/
server.go
554 lines (481 loc) · 16.8 KB
/
server.go
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package pmtiles
import (
"bytes"
"compress/gzip"
"container/list"
"context"
"encoding/json"
"errors"
"io"
"log"
"net/http"
"regexp"
"strconv"
"time"
)
type cacheKey struct {
name string
etag string
offset uint64 // is 0 for header
length uint64 // is 0 for header
}
type request struct {
key cacheKey
value chan cachedValue
purgeEtag string
}
type cachedValue struct {
header HeaderV3
directory []EntryV3
etag string
ok bool
badEtag bool
}
type response struct {
key cacheKey
value cachedValue
size int
ok bool
}
// Server is an HTTP server for tiles and metadata.
type Server struct {
reqs chan request
bucket Bucket
logger *log.Logger
cacheSize int
cors string
publicURL string
metrics *metrics
}
// NewServer creates a new pmtiles HTTP server.
func NewServer(bucketURL string, prefix string, logger *log.Logger, cacheSize int, cors string, publicURL string) (*Server, error) {
ctx := context.Background()
bucketURL, _, err := NormalizeBucketKey(bucketURL, prefix, "")
if err != nil {
return nil, err
}
bucket, err := OpenBucket(ctx, bucketURL, prefix)
if err != nil {
return nil, err
}
return NewServerWithBucket(bucket, prefix, logger, cacheSize, cors, publicURL)
}
// NewServerWithBucket creates a new HTTP server for a gocloud Bucket.
func NewServerWithBucket(bucket Bucket, _ string, logger *log.Logger, cacheSize int, cors string, publicURL string) (*Server, error) {
reqs := make(chan request, 8)
l := &Server{
reqs: reqs,
bucket: bucket,
logger: logger,
cacheSize: cacheSize,
cors: cors,
publicURL: publicURL,
metrics: createMetrics("", logger), // change scope string if there are multiple servers running in one process
}
return l, nil
}
// Start the server HTTP listener.
func (server *Server) Start() {
go func() {
cache := make(map[cacheKey]*list.Element)
inflight := make(map[cacheKey][]request)
resps := make(chan response, 8)
evictList := list.New()
totalSize := 0
ctx := context.Background()
server.metrics.initCacheStats(server.cacheSize * 1000 * 1000)
for {
select {
case req := <-server.reqs:
if len(req.purgeEtag) > 0 {
if _, dup := inflight[req.key]; !dup {
server.metrics.reloadFile(req.key.name)
server.logger.Printf("re-fetching directories for changed file %s", req.key.name)
}
for k, v := range cache {
resp := v.Value.(*response)
if k.name == req.key.name && (k.etag == req.purgeEtag || resp.value.etag == req.purgeEtag) {
evictList.Remove(v)
delete(cache, k)
totalSize -= resp.size
}
}
server.metrics.updateCacheStats(totalSize, len(cache))
}
key := req.key
isRoot := (key.offset == 0 && key.length == 0)
kind := "leaf"
if isRoot {
kind = "root"
}
if val, ok := cache[key]; ok {
evictList.MoveToFront(val)
req.value <- val.Value.(*response).value
server.metrics.cacheRequest(key.name, kind, "hit")
} else if _, ok := inflight[key]; ok {
inflight[key] = append(inflight[key], req)
server.metrics.cacheRequest(key.name, kind, "hit") // treat inflight as a hit since it doesn't make a new server request
} else {
inflight[key] = []request{req}
server.metrics.cacheRequest(key.name, kind, "miss")
go func() {
var result cachedValue
offset := int64(key.offset)
length := int64(key.length)
if isRoot {
offset = 0
length = 16384
}
status := ""
tracker := server.metrics.startBucketRequest(key.name, kind)
defer func() { tracker.finish(ctx, status) }()
server.logger.Printf("fetching %s %d-%d", key.name, offset, length)
r, etag, statusCode, err := server.bucket.NewRangeReaderEtag(ctx, key.name+".pmtiles", offset, length, key.etag)
status = strconv.Itoa(statusCode)
if err != nil {
ok = false
result.badEtag = isRefreshRequiredError(err)
resps <- response{key: key, value: result}
server.logger.Printf("failed to fetch %s %d-%d, %v", key.name, key.offset, key.length, err)
return
}
defer r.Close()
b, err := io.ReadAll(r)
if err != nil {
ok = false
status = "error"
resps <- response{key: key, value: result}
