reftable: allow inlining of a few functions

We have a few functions which are basically just accessors to
structures. As those functions are executed inside the hot loop when
iterating through many refs, the fact that they cannot be inlined is
costing us some performance.

Move the function definitions into their respective headers so that they
can be inlined. This results in a performance improvement when iterating
over 1 million refs:

    Benchmark 1: show-ref: single matching ref (revision = HEAD~)
      Time (mean ± σ):     105.9 ms ±   3.6 ms    [User: 103.0 ms, System: 2.8 ms]
      Range (min … max):   103.1 ms … 133.4 ms    1000 runs

    Benchmark 2: show-ref: single matching ref (revision = HEAD)
      Time (mean ± σ):     100.7 ms ±   3.4 ms    [User: 97.8 ms, System: 2.8 ms]
      Range (min … max):    97.8 ms … 124.0 ms    1000 runs

    Summary
      show-ref: single matching ref (revision = HEAD) ran
        1.05 ± 0.05 times faster than show-ref: single matching ref (revision = HEAD~)

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pks-t

reftable/pq.c

@@ -20,16 +20,6 @@ int pq_less(struct pq_entry *a, struct pq_entry *b)
 	return cmp < 0;
 }
 
-struct pq_entry merged_iter_pqueue_top(struct merged_iter_pqueue pq)
-{
-	return pq.heap[0];
-}
-
-int merged_iter_pqueue_is_empty(struct merged_iter_pqueue pq)
-{
-	return pq.len == 0;
-}
-
 struct pq_entry merged_iter_pqueue_remove(struct merged_iter_pqueue *pq)
 {
 	int i = 0;

reftable/pq.h

@@ -22,12 +22,20 @@ struct merged_iter_pqueue {
 	size_t cap;
 };
 
-struct pq_entry merged_iter_pqueue_top(struct merged_iter_pqueue pq);
-int merged_iter_pqueue_is_empty(struct merged_iter_pqueue pq);
 void merged_iter_pqueue_check(struct merged_iter_pqueue pq);
 struct pq_entry merged_iter_pqueue_remove(struct merged_iter_pqueue *pq);
 void merged_iter_pqueue_add(struct merged_iter_pqueue *pq, const struct pq_entry *e);
 void merged_iter_pqueue_release(struct merged_iter_pqueue *pq);
 int pq_less(struct pq_entry *a, struct pq_entry *b);
 
+static inline struct pq_entry merged_iter_pqueue_top(struct merged_iter_pqueue pq)
+{
+	return pq.heap[0];
+}
+
+static inline int merged_iter_pqueue_is_empty(struct merged_iter_pqueue pq)
+{
+	return pq.len == 0;
+}
+
 #endif

reftable/record.c

@@ -1176,11 +1176,6 @@ void reftable_record_key(struct reftable_record *rec, struct strbuf *dest)
 	reftable_record_vtable(rec)->key(reftable_record_data(rec), dest);
 }
 
-uint8_t reftable_record_type(struct reftable_record *rec)
-{
-	return rec->type;
-}
-
 int reftable_record_encode(struct reftable_record *rec, struct string_view dest,
 			   int hash_size)
 {
@@ -1302,12 +1297,6 @@ int reftable_log_record_is_deletion(const struct reftable_log_record *log)
 	return (log->value_type == REFTABLE_LOG_DELETION);
 }
 
-void string_view_consume(struct string_view *s, int n)
-{
-	s->buf += n;
-	s->len -= n;
-}
-
 static void *reftable_record_data(struct reftable_record *rec)
 {
 	switch (rec->type) {

reftable/record.h

@@ -25,7 +25,11 @@ struct string_view {
 };
 
 /* Advance `s.buf` by `n`, and decrease length. */
-void string_view_consume(struct string_view *s, int n);
+static inline void string_view_consume(struct string_view *s, int n)
+{
+	s->buf += n;
+	s->len -= n;
+}
 
 /* utilities for de/encoding varints */
 
@@ -127,7 +131,6 @@ int reftable_record_cmp(struct reftable_record *a, struct reftable_record *b);
 int reftable_record_equal(struct reftable_record *a, struct reftable_record *b, int hash_size);
 void reftable_record_print(struct reftable_record *rec, int hash_size);
 void reftable_record_key(struct reftable_record *rec, struct strbuf *dest);
-uint8_t reftable_record_type(struct reftable_record *rec);
 void reftable_record_copy_from(struct reftable_record *rec,
 			       struct reftable_record *src, int hash_size);
 uint8_t reftable_record_val_type(struct reftable_record *rec);
@@ -138,6 +141,11 @@ int reftable_record_decode(struct reftable_record *rec, struct strbuf key,
 			   int hash_size);
 int reftable_record_is_deletion(struct reftable_record *rec);
 
+static inline uint8_t reftable_record_type(struct reftable_record *rec)
+{
+	return rec->type;
+}
+
 /* frees and zeroes out the embedded record */
 void reftable_record_release(struct reftable_record *rec);