libringbuffer/frontend_types.h

   1 #ifndef _LINUX_RING_BUFFER_FRONTEND_TYPES_H
   2 #define _LINUX_RING_BUFFER_FRONTEND_TYPES_H
   3
   4 /*
   5  * linux/ringbuffer/frontend_types.h
   6  *
   7  * (C) Copyright 2005-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  *
   9  * Ring Buffer Library Synchronization Header (types).
  10  *
  11  * Author:
  12  *      Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  13  *
  14  * See ring_buffer_frontend.c for more information on wait-free algorithms.
  15  *
  16  * Dual LGPL v2.1/GPL v2 license.
  17  */
  18
  19 #include <string.h>
  20
  21 #include <urcu/list.h>
  22 #include <urcu/uatomic.h>
  23 #include <urcu/ref.h>
  24
  25 #include "ust/core.h"
  26
  27 #include "usterr_signal_safe.h"
  28 #include "config.h"
  29 #include "backend_types.h"
  30 #include "shm.h"
  31
  32 /*
  33  * A switch is done during tracing or as a final flush after tracing (so it
  34  * won't write in the new sub-buffer).
  35  */
  36 enum switch_mode { SWITCH_ACTIVE, SWITCH_FLUSH };
  37
  38 /* channel: collection of per-cpu ring buffers. */
  39 struct channel {
  40         int record_disabled;
  41         unsigned long commit_count_mask;        /*
  42                                                  * Commit count mask, removing
  43                                                  * the MSBs corresponding to
  44                                                  * bits used to represent the
  45                                                  * subbuffer index.
  46                                                  */
  47
  48         struct channel_backend backend;         /* Associated backend */
  49
  50         unsigned long switch_timer_interval;    /* Buffer flush (jiffies) */
  51         unsigned long read_timer_interval;      /* Reader wakeup (jiffies) */
  52         //wait_queue_head_t read_wait;          /* reader wait queue */
  53         int finalized;                          /* Has channel been finalized */
  54         struct urcu_ref ref;                    /* Reference count */
  55         DECLARE_SHMP(struct shm_header, shm_header);
  56 } ____cacheline_aligned;
  57
  58 /* Per-subbuffer commit counters used on the hot path */
  59 struct commit_counters_hot {
  60         union v_atomic cc;              /* Commit counter */
  61         union v_atomic seq;             /* Consecutive commits */
  62 } ____cacheline_aligned;
  63
  64 /* Per-subbuffer commit counters used only on cold paths */
  65 struct commit_counters_cold {
  66         union v_atomic cc_sb;           /* Incremented _once_ at sb switch */
  67 } ____cacheline_aligned;
  68
  69 /* ring buffer state */
  70 struct lib_ring_buffer {
  71         /* First 32 bytes cache-hot cacheline */
  72         union v_atomic offset;          /* Current offset in the buffer */
  73         DECLARE_SHMP(struct commit_counters_hot, commit_hot);
  74                                         /* Commit count per sub-buffer */
  75         long consumed;                  /*
  76                                          * Current offset in the buffer
  77                                          * standard atomic access (shared)
  78                                          */
  79         int record_disabled;
  80         /* End of first 32 bytes cacheline */
  81         union v_atomic last_tsc;        /*
  82                                          * Last timestamp written in the buffer.
  83                                          */
  84
  85         struct lib_ring_buffer_backend backend; /* Associated backend */
  86
  87         DECLARE_SHMP(struct commit_counters_cold, commit_cold);
  88                                         /* Commit count per sub-buffer */
  89         long active_readers;            /*
  90                                          * Active readers count
  91                                          * standard atomic access (shared)
  92                                          */
  93                                         /* Dropped records */
  94         union v_atomic records_lost_full;       /* Buffer full */
  95         union v_atomic records_lost_wrap;       /* Nested wrap-around */
  96         union v_atomic records_lost_big;        /* Events too big */
  97         union v_atomic records_count;   /* Number of records written */
  98         union v_atomic records_overrun; /* Number of overwritten records */
  99         //wait_queue_head_t read_wait;  /* reader buffer-level wait queue */
 100         int finalized;                  /* buffer has been finalized */
 101         //struct timer_list switch_timer;       /* timer for periodical switch */
 102         //struct timer_list read_timer; /* timer for read poll */
 103         unsigned long get_subbuf_consumed;      /* Read-side consumed */
 104         unsigned long prod_snapshot;    /* Producer count snapshot */
 105         unsigned long cons_snapshot;    /* Consumer count snapshot */
 106         int get_subbuf:1;               /* Sub-buffer being held by reader */
 107         int switch_timer_enabled:1;     /* Protected by ring_buffer_nohz_lock */
 108         int read_timer_enabled:1;       /* Protected by ring_buffer_nohz_lock */
 109 } ____cacheline_aligned;
 110
 111 static inline
 112 void *channel_get_private(struct channel *chan)
 113 {
 114         return chan->backend.priv;
 115 }
 116
 117 /*
 118  * Issue warnings and disable channels upon internal error.
 119  * Can receive struct lib_ring_buffer or struct lib_ring_buffer_backend
 120  * parameters.
 121  */
 122 #define CHAN_WARN_ON(c, cond)                                           \
 123         ({                                                              \
 124                 struct channel *__chan;                                 \
 125                 int _____ret = unlikely(cond);                          \
 126                 if (_____ret) {                                         \
 127                         if (__same_type(*(c), struct channel_backend))  \
 128                                 __chan = caa_container_of((void *) (c), \
 129                                                         struct channel, \
 130                                                         backend);       \
 131                         else if (__same_type(*(c), struct channel))     \
 132                                 __chan = (void *) (c);                  \
 133                         else                                            \
 134                                 BUG_ON(1);                              \
 135                         uatomic_inc(&__chan->record_disabled);          \
 136                         WARN_ON(1);                                     \
 137                 }                                                       \
 138                 _____ret;                                               \
 139         })
 140
 141 #endif /* _LINUX_RING_BUFFER_FRONTEND_TYPES_H */