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. Additional selectors may be added in the future, mapping to new
  25  * union fields, which means the overall size of this structure may
  26  * increase. This means this structure should never be nested within a
  27  * public structure interface, nor embedded in an array.
  28  */
  29
  30 struct lttng_ust_ctx_value {
  31         enum lttng_ust_dynamic_type sel;        /* Type selector */
  32         union {
  33                 int64_t s64;
  34                 uint64_t u64;
  35                 const char *str;
  36                 double d;
  37         } u;
  38 };
  39
  40 /*
  41  * Context field
  42  *
  43  * IMPORTANT: this structure is part of the ABI between the probe and
  44  * UST. Fields need to be only added at the end, never reordered, never
  45  * removed.
  46  *
  47  * The field @struct_size should be used to determine the size of the
  48  * structure. It should be queried before using additional fields added
  49  * at the end of the structure.
  50  */
  51
  52 struct lttng_ust_ctx_field {
  53         uint32_t struct_size;
  54         void *priv;
  55
  56         struct lttng_ust_event_field *event_field;
  57         size_t (*get_size)(struct lttng_ust_ctx_field *field, size_t offset);
  58         void (*record)(struct lttng_ust_ctx_field *field,
  59                        struct lttng_ust_lib_ring_buffer_ctx *ctx,
  60                        struct lttng_ust_channel_buffer *chan);
  61         void (*get_value)(struct lttng_ust_ctx_field *field,
  62                          struct lttng_ust_ctx_value *value);
  63         void (*destroy)(struct lttng_ust_ctx_field *field);
  64
  65         /* End of base ABI. Fields below should be used after checking struct_size. */
  66 };
  67
  68 /*
  69  * All context fields for a given event/channel
  70  *
  71  * IMPORTANT: this structure is part of the ABI between the probe and
  72  * UST. Fields need to be only added at the end, never reordered, never
  73  * removed.
  74  *
  75  * The field @struct_size should be used to determine the size of the
  76  * structure. It should be queried before using additional fields added
  77  * at the end of the structure.
  78  */
  79
  80 struct lttng_ust_ctx {
  81         uint32_t struct_size;
  82
  83         struct lttng_ust_ctx_field **fields;
  84         unsigned int nr_fields;
  85         unsigned int allocated_fields;
  86         unsigned int largest_align;
  87
  88         /* End of base ABI. Fields below should be used after checking struct_size. */
  89 };
  90
  91 /*
  92  * Context provider
  93  *
  94  * IMPORTANT: this structure is part of the ABI between the probe and
  95  * UST. Fields need to be only added at the end, never reordered, never
  96  * removed.
  97  *
  98  * The field @struct_size should be used to determine the size of the
  99  * structure. It should be queried before using additional fields added
 100  * at the end of the structure.
 101  */
 102
 103 struct lttng_ust_context_provider {
 104         uint32_t struct_size;
 105
 106         char *name;
 107         size_t (*get_size)(struct lttng_ust_ctx_field *field, size_t offset);
 108         void (*record)(struct lttng_ust_ctx_field *field,
 109                        struct lttng_ust_lib_ring_buffer_ctx *ctx,
 110                        struct lttng_ust_channel_buffer *chan);
 111         void (*get_value)(struct lttng_ust_ctx_field *field,
 112                          struct lttng_ust_ctx_value *value);
 113         struct cds_hlist_node node;
 114
 115         /* End of base ABI. Fields below should be used after checking struct_size. */
 116 };
 117
 118 int lttng_ust_context_provider_register(struct lttng_ust_context_provider *provider);
 119 void lttng_ust_context_provider_unregister(struct lttng_ust_context_provider *provider);
 120
 121 void lttng_ust_context_set_session_provider(const char *name,
 122                 size_t (*get_size)(struct lttng_ust_ctx_field *field, size_t offset),
 123                 void (*record)(struct lttng_ust_ctx_field *field,
 124                         struct lttng_ust_lib_ring_buffer_ctx *ctx,
 125                         struct lttng_ust_channel_buffer *chan),
 126                 void (*get_value)(struct lttng_ust_ctx_field *field,
 127                         struct lttng_ust_ctx_value *value));
 128
 129 int lttng_ust_add_app_context_to_ctx_rcu(const char *name, struct lttng_ust_ctx **ctx);
 130 int lttng_ust_context_set_provider_rcu(struct lttng_ust_ctx **_ctx,
 131                 const char *name,
 132                 size_t (*get_size)(struct lttng_ust_ctx_field *field, size_t offset),
 133                 void (*record)(struct lttng_ust_ctx_field *field,
 134                         struct lttng_ust_lib_ring_buffer_ctx *ctx,
 135                         struct lttng_ust_channel_buffer *chan),
 136                 void (*get_value)(struct lttng_ust_ctx_field *field,
 137                         struct lttng_ust_ctx_value *value));
 138
 139 #endif /* _LTTNG_UST_CONTEXT_PROVIDER_H */