1 files changed, 56 insertions, 0 deletions
diff --git a/src/common/private_timing.h b/src/common/private_timing.h
new file mode 100644
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--- /dev/null
+++ b/src/common/private_timing.h
@@ -0,0 +1,56 @@
+/**
+ * @file
+ * Timing provenance, refresh estimates, and buffer-resize statistics.
+ * All timestamps are monotonic nanoseconds, not wall-clock dates.
+ */
+#ifndef YASL_PRIVATE_TIMING_H
+#define YASL_PRIVATE_TIMING_H
+
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** Cumulative backend buffer-resize measurements; unavailable counters are zero. */
+struct yasl_private_resize_stats {
+    /** Number of measured buffer resizes. */
+    uint64_t count;
+    /** Mean measured resize duration in microseconds. */
+    double avg_us;
+    /** Maximum measured resize duration in microseconds. */
+    double max_us;
+    /** Backend minor page-fault counter, if collected. */
+    long minflt;
+};
+
+/* Describes last_present_ns, not merely availability of an extension. */
+/** Provenance of last_present_ns; only PRESENTATION confirms compositor presentation. */
+enum yasl_private_timing_source {
+    YASL_PRIVATE_TIMING_UNKNOWN = 0, /**< No timing sample yet. */
+    YASL_PRIVATE_TIMING_SUBMISSION, /**< CPU submission time, not scanout confirmation. */
+    YASL_PRIVATE_TIMING_FRAME_CALLBACK, /**< Compositor pacing callback, not scanout confirmation. */
+    YASL_PRIVATE_TIMING_PRESENTATION, /**< Compositor-confirmed presentation. */
+};
+
+/** Snapshot of estimates and timing provenance. Zero timestamps mean no sample yet. */
+struct yasl_private_timing {
+    /** Estimated refresh interval in nanoseconds; zero if unavailable. */
+    double refresh_ns;
+    /** Last timestamp, whose meaning is specified by source. */
+    uint64_t last_present_ns;
+    /** Estimated next presentation time, or zero without a prior sample. */
+    uint64_t next_present_ns;
+    /** Backend skipped-frame counter; not comparable across backends. */
+    uint64_t frames_skipped;
+    /** Provenance of last_present_ns. */
+    enum yasl_private_timing_source source;
+    /** Cumulative backend resize statistics. */
+    struct yasl_private_resize_stats resize;
+};
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* YASL_PRIVATE_TIMING_H */