ref-filter: resolve HEAD when parsing %(HEAD) atom
If the user asks to display (or sort by) the %(HEAD) atom, ref-filter has to compare each refname to the value of HEAD. We do so by resolving HEAD fresh when calling populate_value() on each ref. If there are a large number of refs, this can have a measurable impact on runtime. Instead, let's resolve HEAD once when we realize we need the %(HEAD) atom, allowing us to do a simple string comparison for each ref. On a repository with 3000 branches (high, but an actual example found in the wild) this drops the best-of-five time to run "git branch >/dev/null" from 59ms to 48ms (~20% savings). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Jeff King committed
May 19, 2017 at 02:12 UTC
613a0e52ea11c4496e3e154de192486a18eac2e4
1 file changed
+9
-7
ref-filter.c
+9
-7
@@ -92,6 +92,7 @@ static struct used_atom {
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unsigned int length;
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} objectname;
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struct refname_atom refname;
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+ char *head;
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} u;
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} *used_atom;
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static int used_atom_cnt, need_tagged, need_symref;
@@ -286,6 +287,12 @@ static void if_atom_parser(struct used_atom *atom, const char *arg)
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}
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}
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+static void head_atom_parser(struct used_atom *atom, const char *arg)
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+{
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+ unsigned char unused[GIT_SHA1_RAWSZ];
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+
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+ atom->u.head = resolve_refdup("HEAD", RESOLVE_REF_READING, unused, NULL);
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+}
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static struct {
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const char *name;
@@ -324,7 +331,7 @@ static struct {
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{ "push", FIELD_STR, remote_ref_atom_parser },
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{ "symref", FIELD_STR, refname_atom_parser },
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{ "flag" },
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- { "HEAD" },
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+ { "HEAD", FIELD_STR, head_atom_parser },
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{ "color", FIELD_STR, color_atom_parser },
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{ "align", FIELD_STR, align_atom_parser },
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{ "end" },
@@ -1366,12 +1373,7 @@ static void populate_value(struct ref_array_item *ref)
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} else if (!deref && grab_objectname(name, ref->objectname, v, atom)) {
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continue;
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} else if (!strcmp(name, "HEAD")) {
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- const char *head;
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- unsigned char sha1[20];
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-
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- head = resolve_ref_unsafe("HEAD", RESOLVE_REF_READING,
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- sha1, NULL);
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- if (head && !strcmp(ref->refname, head))
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+ if (atom->u.head && !strcmp(ref->refname, atom->u.head))
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v->s = "*";
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else
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v->s = " ";