-	return Clone{
-		ReferenceDiscovery: referenceDiscovery,
-		FetchPack:          fetchPack,
-	}, nil
-}
-
-func ctxErr(ctx context.Context, err error) error {
-	if ctx.Err() != nil {
-		return ctx.Err()
-	}
-	return err
-}
-
-// HTTPReferenceDiscovery is a ReferenceDiscovery obtained via a clone of a target repository via
-// HTTP. It contains additional information about the cloning process like status codes and
-// timings.
-type HTTPReferenceDiscovery struct {
-	start          time.Time
-	responseHeader time.Duration
-	httpStatus     int
-	stats          ReferenceDiscovery
-}
-
-// ResponseHeader returns how long it took to receive the response header.
-func (d HTTPReferenceDiscovery) ResponseHeader() time.Duration { return d.responseHeader }
-
-// HTTPStatus returns the HTTP status code.
-func (d HTTPReferenceDiscovery) HTTPStatus() int { return d.httpStatus }
-
-// FirstGitPacket returns how long it took to receive the first Git packet.
-func (d HTTPReferenceDiscovery) FirstGitPacket() time.Duration {
-	return d.stats.FirstPacket.Sub(d.start)
-}
-
-// ResponseBody returns how long it took to receive the first bytes of the response body.
-func (d HTTPReferenceDiscovery) ResponseBody() time.Duration {
-	return d.stats.LastPacket.Sub(d.start)
-}
-
-// Refs returns all announced references.
-func (d HTTPReferenceDiscovery) Refs() []Reference { return d.stats.Refs }
-
-// Packets returns the number of Git packets received.
-func (d HTTPReferenceDiscovery) Packets() int { return d.stats.Packets }
-
-// PayloadSize returns the total size of all pktlines' data.
-func (d HTTPReferenceDiscovery) PayloadSize() int64 { return d.stats.PayloadSize }
-
-// Caps returns all announced capabilities.
-func (d HTTPReferenceDiscovery) Caps() []string { return d.stats.Caps }
-
-func performReferenceDiscovery(
-	ctx context.Context,
-	url, user, password string,
-	reportProgress func(string, ...interface{}),
-) (HTTPReferenceDiscovery, error) {
-	var referenceDiscovery HTTPReferenceDiscovery
-
-	req, err := http.NewRequest("GET", url+"/info/refs?service=git-upload-pack", nil)
-	if err != nil {
-		return HTTPReferenceDiscovery{}, err
-	}
-
-	req = req.WithContext(ctx)
-	if user != "" {
-		req.SetBasicAuth(user, password)
-	}
-
-	for k, v := range map[string]string{
-		"User-Agent":      "gitaly-debug",
-		"Accept":          "*/*",
-		"Accept-Encoding": "deflate, gzip",
-		"Pragma":          "no-cache",
-	} {
-		req.Header.Set(k, v)
-	}
-
-	referenceDiscovery.start = time.Now()
-	reportProgress("---\n")
-	reportProgress("--- GET %v\n", req.URL)
-	reportProgress("---\n")
-
-	resp, err := http.DefaultClient.Do(req)
-	if err != nil {
-		return HTTPReferenceDiscovery{}, err
-	}
-	defer func() {
-		io.Copy(ioutil.Discard, resp.Body)
-		resp.Body.Close()
-	}()
-
-	if code := resp.StatusCode; code < 200 || code >= 400 {
-		return HTTPReferenceDiscovery{}, fmt.Errorf("git http get: unexpected http status: %d", code)
-	}
-
-	referenceDiscovery.responseHeader = time.Since(referenceDiscovery.start)
-	referenceDiscovery.httpStatus = resp.StatusCode
-	reportProgress("response code: %d\n", resp.StatusCode)
-	reportProgress("response header: %v\n", resp.Header)
-
-	body := resp.Body
-	if resp.Header.Get("Content-Encoding") == "gzip" {
-		body, err = gzip.NewReader(body)
-		if err != nil {
-			return HTTPReferenceDiscovery{}, err
-		}
-	}
-
-	if err := referenceDiscovery.stats.Parse(body); err != nil {
-		return HTTPReferenceDiscovery{}, err
-	}
-
-	return referenceDiscovery, nil
-}
-
 // HTTPFetchPack is a FetchPack obtained via a clone of a target repository via HTTP. It contains
 // additional information about the cloning process like status codes and timings.
