--- /dev/null
+package main
+
+import (
+ "bufio"
+ "crypto/md5"
+ "errors"
+ "fmt"
+ "github.com/gorilla/mux"
+ "log"
+ "net/http"
+ "os"
+ "strings"
+)
+
+const DEFAULT_PORT = 25107
+const BLOCKSIZE = 64 * 1024 * 1024
+
+var KeepVolumes []string
+
+func main() {
+ // Look for local keep volumes.
+ KeepVolumes = FindKeepVolumes()
+ if len(KeepVolumes) == 0 {
+ log.Fatal("could not find any keep volumes")
+ }
+ for _, v := range KeepVolumes {
+ log.Println("keep volume:", v)
+ }
+
+ // Set up REST handlers.
+ //
+ // Start with a router that will route each URL path to an
+ // appropriate handler.
+ //
+ rest := mux.NewRouter()
+ rest.HandleFunc("/{hash:[0-9a-f]{32}}", GetBlockHandler).Methods("GET")
+
+ // Tell the built-in HTTP server to direct all requests to the REST
+ // router.
+ http.Handle("/", rest)
+
+ // Start listening for requests.
+ port := fmt.Sprintf(":%d", DEFAULT_PORT)
+ http.ListenAndServe(port, nil)
+}
+
+// FindKeepVolumes
+// Returns a list of Keep volumes mounted on this system.
+//
+// A Keep volume is a normal or tmpfs volume with a /keep
+// directory at the top level of the mount point.
+//
+func FindKeepVolumes() []string {
+ vols := make([]string, 0)
+
+ if f, err := os.Open("/proc/mounts"); err != nil {
+ log.Fatal("could not read /proc/mounts: ", err)
+ } else {
+ scanner := bufio.NewScanner(f)
+ for scanner.Scan() {
+ args := strings.Fields(scanner.Text())
+ dev, mount := args[0], args[1]
+ if (dev == "tmpfs" || strings.HasPrefix(dev, "/dev/")) && mount != "/" {
+ keep := mount + "/keep"
+ if st, err := os.Stat(keep); err == nil && st.IsDir() {
+ vols = append(vols, keep)
+ }
+ }
+ }
+ if err := scanner.Err(); err != nil {
+ log.Fatal(err)
+ }
+ }
+ return vols
+}
+
+func GetBlockHandler(w http.ResponseWriter, req *http.Request) {
+ hash := mux.Vars(req)["hash"]
+
+ block, err := GetBlock(hash)
+ if err != nil {
+ http.Error(w, err.Error(), 404)
+ return
+ }
+
+ _, err = w.Write(block)
+ if err != nil {
+ log.Printf("GetBlockHandler: writing response: %s", err)
+ }
+
+ return
+}
+
+func GetBlock(hash string) ([]byte, error) {
+ var buf = make([]byte, BLOCKSIZE)
+
+ // Attempt to read the requested hash from a keep volume.
+ for _, vol := range KeepVolumes {
+ var f *os.File
+ var err error
+ var nread int
+
+ path := fmt.Sprintf("%s/%s/%s", vol, hash[0:3], hash)
+
+ f, err = os.Open(path)
+ if err != nil {
+ log.Printf("%s: opening %s: %s\n", vol, path, err)
+ continue
+ }
+
+ nread, err = f.Read(buf)
+ if err != nil {
+ log.Printf("%s: reading %s: %s\n", vol, path, err)
+ continue
+ }
+
+ // Double check the file checksum.
+ //
+ filehash := fmt.Sprintf("%x", md5.Sum(buf[:nread]))
+ if filehash != hash {
+ // TODO(twp): this condition probably represents a bad disk and
+ // should raise major alarm bells for an administrator: e.g.
+ // they should be sent directly to an event manager at high
+ // priority or logged as urgent problems.
+ //
+ log.Printf("%s: checksum mismatch: %s (actual hash %s)\n",
+ vol, path, filehash)
+ continue
+ }
+
+ // Success!
