1 files changed, 194 insertions, 0 deletions
diff --git a/trace2/tr2_tls.c b/trace2/tr2_tls.c
new file mode 100644
index 0000000..601c9e5
--- /dev/null
+++ b/trace2/tr2_tls.c
@@ -0,0 +1,194 @@
+#include "git-compat-util.h"
+#include "thread-utils.h"
+#include "trace.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_base_name,
+					     uint64_t us_thread_start)
+{
+	struct tr2tls_thread_ctx *ctx = xcalloc(1, sizeof(*ctx));
+	struct strbuf buf = STRBUF_INIT;
+
+	/*
+	 * 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(&buf, 0);
+	if (ctx->thread_id)
+		strbuf_addf(&buf, "th%02d:", ctx->thread_id);
+	strbuf_addstr(&buf, thread_base_name);
+	if (buf.len > TR2_MAX_THREAD_NAME)
+		strbuf_setlen(&buf, TR2_MAX_THREAD_NAME);
+	ctx->thread_name = strbuf_detach(&buf, NULL);
+
+	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 current thread's thread-proc did not call
+	 * trace2_thread_start(), then the thread will not have any
+	 * thread-local storage.  Create it now 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);
+
+	free((char *)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);
+
+	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;
+}
+
+void tr2tls_lock(void)
+{
+	pthread_mutex_lock(&tr2tls_mutex);
+}
+
+void tr2tls_unlock(void)
+{
+	pthread_mutex_unlock(&tr2tls_mutex);
+}