Calc: Further cache simulation results

Hi Noel,

        Thanks for your work on this - pushing the thread to the public list
which is perhaps a better place for it.

        I think my interest here is not per-se about broadcaster vs. listener -
but mostly around the complexity of setting up and/or removing listeners
from a broadcaster as/when the sheet is manipulated - creating and
destroying columns eg. which reference another cell - there can be some
performance explosions shuffling things out of std::vectors.

        Kohei poked at a chunk of profiles like this in the past; probably
worth getting his input; any thoughts ?

        Thanks,

                Michael.

On 29/09/18 10:22, Michael Meeks wrote:
> Hi Noel,
>
> On 28/09/18 16:08, Noel Grandin wrote:
> > On 2018/09/27 5:06 PM, Noel Grandin wrote:
> > > I had a quick look at ScFormulaCell with gdb's pahole script, and it
> > > strikes me that
> > >
> > > (a) the biggest chunk is the SvtListener base class (64 bytes!)
> >
> > the attached patch might help
>
>       Interesting. I wonder what the pathological usage patterns of this are.
> My hope is that (these days) if we have a 1m long formula-group that has
> some $a$1 term in it - that we create a single group dependency /
> listener for the whole formula-group - but, of course quite possibly we
> add ~1 million single-cell reference dependency. At which point using
> the set makes sense as that is manipulated.
>
>       Of course - ultimately, it is just bad design to use a bigger structure
> when we don't need to. My hope is that as we re-work the dependency
> engine to use FormulaGroups - that we end up in a situation that the
> vast majority of cells simply have no content in their SvtListener and
> we can replace it with single pointer to a heap allocated listener
> instead that is always NULL; or - even move to looking those up in a
> smallish hash of single-cell dependencies.
>
>       Anyhow - worth checking the corner-cases there, to see if our
> dependency work has simplified and evaporated out lots of single-cell
> dependencies to the point that the vector might work without exploding
> with some 1m^2 insert/delete behavior =)
>
>       Also - we should prolly discuss this on the public dev list; any
> objections ? =)

-- 
michael.meeks@collabora.com <><, GM Collabora Productivity
Hangout: mejmeeks@gmail.com, Skype: mmeeks
(M) +44 7795 666 147 - timezone usually UK / Europe

From 5e0f91830d08aaf641cb3f993cd5cc753b149076 Mon Sep 17 00:00:00 2001
From: Noel Grandin <noel.grandin@collabora.co.uk>
Date: Fri, 28 Sep 2018 17:07:10 +0200
Subject: [PATCH] WIP use std::vector in SvtListener

because
- we mostly listen to zero or one broadcasters
- this reduces the size of ScFormulaCell from 160 bytes to 128 bytes
- has mostly positive (but small) effects on make sc.perfcheck

Change-Id: I0095b646177bdd23c64462afbb924943d598e6bc
---
 include/svl/listener.hxx       |  4 ++--
 svl/source/notify/listener.cxx | 21 +++++++++++----------
 2 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/include/svl/listener.hxx b/include/svl/listener.hxx
index 5f2850ef7f19..649463bb0a83 100644
--- a/include/svl/listener.hxx
+++ b/include/svl/listener.hxx
@@ -21,14 +21,14 @@
 
 #include <svl/svldllapi.h>
 
-#include <unordered_set>
+#include <vector>
 
 class SvtBroadcaster;
 class SfxHint;
 
 class SVL_DLLPUBLIC SvtListener
 {
-    typedef std::unordered_set<SvtBroadcaster*> BroadcastersType;
+    typedef std::vector<SvtBroadcaster*> BroadcastersType;
     BroadcastersType maBroadcasters;
 
     const SvtListener&  operator=(const SvtListener &) = delete;
diff --git a/svl/source/notify/listener.cxx b/svl/source/notify/listener.cxx
index 89306a534a0d..4736a5c205ff 100644
--- a/svl/source/notify/listener.cxx
+++ b/svl/source/notify/listener.cxx
@@ -43,20 +43,21 @@ SvtListener::~SvtListener() COVERITY_NOEXCEPT_FALSE
 
 bool SvtListener::StartListening( SvtBroadcaster& rBroadcaster )
 {
-    std::pair<BroadcastersType::iterator, bool> r =
-        maBroadcasters.insert(&rBroadcaster);
-    if (r.second)
-    {
-        // This is a new broadcaster.
-        rBroadcaster.Add(this);
-    }
-    return r.second;
+    BroadcastersType::iterator it = std::lower_bound(maBroadcasters.begin(), maBroadcasters.end(), 
&rBroadcaster);
+    if (it != maBroadcasters.end() && *it == &rBroadcaster)
+        // already listening to this broadcaster.
+        return false;
+
+    // This is a new broadcaster.
+    maBroadcasters.insert(it, &rBroadcaster); // maintain sorting
+    rBroadcaster.Add(this);
+    return true;
 }
 
 bool SvtListener::EndListening( SvtBroadcaster& rBroadcaster )
 {
-    BroadcastersType::iterator it = maBroadcasters.find(&rBroadcaster);
-    if (it == maBroadcasters.end())
+    BroadcastersType::iterator it = std::lower_bound(maBroadcasters.begin(), maBroadcasters.end(), 
&rBroadcaster);
+    if (it == maBroadcasters.end() || *it != &rBroadcaster)
         // Not listening to this broadcaster.
         return false;
 
-- 
2.17.1