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  * Dual LGPL v2.1/GPL v2 license.
  15  */
  16
  17 #define _UST_CMD(minor)                         (minor)
  18 #define _UST_CMDR(minor, type)                  (minor)
  19 #define _UST_CMDW(minor, type)                  (minor)
  20
  21 /*
  22  * Use RING_BUFFER_GET_NEXT_SUBBUF / RING_BUFFER_PUT_NEXT_SUBBUF to read and
  23  * consume sub-buffers sequentially.
  24  *
  25  * Reading sub-buffers without consuming them can be performed with:
  26  *
  27  * RING_BUFFER_SNAPSHOT
  28  * RING_BUFFER_SNAPSHOT_GET_CONSUMED
  29  * RING_BUFFER_SNAPSHOT_GET_PRODUCED
  30  *
  31  * to get the offset range to consume, and then by passing each sub-buffer
  32  * offset to RING_BUFFER_GET_SUBBUF, read the sub-buffer, and then release it
  33  * with RING_BUFFER_PUT_SUBBUF.
  34  *
  35  * Note that the "snapshot" API can be used to read the sub-buffer in reverse
  36  * order, which is useful for flight recorder snapshots.
  37  */
  38
  39 /* Get a snapshot of the current ring buffer producer and consumer positions */
  40 #define RING_BUFFER_SNAPSHOT                    _UST_CMD(0x00)
  41 /* Get the consumer position (iteration start) */
  42 #define RING_BUFFER_SNAPSHOT_GET_CONSUMED       _UST_CMDR(0x01, unsigned long)
  43 /* Get the producer position (iteration end) */
  44 #define RING_BUFFER_SNAPSHOT_GET_PRODUCED       _UST_CMDR(0x02, unsigned long)
  45 /* Get exclusive read access to the specified sub-buffer position */
  46 #define RING_BUFFER_GET_SUBBUF                  _UST_CMDW(0x03, unsigned long)
  47 /* Release exclusive sub-buffer access */
  48 #define RING_BUFFER_PUT_SUBBUF                  _UST_CMD(0x04)
  49
  50 /* Get exclusive read access to the next sub-buffer that can be read. */
  51 #define RING_BUFFER_GET_NEXT_SUBBUF             _UST_CMD(0x05)
  52 /* Release exclusive sub-buffer access, move consumer forward. */
  53 #define RING_BUFFER_PUT_NEXT_SUBBUF             _UST_CMD(0x06)
  54 /* returns the size of the current sub-buffer, without padding (for mmap). */
  55 #define RING_BUFFER_GET_SUBBUF_SIZE             _UST_CMDR(0x07, unsigned long)
  56 /* returns the size of the current sub-buffer, with padding (for splice). */
  57 #define RING_BUFFER_GET_PADDED_SUBBUF_SIZE      _UST_CMDR(0x08, unsigned long)
  58 /* returns the maximum size for sub-buffers. */
  59 #define RING_BUFFER_GET_MAX_SUBBUF_SIZE         _UST_CMDR(0x09, unsigned long)
  60 /* returns the length to mmap. */
  61 #define RING_BUFFER_GET_MMAP_LEN                _UST_CMDR(0x0A, unsigned long)
  62 /* returns the offset of the subbuffer belonging to the mmap reader. */
  63 #define RING_BUFFER_GET_MMAP_READ_OFFSET        _UST_CMDR(0x0B, unsigned long)
  64 /* flush the current sub-buffer */
  65 #define RING_BUFFER_FLUSH                       _UST_CMD(0x0C)
  66
  67 #endif /* _UST_RING_BUFFER_ABI_H */