bionic (3) TSIOBufferCreate.3ts.gz

NAME

       TSIOBufferCreate - traffic Server IO buffer API

SYNOPSIS

       #include <ts/ts.h>

       TSIOBuffer TSIOBufferCreate(void)

       TSIOBuffer TSIOBufferSizedCreate(TSIOBufferSizeIndex index)

       void TSIOBufferDestroy(TSIOBuffer bufp)

       int64_t TSIOBufferWrite(TSIOBuffer bufp, const void * buf, int64_t length)

       void TSIOBufferProduce(TSIOBuffer bufp, int64_t nbytes)

       int64_t TSIOBufferWaterMarkGet(TSIOBuffer bufp)

       void TSIOBufferWaterMarkSet(TSIOBuffer bufp, int64_t water_mark)

DESCRIPTION

       The  TSIOBuffer data structure is the building block of the TSVConn abstraction. An IO buffer is composed
       of a list of buffer blocks which are reference counted so that they can reside in multiple buffers at the
       same  time.  This  makes  it  extremely  efficient  to  copy  data  from  one  IO buffer to another using
       TSIOBufferCopy()  since  Traffic  Server  only  needs  to  copy  pointers  and  adjust  reference  counts
       appropriately  and  not  actually copy any data. However, applications should still strive to ensure data
       blocks are a reasonable size.

       The IO buffer abstraction provides for a single writer and multiple readers. In order for the readers  to
       have  no knowledge of each other, they manipulate IO buffers through the TSIOBufferReader data structure.
       Since only a single writer is allowed, there is no corresponding  TSIOBufferWriter  data  structure.  The
       writer simply modifies the IO buffer directly.

       TSIOBufferCreate() creates an empty TSIOBuffer.

       TSIOBufferSizedCreate() creates an empty TSIOBuffer with an initial capacity of index bytes.

       TSIOBufferDestroy()  destroys the IO buffer bufp. Since multiple IO buffers can share data, this does not
       necessarily free all of the data associated with the IO buffer  but  simply  decrements  the  appropriate
       reference counts.

       TSIOBufferWrite()  appends  length bytes from the buffer buf to the IO buffer bufp and returns the number
       of bytes successfully written into the IO buffer.

       TSIOBufferProduce() makes nbytes of data available for reading in the IO buffer bufp.  A  common  pattern
       for  writing to an IO buffer is to copy data into a buffer block and then call INKIOBufferProduce to make
       the new data visible to any readers.

       NOTE:
          The above references an old API function: INKIOBufferProduce and needs to be  fixed.  I  don't  see  a
          TSIOBufferProduce function that would be its obvious replacement from the Ink->TS rename.

       The  watermark  of  an  TSIOBuffer  is  the minimum number of bytes of data that have to be in the buffer
       before calling back any continuation that has initiated a read operation on  this  buffer.  As  a  writer
       feeds  data  into  the  TSIOBuffer,  no  readers  are  called  back  until the amount of data reaches the
       watermark. Setting a watermark can improve performance because it avoids frequent callbacks to read small
       amounts of data.  TSIOBufferWaterMarkGet() gets the current watermark for the IO buffer bufp.

       TSIOBufferWaterMarkSet() gets the current watermark for the IO buffer bufp to water_mark bytes.

SEE ALSO

       TSAPI(3ts), TSIOBufferReaderAlloc(3ts)

COPYRIGHT

       2018, dev@trafficserver.apache.org