Some fixes to issues that could cause client hangs.
[cubemap] / server.cpp
index 5f155c0a699a7723fc0aac09083de1df2eb78aee..54e6b5e804d9959632b1ef70df6a53fee7f52fac 100644 (file)
@@ -18,6 +18,7 @@
 #include "metacube.h"
 #include "server.h"
 #include "mutexlock.h"
+#include "parse.h"
 #include "state.pb.h"
 
 using namespace std;
@@ -25,19 +26,21 @@ using namespace std;
 Client::Client(int sock)
        : sock(sock),
          state(Client::READING_REQUEST),
-         header_bytes_sent(0),
+         stream(NULL),
+         header_or_error_bytes_sent(0),
          bytes_sent(0)
 {
        request.reserve(1024);
 }
        
-Client::Client(const ClientProto &serialized)
+Client::Client(const ClientProto &serialized, Stream *stream)
        : sock(serialized.sock()),
          state(State(serialized.state())),
          request(serialized.request()),
          stream_id(serialized.stream_id()),
-         header(serialized.header()),
-         header_bytes_sent(serialized.header_bytes_sent()),
+         stream(stream),
+         header_or_error(serialized.header_or_error()),
+         header_or_error_bytes_sent(serialized.header_or_error_bytes_sent()),
          bytes_sent(serialized.bytes_sent())
 {
 }
@@ -49,8 +52,8 @@ ClientProto Client::serialize() const
        serialized.set_state(state);
        serialized.set_request(request);
        serialized.set_stream_id(stream_id);
-       serialized.set_header(header);
-       serialized.set_header_bytes_sent(serialized.header_bytes_sent());
+       serialized.set_header_or_error(header_or_error);
+       serialized.set_header_or_error_bytes_sent(serialized.header_or_error_bytes_sent());
        serialized.set_bytes_sent(bytes_sent);
        return serialized;
 }
@@ -101,7 +104,14 @@ Server::Server()
 
 Server::~Server()
 {
-       close(epoll_fd);
+       int ret;
+       do {
+               ret = close(epoll_fd);
+       } while (ret == -1 && errno == EINTR);
+
+       if (ret == -1) {
+               perror("close(epoll_fd)");
+       }
 }
 
 void Server::run()
@@ -139,6 +149,9 @@ void Server::do_work()
 {
        for ( ;; ) {
                int nfds = epoll_wait(epoll_fd, events, EPOLL_MAX_EVENTS, EPOLL_TIMEOUT_MS);
+               if (nfds == -1 && errno == EINTR) {
+                       continue;
+               }
                if (nfds == -1) {
                        perror("epoll_wait");
                        exit(1);
@@ -200,16 +213,17 @@ void Server::add_client(int sock)
 void Server::add_client_from_serialized(const ClientProto &client)
 {
        MutexLock lock(&mutex);
-       clients.insert(make_pair(client.sock(), Client(client)));
+       Stream *stream = find_stream(client.stream_id());
+       clients.insert(make_pair(client.sock(), Client(client, stream)));
 
        // Start listening on data from this socket.
        epoll_event ev;
        if (client.state() == Client::READING_REQUEST) {
-               ev.events = EPOLLIN | EPOLLRDHUP;
+               ev.events = EPOLLIN | EPOLLET | EPOLLRDHUP;
        } else {
                // If we don't have more data for this client, we'll be putting it into
                // the sleeping array again soon.
-               ev.events = EPOLLOUT | EPOLLRDHUP;
+               ev.events = EPOLLOUT | EPOLLET | EPOLLRDHUP;
        }
        ev.data.u64 = 0;  // Keep Valgrind happy.
        ev.data.fd = client.sock();
@@ -217,6 +231,8 @@ void Server::add_client_from_serialized(const ClientProto &client)
                perror("epoll_ctl(EPOLL_CTL_ADD)");
                exit(1);
        }
+
+       process_client(&clients[client.sock()]);
 }
 
