4 // Representation of a single, muxed (we only really care about bytes/blocks) stream.
5 // Fed by Input, sent out by Server (to Client).
17 enum StreamStartSuitability {
18 NOT_SUITABLE_FOR_STREAM_START,
19 SUITABLE_FOR_STREAM_START,
23 // Must be in sync with StreamConfig::Encoding.
24 enum Encoding { STREAM_ENCODING_RAW = 0, STREAM_ENCODING_METACUBE };
26 Stream(const std::string &stream_id, size_t backlog_size, size_t prebuffering_bytes, Encoding encoding);
29 // Serialization/deserialization.
30 Stream(const StreamProto &serialized, int data_fd);
31 StreamProto serialize();
33 // Changes the backlog size, restructuring the data as needed.
34 void set_backlog_size(size_t new_size);
36 // Mutex protecting <queued_data> and <queued_data_last_starting_point>.
37 // Note that if you want to hold both this and the owning server's
38 // <mutex> you will need to take <mutex> before this one.
39 mutable pthread_mutex_t queued_data_mutex;
43 // The HTTP response header, without the trailing double newline.
44 std::string http_header;
46 // The video stream header (if any).
47 std::string stream_header;
49 // What encoding we apply to the outgoing data (usually raw, but can also
50 // be Metacube, for reflecting to another Cubemap instance).
53 // The stream data itself, stored in a circular buffer.
55 // We store our data in a file, so that we can send the data to the
56 // kernel only once (with write()). We then use sendfile() for each
57 // client, which effectively zero-copies it out of the kernel's buffer
58 // cache. This is significantly more efficient than doing write() from
59 // a userspace memory buffer, since the latter makes the kernel copy
60 // the same data from userspace many times.
63 // How many bytes <data_fd> can hold (the buffer size).
66 // How many bytes we need to have in the backlog before we start
67 // sending (in practice, we will then send all of them at once,
68 // and then start sending at the normal rate thereafter).
69 // This is basically to force a buffer on the client, which can help
70 // if the client expects us to be able to fill up the buffer much
71 // faster than realtime (ie., it expects a static file).
72 size_t prebuffering_bytes;
74 // How many bytes this stream have received. Can very well be larger
75 // than <backlog_size>, since the buffer wraps.
76 size_t bytes_received;
78 // The last point in the stream that is suitable to start new clients at
79 // (after having sent the header). -1 if no such point exists yet.
80 ssize_t last_suitable_starting_point;
82 // Clients that are in SENDING_DATA, but that we don't listen on,
83 // because we currently don't have any data for them.
84 // See put_client_to_sleep() and wake_up_all_clients().
85 std::vector<Client *> sleeping_clients;
87 // Clients that we recently got data for (when they were in
88 // <sleeping_clients>).
89 std::vector<Client *> to_process;
91 // Maximum pacing rate for the stream.
94 // Queued data, if any. Protected by <queued_data_mutex>.
95 // The data pointers in the iovec are owned by us.
96 std::vector<iovec> queued_data;
98 // Index of the last element in queued_data that is suitable to start streaming at.
99 // -1 if none. Protected by <queued_data_mutex>.
100 int queued_data_last_starting_point;
102 // Put client to sleep, since there is no more data for it; we will on
103 // longer listen on POLLOUT until we get more data. Also, it will be put
104 // in the list of clients to wake up when we do.
105 void put_client_to_sleep(Client *client);
107 // Add more data to <queued_data>, adding Metacube headers if needed.
108 // Does not take ownership of <data>.
109 void add_data_deferred(const char *data, size_t bytes, StreamStartSuitability suitable_for_stream_start);
111 // Add queued data to the stream, if any.
112 // You should hold the owning Server's <mutex>.
113 void process_queued_data();
116 Stream(const Stream& other);
118 // Adds data directly to the stream file descriptor, without adding headers or
119 // going through <queued_data>.
120 // You should hold the owning Server's <mutex>.
121 void add_data_raw(const std::vector<iovec> &data);
124 #endif // !defined(_STREAM_H)