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| author | ajwong@chromium.org <ajwong@chromium.org@0039d316-1c4b-4281-b951-d872f2087c98> | 2011-11-28 22:13:54 +0000 |
|---|---|---|
| committer | ajwong@chromium.org <ajwong@chromium.org@0039d316-1c4b-4281-b951-d872f2087c98> | 2011-11-28 22:13:54 +0000 |
| commit | fccef1559e02b001c69a0d35ad960e37dcbfd650 (patch) | |
| tree | b3ddaa715bf24e5d44a134b7298f39e59b2c1f27 /base/bind.h.pump | |
| parent | 485c5558393ab8fa34c580eed539a37d9d8f1450 (diff) | |
| download | chromium_src-fccef1559e02b001c69a0d35ad960e37dcbfd650.zip chromium_src-fccef1559e02b001c69a0d35ad960e37dcbfd650.tar.gz chromium_src-fccef1559e02b001c69a0d35ad960e37dcbfd650.tar.bz2 | |
Increase Bind/Callback Arity from 6 -> 7.
A few functions need this and the expected compile-speed impact is low. We should be careful when raising this number higher. If you're binding a function that has more parameters than this supports, consider refactoring your API to use a parameter struct or something.
Template equation: (n^2 + 26n) / 2
Template growth: 96 -> 116 types.
BUG=98542
TEST=try bots
Review URL: http://codereview.chromium.org/8728010
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@111788 0039d316-1c4b-4281-b951-d872f2087c98
Diffstat (limited to 'base/bind.h.pump')
| -rw-r--r-- | base/bind.h.pump | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/base/bind.h.pump b/base/bind.h.pump index 11b4667..9d4c5ee 100644 --- a/base/bind.h.pump +++ b/base/bind.h.pump @@ -5,7 +5,25 @@ $$ $$ http://code.google.com/p/googletest/wiki/PumpManual $$ -$var MAX_ARITY = 6 +$$ +$$ MAX_ARITY controls the number of arguments that Bind() supports. +$$ The amount of code, and more importantly, the number of template types +$$ generated by pump grows at O(MAX_ARITY^2). +$$ +$$ We tried going to 11 and found it imposed an extra 10 penalty on windows +$$ cycle times compared to our original baseline of 6. +$$ +$$ Currently 7 is chosen as a compromise between supporting a convenient +$$ number of arguments and keeping compile times low. At 7, we have 115 +$$ templates being generated by pump. +$$ +$$ Be careful when adjusting this number. If people find a need to bind +$$ a larger number of arguments, consider refactoring the function to use +$$ a param struct instead of raising the MAX_ARITY. +$$ +$$ See http://crbug.com/98542 for more context. +$$ +$var MAX_ARITY = 7 // Copyright (c) 2011 The Chromium Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be |