 void Server::add_stream(const string &stream_id)
@@ -271,23 +287,32 @@ void Server::add_data(const string &stream_id, const char *data, size_t bytes)
        memcpy(stream->data + pos, data, bytes);
        wake_up_all_clients();
 }
-       
+
+// See the .h file for postconditions after this function.     
 void Server::process_client(Client *client)
 {
        switch (client->state) {
        case Client::READING_REQUEST: {
+read_request_again:
                // Try to read more of the request.
                char buf[1024];
-               int ret = read(client->sock, buf, sizeof(buf));
+               int ret;
+               do {
+                       ret = read(client->sock, buf, sizeof(buf));
+               } while (ret == -1 && errno == EINTR);
+
+               if (ret == -1 && errno == EAGAIN) {
+                       // No more data right now. Nothing to do.
+                       // This is postcondition #2.
+                       return;
+               }
                if (ret == -1) {
                        perror("read");
                        close_client(client);
                        return;
                }
                if (ret == 0) {
-                       // No data? This really means that we were triggered for something else than
-                       // POLLIN (which suggests a logic error in epoll).
-                       fprintf(stderr, "WARNING: fd %d returned unexpectedly 0 bytes!\n", client->sock);
+                       // OK, the socket is closed.
                        close_client(client);
                        return;
                }
@@ -310,7 +335,8 @@ void Server::process_client(Client *client)
                               "\r\n\r\n", 4));
                if (ptr == NULL) {
                        // OK, we don't have the entire header yet. Fine; we'll get it later.
-                       return;
+                       // See if there's more data for us.
+                       goto read_request_again;
                }
 
                if (ptr != client->request.data() + client->request.size() - 4) {
@@ -319,47 +345,78 @@ void Server::process_client(Client *client)
                        return;
                }
 
-               parse_request(client);
-               construct_header(client);
-               break;
+               int error_code = parse_request(client);
+               if (error_code == 200) {
+                       construct_header(client);
+               } else {
+                       construct_error(client, error_code);
+               }
+
+               // We've changed states, so fall through.
+               assert(client->state == Client::SENDING_ERROR ||
+                      client->state == Client::SENDING_HEADER);
        }
+       case Client::SENDING_ERROR:
        case Client::SENDING_HEADER: {
-               int ret = write(client->sock,
-                               client->header.data() + client->header_bytes_sent,
-                               client->header.size() - client->header_bytes_sent);
+sending_header_or_error_again:
+               int ret;
+               do {
+                       ret = write(client->sock,
+                                   client->header_or_error.data() + client->header_or_error_bytes_sent,
+                                   client->header_or_error.size() - client->header_or_error_bytes_sent);
+               } while (ret == -1 && errno == EINTR);
+
+               if (ret == -1 && errno == EAGAIN) {
+                       // We're out of socket space, so now we're at the “low edge” of epoll's
+                       // edge triggering. epoll will tell us when there is more room, so for now,
+                       // just return.
+                       // This is postcondition #4.
+                       return;
+               }
+
                if (ret == -1) {
+                       // Error! Postcondition #1.
                        perror("write");
                        close_client(client);
                        return;
                }
                
-               client->header_bytes_sent += ret;
-               assert(client->header_bytes_sent <= client->header.size());
+               client->header_or_error_bytes_sent += ret;
+               assert(client->header_or_error_bytes_sent <= client->header_or_error.size());
 
-               if (client->header_bytes_sent < client->header.size()) {
-                       // We haven't sent all yet. Fine; we'll do that later.
-                       return;
+               if (client->header_or_error_bytes_sent < client->header_or_error.size()) {
+                       // We haven't sent all yet. Fine; go another round.
+                       goto sending_header_or_error_again;
                }
 
-               // We're done sending the header! Clear the entire header to release some memory.
-               client->header.clear();
+               // We're done sending the header or error! Clear it to release some memory.
+               client->header_or_error.clear();
+
+               if (client->state == Client::SENDING_ERROR) {
+                       // We're done sending the error, so now close.  
+                       // This is postcondition #1.
+                       close_client(client);
+                       return;
+               }
 
