trace2/tr2_tls.c

   1 #include "cache.h"
   2 #include "thread-utils.h"
   3 #include "trace2/tr2_tls.h"
   4
   5 /*
   6  * Initialize size of the thread stack for nested regions.
   7  * This is used to store nested region start times.  Note that
   8  * this stack is per-thread and not per-trace-key.
   9  */
  10 #define TR2_REGION_NESTING_INITIAL_SIZE (100)
  11
  12 static struct tr2tls_thread_ctx *tr2tls_thread_main;
  13 static uint64_t tr2tls_us_start_process;
  14
  15 static pthread_mutex_t tr2tls_mutex;
  16 static pthread_key_t tr2tls_key;
  17
  18 static int tr2_next_thread_id; /* modify under lock */
  19
  20 void tr2tls_start_process_clock(void)
  21 {
  22         if (tr2tls_us_start_process)
  23                 return;
  24
  25         /*
  26          * Keep the absolute start time of the process (i.e. the main
  27          * process) in a fixed variable since other threads need to
  28          * access it.  This allows them to do that without a lock on
  29          * main thread's array data (because of reallocs).
  30          */
  31         tr2tls_us_start_process = getnanotime() / 1000;
  32 }
  33
  34 struct tr2tls_thread_ctx *tr2tls_create_self(const char *thread_name,
  35                                              uint64_t us_thread_start)
  36 {
  37         struct tr2tls_thread_ctx *ctx = xcalloc(1, sizeof(*ctx));
  38
  39         /*
  40          * Implicitly "tr2tls_push_self()" to capture the thread's start
  41          * time in array_us_start[0].  For the main thread this gives us the
  42          * application run time.
  43          */
  44         ctx->alloc = TR2_REGION_NESTING_INITIAL_SIZE;
  45         ctx->array_us_start = (uint64_t *)xcalloc(ctx->alloc, sizeof(uint64_t));
  46         ctx->array_us_start[ctx->nr_open_regions++] = us_thread_start;
  47
  48         ctx->thread_id = tr2tls_locked_increment(&tr2_next_thread_id);
  49
  50         strbuf_init(&ctx->thread_name, 0);
  51         if (ctx->thread_id)
  52                 strbuf_addf(&ctx->thread_name, "th%02d:", ctx->thread_id);
  53         strbuf_addstr(&ctx->thread_name, thread_name);
  54         if (ctx->thread_name.len > TR2_MAX_THREAD_NAME)
  55                 strbuf_setlen(&ctx->thread_name, TR2_MAX_THREAD_NAME);
  56
  57         pthread_setspecific(tr2tls_key, ctx);
  58
  59         return ctx;
  60 }
  61
  62 struct tr2tls_thread_ctx *tr2tls_get_self(void)
  63 {
  64         struct tr2tls_thread_ctx *ctx;
  65
  66         if (!HAVE_THREADS)
  67                 return tr2tls_thread_main;
  68
  69         ctx = pthread_getspecific(tr2tls_key);
  70
  71         /*
  72          * If the thread-proc did not call trace2_thread_start(), we won't
  73          * have any TLS data associated with the current thread.  Fix it
  74          * here and silently continue.
  75          */
  76         if (!ctx)
  77                 ctx = tr2tls_create_self("unknown", getnanotime() / 1000);
  78
  79         return ctx;
  80 }
  81
  82 int tr2tls_is_main_thread(void)
  83 {
  84         if (!HAVE_THREADS)
  85                 return 1;
  86
  87         return pthread_getspecific(tr2tls_key) == tr2tls_thread_main;
  88 }
  89
  90 void tr2tls_unset_self(void)
  91 {
  92         struct tr2tls_thread_ctx *ctx;
  93
  94         ctx = tr2tls_get_self();
  95
  96         pthread_setspecific(tr2tls_key, NULL);
  97
  98         free(ctx->array_us_start);
  99         free(ctx);
 100 }
 101
 102 void tr2tls_push_self(uint64_t us_now)
 103 {
 104         struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
 105
 106         ALLOC_GROW(ctx->array_us_start, ctx->nr_open_regions + 1, ctx->alloc);
 107         ctx->array_us_start[ctx->nr_open_regions++] = us_now;
 108 }
 109
 110 void tr2tls_pop_self(void)
 111 {
 112         struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
 113
 114         if (!ctx->nr_open_regions)
 115                 BUG("no open regions in thread '%s'", ctx->thread_name.buf);
 116
 117         ctx->nr_open_regions--;
 118 }
 119
 120 void tr2tls_pop_unwind_self(void)
 121 {
 122         struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
 123
 124         while (ctx->nr_open_regions > 1)
 125                 tr2tls_pop_self();
 126 }
 127
 128 uint64_t tr2tls_region_elasped_self(uint64_t us)
 129 {
 130         struct tr2tls_thread_ctx *ctx;
 131         uint64_t us_start;
 132
 133         ctx = tr2tls_get_self();
 134         if (!ctx->nr_open_regions)
 135                 return 0;
 136
 137         us_start = ctx->array_us_start[ctx->nr_open_regions - 1];
 138
 139         return us - us_start;
 140 }
 141
 142 uint64_t tr2tls_absolute_elapsed(uint64_t us)
 143 {
 144         if (!tr2tls_thread_main)
 145                 return 0;
 146
 147         return us - tr2tls_us_start_process;
 148 }
 149
 150 void tr2tls_init(void)
 151 {
 152         tr2tls_start_process_clock();
 153
 154         pthread_key_create(&tr2tls_key, NULL);
 155         init_recursive_mutex(&tr2tls_mutex);
 156
 157         tr2tls_thread_main =
 158                 tr2tls_create_self("main", tr2tls_us_start_process);
 159 }
 160
 161 void tr2tls_release(void)
 162 {
 163         tr2tls_unset_self();
 164         tr2tls_thread_main = NULL;
 165
 166         pthread_mutex_destroy(&tr2tls_mutex);
 167         pthread_key_delete(tr2tls_key);
 168 }
 169
 170 int tr2tls_locked_increment(int *p)
 171 {
 172         int current_value;
 173
 174         pthread_mutex_lock(&tr2tls_mutex);
 175         current_value = *p;
 176         *p = current_value + 1;
 177         pthread_mutex_unlock(&tr2tls_mutex);
 178
 179         return current_value;
 180 }