Rhino: optimization for NativeFunction.java
Date:
Mon, 07 May 2001 14:19:59 +0200
From:
Igor Bukanov <igor.bukanov@windriver.com>
Organization:
Wind River
To:
Norris Boyd <nboyd@atg.com>
Hi, Norris!
This is the first of 3 patches that are completly independent from each
other.
Currently in NativeFunction its name stored as the first element in the
names array. But this lead to creation of a single element array for
each FunctionObject and for each script function that does not have
arguments or variables. The attached patch splits NativeFunction names
into simple functionName and argNames arrays and adjust code elsewhere
accordingly. This patch can increase memory footprint for anonymous
script functions without arguments because it adds additional field to
each NativeFunction, but I do not think this is a case to worry about.
Regards, Igor
Date: Mon, 07 May 2001 14:25:34 +0200
From: Igor Bukanov <igor.bukanov@windriver.com>
Organization: Wind River
To: Norris Boyd <nboyd@atg.com>
The current code that implements execMethod/methodArity for IdFunction
support returns an arbitrary value for id that is not known. This is not
very good behavior because it may hide bugs in the id support and it
also does not allow to distinguish ids that are used for function from
ids used for properties like String.length.
To fix this I changed semantic of the methodArity method to return -1
for an unknown/non-method id and added code to throw an exception for
bad ids. This change requires to adjust all NativeSomething objects that
use IdScriptabl and after a release all such interface changes would be
no go, but is not a release yet, right?
I also eliminated the "IdFunction f" argument from
IdFunction.Master.methodArity and the tagId field from IdFunction. When
I wrote the initial code for IdFunction.java, I added that just to be
able to use same id number in a class that implements IdFunction.Master
and its descendants via checking idTag. But that does not work in
general because IdScriptable can use id for non-function fields as well
so to avoid id clashes another way should be used. For example, if
someone would like to extend NativeMath to support more functionality,
he can use:
class Math2: extends NativeMath {
private static idBase;
{
if (idBase == 0) idBase = super.getMaximumId();
}
public int methodArity(int methodId) {
switch (methodId - idBase) {
case Id_foo: return 2;
case Id_bar: return 3;
}
return super.methodArity(methodId);
}
public Object execMethod
(int methodId, IdFunction f,
Context cx, Scriptable scope, Scriptable thisObj, Object[] args)
throws JavaScriptException
{
switch (methodId - idBase) {
case Id_foo: return ...;
case Id_bar: return ...;
}
return super.execMethod(methodId, f, cx, scope, thisObj, args);
}
protected int getMaximumId() { return idBase + MAX_ID; }
protected String getIdName(int id) {
switch (id - idBase) {
case Id_foo: return "for";
case Id_bar: return "bar";
}
return super.getIdName(id);
}
...
private static final int
Id_foo = 1,
Id_bar = 2,
MAX_ID = 2;
etc.
Note that a simpler solution to make MAX_ID field public in NativeMath
and write in Math2:
private static final int
Id_foo = NativeMath.MAX_ID + 1,
Id_bar = NativeMath.MAX_ID + 2,
MAX_ID = NativeMath.MAX_ID + 2;
does not work because in this way adding any new id to NativeMath would
break binary compatibility with Math2.
Rhino: fix for race conditions in listeners code in Context.java
Date:
Mon, 07 May 2001 14:22:57 +0200
From:
Igor Bukanov <igor.bukanov@windriver.com>
Organization:
Wind River
To:
Norris Boyd <nboyd@atg.com>
The current code for listeners and contextListeners in Context.java is
not race condition free. If contextListeners Vector would be modified
during context event firing loops, the code can produce
index-out-of-bounds exception. The problem with listeners array is more
subbtle and comes from the fact that ListenerCollection.java uses code like:
for(Enumeration enum = getAllListeners();enum.hasMoreElements();) {
Object listener = enum.nextElement();
if(iface.isInstance(listener)) {
array.addElement(listener);
}
}
where getAllListeners() uses Vector.elements to get element enumeration.
But to work with such enumeration in a thread safe way, one has to
synchronized against Vector, otherwise between enum.hasMoreElements()
and enum.nextElement() the last element can be removed.
Initially I thought to fix ListenerCollection and use it for
contextListeners as well, but then I realized that in its current form
ListenerCollection is very inefficient (it produces too many objects
just to get simple array to fire events), so I wrote ListenerArray.java
and use it in Context.java. It makes life simpler and shrinks code as well.
js_SetProtoOrParent should always have used a condvar in addition to a lock.
- Fix bug 79129, assert-botch in js_AllocSlot (r/sr=jband, sr=shaver)
JS_INITIAL_NSLOTS is the minimum number of slots, js_FreeSlot guarantees it.