                // Start sending from the end. In other words, we won't send any of the backlog,
                // but we'll start sending immediately as we get data.
+               // This is postcondition #3.
                client->state = Client::SENDING_DATA;
-               client->bytes_sent = find_stream(client->stream_id)->data_size;
-               break;
+               client->bytes_sent = client->stream->data_size;
+               sleeping_clients.push_back(client);
+               return;
        }
        case Client::SENDING_DATA: {
                // See if there's some data we've lost. Ideally, we should drop to a block boundary,
                // but resync will be the mux's problem.
-               const Stream &stream = *find_stream(client->stream_id);
-               size_t bytes_to_send = stream.data_size - client->bytes_sent;
+               const Stream *stream = client->stream;
+               size_t bytes_to_send = stream->data_size - client->bytes_sent;
                if (bytes_to_send > BACKLOG_SIZE) {
                        fprintf(stderr, "WARNING: fd %d lost %lld bytes, maybe too slow connection\n",
                                client->sock,
                                (long long int)(bytes_to_send - BACKLOG_SIZE));
-                       client->bytes_sent = find_stream(client->stream_id)->data_size - BACKLOG_SIZE;
+                       client->bytes_sent = stream->data_size - BACKLOG_SIZE;
                        bytes_to_send = BACKLOG_SIZE;
                }
 
@@ -369,28 +426,43 @@ void Server::process_client(Client *client)
                        size_t bytes_first_part = BACKLOG_SIZE - (client->bytes_sent % BACKLOG_SIZE);
 
                        iovec iov[2];
-                       iov[0].iov_base = const_cast<char *>(stream.data + (client->bytes_sent % BACKLOG_SIZE));
+                       iov[0].iov_base = const_cast<char *>(stream->data + (client->bytes_sent % BACKLOG_SIZE));
                        iov[0].iov_len = bytes_first_part;
 
-                       iov[1].iov_base = const_cast<char *>(stream.data);
+                       iov[1].iov_base = const_cast<char *>(stream->data);
                        iov[1].iov_len = bytes_to_send - bytes_first_part;
 
-                       ret = writev(client->sock, iov, 2);
+                       do {
+                               ret = writev(client->sock, iov, 2);
+                       } while (ret == -1 && errno == EINTR);
                } else {
-                       ret = write(client->sock,
-                                   stream.data + (client->bytes_sent % BACKLOG_SIZE),
-                                   bytes_to_send);
+                       do {
+                               ret = write(client->sock,
+                                           stream->data + (client->bytes_sent % BACKLOG_SIZE),
+                                           bytes_to_send);
+                       } while (ret == -1 && errno == EINTR);
+               }
+               if (ret == -1 && errno == EAGAIN) {
+                       // We're out of socket space, so return; epoll will wake us up
+                       // when there is more room.
+                       // This is postcondition #4.
+                       return;
                }
                if (ret == -1) {
+                       // Error, close; postcondition #1.
                        perror("write/writev");
                        close_client(client);
                        return;
                }
                client->bytes_sent += ret;
 
-               if (client->bytes_sent == stream.data_size) {
+               if (client->bytes_sent == stream->data_size) {
                        // We don't have any more data for this client, so put it to sleep.
+                       // This is postcondition #3.
                        put_client_to_sleep(client);
+               } else {
+                       // XXX: Do we need to go another round here to explicitly
+                       // get the EAGAIN?
                }
                break;
        }
@@ -399,23 +471,62 @@ void Server::process_client(Client *client)
        }
 }
 
-void Server::parse_request(Client *client)
+int Server::parse_request(Client *client)
 {
-       // TODO: Actually parse the request. :-)
-       client->stream_id = "stream";
+       vector<string> lines = split_lines(client->request);
+       if (lines.empty()) {
+               return 400;  // Bad request (empty).
+       }
+
+       vector<string> request_tokens = split_tokens(lines[0]);
+       if (request_tokens.size() < 2) {
+               return 400;  // Bad request (empty).
+       }
+       if (request_tokens[0] != "GET") {
+               return 400;  // Should maybe be 405 instead?
+       }
+       if (streams.count(request_tokens[1]) == 0) {
+               return 404;  // Not found.
+       }
+
+       client->stream_id = request_tokens[1];
+       client->stream = find_stream(client->stream_id);
        client->request.clear();
+
+       return 200;  // OK!
 }
 
 void Server::construct_header(Client *client)
 {
-       client->header = "HTTP/1.0 200 OK\r\nContent-type: video/x-flv\r\nCache-Control: no-cache\r\n\r\n" +
+       client->header_or_error = "HTTP/1.0 200 OK\r\nContent-type: video/x-flv\r\nCache-Control: no-cache\r\n\r\n" +
                find_stream(client->stream_id)->header;
 
