trace: add high resolution timer function to debug performance issues

diff --git a/sha1_file.c b/sha1_file.c
index 3e9f55f1bb19a33908be174b2fa463f8142d4cae..7a110b513e07a7b0e3a92313e0fb2438bac8c0fb 100644 (file)
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -36,9 +36,6 @@ static inline uintmax_t sz_fmt(size_t s) { return s; }
 
 const unsigned char null_sha1[20];
 
-static const char *no_log_pack_access = "no_log_pack_access";
-static const char *log_pack_access;
-
 /*
  * This is meant to hold a *small* number of objects that you would
  * want read_sha1_file() to be able to return, but yet you do not want
@@ -1437,19 +1434,23 @@ static int open_sha1_file(const unsigned char *sha1)
 {
        int fd;
        struct alternate_object_database *alt;
+       int most_interesting_errno;
 
        fd = git_open_noatime(sha1_file_name(sha1));
        if (fd >= 0)
                return fd;
+       most_interesting_errno = errno;
 
        prepare_alt_odb();
-       errno = ENOENT;
        for (alt = alt_odb_list; alt; alt = alt->next) {
                fill_sha1_path(alt->name, sha1);
                fd = git_open_noatime(alt->base);
                if (fd >= 0)
                        return fd;
+               if (most_interesting_errno == ENOENT)
+                       most_interesting_errno = errno;
        }
+       errno = most_interesting_errno;
        return -1;
 }
 
@@ -2081,27 +2082,9 @@ static void *read_object(const unsigned char *sha1, enum object_type *type,
 
 static void write_pack_access_log(struct packed_git *p, off_t obj_offset)
 {
-       static FILE *log_file;
-
-       if (!log_pack_access)
-               log_pack_access = getenv("GIT_TRACE_PACK_ACCESS");
-       if (!log_pack_access)
-               log_pack_access = no_log_pack_access;
-       if (log_pack_access == no_log_pack_access)
-               return;
-
-       if (!log_file) {
-               log_file = fopen(log_pack_access, "w");
-               if (!log_file) {
-                       error("cannot open pack access log '%s' for writing: %s",
-                             log_pack_access, strerror(errno));
-                       log_pack_access = no_log_pack_access;
-                       return;
-               }
-       }
-       fprintf(log_file, "%s %"PRIuMAX"\n",
-               p->pack_name, (uintmax_t)obj_offset);
-       fflush(log_file);
+       static struct trace_key pack_access = TRACE_KEY_INIT(PACK_ACCESS);
+       trace_printf_key(&pack_access, "%s %"PRIuMAX"\n",
+                        p->pack_name, (uintmax_t)obj_offset);
 }
 
 int do_check_packed_object_crc;
@@ -2126,8 +2109,7 @@ void *unpack_entry(struct packed_git *p, off_t obj_offset,
        int delta_stack_nr = 0, delta_stack_alloc = UNPACK_ENTRY_STACK_PREALLOC;
        int base_from_cache = 0;
 
-       if (log_pack_access != no_log_pack_access)
-               write_pack_access_log(p, obj_offset);
+       write_pack_access_log(p, obj_offset);
 
        /* PHASE 1: drill down to the innermost base object */
        for (;;) {