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if not modules then modules = { } end modules ['luat-cbk'] = {
version = 1.001,
comment = "companion to luat-lib.tex",
author = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
copyright = "PRAGMA ADE / ConTeXt Development Team",
license = "see context related readme files"
}
--[[ldx--
<p>Callbacks are the real asset of <l n='luatex'/>. They permit you to hook
your own code into the <l n='tex'/> engine. Here we implement a few handy
auxiliary functions.</p>
--ldx]]--
callbacks = { }
callbacks.stack = { }
--[[ldx--
<p>When you (temporarily) want to install a callback function, and after a
while wants to revert to the original one, you can use the following two
functions.</p>
--ldx]]--
function callbacks.push(name, func)
if not callbacks.stack[name] then
callbacks.stack[name] = { }
end
table.insert(callbacks.stack[name],callback.find(name))
callback.register(name, func)
end
function callbacks.pop(name)
-- this fails: callback.register(name, table.remove(callbacks.stack[name]))
local func = table.remove(callbacks.stack[name])
callback.register(name, func)
end
--[[ldx--
<p>The simple case is to remove the callback:</p>
<code>
callbacks.push('linebreak_filter')
... some actions ...
callbacks.pop('linebreak_filter')
</code>
<p>Often, in such case, another callback or a macro call will pop
the original.</p>
<p>In practice one will install a new handler, like in:</p>
<code>
callbacks.push('linebreak_filter', function(...)
return something_done(...)
end)
</code>
<p>Even more interesting is:</p>
<code>
callbacks.push('linebreak_filter', function(...)
callbacks.pop('linebreak_filter')
return something_done(...)
end)
</code>
<p>This does a one-shot.</p>
--ldx]]--
--[[ldx--
<p>Callbacks may result in <l n='lua'/> doing some hard work
which takes time and above all resourses. Sometimes it makes
sense to disable or tune the garbage collector in order to
keep the use of resources acceptable.</p>
<p>At some point in the development we did some tests with counting
nodes (in thsi case 121049).</p>
<table>
<tr><td>setstepmul</td><td>seconds</td><td>megabytes</td</tr>
<tr><td>200</td><td>24.0</td><td>80.5</td</tr>
<tr><td>175</td><td>21.0</td><td>78.2</td</tr>
<tr><td>150</td><td>22.0</td><td>74.6</td</tr>
<tr><td>160</td><td>22.0</td><td>74.6</td</tr>
<tr><td>165</td><td>21.0</td><td>77.6</td</tr>
<tr><td>125</td><td>21.5</td><td>89.2</td</tr>
<tr><td>100</td><td>21.5</td><td>88.4</td</tr>
</table>
<p>The following code is kind of experimental. In the documents
that describe the development of <l n='luatex'/> we report
on speed tests. One observation is thta it sometimes helps to
restart the collector.</p>
--ldx]]--
garbagecollector = { }
do
local level = 0
collectgarbage("setstepmul", 165)
garbagecollector.trace = false
garbagecollector.tune = false -- for the moment
function report(format)
if garbagecollector.trace then
-- texio.write_nl(string.format(format,level,status.luastate_bytes))
texio.write_nl(string.format(format,level,collectgarbage("count")))
end
end
function garbagecollector.update()
report("%s: memory before update: %s")
collectgarbage("restart")
end
function garbagecollector.push()
if garbagecollector.tune then
level = level + 1
if level == 1 then
collectgarbage("stop")
end
report("%s: memory after push: %s")
else
garbagecollector.update()
end
end
function garbagecollector.pop()
if garbagecollector.tune then
report("%s: memory before pop: %s")
if level == 1 then
collectgarbage("restart")
end
level = level - 1
end
end
function garbagecollector.cycle()
if garbagecollector.tune then
report("%s: memory before collect: %s")
collectgarbage("collect")
report("%s: memory after collect: %s")
end
end
end
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