include/ust-context-provider.h

   1 /*
   2  * SPDX-License-Identifier: MIT
   3  *
   4  * Copyright (C) 2016 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * The context provider feature is part of the ABI and used by the Java jni
   7  * interface. This header should be moved to the public header directory once
   8  * some test code and documentation is written.
   9  */
  10
  11 #ifndef _LTTNG_UST_CONTEXT_PROVIDER_H
  12 #define _LTTNG_UST_CONTEXT_PROVIDER_H
  13
  14 #include <stddef.h>
  15 #include <lttng/ust-events.h>
  16 #include <urcu/hlist.h>
  17
  18 #include "ust-dynamic-type.h"
  19
  20 /*
  21  * Context value
  22  *
  23  * IMPORTANT: this structure is part of the ABI between the probe and
  24  * UST. Fields need to be only added at the end, never reordered, never
  25  * removed.
  26  *
  27  * The field @struct_size should be used to determine the size of the
  28  * structure. It should be queried before using additional fields added
  29  * at the end of the structure.
  30  */
  31
  32 struct lttng_ust_ctx_value {
  33         uint32_t struct_size;
  34
  35         enum lttng_ust_dynamic_type sel;
  36         union {
  37                 int64_t s64;
  38                 uint64_t u64;
  39                 const char *str;
  40                 double d;
  41         } u;
  42
  43         /* End of base ABI. Fields below should be used after checking struct_size. */
  44 };
  45
  46 /*
  47  * Context field
  48  *
  49  * IMPORTANT: this structure is part of the ABI between the probe and
  50  * UST. Fields need to be only added at the end, never reordered, never
  51  * removed.
  52  *
  53  * The field @struct_size should be used to determine the size of the
  54  * structure. It should be queried before using additional fields added
  55  * at the end of the structure.
  56  */
  57
  58 struct lttng_ust_ctx_field {
  59         uint32_t struct_size;
  60         void *priv;
  61
  62         struct lttng_ust_event_field *event_field;
  63         size_t (*get_size)(struct lttng_ust_ctx_field *field, size_t offset);
  64         void (*record)(struct lttng_ust_ctx_field *field,
  65                        struct lttng_ust_lib_ring_buffer_ctx *ctx,
  66                        struct lttng_channel *chan);
  67         void (*get_value)(struct lttng_ust_ctx_field *field,
  68                          struct lttng_ust_ctx_value *value);
  69         void (*destroy)(struct lttng_ust_ctx_field *field);
  70         char *field_name;       /* Has ownership, dynamically allocated. */
  71
  72         /* End of base ABI. Fields below should be used after checking struct_size. */
  73 };
  74
  75 /*
  76  * All context fields for a given event/channel
  77  *
  78  * IMPORTANT: this structure is part of the ABI between the probe and
  79  * UST. Fields need to be only added at the end, never reordered, never
  80  * removed.
  81  *
  82  * The field @struct_size should be used to determine the size of the
  83  * structure. It should be queried before using additional fields added
  84  * at the end of the structure.
  85  */
  86
  87 struct lttng_ust_ctx {
  88         uint32_t struct_size;
  89
  90         struct lttng_ust_ctx_field **fields;
  91         unsigned int nr_fields;
  92         unsigned int allocated_fields;
  93         unsigned int largest_align;
  94
  95         /* End of base ABI. Fields below should be used after checking struct_size. */
  96 };
  97
  98 /*
  99  * Context provider
 100  *
 101  * IMPORTANT: this structure is part of the ABI between the probe and
 102  * UST. Fields need to be only added at the end, never reordered, never
 103  * removed.
 104  *
 105  * The field @struct_size should be used to determine the size of the
 106  * structure. It should be queried before using additional fields added
 107  * at the end of the structure.
 108  */
 109
 110 struct lttng_ust_context_provider {
 111         uint32_t struct_size;
 112
 113         char *name;
 114         size_t (*get_size)(struct lttng_ust_ctx_field *field, size_t offset);
 115         void (*record)(struct lttng_ust_ctx_field *field,
 116                        struct lttng_ust_lib_ring_buffer_ctx *ctx,
 117                        struct lttng_channel *chan);
 118         void (*get_value)(struct lttng_ust_ctx_field *field,
 119                          struct lttng_ust_ctx_value *value);
 120         struct cds_hlist_node node;
 121
 122         /* End of base ABI. Fields below should be used after checking struct_size. */
 123 };
 124
 125 int lttng_ust_context_provider_register(struct lttng_ust_context_provider *provider);
 126 void lttng_ust_context_provider_unregister(struct lttng_ust_context_provider *provider);
 127
 128 void lttng_ust_context_set_session_provider(const char *name,
 129                 size_t (*get_size)(struct lttng_ust_ctx_field *field, size_t offset),
 130                 void (*record)(struct lttng_ust_ctx_field *field,
 131                         struct lttng_ust_lib_ring_buffer_ctx *ctx,
 132                         struct lttng_channel *chan),
 133                 void (*get_value)(struct lttng_ust_ctx_field *field,
 134                         struct lttng_ust_ctx_value *value));
 135
 136 int lttng_ust_add_app_context_to_ctx_rcu(const char *name, struct lttng_ust_ctx **ctx);
 137 int lttng_ust_context_set_provider_rcu(struct lttng_ust_ctx **_ctx,
 138                 const char *name,
 139                 size_t (*get_size)(struct lttng_ust_ctx_field *field, size_t offset),
 140                 void (*record)(struct lttng_ust_ctx_field *field,
 141                         struct lttng_ust_lib_ring_buffer_ctx *ctx,
 142                         struct lttng_channel *chan),
 143                 void (*get_value)(struct lttng_ust_ctx_field *field,
 144                         struct lttng_ust_ctx_value *value));
 145
 146 #endif /* _LTTNG_UST_CONTEXT_PROVIDER_H */