Subject:
rhino bug(s)
Date:
Mon, 30 Apr 2001 23:07:00 -0700
From:
Mike Dixon <MDixon@placeware.com>
To:
nboyd@atg.com
hi. i'm a happy rhino user, and just stumbled across what looks like a
pretty basic bug in the property stuff on ScriptableObject... (i'm running
1.5, but it looks like this code hasn't changed in CVS.) since it looks
like you're actively developing (even though it's been a while since
1.5...) i figured you might be interested -- apologies if i missed a more
formal bug reporting process...
the symptom was that i got a "Hashtable internal error" thrown from
getSlotToSet. reading the code, here's what i think could happen:
- create a new object (slots.length is initially 5)
- add 3 properties
- delete those 3 properties
(now count == 0, and slots[i] == REMOVED for 3 values of i)
- add 2 more properties
now assume that you're unlucky, and that these two hash to different values
than the first three; now you have 2 elements of slots[] containing real
slots, and the other three containing REMOVED.
now what happens when you try to create another slot? getSlotToSet is only
willing to put something in a null slot[], and you haven't got one, so you
get the internal error.
writing this message encouraged me to try to write a test case to reproduce
it, and in fact it's trivial:
js> x={}; x.a=x.b=x.c=1; delete x.a; delete x.b; delete x.c; x.d=x.e=1
1
js> x.whatever=1
(boom)
by the way, while reading the code i also noticed what looks like another,
less consequential bug: addSlot increments count before deciding to grow
the table, which is done with a recursive call, which will cause count to
be incremented again -- right? as far as i can tell, setting count too big
will only cause it to grow the table a little early next time, so it
doesn't really matter, but it looks wrong.
.mike.
remove jsdIContext and jsdIThreadstate interfaces
add TYPE_BOOLEAN to jsdIValue
update callback signatures to reflect the removal of jsdIContext and jsdIThreadstate
add errorHook and throwHook attributes to jsdIDebuggerService
remove jsdThreadState and jsdContext objects.
consolidate ExecutionHook and BreakpointHook callbacks
remove return value checking from all methods (xpconnect does this for us.)
validate integrity of jsdScript data to guard against calling into a destroyed script.
queue up script deletes that happen during the JS GC cycle, call them when GC finishes (bug 76979.)
don't NS_IF_ADDREF objects that we get using *::FromPtr()
add jsdScript::Invalidate()
move from pc as a ulong to pc as an object wrapped around a uword (jsdIPC)
rename init() to on() on jsdIService
move lineToPc and pcToLine from jsdIThreadState to jsdIScript (where they belong)
add setBreakpoint(), clearBreakpoint(), and clearAllBreakpoints() to jsdIScript
add off(), clearAllBreakpoints(), and breakpointHook attribute to jsdIService
add creatorURL, creatorLine, constructorURL, constructorLine, and value attribut
es to jsdIObject
move from pc as a ulong to pc as an object wrapped around a uword
relocate jsdService constructor to jsd_xpp.cpp in order to initialize the global
service
add global service for the breakpoint callback
add breakpoint callback
move c callbacks to top of source
add creatorURL, creatorLine, constructorURL, constructorLine, and value attribut
es to jsdObject
move from pc as a ulong to pc as an object wrapped around a uword
move lineToPc and pcToLine from ThreadState to Script (where it belongs)
add setBreakpoint(), clearBreakpoint(), and clearAllBreakpoints() to jsdScript
relocate jsdService constructor from jsd_xpp.h in order to initialize the global
service
rename init() to on() on jsdService
add off(), clearAllBreakpoints(), and breakpointHook attribute to jsdService
patch from peterv. We can't use js_* in this module because they're libjs' private stash. I got away with it on Linux somehow, but not on mac, and probably not on windows. jsd_EvaluateScriptInStackFrame now uses JS_EvaluateInStackFrame, instead of doing the inflation itself and calling JS_EvaluateUCInStackFrame.
mozilla/js/rhino/org is now distributed between
mozilla/js/rhino/src and mozilla/js/rhino/toolsrc.
The build.xml has been split in three.
Docs now live in the project directory.
These changes mean that the cvs directories mirror the distribution and thus a distribution
will build the same way as a cvs build.
15.3.4.2 Function.prototype.toString ( )
An implementation-dependent representation of the function is returned. This representation has the syntax of a
FunctionDeclaration. Note in particular that the use and placement of white space, line terminators, and semicolons
within the representation string is implementation-dependent.
add line attribute to jsdIStackFrame
remove isFuction from jsdIValue
add TYPE_UNKNOWN to jsType "enumeration" so we don't fail hard if we can't figure out the type.
add hook type "enumeration" to jsdIExecutionHook
add line attribute to jsdStackFrame
add pcToLine and lineToPc methods to jsdStackFrame
remove isFunction attribute from jsdValue (already covered by jsType attribute)
add propertyCount attribute to jsdValue so you can get the property cound without forcing a bunch of property wrappers to be created (as in GetProperties())
basic methods for jsdIObject and jsdIProperty
tweak string params
most methods for jsdIScript jsdIStackFrame, jsdIThreadState, and jsdIValue
add hack methods enterNestedEventLoop and exitNestedEventLoop. These should be moved to another interface before long.
