nghttpd: Cache fd

Implement fd caching for static files.  The response body for such as
404 was dynamically generated previously, but now it is written in
temporally file and its fd is cached.  Currently, cache is reference
counted and expired when count becomes 0.  This makes caching is not
effective other than "busy" period, but we don't need this feature if
we are not busy.

src/HttpServer.cc

@@ -57,11 +57,6 @@
 namespace nghttp2 {
 
 namespace {
-const std::string STATUS_200 = "200";
-const std::string STATUS_301 = "301";
-const std::string STATUS_304 = "304";
-const std::string STATUS_400 = "400";
-const std::string STATUS_404 = "404";
 const std::string DEFAULT_HTML = "index.html";
 const std::string NGHTTPD_SERVER = "nghttpd nghttp2/" NGHTTP2_VERSION;
 } // namespace
@@ -171,9 +166,10 @@ void fill_callback(nghttp2_session_callbacks *callbacks, const Config *config);
 
 class Sessions {
 public:
-  Sessions(struct ev_loop *loop, const Config *config, SSL_CTX *ssl_ctx)
+  Sessions(HttpServer *sv, struct ev_loop *loop, const Config *config,
-      : loop_(loop), config_(config), ssl_ctx_(ssl_ctx), callbacks_(nullptr),
+           SSL_CTX *ssl_ctx)
-        next_session_id_(1), tstamp_cached_(ev_now(loop)),
+      : sv_(sv), loop_(loop), config_(config), ssl_ctx_(ssl_ctx),
+        callbacks_(nullptr), next_session_id_(1), tstamp_cached_(ev_now(loop)),
         cached_date_(util::http_date(tstamp_cached_)) {
     nghttp2_session_callbacks_new(&callbacks_);
 
@@ -244,9 +240,37 @@ public:
     }
     return cached_date_;
   }
+  FileEntry *get_cached_fd(const std::string &path) {
+    auto i = fd_cache_.find(path);
+    if (i == std::end(fd_cache_)) {
+      return nullptr;
+    }
+    auto &ent = (*i).second;
+    ++ent.usecount;
+    return &ent;
+  }
+  FileEntry *cache_fd(const std::string &path, const FileEntry &ent) {
+    auto rv = fd_cache_.emplace(path, ent);
+    return &(*rv.first).second;
+  }
+  void release_fd(const std::string &path) {
+    auto i = fd_cache_.find(path);
+    if (i == std::end(fd_cache_)) {
+      return;
+    }
+    auto &ent = (*i).second;
+    if (--ent.usecount == 0) {
+      close(ent.fd);
+      fd_cache_.erase(i);
+    }
+  }
+  const HttpServer *get_server() const { return sv_; }
 
 private:
   std::set<Http2Handler *> handlers_;
+  // cache for file descriptors to read file.
+  std::map<std::string, FileEntry> fd_cache_;
+  HttpServer *sv_;
   struct ev_loop *loop_;
   const Config *config_;
   SSL_CTX *ssl_ctx_;
@@ -257,7 +281,8 @@ private:
 };
 
 Stream::Stream(Http2Handler *handler, int32_t stream_id)
-    : handler(handler), body_left(0), stream_id(stream_id), file(-1) {
+    : handler(handler), file_ent(nullptr), body_length(0), body_offset(0),
+      stream_id(stream_id) {
   auto config = handler->get_config();
   ev_timer_init(&rtimer, stream_timeout_cb, 0., config->stream_read_timeout);
   ev_timer_init(&wtimer, stream_timeout_cb, 0., config->stream_write_timeout);
@@ -270,8 +295,9 @@ Stream::Stream(Http2Handler *handler, int32_t stream_id)
 }
 
 Stream::~Stream() {
-  if (file != -1) {
+  if (file_ent != nullptr) {
-    close(file);
+    auto sessions = handler->get_sessions();
+    sessions->release_fd(file_ent->path);
   }
 
   auto loop = handler->get_loop();
@@ -835,12 +861,12 @@ ssize_t file_read_callback(nghttp2_session *session, int32_t stream_id,
   auto hd = static_cast<Http2Handler *>(user_data);
   auto stream = hd->get_stream(stream_id);
 
-  size_t nread = std::min(stream->body_left, static_cast<int64_t>(length));
+  auto nread = std::min(stream->body_length - stream->body_offset,
+                        static_cast<int64_t>(length));
 
   *data_flags |= NGHTTP2_DATA_FLAG_NO_COPY;
 
