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 = pthread_getspecific(tr2tls_key);
  65
  66         /*
  67          * If the thread-proc did not call trace2_thread_start(), we won't
  68          * have any TLS data associated with the current thread.  Fix it
  69          * here and silently continue.
  70          */
  71         if (!ctx)
  72                 ctx = tr2tls_create_self("unknown", getnanotime() / 1000);
  73
  74         return ctx;
  75 }
  76
  77 int tr2tls_is_main_thread(void)
  78 {
  79         struct tr2tls_thread_ctx *ctx = pthread_getspecific(tr2tls_key);
  80
  81         return ctx == tr2tls_thread_main;
  82 }
  83
  84 void tr2tls_unset_self(void)
  85 {
  86         struct tr2tls_thread_ctx *ctx;
  87
  88         ctx = tr2tls_get_self();
  89
  90         pthread_setspecific(tr2tls_key, NULL);
  91
  92         free(ctx->array_us_start);
  93         free(ctx);
  94 }
  95
  96 void tr2tls_push_self(uint64_t us_now)
  97 {
  98         struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
  99
 100         ALLOC_GROW(ctx->array_us_start, ctx->nr_open_regions + 1, ctx->alloc);
 101         ctx->array_us_start[ctx->nr_open_regions++] = us_now;
 102 }
 103
 104 void tr2tls_pop_self(void)
 105 {
 106         struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
 107
 108         if (!ctx->nr_open_regions)
 109                 BUG("no open regions in thread '%s'", ctx->thread_name.buf);
 110
 111         ctx->nr_open_regions--;
 112 }
 113
 114 void tr2tls_pop_unwind_self(void)
 115 {
 116         struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
 117
 118         while (ctx->nr_open_regions > 1)
 119                 tr2tls_pop_self();
 120 }
 121
 122 uint64_t tr2tls_region_elasped_self(uint64_t us)
 123 {
 124         struct tr2tls_thread_ctx *ctx;
 125         uint64_t us_start;
 126
 127         ctx = tr2tls_get_self();
 128         if (!ctx->nr_open_regions)
 129                 return 0;
 130
 131         us_start = ctx->array_us_start[ctx->nr_open_regions - 1];
 132
 133         return us - us_start;
 134 }
 135
 136 uint64_t tr2tls_absolute_elapsed(uint64_t us)
 137 {
 138         if (!tr2tls_thread_main)
 139                 return 0;
 140
 141         return us - tr2tls_us_start_process;
 142 }
 143
 144 void tr2tls_init(void)
 145 {
 146         tr2tls_start_process_clock();
 147
 148         pthread_key_create(&tr2tls_key, NULL);
 149         init_recursive_mutex(&tr2tls_mutex);
 150
 151         tr2tls_thread_main =
 152                 tr2tls_create_self("main", tr2tls_us_start_process);
 153 }
 154
 155 void tr2tls_release(void)
 156 {
 157         tr2tls_unset_self();
 158         tr2tls_thread_main = NULL;
 159
 160         pthread_mutex_destroy(&tr2tls_mutex);
 161         pthread_key_delete(tr2tls_key);
 162 }
 163
 164 int tr2tls_locked_increment(int *p)
 165 {
 166         int current_value;
 167
 168         pthread_mutex_lock(&tr2tls_mutex);
 169         current_value = *p;
 170         *p = current_value + 1;
 171         pthread_mutex_unlock(&tr2tls_mutex);
 172
 173         return current_value;
 174 }