X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/b32e371420fff5763c13c79cd4327692e2a2e1bd..d137cbc6cfdcc541216e68d414c535626e4d8916:/services/keepstore/s3_volume.go diff --git a/services/keepstore/s3_volume.go b/services/keepstore/s3_volume.go index 17cc194a5b..0cfaaaf3b4 100644 --- a/services/keepstore/s3_volume.go +++ b/services/keepstore/s3_volume.go @@ -10,6 +10,7 @@ import ( "net/http" "os" "regexp" + "strings" "time" "github.com/AdRoll/goamz/aws" @@ -17,7 +18,9 @@ import ( ) var ( - ErrS3DeleteNotAvailable = fmt.Errorf("delete without -s3-unsafe-delete is not implemented") + // Returned by Trash if that operation is impossible with the + // current config. + ErrS3TrashDisabled = fmt.Errorf("trash function is disabled because -trash-lifetime=0 and -s3-unsafe-delete=false") s3AccessKeyFile string s3SecretKeyFile string @@ -25,6 +28,7 @@ var ( s3Endpoint string s3Replication int s3UnsafeDelete bool + s3RaceWindow time.Duration s3ACL = s3.Private ) @@ -39,8 +43,7 @@ type s3VolumeAdder struct { } func (s *s3VolumeAdder) Set(bucketName string) error { - if trashLifetime <= 0 { - log.Print("Missing required configuration parameter: trash-lifetime") + if trashLifetime != 0 { return ErrNotImplemented } if bucketName == "" { @@ -77,7 +80,7 @@ func (s *s3VolumeAdder) Set(bucketName string) error { if flagSerializeIO { log.Print("Notice: -serialize is not supported by s3-bucket volumes.") } - v := NewS3Volume(auth, region, bucketName, flagReadonly, s3Replication) + v := NewS3Volume(auth, region, bucketName, s3RaceWindow, flagReadonly, s3Replication) if err := v.Check(); err != nil { return err } @@ -86,7 +89,7 @@ func (s *s3VolumeAdder) Set(bucketName string) error { } func s3regions() (okList []string) { - for r, _ := range aws.Regions { + for r := range aws.Regions { okList = append(okList, r) } return @@ -116,6 +119,11 @@ func init() { "s3-secret-key-file", "", "File containing the secret key used for subsequent -s3-bucket-volume arguments.") + flag.DurationVar( + &s3RaceWindow, + "s3-race-window", + 24*time.Hour, + "Maximum eventual consistency latency for subsequent -s3-bucket-volume arguments.") flag.IntVar( &s3Replication, "s3-replication", @@ -128,8 +136,10 @@ func init() { "EXPERIMENTAL. Enable deletion (garbage collection), even though there are known race conditions that can cause data loss.") } +// S3Volume implements Volume using an S3 bucket. type S3Volume struct { *s3.Bucket + raceWindow time.Duration readonly bool replication int indexPageSize int @@ -138,48 +148,83 @@ type S3Volume struct { // NewS3Volume returns a new S3Volume using the given auth, region, // and bucket name. The replication argument specifies the replication // level to report when writing data. -func NewS3Volume(auth aws.Auth, region aws.Region, bucket string, readonly bool, replication int) *S3Volume { +func NewS3Volume(auth aws.Auth, region aws.Region, bucket string, raceWindow time.Duration, readonly bool, replication int) *S3Volume { return &S3Volume{ Bucket: &s3.Bucket{ S3: s3.New(auth, region), Name: bucket, }, + raceWindow: raceWindow, readonly: readonly, replication: replication, indexPageSize: 1000, } } +// Check returns an error if the volume is inaccessible (e.g., config +// error). func (v *S3Volume) Check() error { return nil } -func (v *S3Volume) Get(loc string) ([]byte, error) { - rdr, err := v.Bucket.GetReader(loc) +// getReader wraps (Bucket)GetReader. +// +// In situations where (Bucket)GetReader would fail because the block +// disappeared in a