-  stream->body_left -= nread;
+  if (nread == 0 || stream->body_length == stream->body_offset + nread) {
-  if (nread == 0 || stream->body_left <= 0) {
     *data_flags |= NGHTTP2_DATA_FLAG_EOF;
 
     auto config = hd->get_config();
@@ -872,59 +898,27 @@ ssize_t file_read_callback(nghttp2_session *session, int32_t stream_id,
 }
 
 namespace {
-void prepare_status_response(Stream *stream, Http2Handler *hd,
+void prepare_status_response(Stream *stream, Http2Handler *hd, int status) {
-                             const std::string &status) {
+  auto sessions = hd->get_sessions();
-  int pipefd[2];
+  auto status_page = sessions->get_server()->get_status_page(status);
-  if (status == STATUS_304 || pipe(pipefd) == -1) {
+  auto file_ent = &status_page->file_ent;
-    hd->submit_response(status, stream->stream_id, 0);
+
-    return;
+  // we don't set stream->file_ent since we don't want to expire it.
-  }
+  stream->body_length = file_ent->length;
-  std::string body;
+  nghttp2_data_provider data_prd;
-  body.reserve(256);
+  data_prd.source.fd = file_ent->fd;
-  body = "<html><head><title>";
+  data_prd.read_callback = file_read_callback;
-  body += status;
-  body += "</title></head><body><h1>";
-  body += status;
-  body += "</h1><hr><address>";
-  body += NGHTTPD_SERVER;
-  body += " at port ";
-  body += util::utos(hd->get_config()->port);
-  body += "</address>";
-  body += "</body></html>";
 
   Headers headers;
-  if (hd->get_config()->error_gzip) {
-    gzFile write_fd = gzdopen(pipefd[1], "w");
-    gzwrite(write_fd, body.c_str(), body.size());
-    gzclose(write_fd);
-    headers.emplace_back("content-encoding", "gzip");
-  } else {
-    ssize_t rv;
-
-    while ((rv = write(pipefd[1], body.c_str(), body.size())) == -1 &&
-           errno == EINTR)
-      ;
-
-    if (rv != static_cast<ssize_t>(body.size())) {
-      std::cerr << "Could not write all response body: " << rv << std::endl;
-    }
-  }
-  close(pipefd[1]);
-
-  stream->file = pipefd[0];
-  stream->body_left = body.size();
-  nghttp2_data_provider data_prd;
-  data_prd.source.fd = pipefd[0];
-  data_prd.read_callback = file_read_callback;
   headers.emplace_back("content-type", "text/html; charset=UTF-8");
-  hd->submit_response(status, stream->stream_id, headers, &data_prd);
+  hd->submit_response(status_page->status, stream->stream_id, headers,
+                      &data_prd);
 }
 } // namespace
 
 namespace {
 void prepare_redirect_response(Stream *stream, Http2Handler *hd,
-                               const std::string &path,
+                               const std::string &path, int status) {
-                               const std::string &status) {
   auto scheme =
       http2::get_header(stream->hdidx, http2::HD__SCHEME, stream->headers);
   auto authority =
@@ -941,7 +935,10 @@ void prepare_redirect_response(Stream *stream, Http2Handler *hd,
 
   auto headers = Headers{{"location", redirect_url}};
 
-  hd->submit_response(status, stream->stream_id, headers, nullptr);
+  auto sessions = hd->get_sessions();
+  auto status_page = sessions->get_server()->get_status_page(status);
+
+  hd->submit_response(status_page->status, stream->stream_id, headers, nullptr);
 }
 } // namespace
 
@@ -975,7 +972,7 @@ void prepare_response(Stream *stream, Http2Handler *hd,
 
   url = util::percentDecode(url.begin(), url.end());
   if (!util::check_path(url)) {
-    prepare_status_response(stream, hd, STATUS_404);
+    prepare_status_response(stream, hd, 404);
     return;
   }
   auto push_itr = hd->get_config()->push.find(url);
@@ -992,9 +989,14 @@ void prepare_response(Stream *stream, Http2Handler *hd,
   if (path[path.size() - 1] == '/') {
     path += DEFAULT_HTML;
   }
+
+  auto sessions = hd->get_sessions();
+  auto file_ent = sessions->get_cached_fd(path);
+
+  if (file_ent == nullptr) {
     int file = open(path.c_str(), O_RDONLY | O_BINARY);
     if (file == -1) {
-    prepare_status_response(stream, hd, STATUS_404);
+      prepare_status_response(stream, hd, 404);
 
       return;
     }
@@ -1003,7 +1005,7 @@ void prepare_response(Stream *stream, Http2Handler *hd,
 
     if (fstat(file, &buf) == -1) {
       close(file);
-    prepare_status_response(stream, hd, STATUS_404);
+      prepare_status_response(stream, hd, 404);
 
       return;
     }
@@ -1017,26 +1019,36 @@ void prepare_response(Stream *stream, Http2Handler *hd,
         reqpath.insert(query_pos, "/");
       }
 
