From 290a4cf9455f45895718ed698147061fcd0a2dcb Mon Sep 17 00:00:00 2001
From: Julian Andres Klode <julian.klode@canonical.com>
Date: Thu, 17 Dec 2020 13:20:53 +0100
Subject: depcache: Cache our InRootSetFunc

This avoids the cost of setting up the function every time
we mark and sweep.
---
 apt-pkg/depcache.cc | 26 +++++++++++++++++++-------
 apt-pkg/depcache.h  |  6 +++++-
 2 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/apt-pkg/depcache.cc b/apt-pkg/depcache.cc
index c7ef7a400..3c9695d56 100644
--- a/apt-pkg/depcache.cc
+++ b/apt-pkg/depcache.cc
@@ -95,10 +95,14 @@ pkgDepCache::ActionGroup::~ActionGroup()
 // DepCache::pkgDepCache - Constructors					/*{{{*/
 // ---------------------------------------------------------------------
 /* */
-pkgDepCache::pkgDepCache(pkgCache * const pCache,Policy * const Plcy) :
-  group_level(0), Cache(pCache), PkgState(0), DepState(0),
-   iUsrSize(0), iDownloadSize(0), iInstCount(0), iDelCount(0), iKeepCount(0),
-   iBrokenCount(0), iPolicyBrokenCount(0), iBadCount(0), d(NULL)
+
+struct pkgDepCache::Private
+{
+   std::unique_ptr<InRootSetFunc> inRootSetFunc;
+};
+pkgDepCache::pkgDepCache(pkgCache *const pCache, Policy *const Plcy) : group_level(0), Cache(pCache), PkgState(0), DepState(0),
+								       iUsrSize(0), iDownloadSize(0), iInstCount(0), iDelCount(0), iKeepCount(0),
+								       iBrokenCount(0), iPolicyBrokenCount(0), iBadCount(0), d(new Private)
 {
    DebugMarker = _config->FindB("Debug::pkgDepCache::Marker", false);
    DebugAutoInstall = _config->FindB("Debug::pkgDepCache::AutoInstall", false);
@@ -116,6 +120,7 @@ pkgDepCache::~pkgDepCache()
    delete [] PkgState;
    delete [] DepState;
    delete delLocalPolicy;
+   delete d;
 }
 									/*}}}*/
 bool pkgDepCache::CheckConsistency(char const *const msgtag)		/*{{{*/
@@ -2157,6 +2162,13 @@ pkgDepCache::InRootSetFunc *pkgDepCache::GetRootSetFunc()		/*{{{*/
       return NULL;
     }
 }
+
+pkgDepCache::InRootSetFunc *pkgDepCache::GetCachedRootSetFunc()
+{
+   if (d->inRootSetFunc == nullptr)
+      d->inRootSetFunc.reset(GetRootSetFunc());
+   return d->inRootSetFunc.get();
+}
 									/*}}}*/
 bool pkgDepCache::MarkFollowsRecommends()
 {
@@ -2369,9 +2381,9 @@ bool pkgDepCache::MarkAndSweep(InRootSetFunc &rootFunc)
 }
 bool pkgDepCache::MarkAndSweep()
 {
-   std::unique_ptr<InRootSetFunc> f(GetRootSetFunc());
-   if(f.get() != NULL)
-      return MarkAndSweep(*f.get());
+   InRootSetFunc *f(GetCachedRootSetFunc());
+   if (f != NULL)
+      return MarkAndSweep(*f);
    else
       return false;
 }
diff --git a/apt-pkg/depcache.h b/apt-pkg/depcache.h
index 78f88ba2f..9a6019092 100644
--- a/apt-pkg/depcache.h
+++ b/apt-pkg/depcache.h
@@ -380,6 +380,9 @@ class APT_PUBLIC pkgDepCache : protected pkgCache::Namespace
     */
    virtual InRootSetFunc *GetRootSetFunc();
 
+   /** This should return const really - do not delete. */
+   InRootSetFunc *GetCachedRootSetFunc() APT_HIDDEN;
+
    /** \return \b true if the garbage collector should follow recommendations.
     */
    virtual bool MarkFollowsRecommends();
@@ -516,7 +519,8 @@ class APT_PUBLIC pkgDepCache : protected pkgCache::Namespace
 	 bool const rPurge, unsigned long const Depth, bool const FromUser);
 
    private:
-   void * const d;
+   struct Private;
+   Private *const d;
 
    APT_HIDDEN bool MarkInstall_StateChange(PkgIterator const &Pkg, bool AutoInst, bool FromUser);
    APT_HIDDEN bool MarkInstall_DiscardInstall(PkgIterator const &Pkg);
-- 
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