Trash race, getReader calls fixRace to recover the +// data, and tries again. +func (v *S3Volume) getReader(loc string) (rdr io.ReadCloser, err error) { + rdr, err = v.Bucket.GetReader(loc) + err = v.translateError(err) + if err == nil || !os.IsNotExist(err) { + return + } + _, err = v.Bucket.Head("recent/"+loc, nil) + err = v.translateError(err) + if err != nil { + // If we can't read recent/X, there's no point in + // trying fixRace. Give up. + return + } + if !v.fixRace(loc) { + err = os.ErrNotExist + return + } + rdr, err = v.Bucket.GetReader(loc) + if err != nil { + log.Printf("warning: reading %s after successful fixRace: %s", loc, err) + err = v.translateError(err) + } + return +} + +// Get a block: copy the block data into buf, and return the number of +// bytes copied. +func (v *S3Volume) Get(loc string, buf []byte) (int, error) { + rdr, err := v.getReader(loc) if err != nil { - return nil, v.translateError(err) + return 0, err } defer rdr.Close() - buf := bufs.Get(BlockSize) n, err := io.ReadFull(rdr, buf) switch err { case nil, io.EOF, io.ErrUnexpectedEOF: - return buf[:n], nil + return n, nil default: - bufs.Put(buf) - return nil, v.translateError(err) + return 0, v.translateError(err) } } +// Compare the given data with the stored data. func (v *S3Volume) Compare(loc string, expect []byte) error { - rdr, err := v.Bucket.GetReader(loc) + rdr, err := v.getReader(loc) if err != nil { - return v.translateError(err) + return err } defer rdr.Close() return v.translateError(compareReaderWithBuf(rdr, expect, loc[:32])) } +// Put writes a block. func (v *S3Volume) Put(loc string, block []byte) error { if v.readonly { return MethodDisabledError @@ -192,75 +237,117 @@ func (v *S3Volume) Put(loc string, block []byte) error { } opts.ContentMD5 = base64.StdEncoding.EncodeToString(md5) } - return v.translateError( - v.Bucket.Put( - loc, block, "application/octet-stream", s3ACL, opts)) + err := v.Bucket.Put(loc, block, "application/octet-stream", s3ACL, opts) + if err != nil { + return v.translateError(err) + } + err = v.Bucket.Put("recent/"+loc, nil, "application/octet-stream", s3ACL, s3.Options{}) + return v.translateError(err) } +// Touch sets the timestamp for the given locator to the current time. func (v *S3Volume) Touch(loc string) error { if v.readonly { return MethodDisabledError } - result, err := v.Bucket.PutCopy(loc, s3ACL, s3.CopyOptions{ - ContentType: "application/octet-stream", - MetadataDirective: "REPLACE", - }, v.Bucket.Name+"/"+loc) - if err != nil { - return v.translateError(err) - } - t, err := time.Parse(time.RFC3339, result.LastModified) - if err != nil { + _, err := v.Bucket.Head(loc, nil) + err = v.translateError(err) + if os.IsNotExist(err) && v.fixRace(loc) { + // The data object got trashed in a race, but fixRace + // rescued it. + } else if err != nil { return err } - if time.Since(t) > maxClockSkew { - return fmt.Errorf("PutCopy returned old LastModified %s => %s (%s ago)", result.LastModified, t, time.Since(t)) - } - return nil + err = v.Bucket.Put("recent/"+loc, nil, "application/octet-stream", s3ACL, s3.Options{}) + return v.translateError(err) } +// Mtime returns the stored timestamp for the given locator. func (v *S3Volume) Mtime(loc string) (time.Time, error) { - resp, err := v.Bucket.Head(loc, nil) + _, err := v.Bucket.Head(loc, nil) if err != nil { return zeroTime, v.translateError(err) } - hdr := resp.Header.Get("Last-Modified") - t, err := time.Parse(time.RFC1123, hdr) - if err != nil && hdr != "" { - // AWS example