1 files changed, 91 insertions, 10 deletions
diff --git a/trace2.h b/trace2.h
index 88d906ea83..4ced30c0db 100644
--- a/trace2.h
+++ b/trace2.h
@@ -51,6 +51,8 @@ struct json_writer;
  * [] trace2_region*    -- emit region nesting messages.
  * [] trace2_data*      -- emit region/thread/repo data messages.
  * [] trace2_printf*    -- legacy trace[1] messages.
+ * [] trace2_timer*     -- stopwatch timers (messages are deferred).
+ * [] trace2_counter*   -- global counters (messages are deferred).
  */
 
 /*
@@ -73,8 +75,7 @@ void trace2_initialize_clock(void);
 /*
  * Initialize TRACE2 tracing facility if any of the builtin TRACE2
  * targets are enabled in the system config or the environment.
- * This includes setting up the Trace2 thread local storage (TLS).
- * Emits a 'version' message containing the version of git
+ * This emits a 'version' message containing the version of git
  * and the Trace2 protocol.
  *
  * This function should be called from `main()` as early as possible in
@@ -302,21 +303,23 @@ void trace2_exec_result_fl(const char *file, int line, int exec_id, int code);
 
 /*
  * Emit a 'thread_start' event.  This must be called from inside the
- * thread-proc to set up the trace2 TLS data for the thread.
+ * thread-proc to allow the thread to create its own thread-local
+ * storage.
  *
- * Thread names should be descriptive, like "preload_index".
- * Thread names will be decorated with an instance number automatically.
+ * The thread base name should be descriptive, like "preload_index" or
+ * taken from the thread-proc function.  A unique thread name will be
+ * created from the given base name and the thread id automatically.
  */
 void trace2_thread_start_fl(const char *file, int line,
-			    const char *thread_name);
+			    const char *thread_base_name);
 
-#define trace2_thread_start(thread_name) \
-	trace2_thread_start_fl(__FILE__, __LINE__, (thread_name))
+#define trace2_thread_start(thread_base_name) \
+	trace2_thread_start_fl(__FILE__, __LINE__, (thread_base_name))
 
 /*
  * Emit a 'thread_exit' event.  This must be called from inside the
- * thread-proc to report thread-specific data and cleanup TLS data
- * for the thread.
+ * thread-proc so that the thread can access and clean up its
+ * thread-local storage.
  */
 void trace2_thread_exit_fl(const char *file, int line);
 
@@ -485,6 +488,84 @@ void trace2_printf_fl(const char *file, int line, const char *fmt, ...);
 #define trace2_printf(...) trace2_printf_fl(__FILE__, __LINE__, __VA_ARGS__)
 
 /*
+ * Define the set of stopwatch timers.
+ *
+ * We can add more at any time, but they must be defined at compile
+ * time (to avoid the need to dynamically allocate and synchronize
+ * them between different threads).
+ *
+ * These must start at 0 and be contiguous (because we use them
+ * elsewhere as array indexes).
+ *
+ * Any values added to this enum must also be added to the
+ * `tr2_timer_metadata[]` in `trace2/tr2_tmr.c`.
+ */
+enum trace2_timer_id {
+	/*
+	 * Define two timers for testing.  See `t/helper/test-trace2.c`.
+	 * These can be used for ad hoc testing, but should not be used
+	 * for permanent analysis code.
+	 */
+	TRACE2_TIMER_ID_TEST1 = 0, /* emits summary event only */
+	TRACE2_TIMER_ID_TEST2,     /* emits summary and thread events */
+
+	/* Add additional timer definitions before here. */
+	TRACE2_NUMBER_OF_TIMERS
+};
+
+/*
+ * Start/Stop the indicated stopwatch timer in the current thread.
+ *
+ * The time spent by the current thread between the _start and _stop
+ * calls will be added to the thread's partial sum for this timer.
+ *
+ * Timer events are emitted at thread and program exit.
+ *
+ * Note: Since the stopwatch API routines do not generate individual
+ * events, they do not take (file, line) arguments.  Similarly, the
+ * category and timer name values are defined at compile-time in the
+ * timer definitions array, so they are not needed here in the API.
+ */
+void trace2_timer_start(enum trace2_timer_id tid);
+void trace2_timer_stop(enum trace2_timer_id tid);
+
+/*
+ * Define the set of global counters.
+ *
+ * We can add more at any time, but they must be defined at compile
+ * time (to avoid the need to dynamically allocate and synchronize
+ * them between different threads).
+ *
+ * These must start at 0 and be contiguous (because we use them
+ * elsewhere as array indexes).
+ *
+ * Any values added to this enum be also be added to the
+ * `tr2_counter_metadata[]` in `trace2/tr2_tr2_ctr.c`.
+ */
+enum trace2_counter_id {
+	/*
+	 * Define two counters for testing.  See `t/helper/test-trace2.c`.
+	 * These can be used for ad hoc testing, but should not be used
+	 * for permanent analysis code.
+	 */
+	TRACE2_COUNTER_ID_TEST1 = 0, /* emits summary event only */
+	TRACE2_COUNTER_ID_TEST2,     /* emits summary and thread events */
+
+	/* Add additional counter definitions before here. */
+	TRACE2_NUMBER_OF_COUNTERS
+};
+
+/*
+ * Increase the named global counter by value.
+ *
+ * Note that this adds `value` to the current thread's partial sum for
+ * this counter (without locking) and that the complete sum is not
+ * available until all threads have exited, so it does not return the
+ * new value of the counter.
+ */
+void trace2_counter_add(enum trace2_counter_id cid, uint64_t value);
+
+/*
  * Optional platform-specific code to dump information about the
  * current and any parent process(es).  This is intended to allow
  * post-processors to know who spawned this git instance and anything