include/lttng/ringbuffer-abi.h

   1 #ifndef _LTTNG_RING_BUFFER_ABI_H
   2 #define _LTTNG_RING_BUFFER_ABI_H
   3
   4 /*
   5  * lttng/ringbuffer-abi.h
   6  *
   7  * (C) Copyright 2005-2012 - 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  * Permission is hereby granted, free of charge, to any person obtaining a copy
  15  * of this software and associated documentation files (the "Software"), to deal
  16  * in the Software without restriction, including without limitation the rights
  17  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  18  * copies of the Software, and to permit persons to whom the Software is
  19  * furnished to do so, subject to the following conditions:
  20  *
  21  * The above copyright notice and this permission notice shall be included in
  22  * all copies or substantial portions of the Software.
  23  *
  24  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  25  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  26  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  27  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  28  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  29  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  30  * SOFTWARE.
  31  */
  32
  33 #define _UST_CMD(minor)                         (minor)
  34 #define _UST_CMDR(minor, type)                  (minor)
  35 #define _UST_CMDW(minor, type)                  (minor)
  36
  37 /*
  38  * Use RING_BUFFER_GET_NEXT_SUBBUF / RING_BUFFER_PUT_NEXT_SUBBUF to read and
  39  * consume sub-buffers sequentially.
  40  *
  41  * Reading sub-buffers without consuming them can be performed with:
  42  *
  43  * RING_BUFFER_SNAPSHOT
  44  * RING_BUFFER_SNAPSHOT_GET_CONSUMED
  45  * RING_BUFFER_SNAPSHOT_GET_PRODUCED
  46  *
  47  * to get the offset range to consume, and then by passing each sub-buffer
  48  * offset to RING_BUFFER_GET_SUBBUF, read the sub-buffer, and then release it
  49  * with RING_BUFFER_PUT_SUBBUF.
  50  *
  51  * Note that the "snapshot" API can be used to read the sub-buffer in reverse
  52  * order, which is useful for flight recorder snapshots.
  53  */
  54
  55 /* Get a snapshot of the current ring buffer producer and consumer positions */
  56 #define RING_BUFFER_SNAPSHOT                    _UST_CMD(0x00)
  57 /* Get the consumer position (iteration start) */
  58 #define RING_BUFFER_SNAPSHOT_GET_CONSUMED       _UST_CMDR(0x01, unsigned long)
  59 /* Get the producer position (iteration end) */
  60 #define RING_BUFFER_SNAPSHOT_GET_PRODUCED       _UST_CMDR(0x02, unsigned long)
  61 /* Get exclusive read access to the specified sub-buffer position */
  62 #define RING_BUFFER_GET_SUBBUF                  _UST_CMDW(0x03, unsigned long)
  63 /* Release exclusive sub-buffer access */
  64 #define RING_BUFFER_PUT_SUBBUF                  _UST_CMD(0x04)
  65
  66 /* Get exclusive read access to the next sub-buffer that can be read. */
  67 #define RING_BUFFER_GET_NEXT_SUBBUF             _UST_CMD(0x05)
  68 /* Release exclusive sub-buffer access, move consumer forward. */
  69 #define RING_BUFFER_PUT_NEXT_SUBBUF             _UST_CMD(0x06)
  70 /* returns the size of the current sub-buffer, without padding (for mmap). */
  71 #define RING_BUFFER_GET_SUBBUF_SIZE             _UST_CMDR(0x07, unsigned long)
  72 /* returns the size of the current sub-buffer, with padding (for splice). */
  73 #define RING_BUFFER_GET_PADDED_SUBBUF_SIZE      _UST_CMDR(0x08, unsigned long)
  74 /* returns the maximum size for sub-buffers. */
  75 #define RING_BUFFER_GET_MAX_SUBBUF_SIZE         _UST_CMDR(0x09, unsigned long)
  76 /* returns the length to mmap. */
  77 #define RING_BUFFER_GET_MMAP_LEN                _UST_CMDR(0x0A, unsigned long)
  78 /* returns the offset of the subbuffer belonging to the mmap reader. */
  79 #define RING_BUFFER_GET_MMAP_READ_OFFSET        _UST_CMDR(0x0B, unsigned long)
  80 /* flush the current sub-buffer */
  81 #define RING_BUFFER_FLUSH                       _UST_CMD(0x0C)
  82
  83 #endif /* _LTTNG_RING_BUFFER_ABI_H */