+ vector<iovec> ret;
+ size_t max_iovecs = std::min<size_t>(data.size(), IOV_MAX);
+ for (size_t i = 0; i < max_iovecs && bytes_wanted > 0; ++i) {
+ if (data[i].iov_len <= bytes_wanted) {
+ // Consume the entire iovec.
+ ret.push_back(data[i]);
+ bytes_wanted -= data[i].iov_len;
+ } else {
+ // Take only parts of this iovec.
+ iovec iov;
+ iov.iov_base = data[i].iov_base;
+ iov.iov_len = bytes_wanted;
+ ret.push_back(iov);
+ bytes_wanted = 0;
+ }
+ }
+ return ret;
+}
+
+// Return a new set of iovecs that contains all of <data> except the first <bytes_wanted> bytes.
+vector<iovec> remove_iovecs(const vector<iovec> &data, size_t bytes_wanted)
+{
+ vector<iovec> ret;
+ size_t i;
+ for (i = 0; i < data.size() && bytes_wanted > 0; ++i) {
+ if (data[i].iov_len <= bytes_wanted) {
+ // Consume the entire iovec.
+ bytes_wanted -= data[i].iov_len;
+ } else {
+ // Take only parts of this iovec.
+ iovec iov;
+ iov.iov_base = reinterpret_cast<char *>(data[i].iov_base) + bytes_wanted;
+ iov.iov_len = data[i].iov_len - bytes_wanted;
+ ret.push_back(iov);
+ bytes_wanted = 0;
+ }
+ }
+
+ // Add the rest of the iovecs unchanged.
+ ret.insert(ret.end(), data.begin() + i, data.end());
+ return ret;
+}
+
+void Stream::add_data_raw(const vector<iovec> &orig_data)
+{
+ vector<iovec> data = orig_data;
+ while (!data.empty()) {
+ size_t pos = bytes_received % backlog_size;
+
+ // Collect as many iovecs as we can before we hit the point
+ // where the circular buffer wraps around.
+ vector<iovec> to_write = collect_iovecs(data, backlog_size - pos);
+ ssize_t ret;
+ do {
+ ret = pwritev(data_fd, to_write.data(), to_write.size(), pos);
+ } while (ret == -1 && errno == EINTR);
+
+ if (ret == -1) {
+ log_perror("pwritev");
+ // Dazed and confused, but trying to continue...
+ return;
+ }
+ bytes_received += ret;
+
+ // Remove the data that was actually written from the set of iovecs.
+ data = remove_iovecs(data, ret);
+ }
+}
+
+void Stream::add_data_deferred(const char *data, size_t bytes)
+{
+ if (encoding == Stream::STREAM_ENCODING_METACUBE) {
+ // Add a Metacube block header before the data.
+ metacube_block_header hdr;
+ memcpy(hdr.sync, METACUBE_SYNC, sizeof(hdr.sync));
+ hdr.size = htonl(bytes);
+ hdr.flags = htonl(0);
+
+ iovec iov;
+ iov.iov_base = new char[bytes + sizeof(hdr)];
+ iov.iov_len = bytes + sizeof(hdr);
+
+ memcpy(iov.iov_base, &hdr, sizeof(hdr));
+ memcpy(reinterpret_cast<char *>(iov.iov_base) + sizeof(hdr), data, bytes);
+
+ queued_data.push_back(iov);
+ } else if (encoding == Stream::STREAM_ENCODING_RAW) {
+ // Just add the data itself.
+ iovec iov;
+ iov.iov_base = new char[bytes];
+ memcpy(iov.iov_base, data, bytes);
+ iov.iov_len = bytes;
+
+ queued_data.push_back(iov);
+ } else {
+ assert(false);
+ }
+}
+
+void Stream::process_queued_data()
+{
+ if (queued_data.empty()) {
+ return;
+ }
+
+ add_data_raw(queued_data);
+ for (size_t i = 0; i < queued_data.size(); ++i) {
+ char *data = reinterpret_cast<char *>(queued_data[i].iov_base);
+ delete[] data;
+ }
+ queued_data.clear();
+
+ // We have more data, so wake up all clients.