server.logger.Printf("failed to fetch %s %d-%d, %v", key.name, key.offset, key.length, err)
return
}
if isRoot {
header, err := deserializeHeader(b[0:HeaderV3LenBytes])
if err != nil {
status = "error"
server.logger.Printf("parsing header failed: %v", err)
return
}
// populate the root first before header
rootEntries := deserializeEntries(bytes.NewBuffer(b[header.RootOffset : header.RootOffset+header.RootLength]))
result2 := cachedValue{directory: rootEntries, ok: true, etag: etag}
rootKey := cacheKey{name: key.name, offset: header.RootOffset, length: header.RootLength}
resps <- response{key: rootKey, value: result2, size: 24 * len(rootEntries), ok: true}
result = cachedValue{header: header, ok: true, etag: etag}
resps <- response{key: key, value: result, size: 127, ok: true}
} else {
directory := deserializeEntries(bytes.NewBuffer(b))
result = cachedValue{directory: directory, ok: true, etag: etag}
resps <- response{key: key, value: result, size: 24 * len(directory), ok: true}
}
server.logger.Printf("fetched %s %d-%d", key.name, key.offset, length)
}()
}
case resp := <-resps:
key := resp.key
// check if there are any requests waiting on the key
for _, v := range inflight[key] {
v.value <- resp.value
}
delete(inflight, key)
if resp.ok {
totalSize += resp.size
ent := &resp
entry := evictList.PushFront(ent)
cache[key] = entry
for {
if totalSize < server.cacheSize*1000*1000 {
break
}
ent := evictList.Back()
if ent != nil {
evictList.Remove(ent)
kv := ent.Value.(*response)
delete(cache, kv.key)
totalSize -= kv.size
}
}
server.metrics.updateCacheStats(totalSize, len(cache))
}
}
}
}()
}
func (server *Server) getHeaderMetadata(ctx context.Context, name string) (bool, HeaderV3, []byte, error) {
found, header, metadataBytes, purgeEtag, err := server.getHeaderMetadataAttempt(ctx, name, "")
if len(purgeEtag) > 0 {
found, header, metadataBytes, _, err = server.getHeaderMetadataAttempt(ctx, name, purgeEtag)
}
return found, header, metadataBytes, err
}
func (server *Server) getHeaderMetadataAttempt(ctx context.Context, name, purgeEtag string) (bool, HeaderV3, []byte, string, error) {
rootReq := request{key: cacheKey{name: name, offset: 0, length: 0}, value: make(chan cachedValue, 1), purgeEtag: purgeEtag}
server.reqs <- rootReq
rootValue := <-rootReq.value
header := rootValue.header
if !rootValue.ok {
return false, HeaderV3{}, nil, "", nil
}
status := ""
tracker := server.metrics.startBucketRequest(name, "metadata")
defer func() { tracker.finish(ctx, status) }()
r, _, statusCode, err := server.bucket.NewRangeReaderEtag(ctx, name+".pmtiles", int64(header.MetadataOffset), int64(header.MetadataLength), rootValue.etag)
status = strconv.Itoa(statusCode)
if isRefreshRequiredError(err) {
return false, HeaderV3{}, nil, rootValue.etag, nil
}
if err != nil {
return false, HeaderV3{}, nil, "", nil
}
defer r.Close()
var metadataBytes []byte
if header.InternalCompression == Gzip {
metadataReader, _ := gzip.NewReader(r)
defer metadataReader.Close()
metadataBytes, err = io.ReadAll(metadataReader)
} else if header.InternalCompression == NoCompression {
metadataBytes, err = io.ReadAll(r)
} else {
status = "error"
return true, HeaderV3{}, nil, "", errors.New("unknown compression")
}
return true, header, metadataBytes, "", nil
}
func (server *Server) getTileJSON(ctx context.Context, httpHeaders map[string]string, name string) (int, map[string]string, []byte) {
found, header, metadataBytes, err := server.getHeaderMetadata(ctx, name)
if err != nil {
return 500, httpHeaders, []byte("I/O Error")
}
if !found {
return 404, httpHeaders, []byte("Archive not found")
}
var metadataMap map[string]interface{}
json.Unmarshal(metadataBytes, &metadataMap)
if server.publicURL == "" {
return 501, httpHeaders, []byte("PUBLIC_URL must be set for TileJSON")
}
tilejsonBytes, err := CreateTileJSON(header, metadataBytes, server.publicURL+"/"+name)
if err != nil {
return 500, httpHeaders, []byte("Error generating tilejson")
}
httpHeaders["Content-Type"] = "application/json"
httpHeaders["ETag"] = generateEtag(tilejsonBytes)
