#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/epoll.h>
+#include <sys/sendfile.h>
#include <time.h>
#include <signal.h>
#include <errno.h>
#include "server.h"
#include "mutexlock.h"
#include "parse.h"
+#include "util.h"
#include "state.pb.h"
using namespace std;
Stream::Stream(const string &stream_id)
: stream_id(stream_id),
- data(new char[BACKLOG_SIZE]),
+ data_fd(make_tempfile("")),
data_size(0),
mark_pool(NULL)
{
- memset(data, 0, BACKLOG_SIZE);
+ if (data_fd == -1) {
+ exit(1);
+ }
}
Stream::~Stream()
{
- delete[] data;
+ if (data_fd != -1) {
+ int ret;
+ do {
+ ret = close(data_fd);
+ } while (ret == -1 && errno == EINTR);
+ if (ret == -1) {
+ perror("close");
+ }
+ }
}
Stream::Stream(const StreamProto &serialized)
: stream_id(serialized.stream_id()),
header(serialized.header()),
- data(new char[BACKLOG_SIZE]),
+ data_fd(make_tempfile(serialized.data())),
data_size(serialized.data_size()),
mark_pool(NULL)
{
- assert(serialized.data().size() == BACKLOG_SIZE);
- memcpy(data, serialized.data().data(), BACKLOG_SIZE);
+ if (data_fd == -1) {
+ exit(1);
+ }
}
-StreamProto Stream::serialize() const
+StreamProto Stream::serialize()
{
StreamProto serialized;
serialized.set_header(header);
- serialized.set_data(string(data, data + BACKLOG_SIZE));
+ if (!read_tempfile(data_fd, serialized.mutable_data())) { // Closes data_fd.
+ exit(1);
+ }
serialized.set_data_size(data_size);
serialized.set_stream_id(stream_id);
+ data_fd = -1;
return serialized;
}
queued_data[stream_id].append(string(data, data + bytes));
}
-void Server::add_data(const string &stream_id, const char *data, size_t bytes)
+void Server::add_data(const string &stream_id, const char *data, ssize_t bytes)
{
Stream *stream = find_stream(stream_id);
size_t pos = stream->data_size % BACKLOG_SIZE;
stream->data_size += bytes;
if (pos + bytes > BACKLOG_SIZE) {
- size_t to_copy = BACKLOG_SIZE - pos;
- memcpy(stream->data + pos, data, to_copy);
- data += to_copy;
- bytes -= to_copy;
+ ssize_t to_copy = BACKLOG_SIZE - pos;
+ while (to_copy > 0) {
+ int ret = pwrite(stream->data_fd, data, to_copy, pos);
+ if (ret == -1 && errno == EINTR) {
+ continue;
+ }
+ if (ret == -1) {
+ perror("pwrite");
+ // Dazed and confused, but trying to continue...
+ break;
+ }
+ pos += ret;
+ data += ret;
+ to_copy -= ret;
+ bytes -= ret;
+ }
pos = 0;
}
- memcpy(stream->data + pos, data, bytes);
+ while (bytes > 0) {
+ int ret = pwrite(stream->data_fd, data, bytes, pos);
+ if (ret == -1 && errno == EINTR) {
+ continue;
+ }
+ if (ret == -1) {
+ perror("pwrite");
+ // Dazed and confused, but trying to continue...
+ break;
+ }
+ pos += ret;
+ data += ret;
+ bytes -= ret;
+ }
+
stream->wake_up_all_clients();
}
return;
}
case Client::SENDING_DATA: {
+sending_data_again:
// See if there's some data we've lost. Ideally, we should drop to a block boundary,
// but resync will be the mux's problem.
Stream *stream = client->stream;
}
// See if we need to split across the circular buffer.
- ssize_t ret;
+ bool more_data = false;
if ((client->bytes_sent % BACKLOG_SIZE) + bytes_to_send > BACKLOG_SIZE) {
- size_t bytes_first_part = BACKLOG_SIZE - (client->bytes_sent % BACKLOG_SIZE);
-
- iovec iov[2];
- iov[0].iov_base = const_cast<char *>(stream->data + (client->bytes_sent % BACKLOG_SIZE));
- iov[0].iov_len = bytes_first_part;
+ bytes_to_send = BACKLOG_SIZE - (client->bytes_sent % BACKLOG_SIZE);
+ more_data = true;
+ }
- iov[1].iov_base = const_cast<char *>(stream->data);
- iov[1].iov_len = bytes_to_send - bytes_first_part;
+ ssize_t ret;
+ do {
+ loff_t offset = client->bytes_sent % BACKLOG_SIZE;
+ ret = sendfile(client->sock, stream->data_fd, &offset, bytes_to_send);
+ } while (ret == -1 && errno == EINTR);
- do {
- ret = writev(client->sock, iov, 2);
- } while (ret == -1 && errno == EINTR);
- } else {
- do {
- ret = write(client->sock,
- stream->data + (client->bytes_sent % BACKLOG_SIZE),
- bytes_to_send);
- } while (ret == -1 && errno == EINTR);
- }
if (ret == -1 && errno == EAGAIN) {
// We're out of socket space, so return; epoll will wake us up
// when there is more room.
}
if (ret == -1) {
// Error, close; postcondition #1.
- perror("write/writev");
+ perror("sendfile");
close_client(client);
return;
}
// We don't have any more data for this client, so put it to sleep.
// This is postcondition #3.
stream->put_client_to_sleep(client);
- } else {
- // XXX: Do we need to go another round here to explicitly
- // get the EAGAIN?
+ } else if (more_data) {
+ goto sending_data_again;
}
break;
}
// Serialization/deserialization.
Stream(const StreamProto &serialized);
- StreamProto serialize() const;
+ StreamProto serialize();
std::string stream_id;
// The HTTP response header, plus the video stream header (if any).
std::string header;
- // The stream data itself, stored in a circular buffer.
- char *data;
+ // The stream data itself, stored in a circular buffer.q
+ //
+ // We store our data in a file, so that we can send the data to the
+ // kernel only once (with write()). We then use sendfile() for each
+ // client, which effectively zero-copies it out of the kernel's buffer
+ // cache. This is significantly more efficient than doing write() from
+ // a userspace memory buffer, since the latter makes the kernel copy
+ // the same data from userspace many times.
+ int data_fd;
// How many bytes <data> contains. Can very well be larger than BACKLOG_SIZE,
// since the buffer wraps.
void process_queued_data();
void add_client(int sock);
- void add_data(const std::string &stream_id, const char *data, size_t bytes);
+ void add_data(const std::string &stream_id, const char *data, ssize_t bytes);
};
#endif // !defined(_SERVER_H)