Merge branch 'jh/trace2-timers-and-counters'

Two new facilities, "timer" and "counter", are introduced to the
trace2 API.

* jh/trace2-timers-and-counters:
  trace2: add global counter mechanism
  trace2: add stopwatch timers
  trace2: convert ctx.thread_name from strbuf to pointer
  trace2: improve thread-name documentation in the thread-context
  trace2: rename the thread_name argument to trace2_thread_start
  api-trace2.txt: elminate section describing the public trace2 API
  tr2tls: clarify TLS terminology
  trace2: use size_t alloc,nr_open_regions in tr2tls_thread_ctx

1 files changed, 101 insertions, 0 deletions

diff --git a/trace2/tr2_ctr.c b/trace2/tr2_ctr.c
new file mode 100644
index 0000000000..483ca7c308
--- /dev/null
+++ b/trace2/tr2_ctr.c
@@ -0,0 +1,101 @@
+#include "cache.h"
+#include "thread-utils.h"
+#include "trace2/tr2_tgt.h"
+#include "trace2/tr2_tls.h"
+#include "trace2/tr2_ctr.h"
+
+/*
+ * A global counter block to aggregrate values from the partial sums
+ * from each thread.
+ */
+static struct tr2_counter_block final_counter_block; /* access under tr2tls_mutex */
+
+/*
+ * Define metadata for each global counter.
+ *
+ * This array must match the "enum trace2_counter_id" and the values
+ * in "struct tr2_counter_block.counter[*]".
+ */
+static struct tr2_counter_metadata tr2_counter_metadata[TRACE2_NUMBER_OF_COUNTERS] = {
+	[TRACE2_COUNTER_ID_TEST1] = {
+		.category = "test",
+		.name = "test1",
+		.want_per_thread_events = 0,
+	},
+	[TRACE2_COUNTER_ID_TEST2] = {
+		.category = "test",
+		.name = "test2",
+		.want_per_thread_events = 1,
+	},
+
+	/* Add additional metadata before here. */
+};
+
+void tr2_counter_increment(enum trace2_counter_id cid, uint64_t value)
+{
+	struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
+	struct tr2_counter *c = &ctx->counter_block.counter[cid];
+
+	c->value += value;
+
+	ctx->used_any_counter = 1;
+	if (tr2_counter_metadata[cid].want_per_thread_events)
+		ctx->used_any_per_thread_counter = 1;
+}
+
+void tr2_update_final_counters(void)
+{
+	struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
+	enum trace2_counter_id cid;
+
+	if (!ctx->used_any_counter)
+		return;
+
+	/*
+	 * Access `final_counter_block` requires holding `tr2tls_mutex`.
+	 * We assume that our caller is holding the lock.
+	 */
+
+	for (cid = 0; cid < TRACE2_NUMBER_OF_COUNTERS; cid++) {
+		struct tr2_counter *c_final = &final_counter_block.counter[cid];
+		const struct tr2_counter *c = &ctx->counter_block.counter[cid];
+
+		c_final->value += c->value;
+	}
+}
+
+void tr2_emit_per_thread_counters(tr2_tgt_evt_counter_t *fn_apply)
+{
+	struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
+	enum trace2_counter_id cid;
+
+	if (!ctx->used_any_per_thread_counter)
+		return;
+
+	/*
+	 * For each counter, if the counter wants per-thread events
+	 * and this thread used it (the value is non-zero), emit it.
+	 */
+	for (cid = 0; cid < TRACE2_NUMBER_OF_COUNTERS; cid++)
+		if (tr2_counter_metadata[cid].want_per_thread_events &&
+		    ctx->counter_block.counter[cid].value)
+			fn_apply(&tr2_counter_metadata[cid],
+				 &ctx->counter_block.counter[cid],
+				 0);
+}
+
+void tr2_emit_final_counters(tr2_tgt_evt_counter_t *fn_apply)
+{
+	enum trace2_counter_id cid;
+
+	/*
+	 * Access `final_counter_block` requires holding `tr2tls_mutex`.
+	 * We assume that our caller is holding the lock.
+	 */
+
+	for (cid = 0; cid < TRACE2_NUMBER_OF_COUNTERS; cid++)
+		if (final_counter_block.counter[cid].value)
+			fn_apply(&tr2_counter_metadata[cid],
+				 &final_counter_block.counter[cid],
+				 1);
+}