return 200, httpHeaders, tilejsonBytes
}
func (server *Server) getMetadata(ctx context.Context, httpHeaders map[string]string, name string) (int, map[string]string, []byte) {
found, _, metadataBytes, err := server.getHeaderMetadata(ctx, name)
if err != nil {
return 500, httpHeaders, []byte("I/O Error")
}
if !found {
return 404, httpHeaders, []byte("Archive not found")
}
httpHeaders["Content-Type"] = "application/json"
httpHeaders["ETag"] = generateEtag(metadataBytes)
return 200, httpHeaders, metadataBytes
}
func (server *Server) getTile(ctx context.Context, httpHeaders map[string]string, name string, z uint8, x uint32, y uint32, ext string) (int, map[string]string, []byte) {
status, headers, data, purgeEtag := server.getTileAttempt(ctx, httpHeaders, name, z, x, y, ext, "")
if len(purgeEtag) > 0 {
// file has new etag, retry once force-purging the etag that is no longer value
status, headers, data, _ = server.getTileAttempt(ctx, httpHeaders, name, z, x, y, ext, purgeEtag)
}
return status, headers, data
}
func (server *Server) getTileAttempt(ctx context.Context, httpHeaders map[string]string, name string, z uint8, x uint32, y uint32, ext string, purgeEtag string) (int, map[string]string, []byte, string) {
rootReq := request{key: cacheKey{name: name, offset: 0, length: 0}, value: make(chan cachedValue, 1), purgeEtag: purgeEtag}
server.reqs <- rootReq
// https://golang.org/doc/faq#atomic_maps
rootValue := <-rootReq.value
header := rootValue.header
if !rootValue.ok {
return 404, httpHeaders, []byte("Archive not found"), ""
}
if z < header.MinZoom || z > header.MaxZoom {
return 404, httpHeaders, []byte("Tile not found"), ""
}
switch header.TileType {
case Mvt:
if ext != "mvt" {
return 400, httpHeaders, []byte("path mismatch: archive is type MVT (.mvt)"), ""
}
case Png:
if ext != "png" {
return 400, httpHeaders, []byte("path mismatch: archive is type PNG (.png)"), ""
}
case Jpeg:
if ext != "jpg" {
return 400, httpHeaders, []byte("path mismatch: archive is type JPEG (.jpg)"), ""
}
case Webp:
if ext != "webp" {
return 400, httpHeaders, []byte("path mismatch: archive is type WebP (.webp)"), ""
}
case Avif:
if ext != "avif" {
return 400, httpHeaders, []byte("path mismatch: archive is type AVIF (.avif)"), ""
}
}
tileID := ZxyToID(z, x, y)
dirOffset, dirLen := header.RootOffset, header.RootLength
for depth := 0; depth <= 3; depth++ {
dirReq := request{key: cacheKey{name: name, offset: dirOffset, length: dirLen, etag: rootValue.etag}, value: make(chan cachedValue, 1)}
server.reqs <- dirReq
dirValue := <-dirReq.value
if dirValue.badEtag {
return 500, httpHeaders, []byte("I/O Error"), rootValue.etag
}
directory := dirValue.directory
entry, ok := findTile(directory, tileID)
if !ok {
break
}
if entry.RunLength > 0 {
status := ""
tracker := server.metrics.startBucketRequest(name, "tile")
defer func() { tracker.finish(ctx, status) }()
r, _, statusCode, err := server.bucket.NewRangeReaderEtag(ctx, name+".pmtiles", int64(header.TileDataOffset+entry.Offset), int64(entry.Length), rootValue.etag)
status = strconv.Itoa(statusCode)
if isRefreshRequiredError(err) {
return 500, httpHeaders, []byte("I/O Error"), rootValue.etag
}
// possible we have the header/directory cached but the archive has disappeared
if err != nil {
if isCanceled(ctx) {
return 499, httpHeaders, []byte("Canceled"), ""
}
server.logger.Printf("failed to fetch tile %s %d-%d %v", name, entry.Offset, entry.Length, err)
return 404, httpHeaders, []byte("Tile not found"), ""
}
defer r.Close()
b, err := io.ReadAll(r)
if err != nil {
status = "error"
if isCanceled(ctx) {
return 499, httpHeaders, []byte("Canceled"), ""
}
return 500, httpHeaders, []byte("I/O error"), ""
}
httpHeaders["ETag"] = generateEtag(b)
if headerVal, ok := headerContentType(header); ok {
httpHeaders["Content-Type"] = headerVal
}
if headerVal, ok := headerContentEncoding(header.TileCompression); ok {
httpHeaders["Content-Encoding"] = headerVal
}
return 200, httpHeaders, b, ""
}