is "Sun, 1 Jan 2006 12:00:00 GMT", - // which isn't quite "Sun, 01 Jan 2006 12:00:00 GMT" - // as required by HTTP spec. If it's not a valid HTTP - // header value, it's probably AWS (or s3test) giving - // us a nearly-RFC1123 timestamp. - t, err = time.Parse(nearlyRFC1123, hdr) + resp, err := v.Bucket.Head("recent/"+loc, nil) + err = v.translateError(err) + if os.IsNotExist(err) { + // The data object X exists, but recent/X is missing. + err = v.Bucket.Put("recent/"+loc, nil, "application/octet-stream", s3ACL, s3.Options{}) + if err != nil { + log.Printf("error: creating %q: %s", "recent/"+loc, err) + return zeroTime, v.translateError(err) + } + log.Printf("info: created %q to migrate existing block to new storage scheme", "recent/"+loc) + resp, err = v.Bucket.Head("recent/"+loc, nil) + if err != nil { + log.Printf("error: created %q but HEAD failed: %s", "recent/"+loc, err) + return zeroTime, v.translateError(err) + } + } else if err != nil { + // HEAD recent/X failed for some other reason. + return zeroTime, err } - return t, err + return v.lastModified(resp) } +// IndexTo writes a complete list of locators with the given prefix +// for which Get() can retrieve data. func (v *S3Volume) IndexTo(prefix string, writer io.Writer) error { - nextMarker := "" - for { - listResp, err := v.Bucket.List(prefix, "", nextMarker, v.indexPageSize) - if err != nil { - return err + // Use a merge sort to find matching sets of X and recent/X. + dataL := s3Lister{ + Bucket: v.Bucket, + Prefix: prefix, + PageSize: v.indexPageSize, + } + recentL := s3Lister{ + Bucket: v.Bucket, + Prefix: "recent/" + prefix, + PageSize: v.indexPageSize, + } + for data, recent := dataL.First(), recentL.First(); data != nil; data = dataL.Next() { + if data.Key >= "g" { + // Conveniently, "recent/*" and "trash/*" are + // lexically greater than all hex-encoded data + // hashes, so stopping here avoids iterating + // over all of them needlessly with dataL. + break } - for _, key := range listResp.Contents { - t, err := time.Parse(time.RFC3339, key.LastModified) - if err != nil { - return err - } - if !v.isKeepBlock(key.Key) { + if !v.isKeepBlock(data.Key) { + continue + } + + // stamp is the list entry we should use to report the + // last-modified time for this data block: it will be + // the recent/X entry if one exists, otherwise the + // entry for the data block itself. + stamp := data + + // Advance to the corresponding recent/X marker, if any + for recent != nil { + if cmp := strings.Compare(recent.Key[7:], data.Key); cmp < 0 { + recent = recentL.Next() continue + } else if cmp == 0 { + stamp = recent + recent = recentL.Next() + break + } else { + // recent/X marker is missing: we'll + // use the timestamp on the data + // object. + break } - fmt.Fprintf(writer, "%s+%d %d\n", key.Key, key.Size, t.Unix()) } - if !listResp.IsTruncated { - break + t, err := time.Parse(time.RFC3339, stamp.LastModified) + if err != nil { + return err } - nextMarker = listResp.NextMarker + fmt.Fprintf(writer, "%s+%d %d\n", data.Key, data.Size, t.UnixNano()) } return nil } +// Trash a Keep block. func (v *S3Volume) Trash(loc string) error { if v.readonly { return MethodDisabledError @@ -270,17 +357,105 @@ func (v *S3Volume) Trash(loc string) error { } else if time.Since(t) < blobSignatureTTL { return nil } - if !s3UnsafeDelete { - return ErrS3DeleteNotAvailable + if trashLifetime == 0 { + if !s3UnsafeDelete { + return ErrS3TrashDisabled + } + return v.Bucket.Del(loc) } - return v.Bucket.Del(loc) + err := v.checkRaceWindow(loc) + if err != nil { + return err + } + err = v.safeCopy("trash/"+loc, loc) + if err != nil { + return err + } + return v.translateError(v.Bucket.Del(loc)) } -// TBD -func (v *S3Volume) Untrash(loc string) error { +// checkRaceWindow returns a non-nil error if trash/loc is, or might +// be, in the race window (i.e., it's not safe to trash loc). +func (v *S3Volume) checkRaceWindow(loc string) error { + resp, err := v.Bucket.Head("trash/"+loc, nil) + err = v.translateError(err) + if os.IsNotExist(err) { + // OK, trash/X doesn't exist so we're not in the race + // window + return nil + } else if err != nil { + // Error looking up trash/X. We don't know whether + // we're in the race window + return err + } + t, err := v.lastModified(resp) + if err != nil { + // Can't parse timestamp + return err + } + safeWindow := t.Add(trashLifetime).Sub(time.Now().Add(v.raceWindow)) + if safeWindow <= 0 { + // We can't count on "touch trash/X" to prolong + // trash/X's lifetime. The new timestamp might not + // become visible until now+raceWindow, and EmptyTrash + // is allowed to delete trash/X before then. + return fmt.Errorf("same block is already in trash, and safe window ended %s ago", -safeWindow) + } + // trash/X exists, but it won't be eligible for deletion until + // after now+raceWindow, so it's safe to overwrite it. + return nil +} + +// safeCopy calls PutCopy, and checks the response to make sure the +// copy succeeded and updated the timestamp on the destination object +// (PutCopy returns 200 OK if the request was received, even if the +// copy failed). +func (v *S3Volume) safeCopy(dst, src string) error { + resp, err := v.Bucket.PutCopy(dst, s3ACL, s3.CopyOptions{ + ContentType: "application/octet-stream", + MetadataDirective: "REPLACE", + }, v.Bucket.Name+"/"+src) + err = v.translateError(err) + if err != nil { + return err + } + if t, err := time.Parse(time.RFC3339Nano, resp.LastModified); err != nil { + return fmt.Errorf("PutCopy succeeded but did not return a timestamp: %q: %s", resp.LastModified, err) + } else if time.Now().Sub(t) > maxClockSkew { + return fmt.Errorf("PutCopy succeeded but returned an old timestamp: %q: %s", resp.LastModified, t) + } return nil } +// Get the LastModified header from resp, and parse it as RFC1123 or +// -- if it isn't valid RFC1123 -- as Amazon's variant of RFC1123. +func (v *S3Volume) lastModified(resp *http.Response) (t time.Time, err error) { + s := resp.Header.Get("Last-Modified") + t, err = time.Parse(time.RFC1123, s) + if err != nil && s != "" { + // AWS example is "Sun, 1 Jan 2006 12:00:00 GMT", + // which isn't quite "Sun, 01 Jan 2006 12:00:00 GMT" + // as required by HTTP spec. If it's not a valid HTTP + // header value, it's probably AWS (or s3test) giving + // us a nearly-RFC1123 timestamp. + t, err = time.Parse(nearlyRFC1123, s) + } + return +} + +// Untrash moves block from trash back into store +func (v *S3Volume) Untrash(loc string) error { + err := v.safeCopy(loc, "trash/"+loc) + if err != nil { + return err + } + err = v.Bucket.Put("recent/"+loc, nil, "application/octet-stream", s3ACL, s3.Options{}) + return v.translateError(err) +} + +// Status returns a *VolumeStatus representing the current in-use +// storage capacity and a fake available capacity that doesn't make +// the volume seem full or nearly-full. func (v *S3Volume) Status() *VolumeStatus { return &VolumeStatus{ DeviceNum: 1, @@ -289,13 +464,19 @@ func (v *S3Volume) Status() *VolumeStatus { } } +// String implements