Use in-class initialization for making it harder to forget to set a default.

[cubemap] / server.h

#ifndef _SERVER_H
#define _SERVER_H 1

#include <pthread.h>
#include <stddef.h>
#include <stdint.h>
#include <sys/epoll.h>
#include <sys/types.h>
#include <time.h>
#include <map>
#include <memory>
#include <queue>
#include <string>
#include <vector>

#include "tlse.h"

#include "client.h"
#include "stream.h"
#include "thread.h"

class Acceptor;
class ClientProto;
struct Stream;

#define EPOLL_MAX_EVENTS 8192
#define EPOLL_TIMEOUT_MS 20
#define MAX_CLIENT_REQUEST 16384
#define REQUEST_READ_TIMEOUT_SEC 60

class CubemapStateProto;
class StreamProto;

class Server : public Thread {
public:
        Server();
        ~Server();

        // Get the list of all currently connected clients.     
        std::vector<ClientStats> get_client_stats() const;

        // Set header (both HTTP header and any stream headers) for the given stream.
        void set_header(int stream_index,
                        const std::string &http_header,
                        const std::string &stream_header);

        // Set that the given stream should use the given max pacing rate from now on.
        // NOTE: This should be set before any clients are connected!
        void set_pacing_rate(int stream_index, uint32_t pacing_rate);

        // These will be deferred until the next time an iteration in do_work() happens,
        // and the order between them are undefined.
        // XXX: header should ideally be ordered with respect to data.
        void add_client_deferred(int sock, Acceptor *acceptor);
        void add_data_deferred(int stream_index, const char *data, size_t bytes, uint16_t metacube_flags);

        // These should not be called while running, since that would violate
        // threading assumptions (ie., that epoll is only called from one thread
        // at the same time).
        CubemapStateProto serialize();
        void add_client_from_serialized(const ClientProto &client);
        int add_stream(const std::string &url, size_t bytes_received, size_t prebuffering_bytes, Stream::Encoding encoding, Stream::Encoding src_encoding);
        int add_stream_from_serialized(const StreamProto &stream, int data_fd);
        int lookup_stream_by_url(const std::string &url) const;
        void set_backlog_size(int stream_index, size_t new_size);
        void set_prebuffering_bytes(int stream_index, size_t new_amount);
        void set_encoding(int stream_index, Stream::Encoding encoding);
        void set_src_encoding(int stream_index, Stream::Encoding encoding);
        void add_gen204(const std::string &url, const std::string &allow_origin);
        void create_tls_context_for_acceptor(const Acceptor *acceptor);

private:
        // Mutex protecting queued_add_clients.
        // Note that if you want to hold both this and <mutex> below,
        // you will need to take <mutex> before this one.
        mutable pthread_mutex_t queued_clients_mutex;

        // Deferred commands that should be run from the do_work() thread as soon as possible.
        // We defer these for two reasons:
        //
        //  - We only want to fiddle with epoll from one thread at any given time,
        //    and doing add_client() from the acceptor thread would violate that.
        //  - We don't want the input thread(s) hanging on <mutex> when doing
        //    add_data(), since they want to do add_data() rather often, and <mutex>
        //    can be taken a lot of the time.
        //      
        // Protected by <queued_clients_mutex>.
        std::vector<std::pair<int, Acceptor *>> queued_add_clients;

        // All variables below this line are protected by the mutex.
        mutable pthread_mutex_t mutex;

        // All streams.
        std::vector<std::unique_ptr<Stream>> streams;

        // Map from URL to index into <streams>.
        std::map<std::string, int> stream_url_map;

        // Map from URL to CORS Allow-Origin header (or empty string).
        std::map<std::string, std::string> ping_url_map;

        // Map from file descriptor to client.
        std::map<int, Client> clients;

        // A list of all clients, ordered by the time they connected (first element),
        // and their file descriptor (second element). It is ordered by connection time
        // (and thus also by read timeout time) so that we can read clients from the
        // start and stop processing once we get to one that isn't ready to be
        // timed out yet (which means we only have to look at each client exactly once,
        // save for the first element of the queue, which is always checked).
        //
        // Note that when we delete a client, we don't update this queue.
        // This means that when reading it, we need to check if the client it
        // describes is still exists (ie., that the fd still exists, and that
        // the timespec matches).
        std::queue<std::pair<timespec, int>> clients_ordered_by_connect_time;

        // Used for epoll implementation (obviously).
        int epoll_fd;
        epoll_event events[EPOLL_MAX_EVENTS];

        // For each TLS-enabled acceptor, our private server context for its key pair.
        std::map<const Acceptor *, TLSContext *> tls_server_contexts;

        // The actual worker thread.
        virtual void do_work();

        // Process a client; read and write data as far as we can.
        // After this call, one of these four is true:
        //
        //  1. The socket is closed, and the client deleted.
        //  2. We are still waiting for more data from the client.
        //  3. We've sent all the data we have to the client,
        //     and put it in <sleeping_clients>.
        //  4. The socket buffer is full (which means we still have
        //     data outstanding).
        //
        // For #2, we listen for EPOLLIN events. For #3 and #4, we listen
        // for EPOLLOUT in edge-triggered mode; it will never fire for #3,
        // but it's cheaper than taking it in and out all the time.
        void process_client(Client *client);

        // If the TLS library wants to write anything to this client,
        // output it. Returns true if the processing should go to sleep
        // (an error, or lack of outgoing buffer space).
        bool send_pending_tls_data(Client *client);

        // Reads regular data fro ma socket. Returns -1 if the processing
        // should go to sleep (an error, or no data available yet), otherwise
        // the number of bytes read.
        int read_nontls_data(Client *client, char *buf, size_t max_size);

        // Reads (decrypted) data from a TLS socket. Returns -1 if the processing
        // should go to sleep (an error, or no data available yet), otherwise
        // the number of bytes read. The buffer will be used as scratch space
        // for TLS data, so it can be overwritten by more bytes than what is returned.
        int read_tls_data(Client *client, char *buf, size_t max_size);

        // Close a given client socket, and clean up after it.
        void close_client(Client *client);

        // Listen for a different set of epoll events.
        void change_epoll_events(Client *client, uint32_t events);

        // Parse the HTTP request. Returns a HTTP status code (200/204/400/404).
        int parse_request(Client *client);

        // Construct the HTTP header, and set the client into
        // the SENDING_HEADER state.
        void construct_header(Client *client);

        // Construct a generic error with the given line, and set the client into
        // the SENDING_SHORT_RESPONSE state.
        void construct_error(Client *client, int error_code);

        // Construct a 204, and set the client into the SENDING_SHORT_RESPONSE state.
        void construct_204(Client *client);

        void process_queued_data();
        void skip_lost_data(Client *client);

        void add_client(int sock, Acceptor *acceptor);
};

#endif  // !defined(_SERVER_H)