dirOffset = header.LeafDirectoryOffset + entry.Offset
dirLen = uint64(entry.Length)
}
return 204, httpHeaders, nil, ""
}
func isRefreshRequiredError(err error) bool {
_, ok := err.(*RefreshRequiredError)
return ok
}
func isCanceled(ctx context.Context) bool {
return errors.Is(ctx.Err(), context.Canceled)
}
var tilePattern = regexp.MustCompile(`^\/([-A-Za-z0-9_\/!-_\.\*'\(\)']+)\/(\d+)\/(\d+)\/(\d+)\.([a-z]+)$`)
var metadataPattern = regexp.MustCompile(`^\/([-A-Za-z0-9_\/!-_\.\*'\(\)']+)\/metadata$`)
var tileJSONPattern = regexp.MustCompile(`^\/([-A-Za-z0-9_\/!-_\.\*'\(\)']+)\.json$`)
func parseTilePath(path string) (bool, string, uint8, uint32, uint32, string) {
if res := tilePattern.FindStringSubmatch(path); res != nil {
name := res[1]
z, _ := strconv.ParseUint(res[2], 10, 8)
x, _ := strconv.ParseUint(res[3], 10, 32)
y, _ := strconv.ParseUint(res[4], 10, 32)
ext := res[5]
return true, name, uint8(z), uint32(x), uint32(y), ext
}
return false, "", 0, 0, 0, ""
}
func parseTilejsonPath(path string) (bool, string) {
if res := tileJSONPattern.FindStringSubmatch(path); res != nil {
name := res[1]
return true, name
}
return false, ""
}
func parseMetadataPath(path string) (bool, string) {
if res := metadataPattern.FindStringSubmatch(path); res != nil {
name := res[1]
return true, name
}
return false, ""
}
func (server *Server) get(ctx context.Context, unsanitizedPath string) (archive, handler string, status int, headers map[string]string, data []byte) {
handler = ""
archive = ""
headers = make(map[string]string)
if len(server.cors) > 0 {
headers["Access-Control-Allow-Origin"] = server.cors
}
if ok, key, z, x, y, ext := parseTilePath(unsanitizedPath); ok {
archive, handler = key, "tile"
status, headers, data = server.getTile(ctx, headers, key, z, x, y, ext)
} else if ok, key := parseTilejsonPath(unsanitizedPath); ok {
archive, handler = key, "tilejson"
status, headers, data = server.getTileJSON(ctx, headers, key)
} else if ok, key := parseMetadataPath(unsanitizedPath); ok {
archive, handler = key, "metadata"
status, headers, data = server.getMetadata(ctx, headers, key)
} else if unsanitizedPath == "/" {
handler, status, data = "/", 204, []byte{}
} else {
handler, status, data = "404", 404, []byte("Path not found")
}
return
}
// Get a response for the given path.
// Return status code, HTTP headers, and body.
func (server *Server) Get(ctx context.Context, path string) (int, map[string]string, []byte) {
tracker := server.metrics.startRequest()
archive, handler, status, headers, data := server.get(ctx, path)
tracker.finish(ctx, archive, handler, status, len(data), true)
return status, headers, data
}
type loggingResponseWriter struct {
http.ResponseWriter
statusCode int
}
func (lrw *loggingResponseWriter) WriteHeader(code int) {
lrw.statusCode = code
lrw.ResponseWriter.WriteHeader(code)
}
// Serve an HTTP response from the archive
func (server *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) int {
tracker := server.metrics.startRequest()
if r.Method == http.MethodOptions {
if len(server.cors) > 0 {
w.Header().Set("Access-Control-Allow-Origin", server.cors)
}
w.WriteHeader(204)
tracker.finish(r.Context(), "", r.Method, 204, 0, false)
return 204
} else if r.Method != http.MethodGet && r.Method != http.MethodHead {
w.WriteHeader(405)
tracker.finish(r.Context(), "", r.Method, 405, 0, false)
return 405
}
archive, handler, statusCode, headers, body := server.get(r.Context(), r.URL.Path)
for k, v := range headers {
w.Header().Set(k, v)
}
if statusCode == 200 {
lrw := &loggingResponseWriter{w, 200}
// handle if-match, if-none-match request headers based on response etag
http.ServeContent(
lrw, r,
"", // name used to infer content-type, but we've already set that
time.UnixMilli(0), // ignore setting last-modified time and handling if-modified-since headers
bytes.NewReader(body),
)
statusCode = lrw.statusCode
} else {
w.WriteHeader(statusCode)
w.Write(body)
}
tracker.finish(r.Context(), archive, handler, statusCode, len(body), true)
return statusCode
}