        // Switch states.
        client->state = Client::SENDING_HEADER;
 
        epoll_event ev;
-       ev.events = EPOLLOUT | EPOLLRDHUP;
+       ev.events = EPOLLOUT | EPOLLET | EPOLLRDHUP;
+       ev.data.u64 = 0;  // Keep Valgrind happy.
+       ev.data.fd = client->sock;
+
+       if (epoll_ctl(epoll_fd, EPOLL_CTL_MOD, client->sock, &ev) == -1) {
+               perror("epoll_ctl(EPOLL_CTL_MOD)");
+               exit(1);
+       }
+}
+       
+void Server::construct_error(Client *client, int error_code)
+{
+       char error[256];
+       snprintf(error, 256, "HTTP/1.0 %d Error\r\nContent-type: text/plain\r\n\r\nSomething went wrong. Sorry.\r\n",
+               error_code);
+       client->header_or_error = error;
+
+       // Switch states.
+       client->state = Client::SENDING_ERROR;
+
+       epoll_event ev;
+       ev.events = EPOLLOUT | EPOLLET | EPOLLRDHUP;
        ev.data.u64 = 0;  // Keep Valgrind happy.
        ev.data.fd = client->sock;
 
@@ -433,43 +544,35 @@ void Server::close_client(Client *client)
        }
 
        // This client could be sleeping, so we'll need to fix that. (Argh, O(n).)
-       vector<int>::iterator new_end =
-               remove(sleeping_clients.begin(), sleeping_clients.end(), client->sock);
+       vector<Client *>::iterator new_end =
+               remove(sleeping_clients.begin(), sleeping_clients.end(), client);
        sleeping_clients.erase(new_end, sleeping_clients.end());
        
        // Bye-bye!
-       close(client->sock);
+       int ret;
+       do {
+               ret = close(client->sock);
+       } while (ret == -1 && errno == EINTR);
+
+       if (ret == -1) {
+               perror("close");
+       }
+
        clients.erase(client->sock);
 }
        
 void Server::put_client_to_sleep(Client *client)
 {
-       epoll_event ev;
-       ev.events = EPOLLRDHUP;
-       ev.data.u64 = 0;  // Keep Valgrind happy.
-       ev.data.fd = client->sock;
-
-       if (epoll_ctl(epoll_fd, EPOLL_CTL_MOD, client->sock, &ev) == -1) {
-               perror("epoll_ctl(EPOLL_CTL_MOD)");
-               exit(1);
-       }
-
-       sleeping_clients.push_back(client->sock);
+       sleeping_clients.push_back(client);
 }
 
 void Server::wake_up_all_clients()
 {
-       for (unsigned i = 0; i < sleeping_clients.size(); ++i) {
-               epoll_event ev;
-               ev.events = EPOLLOUT | EPOLLRDHUP;
-               ev.data.u64 = 0;  // Keep Valgrind happy.
-               ev.data.fd = sleeping_clients[i];
-               if (epoll_ctl(epoll_fd, EPOLL_CTL_MOD, sleeping_clients[i], &ev) == -1) {
-                       perror("epoll_ctl(EPOLL_CTL_MOD)");
-                       exit(1);
-               }
+       vector<Client *> to_process;
+       swap(sleeping_clients, to_process);
+       for (unsigned i = 0; i < to_process.size(); ++i) {
+               process_client(to_process[i]);
        }
-       sleeping_clients.clear();
 }
        
 Stream *Server::find_stream(const string &stream_id)