include/lttng/channel.h

   1 /*
   2  * Copyright (C) 2014 - David Goulet <dgoulet@efficios.com>
   3  *
   4  * This library is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU Lesser General Public License, version 2.1 only,
   6  * as published by the Free Software Foundation.
   7  *
   8  * This library is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
  11  * for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public License
  14  * along with this library; if not, write to the Free Software Foundation,
  15  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  16  */
  17
  18 #ifndef LTTNG_CHANNEL_H
  19 #define LTTNG_CHANNEL_H
  20
  21 #include <lttng/domain.h>
  22 #include <lttng/event.h>
  23
  24 #ifdef __cplusplus
  25 extern "C" {
  26 #endif
  27
  28 /*
  29  * Tracer channel attributes. For both kernel and user-space.
  30  *
  31  * The structures should be initialized to zero before use.
  32  */
  33 #define LTTNG_CHANNEL_ATTR_PADDING1        LTTNG_SYMBOL_NAME_LEN + 12
  34 struct lttng_channel_attr {
  35         int overwrite;                      /* 1: overwrite, 0: discard */
  36         uint64_t subbuf_size;               /* bytes, power of 2 */
  37         uint64_t num_subbuf;                /* power of 2 */
  38         unsigned int switch_timer_interval; /* usec */
  39         unsigned int read_timer_interval;   /* usec */
  40         enum lttng_event_output output;     /* splice, mmap */
  41         /* LTTng 2.1 padding limit */
  42         uint64_t tracefile_size;            /* bytes */
  43         uint64_t tracefile_count;           /* number of tracefiles */
  44         /* LTTng 2.3 padding limit */
  45         unsigned int live_timer_interval;   /* usec */
  46         /* LTTng 2.7 padding limit */
  47         uint32_t align_to_64;
  48         union {
  49                 uint64_t padding;
  50                 void *ptr;
  51         } extended;
  52
  53         char padding[LTTNG_CHANNEL_ATTR_PADDING1];
  54 };
  55
  56 /*
  57  * Channel information structure. For both kernel and user-space.
  58  *
  59  * The structures should be initialized to zero before use.
  60  */
  61 #define LTTNG_CHANNEL_PADDING1             16
  62 struct lttng_channel {
  63         char name[LTTNG_SYMBOL_NAME_LEN];
  64         uint32_t enabled;
  65         struct lttng_channel_attr attr;
  66
  67         char padding[LTTNG_CHANNEL_PADDING1];
  68 };
  69
  70 /*
  71  * List the channel(s) of a session.
  72  *
  73  * The handle CAN NOT be NULL.
  74  *
  75  * Return the size (number of entries) of the "lttng_channel" array. Caller
  76  * must free channels. On error, a negative LTTng error code is returned.
  77  */
  78 extern int lttng_list_channels(struct lttng_handle *handle,
  79                 struct lttng_channel **channels);
  80
  81 /*
  82  * Create or enable a channel.
  83  *
  84  * The chan and handle params can not be NULL.
  85  *
  86  * Return 0 on success else a negative LTTng error code.
  87  */
  88 extern int lttng_enable_channel(struct lttng_handle *handle,
  89                 struct lttng_channel *chan);
  90
  91 /*
  92  * Disable channel.
  93  *
  94  * Name and handle CAN NOT be NULL.
  95  *
  96  * Return 0 on success else a negative LTTng error code.
  97  */
  98 extern int lttng_disable_channel(struct lttng_handle *handle,
  99                 const char *name);
 100
 101 /*
 102  * Set the default channel attributes for a specific domain and an allocated
 103  * lttng_channel_attr pointer.
 104  *
 105  * If one or both arguments are NULL, nothing happens.
 106  */
 107 extern void lttng_channel_set_default_attr(struct lttng_domain *domain,
 108                 struct lttng_channel_attr *attr);
 109
 110 #ifdef __cplusplus
 111 }
 112 #endif
 113
 114 #endif /* LTTNG_CHANNEL_H */