From 2fbbdf3c4a4ffd2d90c102a37c7a02b5b6f80216 Mon Sep 17 00:00:00 2001 From: "Steinar H. Gunderson" Date: Thu, 23 Jul 2015 17:48:06 +0200 Subject: [PATCH] Store multiple suitable starting points for each stream. We still only use the last one. This will change soon. --- server.cpp | 5 +++-- state.proto | 2 +- stream.cpp | 48 +++++++++++++++++++++++++++++++++++++++++------- stream.h | 15 +++++++++++---- 4 files changed, 56 insertions(+), 14 deletions(-) diff --git a/server.cpp b/server.cpp index 7116a73..946dc5d 100644 --- a/server.cpp +++ b/server.cpp @@ -479,14 +479,15 @@ sending_header_or_error_again: } case Client::WAITING_FOR_KEYFRAME: { Stream *stream = client->stream; - if (ssize_t(client->stream_pos) > stream->last_suitable_starting_point) { + if (stream->suitable_starting_points.empty() || + client->stream_pos > stream->suitable_starting_points.back()) { // We haven't received a keyframe since this stream started waiting, // so keep on waiting for one. // This is postcondition #3. stream->put_client_to_sleep(client); return; } - client->stream_pos = stream->last_suitable_starting_point; + client->stream_pos = stream->suitable_starting_points.back(); client->state = Client::PREBUFFERING; // Fall through. } diff --git a/state.proto b/state.proto index 3a61108..9422540 100644 --- a/state.proto +++ b/state.proto @@ -26,7 +26,7 @@ message StreamProto { optional int64 backlog_size = 5 [default=10485760]; optional int64 prebuffering_bytes = 10 [default=0]; optional int64 bytes_received = 3; - optional int64 last_suitable_starting_point = 9; + repeated int64 suitable_starting_point = 9; optional string url = 4; }; diff --git a/stream.cpp b/stream.cpp index 50679ca..d416803 100644 --- a/stream.cpp +++ b/stream.cpp @@ -8,6 +8,7 @@ #include #include #include +#include #include #include "log.h" @@ -26,7 +27,6 @@ Stream::Stream(const string &url, size_t backlog_size, size_t prebuffering_bytes backlog_size(backlog_size), prebuffering_bytes(prebuffering_bytes), bytes_received(0), - last_suitable_starting_point(-1), pacing_rate(~0U) { if (data_fd == -1) { @@ -58,8 +58,16 @@ Stream::Stream(const StreamProto &serialized, int data_fd) exit(1); } - assert(serialized.has_last_suitable_starting_point()); - last_suitable_starting_point = serialized.last_suitable_starting_point(); + for (int i = 0; i < serialized.suitable_starting_point_size(); ++i) { + ssize_t point = serialized.suitable_starting_point(i); + if (point == -1) { + // Can happen when upgrading from before 1.1.3, + // where this was an optional field with -1 signifying + // "no such point". + continue; + } + suitable_starting_points.push_back(point); + } pthread_mutex_init(&queued_data_mutex, NULL); } @@ -73,7 +81,9 @@ StreamProto Stream::serialize() serialized.set_backlog_size(backlog_size); serialized.set_prebuffering_bytes(prebuffering_bytes); serialized.set_bytes_received(bytes_received); - serialized.set_last_suitable_starting_point(last_suitable_starting_point); + for (size_t i = 0; i < suitable_starting_points.size(); ++i) { + serialized.add_suitable_starting_point(suitable_starting_points[i]); + } serialized.set_url(url); data_fd = -1; return serialized; @@ -122,6 +132,7 @@ void Stream::set_backlog_size(size_t new_size) vector data_elements; data_elements.push_back(data_element); add_data_raw(data_elements); + remove_obsolete_starting_points(); } void Stream::put_client_to_sleep(Client *client) @@ -202,6 +213,16 @@ void Stream::add_data_raw(const vector &orig_data) } } +void Stream::remove_obsolete_starting_points() +{ + // We could do a binary search here (std::lower_bound), but it seems + // overkill for removing what's probably only a few points. + while (!suitable_starting_points.empty() && + bytes_received - suitable_starting_points[0] > backlog_size) { + suitable_starting_points.pop_front(); + } +} + void Stream::add_data_deferred(const char *data, size_t bytes, StreamStartSuitability suitable_for_stream_start) { MutexLock lock(&queued_data_mutex); @@ -256,17 +277,30 @@ void Stream::process_queued_data() swap(queued_data, queued_data_copy); } - // Update the last suitable starting point for the stream, - // if the queued data contains such a starting point. + // Add suitable starting points for the stream, if the queued data + // contains such starting points. Note that we drop starting points + // if they're less than 10 kB apart, so that we don't get a huge + // amount of them for e.g. each and every MPEG-TS 188-byte cell. + // The 10 kB value is somewhat arbitrary, but at least it should make + // the RAM cost of saving the position ~0.1% (or less) of the actual + // data, and 10 kB is a very fine granularity in most streams. + static const int minimum_start_point_distance = 10240; size_t byte_position = bytes_received; for (size_t i = 0; i < queued_data_copy.size(); ++i) { if (queued_data_copy[i].suitable_for_stream_start == SUITABLE_FOR_STREAM_START) { - last_suitable_starting_point = byte_position; + size_t num_points = suitable_starting_points.size(); + if (num_points >= 2 && + suitable_starting_points[num_points - 1] - suitable_starting_points[num_points - 2] < minimum_start_point_distance) { + // p[n-1] - p[n-2] < 10 kB, so drop p[n-1]. + suitable_starting_points.pop_back(); + } + suitable_starting_points.push_back(byte_position); } byte_position += queued_data_copy[i].data.iov_len; } add_data_raw(queued_data_copy); + remove_obsolete_starting_points(); for (size_t i = 0; i < queued_data_copy.size(); ++i) { char *data = reinterpret_cast(queued_data_copy[i].data.iov_base); delete[] data; diff --git a/stream.h b/stream.h index 9a9982a..c98feb4 100644 --- a/stream.h +++ b/stream.h @@ -8,6 +8,7 @@ #include #include #include +#include #include #include @@ -75,9 +76,9 @@ struct Stream { // than , since the buffer wraps. size_t bytes_received; - // The last point in the stream that is suitable to start new clients at - // (after having sent the header). -1 if no such point exists yet. - ssize_t last_suitable_starting_point; + // A list of points in the stream that is suitable to start new clients at + // (after having sent the header). Empty if no such point exists yet. + std::deque suitable_starting_points; // Clients that are in SENDING_DATA, but that we don't listen on, // because we currently don't have any data for them. @@ -117,8 +118,14 @@ private: // Adds data directly to the stream file descriptor, without adding headers or // going through . - // You should hold the owning Server's . + // You should hold the owning Server's , and probably call + // remove_obsolete_starting_points() afterwards. void add_data_raw(const std::vector &data); + + // Remove points from that are no longer + // in the backlog. + // You should hold the owning Server's . + void remove_obsolete_starting_points(); }; #endif // !defined(_STREAM_H) -- 2.39.2