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_main;
  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 struct tr2tls_thread_ctx *tr2tls_create_self(const char *thread_name)
  21 {
  22         uint64_t us_now = getnanotime() / 1000;
  23         struct tr2tls_thread_ctx *ctx = xcalloc(1, sizeof(*ctx));
  24
  25         /*
  26          * Implicitly "tr2tls_push_self()" to capture the thread's start
  27          * time in array_us_start[0].  For the main thread this gives us the
  28          * application run time.
  29          */
  30         ctx->alloc = TR2_REGION_NESTING_INITIAL_SIZE;
  31         ctx->array_us_start = (uint64_t *)xcalloc(ctx->alloc, sizeof(uint64_t));
  32         ctx->array_us_start[ctx->nr_open_regions++] = us_now;
  33
  34         ctx->thread_id = tr2tls_locked_increment(&tr2_next_thread_id);
  35
  36         strbuf_init(&ctx->thread_name, 0);
  37         if (ctx->thread_id)
  38                 strbuf_addf(&ctx->thread_name, "th%02d:", ctx->thread_id);
  39         strbuf_addstr(&ctx->thread_name, thread_name);
  40         if (ctx->thread_name.len > TR2_MAX_THREAD_NAME)
  41                 strbuf_setlen(&ctx->thread_name, TR2_MAX_THREAD_NAME);
  42
  43         pthread_setspecific(tr2tls_key, ctx);
  44
  45         return ctx;
  46 }
  47
  48 struct tr2tls_thread_ctx *tr2tls_get_self(void)
  49 {
  50         struct tr2tls_thread_ctx *ctx = pthread_getspecific(tr2tls_key);
  51
  52         /*
  53          * If the thread-proc did not call trace2_thread_start(), we won't
  54          * have any TLS data associated with the current thread.  Fix it
  55          * here and silently continue.
  56          */
  57         if (!ctx)
  58                 ctx = tr2tls_create_self("unknown");
  59
  60         return ctx;
  61 }
  62
  63 int tr2tls_is_main_thread(void)
  64 {
  65         struct tr2tls_thread_ctx *ctx = pthread_getspecific(tr2tls_key);
  66
  67         return ctx == tr2tls_thread_main;
  68 }
  69
  70 void tr2tls_unset_self(void)
  71 {
  72         struct tr2tls_thread_ctx *ctx;
  73
  74         ctx = tr2tls_get_self();
  75
  76         pthread_setspecific(tr2tls_key, NULL);
  77
  78         free(ctx->array_us_start);
  79         free(ctx);
  80 }
  81
  82 void tr2tls_push_self(uint64_t us_now)
  83 {
  84         struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
  85
  86         ALLOC_GROW(ctx->array_us_start, ctx->nr_open_regions + 1, ctx->alloc);
  87         ctx->array_us_start[ctx->nr_open_regions++] = us_now;
  88 }
  89
  90 void tr2tls_pop_self(void)
  91 {
  92         struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
  93
  94         if (!ctx->nr_open_regions)
  95                 BUG("no open regions in thread '%s'", ctx->thread_name.buf);
  96
  97         ctx->nr_open_regions--;
  98 }
  99
 100 void tr2tls_pop_unwind_self(void)
 101 {
 102         struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
 103
 104         while (ctx->nr_open_regions > 1)
 105                 tr2tls_pop_self();
 106 }
 107
 108 uint64_t tr2tls_region_elasped_self(uint64_t us)
 109 {
 110         struct tr2tls_thread_ctx *ctx;
 111         uint64_t us_start;
 112
 113         ctx = tr2tls_get_self();
 114         if (!ctx->nr_open_regions)
 115                 return 0;
 116
 117         us_start = ctx->array_us_start[ctx->nr_open_regions - 1];
 118
 119         return us - us_start;
 120 }
 121
 122 uint64_t tr2tls_absolute_elapsed(uint64_t us)
 123 {
 124         if (!tr2tls_thread_main)
 125                 return 0;
 126
 127         return us - tr2tls_us_start_main;
 128 }
 129
 130 void tr2tls_init(void)
 131 {
 132         pthread_key_create(&tr2tls_key, NULL);
 133         init_recursive_mutex(&tr2tls_mutex);
 134
 135         tr2tls_thread_main = tr2tls_create_self("main");
 136         /*
 137          * Keep a copy of the absolute start time of the main thread
 138          * in a fixed variable since other threads need to access it.
 139          * This also eliminates the need to lock accesses to the main
 140          * thread's array (because of reallocs).
 141          */
 142         tr2tls_us_start_main = tr2tls_thread_main->array_us_start[0];
 143 }
 144
 145 void tr2tls_release(void)
 146 {
 147         tr2tls_unset_self();
 148         tr2tls_thread_main = NULL;
 149
 150         pthread_mutex_destroy(&tr2tls_mutex);
 151         pthread_key_delete(tr2tls_key);
 152 }
 153
 154 int tr2tls_locked_increment(int *p)
 155 {
 156         int current_value;
 157
 158         pthread_mutex_lock(&tr2tls_mutex);
 159         current_value = *p;
 160         *p = current_value + 1;
 161         pthread_mutex_unlock(&tr2tls_mutex);
 162
 163         return current_value;
 164 }