void
nsPipe::AdvanceWriteCursor(PRUint32 bytesWritten)
{
NS_ASSERTION(bytesWritten, "dont call if no bytes written");
nsPipeEvents events;
{
nsAutoMonitor mon(mMonitor);
LOG(("OOO advancing write cursor by %u\n", bytesWritten));
char *newWriteCursor = mWriteCursor + bytesWritten;
NS_ASSERTION(newWriteCursor <= mWriteLimit, "write cursor exceeds limit");
// update read limit if reading in the same segment
if (mWriteSegment == 0 && mReadLimit == mWriteCursor)
mReadLimit = newWriteCursor;
mWriteCursor = newWriteCursor;
NS_ASSERTION(mReadCursor != mWriteCursor, "read cursor is bad");
// update the writable flag on the output stream
if (mWriteCursor == mWriteLimit) {
if (mBuffer.GetSize() >= mBuffer.GetMaxSize())
mOutput.SetWritable(PR_FALSE);
}
// notify input stream that pipe now contains additional data
if (mInput.OnInputReadable(bytesWritten, events))
mon.Notify();
}
}
void
nsPipe::AdvanceWriteCursor(PRUint32 bytesWritten)
{
NS_ASSERTION(bytesWritten, "don't call if no bytes written");
nsPipeEvents events;
{
MonitorAutoEnter mon(mMonitor);
LOG(("OOO advancing write cursor by %u\n", bytesWritten));
char *newWriteCursor = mWriteCursor + bytesWritten;
NS_ASSERTION(newWriteCursor <= mWriteLimit, "write cursor exceeds limit");
// update read limit if reading in the same segment
if (mWriteSegment == 0 && mReadLimit == mWriteCursor)
mReadLimit = newWriteCursor;
mWriteCursor = newWriteCursor;
// The only way mReadCursor == mWriteCursor is if:
//
// - mReadCursor is at the start of a segment (which, based on how
// nsSegmentedBuffer works, means that this segment is the "first"
// segment)
// - mWriteCursor points at the location past the end of the current
// write segment (so the current write filled the current write
// segment, so we've incremented mWriteCursor to point past the end
// of it)
// - the segment to which data has just been written is located
// exactly one segment's worth of bytes before the first segment
// where mReadCursor is located
//
// Consequently, the byte immediately after the end of the current
// write segment is the first byte of the first segment, so
// mReadCursor == mWriteCursor. (Another way to think about this is
// to consider the buffer architecture diagram above, but consider it
// with an arena allocator which allocates from the *end* of the
// arena to the *beginning* of the arena.)
NS_ASSERTION(mReadCursor != mWriteCursor ||
(mBuffer.GetSegment(0) == mReadCursor &&
mWriteCursor == mWriteLimit),
"read cursor is bad");
// update the writable flag on the output stream
if (mWriteCursor == mWriteLimit) {
if (mBuffer.GetSize() >= mBuffer.GetMaxSize())
mOutput.SetWritable(PR_FALSE);
}
// notify input stream that pipe now contains additional data
if (mInput.OnInputReadable(bytesWritten, events))
mon.Notify();
}
}