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git/trace2/tr2_tls.c

181 lines
4.0 KiB

#include "cache.h"
#include "thread-utils.h"
#include "trace2/tr2_tls.h"
/*
* Initialize size of the thread stack for nested regions.
* This is used to store nested region start times. Note that
* this stack is per-thread and not per-trace-key.
*/
#define TR2_REGION_NESTING_INITIAL_SIZE (100)
static struct tr2tls_thread_ctx *tr2tls_thread_main;
static uint64_t tr2tls_us_start_process;
static pthread_mutex_t tr2tls_mutex;
static pthread_key_t tr2tls_key;
static int tr2_next_thread_id; /* modify under lock */
void tr2tls_start_process_clock(void)
{
if (tr2tls_us_start_process)
return;
/*
* Keep the absolute start time of the process (i.e. the main
* process) in a fixed variable since other threads need to
* access it. This allows them to do that without a lock on
* main thread's array data (because of reallocs).
*/
tr2tls_us_start_process = getnanotime() / 1000;
}
struct tr2tls_thread_ctx *tr2tls_create_self(const char *thread_name,
uint64_t us_thread_start)
{
struct tr2tls_thread_ctx *ctx = xcalloc(1, sizeof(*ctx));
/*
* Implicitly "tr2tls_push_self()" to capture the thread's start
* time in array_us_start[0]. For the main thread this gives us the
* application run time.
*/
ctx->alloc = TR2_REGION_NESTING_INITIAL_SIZE;
ctx->array_us_start = (uint64_t *)xcalloc(ctx->alloc, sizeof(uint64_t));
ctx->array_us_start[ctx->nr_open_regions++] = us_thread_start;
ctx->thread_id = tr2tls_locked_increment(&tr2_next_thread_id);
strbuf_init(&ctx->thread_name, 0);
if (ctx->thread_id)
strbuf_addf(&ctx->thread_name, "th%02d:", ctx->thread_id);
strbuf_addstr(&ctx->thread_name, thread_name);
if (ctx->thread_name.len > TR2_MAX_THREAD_NAME)
strbuf_setlen(&ctx->thread_name, TR2_MAX_THREAD_NAME);
pthread_setspecific(tr2tls_key, ctx);
return ctx;
}
struct tr2tls_thread_ctx *tr2tls_get_self(void)
{
struct tr2tls_thread_ctx *ctx;
if (!HAVE_THREADS)
return tr2tls_thread_main;
ctx = pthread_getspecific(tr2tls_key);
/*
* If the thread-proc did not call trace2_thread_start(), we won't
* have any TLS data associated with the current thread. Fix it
* here and silently continue.
*/
if (!ctx)
ctx = tr2tls_create_self("unknown", getnanotime() / 1000);
return ctx;
}
int tr2tls_is_main_thread(void)
{
if (!HAVE_THREADS)
return 1;
return pthread_getspecific(tr2tls_key) == tr2tls_thread_main;
}
void tr2tls_unset_self(void)
{
struct tr2tls_thread_ctx *ctx;
ctx = tr2tls_get_self();
pthread_setspecific(tr2tls_key, NULL);
strbuf_release(&ctx->thread_name);
free(ctx->array_us_start);
free(ctx);
}
void tr2tls_push_self(uint64_t us_now)
{
struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
ALLOC_GROW(ctx->array_us_start, ctx->nr_open_regions + 1, ctx->alloc);
ctx->array_us_start[ctx->nr_open_regions++] = us_now;
}
void tr2tls_pop_self(void)
{
struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
if (!ctx->nr_open_regions)
BUG("no open regions in thread '%s'", ctx->thread_name.buf);
ctx->nr_open_regions--;
}
void tr2tls_pop_unwind_self(void)
{
struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
while (ctx->nr_open_regions > 1)
tr2tls_pop_self();
}
uint64_t tr2tls_region_elasped_self(uint64_t us)
{
struct tr2tls_thread_ctx *ctx;
uint64_t us_start;
ctx = tr2tls_get_self();
if (!ctx->nr_open_regions)
return 0;
us_start = ctx->array_us_start[ctx->nr_open_regions - 1];
return us - us_start;
}
uint64_t tr2tls_absolute_elapsed(uint64_t us)
{
if (!tr2tls_thread_main)
return 0;
return us - tr2tls_us_start_process;
}
void tr2tls_init(void)
{
tr2tls_start_process_clock();
pthread_key_create(&tr2tls_key, NULL);
init_recursive_mutex(&tr2tls_mutex);
tr2tls_thread_main =
tr2tls_create_self("main", tr2tls_us_start_process);
}
void tr2tls_release(void)
{
tr2tls_unset_self();
tr2tls_thread_main = NULL;
pthread_mutex_destroy(&tr2tls_mutex);
pthread_key_delete(tr2tls_key);
}
int tr2tls_locked_increment(int *p)
{
int current_value;
pthread_mutex_lock(&tr2tls_mutex);
current_value = *p;
*p = current_value + 1;
pthread_mutex_unlock(&tr2tls_mutex);
return current_value;
}