include/lttng/ringbuffer-abi.h

   1 #ifndef _UST_RING_BUFFER_ABI_H
   2 #define _UST_RING_BUFFER_ABI_H
   3
   4 /*
   5  * ust/ringbuffer-abi.h
   6  *
   7  * (C) Copyright 2005-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  *
   9  * Wait-free ring buffer ABI.
  10  *
  11  * Author:
  12  *      Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  13  *
  14  * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
  15  * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
  16  *
  17  * Permission is hereby granted to use or copy this program
  18  * for any purpose,  provided the above notices are retained on all copies.
  19  * Permission to modify the code and to distribute modified code is granted,
  20  * provided the above notices are retained, and a notice that the code was
  21  * modified is included with the above copyright notice.
  22  */
  23
  24 #define _UST_CMD(minor)                         (minor)
  25 #define _UST_CMDR(minor, type)                  (minor)
  26 #define _UST_CMDW(minor, type)                  (minor)
  27
  28 /*
  29  * Use RING_BUFFER_GET_NEXT_SUBBUF / RING_BUFFER_PUT_NEXT_SUBBUF to read and
  30  * consume sub-buffers sequentially.
  31  *
  32  * Reading sub-buffers without consuming them can be performed with:
  33  *
  34  * RING_BUFFER_SNAPSHOT
  35  * RING_BUFFER_SNAPSHOT_GET_CONSUMED
  36  * RING_BUFFER_SNAPSHOT_GET_PRODUCED
  37  *
  38  * to get the offset range to consume, and then by passing each sub-buffer
  39  * offset to RING_BUFFER_GET_SUBBUF, read the sub-buffer, and then release it
  40  * with RING_BUFFER_PUT_SUBBUF.
  41  *
  42  * Note that the "snapshot" API can be used to read the sub-buffer in reverse
  43  * order, which is useful for flight recorder snapshots.
  44  */
  45
  46 /* Get a snapshot of the current ring buffer producer and consumer positions */
  47 #define RING_BUFFER_SNAPSHOT                    _UST_CMD(0x00)
  48 /* Get the consumer position (iteration start) */
  49 #define RING_BUFFER_SNAPSHOT_GET_CONSUMED       _UST_CMDR(0x01, unsigned long)
  50 /* Get the producer position (iteration end) */
  51 #define RING_BUFFER_SNAPSHOT_GET_PRODUCED       _UST_CMDR(0x02, unsigned long)
  52 /* Get exclusive read access to the specified sub-buffer position */
  53 #define RING_BUFFER_GET_SUBBUF                  _UST_CMDW(0x03, unsigned long)
  54 /* Release exclusive sub-buffer access */
  55 #define RING_BUFFER_PUT_SUBBUF                  _UST_CMD(0x04)
  56
  57 /* Get exclusive read access to the next sub-buffer that can be read. */
  58 #define RING_BUFFER_GET_NEXT_SUBBUF             _UST_CMD(0x05)
  59 /* Release exclusive sub-buffer access, move consumer forward. */
  60 #define RING_BUFFER_PUT_NEXT_SUBBUF             _UST_CMD(0x06)
  61 /* returns the size of the current sub-buffer, without padding (for mmap). */
  62 #define RING_BUFFER_GET_SUBBUF_SIZE             _UST_CMDR(0x07, unsigned long)
  63 /* returns the size of the current sub-buffer, with padding (for splice). */
  64 #define RING_BUFFER_GET_PADDED_SUBBUF_SIZE      _UST_CMDR(0x08, unsigned long)
  65 /* returns the maximum size for sub-buffers. */
  66 #define RING_BUFFER_GET_MAX_SUBBUF_SIZE         _UST_CMDR(0x09, unsigned long)
  67 /* returns the length to mmap. */
  68 #define RING_BUFFER_GET_MMAP_LEN                _UST_CMDR(0x0A, unsigned long)
  69 /* returns the offset of the subbuffer belonging to the mmap reader. */
  70 #define RING_BUFFER_GET_MMAP_READ_OFFSET        _UST_CMDR(0x0B, unsigned long)
  71 /* flush the current sub-buffer */
  72 #define RING_BUFFER_FLUSH                       _UST_CMD(0x0C)
  73
  74 #endif /* _UST_RING_BUFFER_ABI_H */