TPC::Stream Class Reference

#include <XrdHttpTpcStream.hh>

Collaboration diagram for TPC::Stream:

Public Member Functions
	Stream (std::unique_ptr< XrdSfsFile > fh, size_t max_blocks, size_t buffer_size, XrdSysError &log)
	~Stream ()
size_t	AvailableBuffers () const
void	DumpBuffers () const
bool	Finalize ()
std::string	GetErrorMessage () const
int	Read (off_t offset, char *buffer, size_t size)
int	Stat (struct stat *)
ssize_t	Write (off_t offset, const char *buffer, size_t size, bool force)

Detailed Description

Definition at line 23 of file XrdHttpTpcStream.hh.

Constructor & Destructor Documentation

Stream()

TPC::Stream::Stream ( std::unique_ptr< XrdSfsFile > fh, size_t max_blocks, size_t buffer_size, XrdSysError & log )

inline

Definition at line 25 of file XrdHttpTpcStream.hh.

        : m_open_for_write(false),
          m_avail_count(max_blocks),
          m_fh(std::move(fh)),
          m_offset(0),
          m_log(log)
    {
        m_buffers.reserve(max_blocks);
        for (size_t idx=0; idx < max_blocks; idx++) {
            m_buffers.push_back(std::make_unique<Entry>(buffer_size));
        }
        m_open_for_write = true;
    }

~Stream()

Stream::~Stream

(

)

Definition at line 11 of file XrdHttpTpcStream.cc.

{
    m_fh->close();
}

Member Function Documentation

AvailableBuffers()

size_t TPC::Stream::AvailableBuffers ( ) const

inline

Definition at line 57 of file XrdHttpTpcStream.hh.

{return m_avail_count;}

DumpBuffers()

void Stream::DumpBuffers

(

)

const

Definition at line 208 of file XrdHttpTpcStream.cc.

{
    m_log.Emsg("Stream::DumpBuffers", "Beginning dump of stream buffers.");
    {
        std::stringstream ss;
        ss << "Stream offset: " << m_offset;
        m_log.Emsg("Stream::DumpBuffers", ss.str().c_str());
    }
    size_t idx = 0;
    for (const auto &entry : m_buffers) {
        std::stringstream ss;
        ss << "Buffer " << idx << ": Offset=" << entry->GetOffset() << ", Size="
           << entry->GetSize() << ", Capacity=" << entry->GetCapacity();
        m_log.Emsg("Stream::DumpBuffers", ss.str().c_str());
        idx ++;
    }
    m_log.Emsg("Stream::DumpBuffers", "Finish dump of stream buffers.");
}

Referenced by Write().

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Finalize()

bool Stream::Finalize

(

)

Definition at line 18 of file XrdHttpTpcStream.cc.

{
    // Do not close twice
    if (!m_open_for_write) {
        return false;
    }
    m_open_for_write = false;
 
    // If there are outstanding buffers to reorder, finalization failed; the
    // check has to happen before the buffers are released.
    bool all_buffers_returned = m_avail_count == m_buffers.size();
    m_buffers.clear();
 
    if (m_fh->close() == SFS_ERROR) {
        std::stringstream ss;
        const char *msg = m_fh->error.getErrText();
        if (!msg || (*msg == '\0')) {msg = "(no error message provided)";}
        ss << "Failure when closing file handle: " << msg << " (code=" << m_fh->error.getErrInfo() << ")";
        m_error_buf = ss.str();
        return false;
    }
 
    return all_buffers_returned;
}

References SFS_ERROR.

GetErrorMessage()

std::string TPC::Stream::GetErrorMessage ( ) const

inline

Definition at line 70 of file XrdHttpTpcStream.hh.

{return m_error_buf;}

Read()

int Stream::Read	(	off_t	offset,
		char *	buffer,
		size_t	size )

Definition at line 229 of file XrdHttpTpcStream.cc.

