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if not modules then modules = { } end modules ['luat-cbk'] = {
version = 1.001,
comment = "companion to luat-lib.mkiv",
author = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
copyright = "PRAGMA ADE / ConTeXt Development Team",
license = "see context related readme files"
}
local insert, remove, concat = table.insert, table.remove, table.concat
local find, format = string.find, string.format
local collectgarbage, type, next = collectgarbage, type, next
local round = math.round
local sortedhash, sortedkeys, tohash = table.sortedhash, table.sortedkeys, table.tohash
--[[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 or { }
local callbacks = callbacks
--[[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. This only works for non-frozen ones.</p>
--ldx]]--
local trace_callbacks = false trackers.register("system.callbacks", function(v) trace_callbacks = v end)
local trace_calls = false -- only used when analyzing performance and initializations
local trace_checking = false trackers.register("memory.checking", function(v) trace_checking = v end)
local report_system = logs.reporter("system")
local report_callbacks = logs.reporter("system","callbacks")
local report_memory = logs.reporter("system","memory")
local register_callback = callback.register
local find_callback = callback.find
local list_callbacks = callback.list
local register_usercall = false
local original_register = register_callback
local frozen = { }
local stack = { }
local list = callbacks.list
local permit_overloads = false
local block_overloads = false
--[[ldx--
<p>By now most callbacks are frozen and most provide a way to plug in your own code. For instance
all node list handlers provide before/after namespaces and the file handling code can be extended
by adding schemes and if needed I can add more hooks. So there is no real need to overload a core
callback function. It might be ok for quick and dirty testing but anyway you're on your own if
you permanently overload callback functions.</p>
--ldx]]--
-- This might become a configuration file only option when it gets abused too much.
directives.register("system.callbacks.permitoverloads", function(v)
if block_overloads or permit_overloads then
-- once bad news, always bad news
elseif v then
permit_overloads = { }
report_system()
report_system("The callback system has been brought in an unprotected state. As a result of directly")
report_system("setting of callbacks subsystems of ConTeXt can stop working. There is no support for")
report_system("bugs resulting from this state. It's better to use the official extension mechanisms.")
report_system()
end
end)
sandbox.initializer(function()
block_overloads = true
end)
if not list then -- otherwise counters get reset
list = utilities.storage.allocate(list_callbacks())
for k in next, list do
list[k] = 0
end
callbacks.list = list
end
local delayed = tohash {
"buildpage_filter",
}
if trace_calls then
local functions = { }
register_callback = function(name,func)
if type(func) == "function" then
if functions[name] then
functions[name] = func
return find_callback(name)
else
functions[name] = func
local cnuf = function(...)
list[name] = list[name] + 1
return functions[name](...)
end
return original_register(name,cnuf)
end
else
return original_register(name,func)
end
end
end
local reported = { }
local function register_usercall(what,name,func)
if list[name] then
if trace_callbacks or not reported[name] then
report_system()
report_system("disabling core code by %s user function into callback '%s' (reported only once)",what,name)
report_system()
reported[name] = true
end
permit_overloads[name] = true
return original_register(name,function(...)
if trace_callbacks then
report_callbacks("calling user function from '%s'",name)
end
return func(...)
