refactor all file serve logic into internal/cache

internal/cache/cache.go

@@ -3,11 +3,8 @@ package cache
 import (
 	"fmt"
 	"io"
-	"log"
 	"net"
 	"net/http"
-	"os"
-	"path/filepath"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -15,6 +12,8 @@ import (
 	"golang.org/x/sync/singleflight"
 )
 
+const userAgent = "pacman/7.1.0 (Linux x86_64) libalpm/16.0.1"
+
 type Cache struct {
 	cfg       CacheConfig
 	mirrorIdx atomic.Uint32
@@ -27,21 +26,25 @@ type CacheConfig struct {
 	cacheRoot             string
 	mirrorURLs            []string
 	mirroredRepos         []string
-	userAgent             string
 	DialTimeout           time.Duration
 	ResponseHeaderTimeout time.Duration
 	ClientTimeout         time.Duration
 }
 
+type CacheFile struct {
+	Reader   io.ReadCloser
+	Size     int64
+	Filename string
+}
+
 func NewCache(cacheRoot string, mirrorURLs []string, mirroredRepos []string) *Cache {
 	cfg := CacheConfig{
 		cacheRoot:             cacheRoot,
 		mirrorURLs:            mirrorURLs,
 		mirroredRepos:         mirroredRepos,
-		userAgent:             "pacman/7.1.0 (Linux x86_64) libalpm/16.0.1",
 		DialTimeout:           5 * time.Second,
 		ResponseHeaderTimeout: 10 * time.Second,
-		ClientTimeout:         15 * time.Second,
+		ClientTimeout:         0 * time.Second,
 	}
 
 	transport := &http.Transport{
@@ -60,15 +63,6 @@ func NewCache(cacheRoot string, mirrorURLs []string, mirroredRepos []string) *Ca
 	}
 }
 
-func (c *Cache) Fetch(pkgPath string) error {
-	log.Printf("pkgPath from Fetch %v", pkgPath)
-	_, err, _ := c.sf.Do(pkgPath, func() (any, error) {
-		log.Print("calling fetch")
-		return nil, c.fetch(pkgPath)
-	})
-	return err
-}
-
 type UpstreamError struct {
 	StatusCode int
 }
@@ -76,82 +70,3 @@ type UpstreamError struct {
 func (e *UpstreamError) Error() string {
 	return fmt.Sprintf("upstream returned %d", e.StatusCode)
 }
-
-func (c *Cache) fetch(pkgName string) error {
-	// pkgName is relative to the localRoot
-	// ie pkgName includes /{repo}/os/{arch}/ and the actual name linux-x.x.x.pkg.tar.zst
-
-	tempPkgName := pkgName + ".tmp"
-	tempPkgPath := filepath.Join(c.cfg.cacheRoot, tempPkgName) //full tmp write path
-
-	// final file name and path
-	outPkg := filepath.Join(c.cfg.cacheRoot, pkgName)
-
-	// declare vars outside loop
-	var resp *http.Response
-	var req *http.Request
-	var err error
-	// fetch pkgs from mirror with retry logic
-	for range len(c.cfg.mirrorURLs) {
-		pkgURL := c.nextMirror() + pkgName
-		log.Printf("fetching %v", pkgURL)
-
-		// set the user agent
-		req, err = http.NewRequest("GET", pkgURL, nil)
-		if err != nil {
-			log.Printf("failed to create request: %v", err)
-			return &UpstreamError{StatusCode: http.StatusInternalServerError}
-		}
-		req.Header.Set("User-Agent", c.cfg.userAgent)
-
-		resp, err = c.client.Do(req)
-		if err != nil {
-			log.Printf("error fetching %s: %v", pkgURL, err)
-			continue
-		}
-		if resp.StatusCode == http.StatusOK {
-			break
-		}
-		log.Printf("retrying on code %v", resp.StatusCode)
-		resp.Body.Close()
-	}
-	if resp == nil {
-		return fmt.Errorf("all mirrors exhausted")
-	}
-	defer resp.Body.Close()
-
-	if err != nil {
-		log.Printf("exhauted all mirrors error: %v", err)
-		return err
-	}
-
-	if resp.StatusCode != http.StatusOK {
-		log.Printf("exhauted all mirrors %v", resp.StatusCode)
-		return &UpstreamError{StatusCode: resp.StatusCode}
-	}
-
-	// use a tmp file for the initial fetch in case it fails
-	outFile, err := os.Create(tempPkgPath)
-	if err != nil {
-		return err
-	}
-	defer outFile.Close()
-
-	_, err = io.Copy(outFile, resp.Body)
-	if err != nil {
-		os.Remove(tempPkgPath)
-		return err
-	}
-
-	// mv file to final location
-	if err := os.Rename(tempPkgPath, outPkg); err != nil {
-		os.Remove(tempPkgPath)
-		return err
-	}
-	return nil
-}
-
-func (c *Cache) nextMirror() string {
-	idx := c.mirrorIdx.Add(1) - 1
-	return c.cfg.mirrorURLs[idx%uint32(len(c.cfg.mirrorURLs))]
-}