{
    return m_fh->read(offset, buf, size);
}

Stat()

int Stream::Stat

(

struct stat *

buf

)

Definition at line 45 of file XrdHttpTpcStream.cc.

{
    return m_fh->stat(buf);
}

References stat.

Write()

ssize_t Stream::Write	(	off_t	offset,
		const char *	buffer,
		size_t	size,
		bool	force )

Definition at line 51 of file XrdHttpTpcStream.cc.

{
/*
 *  NOTE: these lines are useful for debuggin the state of the buffer
 *  management code; too expensive to compile in and have a runtime switch.
    std::stringstream ss;
    ss << "Offset=" << offset << ", Size=" << size << ", force=" << force;
    m_log.Emsg("Stream::Write", ss.str().c_str());
    DumpBuffers();
*/
    if (!m_open_for_write) {
        if (!m_error_buf.size()) {m_error_buf = "Logic error: writing to a buffer not opened for write";}
        return SFS_ERROR;
    }
    size_t bytes_accepted = 0;
    ssize_t retval = size;
    if (offset < m_offset) {
        if (!m_error_buf.size()) {m_error_buf = "Logic error: writing to a prior offset";}
        return SFS_ERROR;
    }
    // If this is write is appending to the stream and
    // MB-aligned, then we write it to disk; otherwise, the
    // data will be buffered.
    if (offset == m_offset && (force || (size && !(size % (1024*1024))))) {
        retval = WriteImpl(offset, buf, size);
        bytes_accepted = retval;
            // On failure, we don't care about flushing buffers from memory --
            // the stream is now invalid.
        if (retval < 0) {
            return retval;
        }
        // If there are no in-use buffers, then we don't need to
        // do any accounting.
        if (m_avail_count == m_buffers.size()) {
            return retval;
        }
    }
    // Even if we already accepted the current data, always iterate through the
    // buffers and try to write as much out to disk as possible.
    //
    // Accepting data can complete a buffer, and flushing a buffer advances
    // m_offset, which can in turn let another buffer accept more data or become
    // writable.  Alternate between the two until neither makes progress.  When
    // size == 0 we force a flush even if things are not MB-aligned.
    ssize_t buffers_flushed;
    do {
        bytes_accepted += AcceptIntoBuffers(offset + bytes_accepted,
                                            buf + bytes_accepted,
                                            size - bytes_accepted);
        buffers_flushed = FlushBuffers(size == 0);
        if (buffers_flushed == SFS_ERROR) {return SFS_ERROR;}
    } while ((buffers_flushed > 0) && (bytes_accepted != size));
 
    if (bytes_accepted != size && size) {  // No place for this data in the buffers currently in use
        Entry *avail_entry = FirstAvailableBuffer();
        if (!avail_entry) {  // No available buffers to allocate; logic error, should not happen.
            DumpBuffers();
            m_error_buf = "No empty buffers available to place unordered data.";
            return SFS_ERROR;
        }
        if (avail_entry->Accept(offset + bytes_accepted, buf + bytes_accepted, size - bytes_accepted) != size - bytes_accepted) {  // Empty buffer cannot accept?!?
            m_error_buf = "Empty re-ordering buffer was unable to to accept data; internal logic error.";
            return SFS_ERROR;
        }
        // The buffer we just filled may already be complete and contiguous with
        // m_offset; flush it now instead of waiting for a later callback to
        // notice, as every curl handle may be idle by then.
        if (FlushBuffers(false) == SFS_ERROR) {return SFS_ERROR;}
    }
 
    // If we have low buffer occupancy, then release memory.
    if ((m_buffers.size() > 2) && (m_avail_count * 2 > m_buffers.size())) {
        for (auto &entry : m_buffers) {
            entry->ShrinkIfUnused();
        }
    }
 
    return retval;
}

References DumpBuffers(), and SFS_ERROR.

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The documentation for this class was generated from the following files:

• XrdHttpTpcStream.hh
• XrdHttpTpcStream.cc