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Blame SOURCES/0338-manager-reduce-complexity-of-unit_gc_sweep-3507.patch

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From 33ca0f1f0d4b9a91588c84067d2fb30968e41235 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Luk=C3=A1=C5=A1=20Nykr=C3=BDn?= <lnykryn@redhat.com>
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Date: Tue, 14 Jun 2016 14:20:56 +0200
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Subject: [PATCH] manager: reduce complexity of unit_gc_sweep (#3507)
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When unit is marked as UNSURE, we are trying to find if it state was
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changed over and over again. So lets not go through the UNSURE states
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again. Also when we find a GOOD unit lets propagate the GOOD state to
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all units that this unit reference.
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This is a problem on machines with a lot of initscripts with different
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starting priority, since those units will reference each other and the
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original algorithm might get to n! complexity.
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Thanks HATAYAMA Daisuke for the expand_good_state code.
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Cherry-picked from: 4892084f096c19da0e83f28f250ca187b58c22b2
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Resolves: #1344556
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---
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 src/core/manager.c | 16 +++++++++++++++-
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 1 file changed, 15 insertions(+), 1 deletion(-)
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diff --git a/src/core/manager.c b/src/core/manager.c
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index 370c8cbbed..e5226a8a6f 100644
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--- a/src/core/manager.c
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+++ b/src/core/manager.c
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@@ -838,6 +838,19 @@ enum {
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         _GC_OFFSET_MAX
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 };
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+static void unit_gc_mark_good(Unit *u, unsigned gc_marker)
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+{
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+        Iterator i;
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+        Unit *other;
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+
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+        u->gc_marker = gc_marker + GC_OFFSET_GOOD;
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+
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+        /* Recursively mark referenced units as GOOD as well */
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+        SET_FOREACH(other, u->dependencies[UNIT_REFERENCES], i)
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+                if (other->gc_marker == gc_marker + GC_OFFSET_UNSURE)
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+                        unit_gc_mark_good(other, gc_marker);
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+}
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+
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 static void unit_gc_sweep(Unit *u, unsigned gc_marker) {
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         Iterator i;
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         Unit *other;
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@@ -847,6 +860,7 @@ static void unit_gc_sweep(Unit *u, unsigned gc_marker) {
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         if (u->gc_marker == gc_marker + GC_OFFSET_GOOD ||
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             u->gc_marker == gc_marker + GC_OFFSET_BAD ||
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+            u->gc_marker == gc_marker + GC_OFFSET_UNSURE ||
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             u->gc_marker == gc_marker + GC_OFFSET_IN_PATH)
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                 return;
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@@ -887,7 +901,7 @@ bad:
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         return;
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 good:
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-        u->gc_marker = gc_marker + GC_OFFSET_GOOD;
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+        unit_gc_mark_good(u, gc_marker);
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 }
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 static unsigned manager_dispatch_gc_queue(Manager *m) {