end)
else
report_callbacks("not %s function into invalid callback '%s'",name)
return nil, format("unknown callback '%s'",name)
end
end
local function frozen_callback(name)
report_callbacks("not %s frozen %a","registering",name)
return nil, format("callback '%s' is frozen",name) -- no formatter yet
end
local function state(name)
local f = find_callback(name)
if f == false then
return "disabled"
elseif f then
return "enabled"
else
return "undefined"
end
end
function callbacks.known(name)
return list[name]
end
function callbacks.report()
for name, _ in sortedhash(list) do
local str = frozen[name]
if str then
report_callbacks("%s: %s -> %s",state(name),name,str)
else
report_callbacks("%s: %s",state(name),name)
end
end
end
function callbacks.freeze(name,freeze)
if not permit_overloads then
freeze = type(freeze) == "string" and freeze
if find(name,"*",1,true) then
local pattern = name
for name, _ in next, list do
if find(name,pattern) then
frozen[name] = freeze or frozen[name] or "frozen"
end
end
else
frozen[name] = freeze or frozen[name] or "frozen"
end
end
end
function callbacks.register(name,func,freeze)
if frozen[name] then
if permit_overloads then
return register_usercall("registering",name,func)
else
return frozen_callback(name)
end
elseif freeze then
frozen[name] = type(freeze) == "string" and freeze or "registered"
end
if delayed[name] and environment.initex then
return nil
end
return register_callback(name,func)
end
function callback.register(name,func) -- original
if not frozen[name] then
return register_callback(name,func)
elseif permit_overloads then
return register_usercall("registering",name,func)
else
return frozen_callback(name)
end
end
function callbacks.push(name,func)
if not frozen[name] or permit_overloads then
local sn = stack[name]
if not sn then
sn = { }
stack[name] = sn
end
insert(sn,find_callback(name))
if permit_overloads then
register_usercall("pushing",name,func)
else
register_callback(name,func)
end
else
report_callbacks("not %s frozen %a","pushing",name)
end
end
function callbacks.pop(name)
if not frozen[name] or permit_overloads then
local sn = stack[name]
if not sn or #sn == 0 then
-- some error
register_callback(name,nil) -- ! really needed
else
-- this fails: register_callback(name, remove(stack[name]))
local func = remove(sn)
register_callback(name,func)
end
end
end
if trace_calls then
statistics.register("callback details", function()
local t = { } -- todo: pass function to register and quit at nil
for name, n in sortedhash(list) do
if n > 0 then
t[#t+1] = format("%s -> %s",name,n)
end
end
return concat(t," ")
end)
end
statistics.register("callbacks overloaded by user", function()
if permit_overloads then
return concat(sortedkeys(permit_overloads)," ")
end
end)
-- -- somehow crashes later on
--
-- callbacks.freeze("find_.*_file","finding file")
-- callbacks.freeze("read_.*_file","reading file")
-- callbacks.freeze("open_.*_file","opening file")
--[[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 this 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. Okay, experimental code has been removed,
because messing aroudn with the gc is too unpredictable.</p>
--ldx]]--
-- For the moment we keep this here and not in util-gbc.lua or so.
utilities = utilities or { }
utilities.garbagecollector = utilities.garbagecollector or { }
local garbagecollector = utilities.garbagecollector
garbagecollector.enabled = false -- could become a directive
garbagecollector.criterium = 4*1024*1024
-- Lua allocates up to 12 times the amount of memory needed for
-- handling a string, and for large binary chunks (like chinese otf
-- files) we get a prominent memory consumption. Even when a variable
-- is nilled, there is some delay in freeing the associated memory (the
-- hashed string) because if we do the same thing directly afterwards,
-- we see only a slight increase in memory. For that reason it makes
-- sense to do a collector pass after a huge file.
--
-- test file:
--
-- function test()
-- local b = collectgarbage("count")
-- local s = io.loaddata("some font table, e.g. a big tmc file")
-- local a = collectgarbage("count")
-- print(">>> STATUS",b,a,a-b,#s,1000*(a-b)/#s)
-- end
--
-- test() test() test() test() collectgarbage("collect") test() test() test() test()
--
-- As a result of this, LuaTeX now uses an optimized version of f:read("*a"),
-- one that does not use the 4K allocations but allocates in one step.
function garbagecollector.check(size,criterium)
if garbagecollector.enabled then
criterium = criterium or garbagecollector.criterium
if not size or (criterium and criterium > 0 and size > criterium) then
if trace_checking then
local b = collectgarbage("count")
collectgarbage("collect")
local a = collectgarbage("count")
report_memory("forced sweep, collected: %s MB, used: %s MB",round((b-a)/1000),round(a/1000))
else
collectgarbage("collect")
end
end
end
end
-- this will move to a module
commands = commands or { }
function commands.showcallbacks()
local NC, NR, verbatim = context.NC, context.NR, context.type
context.starttabulate { "|l|l|p|" }
for name, _ in sortedhash(list) do
NC() verbatim(name) NC() verbatim(state(name)) NC() context(frozen[name] or "") NC() NR()
end
context.stoptabulate()
end
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