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 */
  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
  47         char padding[LTTNG_CHANNEL_ATTR_PADDING1];
  48 };
  49
  50 /*
  51  * Channel information structure. For both kernel and user-space.
  52  *
  53  * The structures should be initialized to zero before use.
  54  */
  55 #define LTTNG_CHANNEL_PADDING1             16
  56 struct lttng_channel {
  57         char name[LTTNG_SYMBOL_NAME_LEN];
  58         uint32_t enabled;
  59         struct lttng_channel_attr attr;
  60
  61         char padding[LTTNG_CHANNEL_PADDING1];
  62 };
  63
  64 /*
  65  * List the channel(s) of a session.
  66  *
  67  * The handle CAN NOT be NULL.
  68  *
  69  * Return the size (number of entries) of the "lttng_channel" array. Caller
  70  * must free channels. On error, a negative LTTng error code is returned.
  71  */
  72 extern int lttng_list_channels(struct lttng_handle *handle,
  73                 struct lttng_channel **channels);
  74
  75 /*
  76  * Create or enable a channel.
  77  *
  78  * The chan and handle params can not be NULL.
  79  *
  80  * Return 0 on success else a negative LTTng error code.
  81  */
  82 extern int lttng_enable_channel(struct lttng_handle *handle,
  83                 struct lttng_channel *chan);
  84
  85 /*
  86  * Disable channel.
  87  *
  88  * Name and handle CAN NOT be NULL.
  89  *
  90  * Return 0 on success else a negative LTTng error code.
  91  */
  92 extern int lttng_disable_channel(struct lttng_handle *handle,
  93                 const char *name);
  94
  95 /*
  96  * Set the default channel attributes for a specific domain and an allocated
  97  * lttng_channel_attr pointer.
  98  *
  99  * If one or both arguments are NULL, nothing happens.
 100  */
 101 extern void lttng_channel_set_default_attr(struct lttng_domain *domain,
 102                 struct lttng_channel_attr *attr);
 103
 104 #ifdef __cplusplus
 105 }
 106 #endif
 107
 108 #endif /* LTTNG_CHANNEL_H */