C++ ostream::setstate方法代码示例

//.........这里部分代码省略.........
            // Even if we are at the end of the buffer, or within range. If we are filtering,
            // we will need to make sure we are not spinning when there are no valid events
            // to be reported. we will waste cycles spinning on the end of the buffer when
            // we should be in a heartbeat wait as well.
            if (!endOfBuffer) {
                // If we're not at the end of the buffer, move to the end of the previous set and
                // begin filtering from where we left off.
                start = end;

                // For replaying of events, we will stream as fast as we can with a 1ms sleep
                // to allow other threads to run.
                dlib::sleep(1);
            } else {
                uint64 delta;

                if (!current) {
                    // Busy wait to make sure the signal was actually signaled. We have observed that
                    // a signal can occur in rare conditions where there are multiple threads listening
                    // on separate condition variables and this pops out too soon. This will make sure
                    // observer was actually signaled and instead of throwing an error will wait again
                    // for the remaining hartbeat interval.
                    delta = (ts.get_timestamp() - last) / 1000;
                    while (delta < aHeartbeat &&
                            observer.wait(aHeartbeat - delta) &&
                            !observer.wasSignaled()) {
                        delta = (ts.get_timestamp() - last) / 1000;
                    }

                    {
                        dlib::auto_mutex lock(*mSequenceLock);

                        // Make sure the observer was signaled!
                        if (!observer.wasSignaled()) {
                            // If nothing came out during the last wait, we may have still have advanced
                            // the sequence number. We should reset the start to something closer to the
                            // current sequence. If we lock the sequence lock, we can check if the observer
                            // was signaled between the time the wait timed out and the mutex was locked.
                            // Otherwise, nothing has arrived and we set to the next sequence number to
                            // the next sequence number to be allocated and continue.
                            start = mSequence;
                        } else {
                            // Get the sequence # signaled in the observer when the earliest event arrived.
                            // This will allow the next set of data to be pulled. Any later events will have
                            // greater sequence numbers, so this should not cause a problem. Also, signaled
                            // sequence numbers can only decrease, never increase.
                            start = observer.getSequence();
                        }
                    }
                }

                // Now wait the remainder if we triggered before the timer was up.
                delta = ts.get_timestamp() - last;
                if (delta < interMicros) {
                    // Sleep the remainder
                    dlib::sleep((interMicros - delta) / 1000);
                }
            }
        }
    }
    catch (ParameterError &aError)
    {
        sLogger << LINFO << "Caught a parameter error.";
        if (out.good()) {
            ostringstream str;
            string content = printError(aError.mCode, aError.mMessage);
            str << "--" << boundary << "\r\n"
                "Content-type: text/xml\r\n"
                "Content-length: " << content.length() << "\r\n\r\n"
                << content;

            string chunk = str.str();
            out.setf(ios::hex, ios::basefield);
            out << chunk.length() << "\r\n";
            out << chunk << "\r\n";
            out.flush();
        }
    }

    catch (...)
    {
        sLogger << LWARN << "Error occurred during streaming data";
        if (out.good()) {
            ostringstream str;
            string content = printError("INTERNAL_ERROR", "Unknown error occurred during streaming");
            str << "--" << boundary << "\r\n"
                "Content-type: text/xml\r\n"
                "Content-length: " << content.length() << "\r\n\r\n"
                << content;

            string chunk = str.str();
            out.setf(ios::hex, ios::basefield);
            out << chunk.length() << "\r\n";
            out << chunk;
            out.flush();
        }
    }

    out.setstate(ios::badbit);
    // Observer is auto removed from signalers
}