-    prepare_redirect_response(stream, hd, reqpath, STATUS_301);
+      prepare_redirect_response(stream, hd, reqpath, 301);
 
       return;
     }
 
-  stream->file = file;
+    if (last_mod_found && buf.st_mtime <= last_mod) {
-  stream->body_left = buf.st_size;
+      close(file);
+      prepare_status_response(stream, hd, 304);
+
+      return;
+    }
+
+    file_ent = sessions->cache_fd(
+        path, FileEntry(path, buf.st_size, buf.st_mtime, file));
+  } else if (last_mod_found && file_ent->mtime <= last_mod) {
+    sessions->release_fd(file_ent->path);
+    prepare_status_response(stream, hd, 304);
+
+    return;
+  }
+
+  stream->file_ent = file_ent;
+  stream->body_length = file_ent->length;
 
   nghttp2_data_provider data_prd;
 
-  data_prd.source.fd = file;
+  data_prd.source.fd = file_ent->fd;
   data_prd.read_callback = file_read_callback;
 
-  if (last_mod_found && buf.st_mtime <= last_mod) {
+  hd->submit_file_response("200", stream, file_ent->mtime, file_ent->length,
-    prepare_status_response(stream, hd, STATUS_304);
-
-    return;
-  }
-
-  hd->submit_file_response(STATUS_200, stream, buf.st_mtime, buf.st_size,
                            &data_prd);
 }
 } // namespace
@@ -1220,6 +1232,7 @@ int send_data_callback(nghttp2_session *session, nghttp2_frame *frame,
   auto hd = static_cast<Http2Handler *>(user_data);
   auto wb = hd->get_wb();
   auto padlen = frame->data.padlen;
+  auto stream = hd->get_stream(frame->hd.stream_id);
 
   if (wb->wleft() < 9 + length + padlen) {
     return NGHTTP2_ERR_WOULDBLOCK;
@@ -1237,17 +1250,18 @@ int send_data_callback(nghttp2_session *session, nghttp2_frame *frame,
 
   while (length) {
     ssize_t nread;
-    while ((nread = read(fd, p, length)) == -1 && errno == EINTR)
+    while ((nread = pread(fd, p, length, stream->body_offset)) == -1 &&
+           errno == EINTR)
       ;
 
     if (nread == -1) {
-      auto stream = hd->get_stream(frame->hd.stream_id);
       remove_stream_read_timeout(stream);
       remove_stream_write_timeout(stream);
 
       return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
     }
 
+    stream->body_offset += nread;
     length -= nread;
     p += nread;
   }
@@ -1380,7 +1394,7 @@ void run_worker(Worker *worker) {
 
 class AcceptHandler {
 public:
-  AcceptHandler(Sessions *sessions, const Config *config)
+  AcceptHandler(HttpServer *sv, Sessions *sessions, const Config *config)
       : sessions_(sessions), config_(config), next_worker_(0) {
     if (config_->num_worker == 1) {
       return;
@@ -1392,7 +1406,7 @@ public:
       auto worker = make_unique<Worker>();
       auto loop = ev_loop_new(0);
       worker->sessions =
-          make_unique<Sessions>(loop, config_, sessions_->get_ssl_ctx());
+          make_unique<Sessions>(sv, loop, config_, sessions_->get_ssl_ctx());
       ev_async_init(&worker->w, worker_acceptcb);
       worker->w.data = worker.get();
       ev_async_start(loop, &worker->w);
@@ -1476,7 +1490,61 @@ void acceptcb(struct ev_loop *loop, ev_io *w, int revents) {
 }
 } // namespace
 