fmt.Stringer. func (v *S3Volume) String() string { return fmt.Sprintf("s3-bucket:%+q", v.Bucket.Name) } +// Writable returns false if all future Put, Mtime, and Delete calls +// are expected to fail. func (v *S3Volume) Writable() bool { return !v.readonly } + +// Replication returns the storage redundancy of the underlying +// device. Configured via command line flag. func (v *S3Volume) Replication() int { return v.replication } @@ -306,10 +487,57 @@ func (v *S3Volume) isKeepBlock(s string) bool { return s3KeepBlockRegexp.MatchString(s) } +// fixRace(X) is called when "recent/X" exists but "X" doesn't +// exist. If the timestamps on "recent/"+loc and "trash/"+loc indicate +// there was a race between Put and Trash, fixRace recovers from the +// race by Untrashing the block. +func (v *S3Volume) fixRace(loc string) bool { + trash, err := v.Bucket.Head("trash/"+loc, nil) + if err != nil { + if !os.IsNotExist(v.translateError(err)) { + log.Printf("error: fixRace: HEAD %q: %s", "trash/"+loc, err) + } + return false + } + trashTime, err := v.lastModified(trash) + if err != nil { + log.Printf("error: fixRace: parse %q: %s", trash.Header.Get("Last-Modified"), err) + return false + } + + recent, err := v.Bucket.Head("recent/"+loc, nil) + if err != nil { + log.Printf("error: fixRace: HEAD %q: %s", "recent/"+loc, err) + return false + } + recentTime, err := v.lastModified(recent) + if err != nil { + log.Printf("error: fixRace: parse %q: %s", recent.Header.Get("Last-Modified"), err) + return false + } + + ageWhenTrashed := trashTime.Sub(recentTime) + if ageWhenTrashed >= blobSignatureTTL { + // No evidence of a race: block hasn't been written + // since it became eligible for Trash. No fix needed. + return false + } + + log.Printf("notice: fixRace: %q: trashed at %s but touched at %s (age when trashed = %s < %s)", loc, trashTime, recentTime, ageWhenTrashed, blobSignatureTTL) + log.Printf("notice: fixRace: copying %q to %q to recover from race between Put/Touch and Trash", "recent/"+loc, loc) + err = v.safeCopy(loc, "trash/"+loc) + if err != nil { + log.Printf("error: fixRace: %s", err) + return false + } + return true +} + func (v *S3Volume) translateError(err error) error { switch err := err.(type) { case *s3.Error: - if err.StatusCode == http.StatusNotFound && err.Code == "NoSuchKey" { + if (err.StatusCode == http.StatusNotFound && err.Code == "NoSuchKey") || + strings.Contains(err.Error(), "Not Found") { return os.ErrNotExist } // Other 404 errors like NoSuchVersion and @@ -319,3 +547,148 @@ func (v *S3Volume) translateError(err error) error { } return err } + +// EmptyTrash looks for trashed blocks that exceeded trashLifetime +// and deletes them from the volume. +func (v *S3Volume) EmptyTrash() { + var bytesInTrash, blocksInTrash, bytesDeleted, blocksDeleted int64 + + // Use a merge sort to find matching sets of trash/X and recent/X. + trashL := s3Lister{ + Bucket: v.Bucket, + Prefix: "trash/", + PageSize: v.indexPageSize, + } + // Define "ready to delete" as "...when EmptyTrash started". + startT := time.Now() + for trash := trashL.First(); trash != nil; trash = trashL.Next() { + loc := trash.Key[6:] + if !v.isKeepBlock(loc) { + continue + } + bytesInTrash += trash.Size + blocksInTrash++ + + trashT, err := time.Parse(time.RFC3339, trash.LastModified) + if err != nil { + log.Printf("warning: %s: EmptyTrash: %q: parse %q: %s", v, trash.Key, trash.LastModified, err) + continue + } + recent, err := v.Bucket.Head("recent/"+loc, nil) + if err != nil { + log.Printf("warning: %s: EmptyTrash: cannot delete trash %q with no corresponding recent/* marker", v, trash.Key) + continue + } + recentT, err := v.lastModified(recent) + if err != nil { + log.Printf("warning: %s: EmptyTrash: %q: parse %q: %s", v, "recent/"+loc, recent.Header.Get("Last-Modified"), err) + continue + } + if trashT.Sub(recentT) < blobSignatureTTL { + if age := startT.Sub(recentT); age >= blobSignatureTTL - v.raceWindow { + // recent/loc is too old to protect + // loc from being Trashed again during + // the raceWindow that starts if we + // delete trash/X now. + // + // Note this means (trashCheckInterval + // < blobSignatureTTL - raceWindow) is + // necessary to avoid starvation. + log.Printf("notice: %s: EmptyTrash: detected old race for %q, calling fixRace + Touch", v, loc) + v.fixRace(loc) + v.Touch(loc) + continue + } else if _, err := v.Bucket.Head(loc, nil); os.IsNotExist(err) { + log.Printf("notice: %s: EmptyTrash: detected recent race for %q, calling fixRace", v, loc) + v.fixRace(loc) + continue + } else if err != nil { + log.Printf("warning: %s: EmptyTrash: HEAD %q: %s", v, loc, err) + continue + } + } + if startT.Sub(trashT) < trashLifetime { + continue + } + err = v.Bucket.Del(trash.Key) + if err != nil { + log.Printf("warning: %s: EmptyTrash: deleting %q: %s", v, trash.Key, err) + continue + } + bytesDeleted += trash.Size + blocksDeleted++ + + _, err = v.Bucket.Head(loc, nil) + if os.IsNotExist(err) { + err = v.Bucket.Del("recent/" + loc) + if err != nil { + log.Printf("warning: %s: EmptyTrash: deleting %q: %s", v, "recent/"+loc, err) + } + } else if err != nil { + log.Printf("warning: %s: EmptyTrash: HEAD %q: %s", v, "recent/"+loc, err) + } + } + if err := trashL.Error(); err != nil { + log.Printf("error: %s: EmptyTrash: lister: %s", v, err) + } + log.Printf("EmptyTrash stats for %v: Deleted %v bytes in %v blocks. Remaining in trash: %v bytes in %v blocks.", v.String(), bytesDeleted, blocksDeleted, bytesInTrash-bytesDeleted, blocksInTrash-blocksDeleted) +} + +type s3Lister struct { + Bucket *s3.Bucket + Prefix string + PageSize int + nextMarker string + buf []s3.Key + err error +} + +// First fetches the first page and returns the first item. It returns +// nil if the response is the empty set or an error occurs. +func (lister *s3Lister) First() *s3.Key { + lister.getPage() + return lister.pop() +} + +// Next returns the next item, fetching the next page if necessary. It +// returns nil if the last available item has already been fetched, or +// an error occurs. +func (lister *s3Lister) Next() *s3.Key { + if len(lister.buf) == 0 && lister.nextMarker != "" { + lister.getPage() + } + return lister.pop() +} + +// Return the most recent error encountered by First or Next. +func (lister *s3Lister) Error() error { + return lister.err +} + +func (lister *s3Lister) getPage() { + resp, err := lister.Bucket.List(lister.Prefix, "", lister.nextMarker, lister.PageSize) + lister.nextMarker = "" + if err != nil { + lister.err = err + return + } + if resp.IsTruncated { + lister.nextMarker = resp.NextMarker + } + lister.buf = make([]s3.Key, 0, len(resp.Contents)) + for _, key := range resp.Contents { + if !strings.HasPrefix(key.Key, lister.Prefix) { + log.Printf("warning: s3Lister: S3 Bucket.List(prefix=%q) returned key %q", lister.Prefix, key.Key) + continue + } + lister.buf = append(lister.buf, key) + } +} + +func (lister *s3Lister) pop() (k *s3.Key) { + if len(lister.buf) > 0 { + k = &lister.buf[0] + lister.buf = lister.buf[1:] + } + return +}