libringbuffer/backend_types.h

   1 #ifndef _LTTNG_RING_BUFFER_BACKEND_TYPES_H
   2 #define _LTTNG_RING_BUFFER_BACKEND_TYPES_H
   3
   4 /*
   5  * linux/ringbuffer/backend_types.h
   6  *
   7  * Ring buffer backend (types).
   8  *
   9  * Copyright (C) 2008-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  10  *
  11  * This library is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU Lesser General Public
  13  * License as published by the Free Software Foundation; only
  14  * version 2.1 of the License.
  15  *
  16  * This library is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  19  * Lesser General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU Lesser General Public
  22  * License along with this library; if not, write to the Free Software
  23  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  24  */
  25
  26 #include <limits.h>
  27 #include <stdint.h>
  28 #include "shm_internal.h"
  29 #include "vatomic.h"
  30
  31 #define RB_BACKEND_PAGES_PADDING        16
  32 struct lttng_ust_lib_ring_buffer_backend_pages {
  33         unsigned long mmap_offset;      /* offset of the subbuffer in mmap */
  34         union v_atomic records_commit;  /* current records committed count */
  35         union v_atomic records_unread;  /* records to read */
  36         unsigned long data_size;        /* Amount of data to read from subbuf */
  37         DECLARE_SHMP(char, p);          /* Backing memory map */
  38         char padding[RB_BACKEND_PAGES_PADDING];
  39 };
  40
  41 struct lttng_ust_lib_ring_buffer_backend_subbuffer {
  42         /* Identifier for subbuf backend pages. Exchanged atomically. */
  43         unsigned long id;               /* backend subbuffer identifier */
  44 };
  45
  46 struct lttng_ust_lib_ring_buffer_backend_counts {
  47         /*
  48          * Counter specific to the sub-buffer location within the ring buffer.
  49          * The actual sequence number of the packet within the entire ring
  50          * buffer can be derived from the formula nr_subbuffers * seq_cnt +
  51          * subbuf_idx.
  52          */
  53         uint64_t seq_cnt;               /* packet sequence number */
  54 };
  55
  56 /*
  57  * Forward declaration of frontend-specific channel and ring_buffer.
  58  */
  59 struct channel;
  60 struct lttng_ust_lib_ring_buffer;
  61
  62 struct lttng_ust_lib_ring_buffer_backend_pages_shmp {
  63         DECLARE_SHMP(struct lttng_ust_lib_ring_buffer_backend_pages, shmp);
  64 };
  65
  66 #define RB_BACKEND_RING_BUFFER_PADDING          64
  67 struct lttng_ust_lib_ring_buffer_backend {
  68         /* Array of ring_buffer_backend_subbuffer for writer */
  69         DECLARE_SHMP(struct lttng_ust_lib_ring_buffer_backend_subbuffer, buf_wsb);
  70         /* ring_buffer_backend_subbuffer for reader */
  71         struct lttng_ust_lib_ring_buffer_backend_subbuffer buf_rsb;
  72         /* Array of lib_ring_buffer_backend_counts for the packet counter */
  73         DECLARE_SHMP(struct lttng_ust_lib_ring_buffer_backend_counts, buf_cnt);
  74         /*
  75          * Pointer array of backend pages, for whole buffer.
  76          * Indexed by ring_buffer_backend_subbuffer identifier (id) index.
  77          */
  78         DECLARE_SHMP(struct lttng_ust_lib_ring_buffer_backend_pages_shmp, array);
  79         DECLARE_SHMP(char, memory_map); /* memory mapping */
  80
  81         DECLARE_SHMP(struct channel, chan);     /* Associated channel */
  82         int cpu;                        /* This buffer's cpu. -1 if global. */
  83         union v_atomic records_read;    /* Number of records read */
  84         unsigned int allocated:1;       /* is buffer allocated ? */
  85         char padding[RB_BACKEND_RING_BUFFER_PADDING];
  86 };
  87
  88 struct lttng_ust_lib_ring_buffer_shmp {
  89         DECLARE_SHMP(struct lttng_ust_lib_ring_buffer, shmp); /* Channel per-cpu buffers */
  90 };
  91
  92 #define RB_BACKEND_CHANNEL_PADDING      64
  93 struct channel_backend {
  94         unsigned long buf_size;         /* Size of the buffer */
  95         unsigned long subbuf_size;      /* Sub-buffer size */
  96         unsigned int subbuf_size_order; /* Order of sub-buffer size */
  97         unsigned int num_subbuf_order;  /*
  98                                          * Order of number of sub-buffers/buffer
  99                                          * for writer.
 100                                          */
 101         unsigned int buf_size_order;    /* Order of buffer size */
 102         unsigned int extra_reader_sb:1; /* has extra reader subbuffer ? */
 103         unsigned long num_subbuf;       /* Number of sub-buffers for writer */
 104         uint64_t start_tsc;             /* Channel creation TSC value */
 105         DECLARE_SHMP(void *, priv_data);/* Client-specific information */
 106         struct lttng_ust_lib_ring_buffer_config config; /* Ring buffer configuration */
 107         char name[NAME_MAX];            /* Channel name */
 108         char padding[RB_BACKEND_CHANNEL_PADDING];
 109         struct lttng_ust_lib_ring_buffer_shmp buf[];
 110 };
 111
 112 #endif /* _LTTNG_RING_BUFFER_BACKEND_TYPES_H */