 type HTTPFetchPack struct {
diff --git a/internal/git/stats/http_reference_discovery.go b/internal/git/stats/http_reference_discovery.go
new file mode 100644
index 000000000..7792f49f3
--- /dev/null
+++ b/internal/git/stats/http_reference_discovery.go
@@ -0,0 +1,113 @@
+package stats
+
+import (
+	"compress/gzip"
+	"context"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"time"
+)
+
+// HTTPReferenceDiscovery is a ReferenceDiscovery obtained via a clone of a target repository via
+// HTTP. It contains additional information about the cloning process like status codes and
+// timings.
+type HTTPReferenceDiscovery struct {
+	start          time.Time
+	responseHeader time.Duration
+	httpStatus     int
+	stats          ReferenceDiscovery
+}
+
+// ResponseHeader returns how long it took to receive the response header.
+func (d HTTPReferenceDiscovery) ResponseHeader() time.Duration { return d.responseHeader }
+
+// HTTPStatus returns the HTTP status code.
+func (d HTTPReferenceDiscovery) HTTPStatus() int { return d.httpStatus }
+
+// FirstGitPacket returns how long it took to receive the first Git packet.
+func (d HTTPReferenceDiscovery) FirstGitPacket() time.Duration {
+	return d.stats.FirstPacket.Sub(d.start)
+}
+
+// ResponseBody returns how long it took to receive the first bytes of the response body.
+func (d HTTPReferenceDiscovery) ResponseBody() time.Duration {
+	return d.stats.LastPacket.Sub(d.start)
+}
+
+// Refs returns all announced references.
+func (d HTTPReferenceDiscovery) Refs() []Reference { return d.stats.Refs }
+
+// Packets returns the number of Git packets received.
+func (d HTTPReferenceDiscovery) Packets() int { return d.stats.Packets }
+
+// PayloadSize returns the total size of all pktlines' data.
+func (d HTTPReferenceDiscovery) PayloadSize() int64 { return d.stats.PayloadSize }
+
+// Caps returns all announced capabilities.
+func (d HTTPReferenceDiscovery) Caps() []string { return d.stats.Caps }
+
+func performHTTPReferenceDiscovery(
+	ctx context.Context,
+	url, user, password string,
+	reportProgress func(string, ...interface{}),
+) (HTTPReferenceDiscovery, error) {
+	var referenceDiscovery HTTPReferenceDiscovery
+
+	req, err := http.NewRequest("GET", url+"/info/refs?service=git-upload-pack", nil)
+	if err != nil {
+		return HTTPReferenceDiscovery{}, err
+	}
+
+	req = req.WithContext(ctx)
+	if user != "" {
+		req.SetBasicAuth(user, password)
+	}
+
+	for k, v := range map[string]string{
+		"User-Agent":      "gitaly-debug",
+		"Accept":          "*/*",
+		"Accept-Encoding": "deflate, gzip",
+		"Pragma":          "no-cache",
+	} {
+		req.Header.Set(k, v)
+	}
+
+	referenceDiscovery.start = time.Now()
+	reportProgress("---\n")
+	reportProgress("--- GET %v\n", req.URL)
+	reportProgress("---\n")
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return HTTPReferenceDiscovery{}, err
+	}
+	defer func() {
+		io.Copy(ioutil.Discard, resp.Body)
+		resp.Body.Close()
+	}()
+
+	if code := resp.StatusCode; code < 200 || code >= 400 {
+		return HTTPReferenceDiscovery{}, fmt.Errorf("git http get: unexpected http status: %d", code)
+	}
+
+	referenceDiscovery.responseHeader = time.Since(referenceDiscovery.start)
+	referenceDiscovery.httpStatus = resp.StatusCode
+	reportProgress("response code: %d\n", resp.StatusCode)
+	reportProgress("response header: %v\n", resp.Header)
+
+	body := resp.Body
+	if resp.Header.Get("Content-Encoding") == "gzip" {
+		body, err = gzip.NewReader(body)
+		if err != nil {
+			return HTTPReferenceDiscovery{}, err
+		}
+	}
+
+	if err := referenceDiscovery.stats.Parse(body); err != nil {
+		return HTTPReferenceDiscovery{}, err
+	}
+
+	return referenceDiscovery, nil
+}