4 // Representation of a single, muxed (we only really care about bytes/blocks) stream.
5 // Fed by Input, sent out by Server (to Client).
18 enum StreamStartSuitability {
19 NOT_SUITABLE_FOR_STREAM_START,
20 SUITABLE_FOR_STREAM_START,
24 // Must be in sync with StreamConfig::Encoding.
25 enum Encoding { STREAM_ENCODING_RAW = 0, STREAM_ENCODING_METACUBE };
27 Stream(const std::string &stream_id, size_t backlog_size, size_t prebuffering_bytes, Encoding encoding);
30 // Serialization/deserialization.
31 Stream(const StreamProto &serialized, int data_fd);
32 StreamProto serialize();
34 // Changes the backlog size, restructuring the data as needed.
35 void set_backlog_size(size_t new_size);
37 // Mutex protecting <queued_data> and <queued_data_last_starting_point>.
38 // Note that if you want to hold both this and the owning server's
39 // <mutex> you will need to take <mutex> before this one.
40 mutable pthread_mutex_t queued_data_mutex;
44 // The HTTP response header, without the trailing double newline.
45 std::string http_header;
47 // The video stream header (if any).
48 std::string stream_header;
50 // What encoding we apply to the outgoing data (usually raw, but can also
51 // be Metacube, for reflecting to another Cubemap instance).
54 // The stream data itself, stored in a circular buffer.
56 // We store our data in a file, so that we can send the data to the
57 // kernel only once (with write()). We then use sendfile() for each
58 // client, which effectively zero-copies it out of the kernel's buffer
59 // cache. This is significantly more efficient than doing write() from
60 // a userspace memory buffer, since the latter makes the kernel copy
61 // the same data from userspace many times.
64 // How many bytes <data_fd> can hold (the buffer size).
67 // How many bytes we need to have in the backlog before we start
68 // sending (in practice, we will then send all of them at once,
69 // and then start sending at the normal rate thereafter).
70 // This is basically to force a buffer on the client, which can help
71 // if the client expects us to be able to fill up the buffer much
72 // faster than realtime (ie., it expects a static file).
73 size_t prebuffering_bytes;
75 // How many bytes this stream have received. Can very well be larger
76 // than <backlog_size>, since the buffer wraps.
77 size_t bytes_received;
79 // A list of points in the stream that is suitable to start new clients at
80 // (after having sent the header). Empty if no such point exists yet.
81 std::deque<size_t> suitable_starting_points;
83 // Clients that are in SENDING_DATA, but that we don't listen on,
84 // because we currently don't have any data for them.
85 // See put_client_to_sleep() and wake_up_all_clients().
86 std::vector<Client *> sleeping_clients;
88 // Clients that we recently got data for (when they were in
89 // <sleeping_clients>).
90 std::vector<Client *> to_process;
92 // Maximum pacing rate for the stream.
95 // Queued data, if any. Protected by <queued_data_mutex>.
96 // The data pointers in the iovec are owned by us.
99 StreamStartSuitability suitable_for_stream_start;
101 std::vector<DataElement> queued_data;
103 // Put client to sleep, since there is no more data for it; we will on
104 // longer listen on POLLOUT until we get more data. Also, it will be put
105 // in the list of clients to wake up when we do.
106 void put_client_to_sleep(Client *client);
108 // Add more data to <queued_data>, adding Metacube headers if needed.
109 // Does not take ownership of <data>.
110 void add_data_deferred(const char *data, size_t bytes, StreamStartSuitability suitable_for_stream_start);
112 // Add queued data to the stream, if any.
113 // You should hold the owning Server's <mutex>.
114 void process_queued_data();
117 Stream(const Stream& other);
119 // Adds data directly to the stream file descriptor, without adding headers or
120 // going through <queued_data>.
121 // You should hold the owning Server's <mutex>, and probably call
122 // remove_obsolete_starting_points() afterwards.
123 void add_data_raw(const std::vector<DataElement> &data);
125 // Remove points from <suitable_starting_points> that are no longer
127 // You should hold the owning Server's <mutex>.
128 void remove_obsolete_starting_points();
131 #endif // !defined(_STREAM_H)