+ return buf[:nread], nil
+ }
+
+ log.Printf("%s: not found on any volumes, giving up\n", hash)
+ return buf, errors.New("not found: " + hash)
+}
--- /dev/null
+package main
+
+import (
+ "fmt"
+ "io/ioutil"
+ "os"
+ "path"
+ "testing"
+)
+
+var TEST_BLOCK = []byte("The quick brown fox jumps over the lazy dog.")
+var TEST_HASH = "e4d909c290d0fb1ca068ffaddf22cbd0"
+var BAD_BLOCK = []byte("The magic words are squeamish ossifrage.")
+
+// Test simple block reads.
+func TestGetBlockOK(t *testing.T) {
+ defer teardown()
+
+ // Create two test Keep volumes and store a block in each of them.
+ setup(t, 2)
+ for _, vol := range KeepVolumes {
+ store(t, vol, TEST_HASH, TEST_BLOCK)
+ }
+
+ // Check that GetBlock returns success.
+ result, err := GetBlock(TEST_HASH)
+ if err != nil {
+ t.Errorf("GetBlock error: %s", err)
+ }
+ if fmt.Sprint(result) != fmt.Sprint(TEST_BLOCK) {
+ t.Errorf("expected %s, got %s", TEST_BLOCK, result)
+ }
+}
+
+// Test block reads when one Keep volume is missing.
+func TestGetBlockOneKeepOK(t *testing.T) {
+ defer teardown()
+
+ // Two test Keep volumes, only the second has a block.
+ setup(t, 2)
+ store(t, KeepVolumes[1], TEST_HASH, TEST_BLOCK)
+
+ // Check that GetBlock returns success.
+ result, err := GetBlock(TEST_HASH)
+ if err != nil {
+ t.Errorf("GetBlock error: %s", err)
+ }
+ if fmt.Sprint(result) != fmt.Sprint(TEST_BLOCK) {
+ t.Errorf("expected %s, got %s", TEST_BLOCK, result)
+ }
+}
+
+// Test block read failure.
+func TestGetBlockFail(t *testing.T) {
+ defer teardown()
+
+ // Create two empty test Keep volumes.
+ setup(t, 2)
+
+ // Check that GetBlock returns failure.
+ result, err := GetBlock(TEST_HASH)
+ if err == nil {
+ t.Errorf("GetBlock incorrectly returned success: ", result)
+ }
+}
+
+// Test reading a corrupt block.
+func TestGetBlockCorrupt(t *testing.T) {
+ defer teardown()
+
+ // Create two test Keep volumes and store a block in each of them,
+ // but the hash of the block does not match the filename.
+ setup(t, 2)
+ for _, vol := range KeepVolumes {
+ store(t, vol, TEST_HASH, BAD_BLOCK)
+ }
+
+ // Check that GetBlock returns failure.
+ result, err := GetBlock(TEST_HASH)
+ if err == nil {
+ t.Errorf("GetBlock incorrectly returned success: %s", result)
+ }
+}
+
+// setup
+// Create KeepVolumes for testing.
+//
+func setup(t *testing.T, num_volumes int) {
+ KeepVolumes = make([]string, num_volumes)
+ for i := range KeepVolumes {
+ if dir, err := ioutil.TempDir(os.TempDir(), "keeptest"); err == nil {
+ KeepVolumes[i] = dir + "/keep"
+ } else {
+ t.Fatal(err)
+ }
+ }
+}
+
+// teardown
+// Cleanup to perform after each test.
+//
+func teardown() {
+ for _, vol := range KeepVolumes {
+ os.RemoveAll(path.Dir(vol))
+ }
+}
+
+// store
+//
+func store(t *testing.T, keepdir string, filename string, block []byte) error {
+ blockdir := fmt.Sprintf("%s/%s", keepdir, filename[:3])
+ if err := os.MkdirAll(blockdir, 0755); err != nil {
+ t.Fatal(err)
+ }
+
+ blockpath := fmt.Sprintf("%s/%s", blockdir, filename)
+ if f, err := os.Create(blockpath); err == nil {
+ f.Write(block)
+ f.Close()
+ } else {
+ t.Fatal(err)
+ }
+
+ return nil
+}
projects / arvados.git / commitdiff