libringbuffer/backend_types.h

   1 /*
   2  * SPDX-License-Identifier: LGPL-2.1-only
   3  *
   4  * Copyright (C) 2008-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * Ring buffer backend (types).
   7  */
   8
   9 #ifndef _LTTNG_RING_BUFFER_BACKEND_TYPES_H
  10 #define _LTTNG_RING_BUFFER_BACKEND_TYPES_H
  11
  12 #include <limits.h>
  13 #include <stdint.h>
  14 #include "shm_internal.h"
  15 #include "vatomic.h"
  16
  17 #define RB_BACKEND_PAGES_PADDING        16
  18 struct lttng_ust_lib_ring_buffer_backend_pages {
  19         unsigned long mmap_offset;      /* offset of the subbuffer in mmap */
  20         union v_atomic records_commit;  /* current records committed count */
  21         union v_atomic records_unread;  /* records to read */
  22         unsigned long data_size;        /* Amount of data to read from subbuf */
  23         DECLARE_SHMP(char, p);          /* Backing memory map */
  24         char padding[RB_BACKEND_PAGES_PADDING];
  25 };
  26
  27 struct lttng_ust_lib_ring_buffer_backend_subbuffer {
  28         /* Identifier for subbuf backend pages. Exchanged atomically. */
  29         unsigned long id;               /* backend subbuffer identifier */
  30 };
  31
  32 struct lttng_ust_lib_ring_buffer_backend_counts {
  33         /*
  34          * Counter specific to the sub-buffer location within the ring buffer.
  35          * The actual sequence number of the packet within the entire ring
  36          * buffer can be derived from the formula nr_subbuffers * seq_cnt +
  37          * subbuf_idx.
  38          */
  39         uint64_t seq_cnt;               /* packet sequence number */
  40 };
  41
  42 /*
  43  * Forward declaration of frontend-specific channel and ring_buffer.
  44  */
  45 struct channel;
  46 struct lttng_ust_lib_ring_buffer;
  47
  48 struct lttng_ust_lib_ring_buffer_backend_pages_shmp {
  49         DECLARE_SHMP(struct lttng_ust_lib_ring_buffer_backend_pages, shmp);
  50 };
  51
  52 #define RB_BACKEND_RING_BUFFER_PADDING          64
  53 struct lttng_ust_lib_ring_buffer_backend {
  54         /* Array of ring_buffer_backend_subbuffer for writer */
  55         DECLARE_SHMP(struct lttng_ust_lib_ring_buffer_backend_subbuffer, buf_wsb);
  56         /* ring_buffer_backend_subbuffer for reader */
  57         struct lttng_ust_lib_ring_buffer_backend_subbuffer buf_rsb;
  58         /* Array of lib_ring_buffer_backend_counts for the packet counter */
  59         DECLARE_SHMP(struct lttng_ust_lib_ring_buffer_backend_counts, buf_cnt);
  60         /*
  61          * Pointer array of backend pages, for whole buffer.
  62          * Indexed by ring_buffer_backend_subbuffer identifier (id) index.
  63          */
  64         DECLARE_SHMP(struct lttng_ust_lib_ring_buffer_backend_pages_shmp, array);
  65         DECLARE_SHMP(char, memory_map); /* memory mapping */
  66
  67         DECLARE_SHMP(struct channel, chan);     /* Associated channel */
  68         int cpu;                        /* This buffer's cpu. -1 if global. */
  69         union v_atomic records_read;    /* Number of records read */
  70         unsigned int allocated:1;       /* is buffer allocated ? */
  71         char padding[RB_BACKEND_RING_BUFFER_PADDING];
  72 };
  73
  74 struct lttng_ust_lib_ring_buffer_shmp {
  75         DECLARE_SHMP(struct lttng_ust_lib_ring_buffer, shmp); /* Channel per-cpu buffers */
  76 };
  77
  78 #define RB_BACKEND_CHANNEL_PADDING      64
  79 struct channel_backend {
  80         unsigned long buf_size;         /* Size of the buffer */
  81         unsigned long subbuf_size;      /* Sub-buffer size */
  82         unsigned int subbuf_size_order; /* Order of sub-buffer size */
  83         unsigned int num_subbuf_order;  /*
  84                                          * Order of number of sub-buffers/buffer
  85                                          * for writer.
  86                                          */
  87         unsigned int buf_size_order;    /* Order of buffer size */
  88         unsigned int extra_reader_sb:1; /* has extra reader subbuffer ? */
  89         unsigned long num_subbuf;       /* Number of sub-buffers for writer */
  90         uint64_t start_tsc;             /* Channel creation TSC value */
  91         DECLARE_SHMP(void *, priv_data);/* Client-specific information */
  92         struct lttng_ust_lib_ring_buffer_config config; /* Ring buffer configuration */
  93         char name[NAME_MAX];            /* Channel name */
  94         char padding[RB_BACKEND_CHANNEL_PADDING];
  95         struct lttng_ust_lib_ring_buffer_shmp buf[];
  96 };
  97
  98 #endif /* _LTTNG_RING_BUFFER_BACKEND_TYPES_H */