-HttpServer::HttpServer(const Config *config) : config_(config) {}
+namespace {
+FileEntry make_status_body(int status, uint16_t port) {
+  std::string body;
+  body = "<html><head><title>";
+  body += http2::get_status_string(status);
+  body += "</title></head><body><h1>";
+  body += http2::get_status_string(status);
+  body += "</h1><hr><address>";
+  body += NGHTTPD_SERVER;
+  body += " at port ";
+  body += util::utos(port);
+  body += "</address>";
+  body += "</body></html>";
+
+  char tempfn[] = "/tmp/nghttpd.temp.XXXXXX";
+  int fd = mkstemp(tempfn);
+  if (fd == -1) {
+    auto error = errno;
+    std::cerr << "Could not open status response body file: errno=" << error;
+    assert(0);
+  }
+  unlink(tempfn);
+  ssize_t nwrite;
+  while ((nwrite = write(fd, body.c_str(), body.size())) == -1 &&
+         errno == EINTR)
+    ;
+  if (nwrite == -1) {
+    auto error = errno;
+    std::cerr << "Could not write status response body into file: errno="
+              << error;
+    assert(0);
+  }
+
+  return FileEntry(util::utos(status), nwrite, 0, fd);
+}
+} // namespace
+
+// index into HttpServer::status_pages_
+enum {
+  IDX_200,
+  IDX_301,
+  IDX_304,
+  IDX_400,
+  IDX_404,
+};
+
+HttpServer::HttpServer(const Config *config) : config_(config) {
+  status_pages_ = std::vector<StatusPage>{
+      {"200", make_status_body(200, config_->port)},
+      {"301", make_status_body(301, config_->port)},
+      {"304", make_status_body(304, config_->port)},
+      {"400", make_status_body(400, config_->port)},
+      {"404", make_status_body(404, config_->port)},
+  };
+}
 
 namespace {
 int next_proto_cb(SSL *s, const unsigned char **data, unsigned int *len,
@@ -1497,14 +1565,14 @@ int verify_callback(int preverify_ok, X509_STORE_CTX *ctx) {
 } // namespace
 
 namespace {
-int start_listen(struct ev_loop *loop, Sessions *sessions,
+int start_listen(HttpServer *sv, struct ev_loop *loop, Sessions *sessions,
                  const Config *config) {
   addrinfo hints;
   int r;
   bool ok = false;
   const char *addr = nullptr;
 
-  auto acceptor = std::make_shared<AcceptHandler>(sessions, config);
+  auto acceptor = std::make_shared<AcceptHandler>(sv, sessions, config);
   auto service = util::utos(config->port);
 
   memset(&hints, 0, sizeof(addrinfo));
@@ -1699,8 +1767,8 @@ int HttpServer::run() {
 
   auto loop = EV_DEFAULT;
 
-  Sessions sessions(loop, config_, ssl_ctx);
+  Sessions sessions(this, loop, config_, ssl_ctx);
-  if (start_listen(loop, &sessions, config_) != 0) {
+  if (start_listen(this, loop, &sessions, config_) != 0) {
     std::cerr << "Could not listen" << std::endl;
     return -1;
   }
@@ -1711,4 +1779,22 @@ int HttpServer::run() {
 
 const Config *HttpServer::get_config() const { return config_; }
 
+const StatusPage *HttpServer::get_status_page(int status) const {
+  switch (status) {
+  case 200:
+    return &status_pages_[IDX_200];
+  case 301:
+    return &status_pages_[IDX_301];
+  case 304:
+    return &status_pages_[IDX_304];
+  case 400:
+    return &status_pages_[IDX_400];
+  case 404:
+    return &status_pages_[IDX_404];
+  default:
+    assert(0);
+  }
+  return nullptr;
+}
+
 } // namespace nghttp2

src/HttpServer.h

@@ -78,14 +78,27 @@ struct Config {
 
 class Http2Handler;
 
+struct FileEntry {
+  FileEntry(std::string path, int64_t length, int64_t mtime, int fd)
+      : path(std::move(path)), length(length), mtime(mtime), dlprev(nullptr),
+        dlnext(nullptr), fd(fd), usecount(1) {}
+  std::string path;
+  int64_t length;
+  int64_t mtime;
+  FileEntry *dlprev, *dlnext;
+  int fd;
+  int usecount;
+};
+
 struct Stream {
   Headers headers;
   Http2Handler *handler;
+  FileEntry *file_ent;
   ev_timer rtimer;
   ev_timer wtimer;
-  int64_t body_left;
+  int64_t body_length;
+  int64_t body_offset;
   int32_t stream_id;
-  int file;
   http2::HeaderIndex hdidx;
   Stream(Http2Handler *handler, int32_t stream_id);
   ~Stream();
@@ -160,14 +173,21 @@ private:
   int fd_;
 };
 
+struct StatusPage {
+  std::string status;
+  FileEntry file_ent;
+};
+
 class HttpServer {
 public:
   HttpServer(const Config *config);
   int listen();
   int run();
   const Config *get_config() const;
+  const StatusPage *get_status_page(int status) const;
 
 private:
+  std::vector<StatusPage> status_pages_;
   const Config *config_;
 };