src/common/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-config.h>
  16 #include <lttng/ust-events.h>
  17
  18 #include "common/dynamic-type.h"
  19
  20 struct lttng_ust_registered_context_provider;
  21 struct lttng_ust_probe_ctx;
  22
  23 /*
  24  * Context value
  25  *
  26  * IMPORTANT: this structure is part of the ABI between the probe and
  27  * UST. Additional selectors may be added in the future, mapping to new
  28  * union fields, which means the overall size of this structure may
  29  * increase. This means this structure should never be nested within a
  30  * public structure interface, nor embedded in an array.
  31  */
  32
  33 struct lttng_ust_ctx_value {
  34         enum lttng_ust_dynamic_type sel;        /* Type selector */
  35         union {
  36                 int64_t s64;
  37                 uint64_t u64;
  38                 const char *str;
  39                 double d;
  40         } u;
  41 };
  42
  43 /*
  44  * Context provider
  45  *
  46  * IMPORTANT: this structure is part of the ABI between the probe and
  47  * UST. Fields need to be only added at the end, never reordered, never
  48  * removed.
  49  *
  50  * The field @struct_size should be used to determine the size of the
  51  * structure. It should be queried before using additional fields added
  52  * at the end of the structure.
  53  */
  54
  55 struct lttng_ust_context_provider {
  56         uint32_t struct_size;
  57
  58         const char *name;
  59         size_t (*get_size)(void *priv, struct lttng_ust_probe_ctx *probe_ctx,
  60                         size_t offset);
  61         void (*record)(void *priv, struct lttng_ust_probe_ctx *probe_ctx,
  62                         struct lttng_ust_ring_buffer_ctx *ctx,
  63                         struct lttng_ust_channel_buffer *chan);
  64         void (*get_value)(void *priv, struct lttng_ust_probe_ctx *probe_ctx,
  65                         struct lttng_ust_ctx_value *value);
  66         void *priv;
  67
  68         /* End of base ABI. Fields below should be used after checking struct_size. */
  69 };
  70
  71 /*
  72  * Application context callback private data
  73  *
  74  * IMPORTANT: this structure is part of the ABI between the probe and
  75  * UST. Fields need to be only added at the end, never reordered, never
  76  * removed.
  77  *
  78  * The field @struct_size should be used to determine the size of the
  79  * structure. It should be queried before using additional fields added
  80  * at the end of the structure.
  81  */
  82
  83 struct lttng_ust_app_context {
  84         uint32_t struct_size;
  85
  86         struct lttng_ust_event_field *event_field;
  87         char *ctx_name;
  88
  89         /* End of base ABI. Fields below should be used after checking struct_size. */
  90 };
  91
  92 /* Custom upgrade 2.12 to 2.13 */
  93 #ifndef LTTNG_UST_CUSTOM_UPGRADE_CONFLICTING_SYMBOLS
  94 #define lttng_ust_context_provider_register             lttng_ust_context_provider_register1
  95 #define lttng_ust_context_provider_unregister           lttng_ust_context_provider_unregister1
  96 #endif
  97
  98 /*
  99  * Returns an opaque pointer on success, which must be passed to
 100  * lttng_ust_context_provider_unregister for unregistration. Returns
 101  * NULL on error.
 102  */
 103 struct lttng_ust_registered_context_provider *lttng_ust_context_provider_register(struct lttng_ust_context_provider *provider);
 104
 105 void lttng_ust_context_provider_unregister(struct lttng_ust_registered_context_provider *reg_provider);
 106
 107 #endif /* _LTTNG_UST_CONTEXT_PROVIDER_H */