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_base_name,
  35                                              uint64_t us_thread_start)
  36 {
  37         struct tr2tls_thread_ctx *ctx = xcalloc(1, sizeof(*ctx));
  38         struct strbuf buf = STRBUF_INIT;
  39
  40         /*
  41          * Implicitly "tr2tls_push_self()" to capture the thread's start
  42          * time in array_us_start[0].  For the main thread this gives us the
  43          * application run time.
  44          */
  45         ctx->alloc = TR2_REGION_NESTING_INITIAL_SIZE;
  46         ctx->array_us_start = (uint64_t *)xcalloc(ctx->alloc, sizeof(uint64_t));
  47         ctx->array_us_start[ctx->nr_open_regions++] = us_thread_start;
  48
  49         ctx->thread_id = tr2tls_locked_increment(&tr2_next_thread_id);
  50
  51         strbuf_init(&buf, 0);
  52         if (ctx->thread_id)
  53                 strbuf_addf(&buf, "th%02d:", ctx->thread_id);
  54         strbuf_addstr(&buf, thread_base_name);
  55         if (buf.len > TR2_MAX_THREAD_NAME)
  56                 strbuf_setlen(&buf, TR2_MAX_THREAD_NAME);
  57         ctx->thread_name = strbuf_detach(&buf, NULL);
  58
  59         pthread_setspecific(tr2tls_key, ctx);
  60
  61         return ctx;
  62 }
  63
  64 struct tr2tls_thread_ctx *tr2tls_get_self(void)
  65 {
  66         struct tr2tls_thread_ctx *ctx;
  67
  68         if (!HAVE_THREADS)
  69                 return tr2tls_thread_main;
  70
  71         ctx = pthread_getspecific(tr2tls_key);
  72
  73         /*
  74          * If the current thread's thread-proc did not call
  75          * trace2_thread_start(), then the thread will not have any
  76          * thread-local storage.  Create it now and silently continue.
  77          */
  78         if (!ctx)
  79                 ctx = tr2tls_create_self("unknown", getnanotime() / 1000);
  80
  81         return ctx;
  82 }
  83
  84 int tr2tls_is_main_thread(void)
  85 {
  86         if (!HAVE_THREADS)
  87                 return 1;
  88
  89         return pthread_getspecific(tr2tls_key) == tr2tls_thread_main;
  90 }
  91
  92 void tr2tls_unset_self(void)
  93 {
  94         struct tr2tls_thread_ctx *ctx;
  95
  96         ctx = tr2tls_get_self();
  97
  98         pthread_setspecific(tr2tls_key, NULL);
  99
 100         free((char *)ctx->thread_name);
 101         free(ctx->array_us_start);
 102         free(ctx);
 103 }
 104
 105 void tr2tls_push_self(uint64_t us_now)
 106 {
 107         struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
 108
 109         ALLOC_GROW(ctx->array_us_start, ctx->nr_open_regions + 1, ctx->alloc);
 110         ctx->array_us_start[ctx->nr_open_regions++] = us_now;
 111 }
 112
 113 void tr2tls_pop_self(void)
 114 {
 115         struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
 116
 117         if (!ctx->nr_open_regions)
 118                 BUG("no open regions in thread '%s'", ctx->thread_name);
 119
 120         ctx->nr_open_regions--;
 121 }
 122
 123 void tr2tls_pop_unwind_self(void)
 124 {
 125         struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
 126
 127         while (ctx->nr_open_regions > 1)
 128                 tr2tls_pop_self();
 129 }
 130
 131 uint64_t tr2tls_region_elasped_self(uint64_t us)
 132 {
 133         struct tr2tls_thread_ctx *ctx;
 134         uint64_t us_start;
 135
 136         ctx = tr2tls_get_self();
 137         if (!ctx->nr_open_regions)
 138                 return 0;
 139
 140         us_start = ctx->array_us_start[ctx->nr_open_regions - 1];
 141
 142         return us - us_start;
 143 }
 144
 145 uint64_t tr2tls_absolute_elapsed(uint64_t us)
 146 {
 147         if (!tr2tls_thread_main)
 148                 return 0;
 149
 150         return us - tr2tls_us_start_process;
 151 }
 152
 153 void tr2tls_init(void)
 154 {
 155         tr2tls_start_process_clock();
 156
 157         pthread_key_create(&tr2tls_key, NULL);
 158         init_recursive_mutex(&tr2tls_mutex);
 159
 160         tr2tls_thread_main =
 161                 tr2tls_create_self("main", tr2tls_us_start_process);
 162 }
 163
 164 void tr2tls_release(void)
 165 {
 166         tr2tls_unset_self();
 167         tr2tls_thread_main = NULL;
 168
 169         pthread_mutex_destroy(&tr2tls_mutex);
 170         pthread_key_delete(tr2tls_key);
 171 }
 172
 173 int tr2tls_locked_increment(int *p)
 174 {
 175         int current_value;
 176
 177         pthread_mutex_lock(&tr2tls_mutex);
 178         current_value = *p;
 179         *p = current_value + 1;
 180         pthread_mutex_unlock(&tr2tls_mutex);
 181
 182         return current_value;
 183 }