| 1 | --- |
| 2 | id: liblttng‑ust‑libc‑pthread-wrapper |
| 3 | --- |
| 4 | |
| 5 | `liblttng-ust-libc-wrapper.so` and `liblttng-ust-pthread-wrapper.so` |
| 6 | can add instrumentation to respectively some C standard library and |
| 7 | POSIX threads functions. |
| 8 | |
| 9 | The following functions are traceable by `liblttng-ust-libc-wrapper.so`: |
| 10 | |
| 11 | <div class="table"> |
| 12 | <table class="func-desc"> |
| 13 | <thead> |
| 14 | <tr> |
| 15 | <th><abbr title="Tracepoint">TP</abbr> provider name</th> |
| 16 | <th><abbr title="Tracepoint">TP</abbr> name</th> |
| 17 | <th>Instrumented function</th> |
| 18 | </tr> |
| 19 | </thead> |
| 20 | <tbody> |
| 21 | <tr> |
| 22 | <td rowspan="6"> |
| 23 | <code class="no-bg">ust_libc</code> |
| 24 | </td> |
| 25 | <td> |
| 26 | <code class="no-bg">malloc</code> |
| 27 | </td> |
| 28 | <td> |
| 29 | <code class="no-bg">malloc()</code> |
| 30 | </td> |
| 31 | </tr> |
| 32 | <tr> |
| 33 | <td> |
| 34 | <code class="no-bg">calloc</code> |
| 35 | </td> |
| 36 | <td> |
| 37 | <code class="no-bg">calloc()</code> |
| 38 | </td> |
| 39 | </tr> |
| 40 | <tr> |
| 41 | <td> |
| 42 | <code class="no-bg">realloc</code> |
| 43 | </td> |
| 44 | <td> |
| 45 | <code class="no-bg">realloc()</code> |
| 46 | </td> |
| 47 | </tr> |
| 48 | <tr> |
| 49 | <td> |
| 50 | <code class="no-bg">free</code> |
| 51 | </td> |
| 52 | <td> |
| 53 | <code class="no-bg">free()</code> |
| 54 | </td> |
| 55 | </tr> |
| 56 | <tr> |
| 57 | <td> |
| 58 | <code class="no-bg">memalign</code> |
| 59 | </td> |
| 60 | <td> |
| 61 | <code class="no-bg">memalign()</code> |
| 62 | </td> |
| 63 | </tr> |
| 64 | <tr> |
| 65 | <td> |
| 66 | <code class="no-bg">posix_memalign</code> |
| 67 | </td> |
| 68 | <td> |
| 69 | <code class="no-bg">posix_memalign()</code> |
| 70 | </td> |
| 71 | </tr> |
| 72 | </tbody> |
| 73 | </table> |
| 74 | </div> |
| 75 | |
| 76 | The following functions are traceable by |
| 77 | `liblttng-ust-pthread-wrapper.so`: |
| 78 | |
| 79 | <div class="table"> |
| 80 | <table class="func-desc"> |
| 81 | <thead> |
| 82 | <tr> |
| 83 | <th><abbr title="Tracepoint">TP</abbr> provider name</th> |
| 84 | <th><abbr title="Tracepoint">TP</abbr> name</th> |
| 85 | <th>Instrumented function</th> |
| 86 | </tr> |
| 87 | </thead> |
| 88 | <tbody> |
| 89 | <tr> |
| 90 | <td rowspan="4"> |
| 91 | <code class="no-bg">ust_pthread</code> |
| 92 | </td> |
| 93 | <td> |
| 94 | <code class="no-bg">pthread_mutex_lock_req</code> |
| 95 | </td> |
| 96 | <td> |
| 97 | <code class="no-bg">pthread_mutex_lock()</code> (request time) |
| 98 | </td> |
| 99 | </tr> |
| 100 | <tr> |
| 101 | <td> |
| 102 | <code class="no-bg">pthread_mutex_lock_acq</code> |
| 103 | </td> |
| 104 | <td> |
| 105 | <code class="no-bg">pthread_mutex_lock()</code> (acquire time) |
| 106 | </td> |
| 107 | </tr> |
| 108 | <tr> |
| 109 | <td> |
| 110 | <code class="no-bg">pthread_mutex_trylock</code> |
| 111 | </td> |
| 112 | <td> |
| 113 | <code class="no-bg">pthread_mutex_trylock()</code> |
| 114 | </td> |
| 115 | </tr> |
| 116 | <tr> |
| 117 | <td> |
| 118 | <code class="no-bg">pthread_mutex_unlock</code> |
| 119 | </td> |
| 120 | <td> |
| 121 | <code class="no-bg">pthread_mutex_unlock()</code> |
| 122 | </td> |
| 123 | </tr> |
| 124 | </tbody> |
| 125 | </table> |
| 126 | </div> |
| 127 | |
| 128 | All tracepoints have fields corresponding to the arguments of the |
| 129 | function they instrument. |
| 130 | |
| 131 | To use one or the other with any user application, independently of |
| 132 | how the latter is built, do: |
| 133 | |
| 134 | <pre class="term"> |
| 135 | LD_PRELOAD=liblttng-ust-libc-wrapper.so my-app |
| 136 | </pre> |
| 137 | |
| 138 | or |
| 139 | |
| 140 | <pre class="term"> |
| 141 | LD_PRELOAD=liblttng-ust-pthread-wrapper.so my-app |
| 142 | </pre> |
| 143 | |
| 144 | To use both, do: |
| 145 | |
| 146 | <pre class="term"> |
| 147 | LD_PRELOAD="liblttng-ust-libc-wrapper.so liblttng-ust-pthread-wrapper.so" my-app |
| 148 | </pre> |
| 149 | |
| 150 | When the shared object is preloaded, it effectively replaces the |
| 151 | functions listed in the above tables by wrappers which add tracepoints |
| 152 | and call the replaced functions. |
| 153 | |
| 154 | Of course, like any other tracepoint, the ones above need to be enabled |
| 155 | in order for LTTng-UST to generate events. This is done using the |
| 156 | `lttng` command line tool |
| 157 | (see [Controlling tracing](#doc-controlling-tracing)). |