tree-walk: report recursion counts

The traverse_trees() method recursively walks through trees, but also
prunes the tree-walk based on a callback. Some callers, such as
unpack_trees(), are quite complicated and can have wildly different
performance between two different commands.

Create constants that count these values and then report the results at
the end of a process. These counts are cumulative across multiple "root"
instances of traverse_trees(), but they provide reproducible values for
demonstrating improvements to the pruning algorithm when possible.

This change is modeled after a similar statistics reporting in 42e50e78
(revision.c: add trace2 stats around Bloom filter usage, 2020-04-06).

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Derrick Stolee 2021-01-04 03:09:10 +00:00 committed by Junio C Hamano
parent 71ca53e812
commit da8be8ced6

View File

@ -4,6 +4,7 @@
#include "object-store.h"
#include "tree.h"
#include "pathspec.h"
#include "json-writer.h"
static const char *get_mode(const char *str, unsigned int *modep)
{
@ -167,6 +168,25 @@ int tree_entry_gently(struct tree_desc *desc, struct name_entry *entry)
return 1;
}
static int traverse_trees_atexit_registered;
static int traverse_trees_count;
static int traverse_trees_cur_depth;
static int traverse_trees_max_depth;
static void trace2_traverse_trees_statistics_atexit(void)
{
struct json_writer jw = JSON_WRITER_INIT;
jw_object_begin(&jw, 0);
jw_object_intmax(&jw, "traverse_trees_count", traverse_trees_count);
jw_object_intmax(&jw, "traverse_trees_max_depth", traverse_trees_max_depth);
jw_end(&jw);
trace2_data_json("traverse_trees", the_repository, "statistics", &jw);
jw_release(&jw);
}
void setup_traverse_info(struct traverse_info *info, const char *base)
{
size_t pathlen = strlen(base);
@ -180,6 +200,11 @@ void setup_traverse_info(struct traverse_info *info, const char *base)
info->namelen = pathlen;
if (pathlen)
info->prev = &dummy;
if (trace2_is_enabled() && !traverse_trees_atexit_registered) {
atexit(trace2_traverse_trees_statistics_atexit);
traverse_trees_atexit_registered = 1;
}
}
char *make_traverse_path(char *path, size_t pathlen,
@ -416,6 +441,12 @@ int traverse_trees(struct index_state *istate,
int interesting = 1;
char *traverse_path;
traverse_trees_count++;
traverse_trees_cur_depth++;
if (traverse_trees_cur_depth > traverse_trees_max_depth)
traverse_trees_max_depth = traverse_trees_cur_depth;
if (n >= ARRAY_SIZE(entry))
BUG("traverse_trees() called with too many trees (%d)", n);
@ -515,6 +546,8 @@ int traverse_trees(struct index_state *istate,
free(traverse_path);
info->traverse_path = NULL;
strbuf_release(&base);
traverse_trees_cur_depth--;
return error;
}