[v2,16/17] libtraceeval histogram: Have traceeval_query() just give the pointer to results

Commit Message

Steven Rostedt Aug. 11, 2023, 5:39 a.m. UTC

From: "Steven Rostedt (Google)" <[e-mail]>

Instead of wasting allocation to return the results for queries,
especially since the query is likely not to modify the results, just give
a direct pointer to the entry->vals.

Mark it as const so (hopefully) nobody modifies it.

We still require the traceeval_results_release() to be called on it, as we
may in the future add a ref count to it and perhaps do a copy-on-write if
an update happens while something still has a hold on it.

Signed-off-by: Steven Rostedt (Google) <[e-mail]>
---
 include/traceeval-hist.h |  4 ++--
 src/histograms.c         | 10 ++++------
 2 files changed, 6 insertions(+), 8 deletions(-)

Patch

diff --git a/include/traceeval-hist.h b/include/traceeval-hist.h
index 839f63630897..315b66adb7ee 100644
--- a/include/traceeval-hist.h
+++ b/include/traceeval-hist.h
@@ -161,10 +161,10 @@  int traceeval_insert(struct traceeval *teval,
 		     const union traceeval_data *vals);
 
 int traceeval_query(struct traceeval *teval, const union traceeval_data *keys,
-		    union traceeval_data **results);
+		    const union traceeval_data **results);
 
 void traceeval_results_release(struct traceeval *teval,
-			       union traceeval_data *results);
+			       const union traceeval_data *results);
 
 struct traceeval_stat *traceeval_stat(struct traceeval *teval,
 				      const union traceeval_data *keys,
diff --git a/src/histograms.c b/src/histograms.c
index 33c87644d468..cd68d4c834af 100644
--- a/src/histograms.c
+++ b/src/histograms.c
@@ -671,7 +671,7 @@  fail:
  * Returns 1 if found, 0 if not found, and -1 on error.
  */
 int traceeval_query(struct traceeval *teval, const union traceeval_data *keys,
-		    union traceeval_data **results)
+		    const union traceeval_data **results)
 {
 	struct entry *entry;
 	int check;
@@ -683,8 +683,8 @@  int traceeval_query(struct traceeval *teval, const union traceeval_data *keys,
 	if ((check = get_entry(teval, keys, &entry)) < 1)
 		return check;
 
-	return copy_traceeval_data_set(teval->nr_val_types, teval->val_types,
-			entry->vals, NULL, results);
+	*results = entry->vals;
+	return 1;
 }
 
 /*
@@ -699,15 +699,13 @@  int traceeval_query(struct traceeval *teval, const union traceeval_data *keys,
  * allow traceeval to clean up its references.
  */
 void traceeval_results_release(struct traceeval *teval,
-			       union traceeval_data *results)
+			       const union traceeval_data *results)
 {
 	if (!teval || !results) {
 		if (!teval)
 			print_err("Results to be freed without accompanied traceeval instance!");
 		return;
 	}
-
-	data_release_and_free(teval->nr_val_types, &results, teval->val_types);
 }
 
 static struct entry *create_hist_entry(struct traceeval *teval,