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, Encoding src_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 // What encoding we expect the incoming data to be in (usually Metacube).
55 Encoding src_encoding;
57 // The stream data itself, stored in a circular buffer.
59 // We store our data in a file, so that we can send the data to the
60 // kernel only once (with write()). We then use sendfile() for each
61 // client, which effectively zero-copies it out of the kernel's buffer
62 // cache. This is significantly more efficient than doing write() from
63 // a userspace memory buffer, since the latter makes the kernel copy
64 // the same data from userspace many times.
67 // How many bytes <data_fd> can hold (the buffer size).
70 // How many bytes we need to have in the backlog before we start
71 // sending (in practice, we will then send all of them at once,
72 // and then start sending at the normal rate thereafter).
73 // This is basically to force a buffer on the client, which can help
74 // if the client expects us to be able to fill up the buffer much
75 // faster than realtime (ie., it expects a static file).
76 size_t prebuffering_bytes;
78 // How many bytes this stream have received. Can very well be larger
79 // than <backlog_size>, since the buffer wraps.
80 size_t bytes_received;
82 // A list of points in the stream that is suitable to start new clients at
83 // (after having sent the header). Empty if no such point exists yet.
84 std::deque<size_t> suitable_starting_points;
86 // Clients that are in SENDING_DATA, but that we don't listen on,
87 // because we currently don't have any data for them.
88 // See put_client_to_sleep() and wake_up_all_clients().
89 std::vector<Client *> sleeping_clients;
91 // Clients that we recently got data for (when they were in
92 // <sleeping_clients>).
93 std::vector<Client *> to_process;
95 // Maximum pacing rate for the stream.
98 // Queued data, if any. Protected by <queued_data_mutex>.
99 // The data pointers in the iovec are owned by us.
102 StreamStartSuitability suitable_for_stream_start;
104 std::vector<DataElement> queued_data;
106 // Put client to sleep, since there is no more data for it; we will on
107 // longer listen on POLLOUT until we get more data. Also, it will be put
108 // in the list of clients to wake up when we do.
109 void put_client_to_sleep(Client *client);
111 // Add more data to <queued_data>, adding Metacube headers if needed.
112 // Does not take ownership of <data>.
113 void add_data_deferred(const char *data, size_t bytes, StreamStartSuitability suitable_for_stream_start);
115 // Add queued data to the stream, if any.
116 // You should hold the owning Server's <mutex>.
117 void process_queued_data();
120 Stream(const Stream& other);
122 // Adds data directly to the stream file descriptor, without adding headers or
123 // going through <queued_data>.
124 // You should hold the owning Server's <mutex>, and probably call
125 // remove_obsolete_starting_points() afterwards.
126 void add_data_raw(const std::vector<DataElement> &data);
128 // Remove points from <suitable_starting_points> that are no longer
130 // You should hold the owning Server's <mutex>.
131 void remove_obsolete_starting_points();
134 #endif // !defined(_STREAM_H)