I attach optimization patch for NativeDate that makes all js... methods
private, removes passing of unnecessary parameters and replaces
checkInstance by realThis call with false as the third parameter.
Regards, Igor
Hi, Norris!
Here is another small optimization for NativeDate in DayFromMonth method
where it replaces arrays by few ifs.
Regards, Igor
Rhino: patch for IdScriptable.java and question about useDynamicScope
Date:
Mon, 16 Apr 2001 17:55:19 +0200
From:
Igor Bukanov <igor.bukanov@windriver.com>
Organization:
Wind River
To:
Norris Boyd <nboyd@atg.com>
Hi, Norris!
Here is a patch to IdScriptable.java that fixes sealed semantic and
makes Something.prototype.constructor to behave just as having DONTENUM
attribute, not DONTENUM|READONLY|PERMANENT. It also renames
seal_function to sealFunctions.
I also have a following question. I added nextInstanceCheck to
IdScriptable.java and its usage in realThis in NativeDate to emulate
code from FunctionObject where it looks up prototype in search for
NativeSomething instance if useDynamicScope is true. But could you
describe why it is necessary? I can understand why doing something like
var proto = new Date();
function Test() { }
Test.prototype = proto;
var test = new Test();
print(test.getDay()); // same as proto.getDay()
would be useful in ceratain situations, but what it has to do with
shared scopes?
Regards, Igor
arguments objects are prototyped by Object.prototype, per ECMA. We still
want a custom class, in order to lazily resolve active-JSStackFrame-based
properties.
- Use a reserved slot to hold a bitmap of deleted arguments elements, so we
don't re-resolve them after they've been deleted (which would make them seem
to be permanent, contrary to ECMA). This work involved sprucing up several
fundamental types (jsbitmap) and macros (jsbitmap helper macros in jsbit.h,
JS_HOWMANY in jstypes.h, JSVAL_INT_BITS in jsapi.h).
to the JS API, for per class extra slots beyond JSSLOT_PRIVATE (or starting
there for a class that lacks JSCLASS_HAS_PRIVATE). To avoid penalizing all
instances, these slots are allocated only upon first property-owned slot
allocation, or upon first JS_SetReservedSlot.
This entailed adding getRequiredSlot and setRequiredSlot hooks to the
JSObjectOps struct, and making obj->slots self-describing, a la BSTR. It
also afforded me a chance to clean up obj->slots locking so that non-native
JSObjectOps didn't risk unlocked accesses! Now there are thread-safe hooks
for all uses of obj.
First consumer is the new, DOM-glue-unifying XPConnect, which needs two
slots per wrapped function. Hence the change to js_FunctionClass.flags'
initializer.
- Commented the heck out of JSClass and JSObjectOps function typedefs in
jspubtd.h. I hope embedders see these comments!
- Fix JS_XDRValue's default case to handle int exclusively, there is no other
possible type (and therefore no JSMSG_BAD_JVAL_TYPE error).
- Clean up tabs in select old, tab-ridden files and sections.
- s/\<fh\>/file/g for stdio FILE * canonical variable names.
Minor fix to JSDebugger
Date:
Wed, 28 Mar 2001 16:34:24 -0800
From:
Christopher Oliver <coliver@mminternet.com>
Organization:
Primary Interface LLC
To:
nboyd@atg.com
Hi Norris,
Attached is a minor fix to the JSDebugger GUI that causes the tool-bar buttons to all have the same width.
I checked out and modified a file from CVS today. See the screenshot below.
Cheers,
Chris
in both directions.
72552: Remedy overzealous CHECK_REQUEST placement in jsapi.c, to produce a
minimal-but-complete set of engine entry points that require a Request
for safe execution.
r=brendan, sr=jband, assist=scc,pinkerton
where any occurrence of arguments.length or arguments[0], e.g., would be
"optimized" to use those bytecodes. This is just wrong if the occurrence
is an operand of delete, ++, --, or the left-hand-side of an assignment
operator!
- [jsfun.c, jsinterp.c] args_getProperty etc. must use JS_GetInstancePrivate,
not JS_GetPrivate, as the arguments object is exposed, and can be made a
prototype of other objects that do not have private data, or private data
that's a JSStackFrame*. Same goes for fun_getProperty, js_GetArgument, etc.
- [jsfun.c, jsobj.c, jsstr.c] No need to specialize fun_delProperty and
str_delProperty to help convince users and ECMA conformance tests that
fun.length and str.length are direct properties of instances, instead of
being delegated to Function.prototype.length and String.prototype.length.
This special case is done universally in js_DeleteProperty for all SHARED
and PERMANENT proto-properties.
- [jshash.c] Sneaking this followup-fix for bug 69271 in: use JS_HASH_BITS
rather than hardcoded 32.
- [jsobj.c, jsscope.[ch]] Fix misnamed js_HashValue (it takes a jsid, so it
is now js_HashId).
- [jsscript.c] script_compile needs to call JS_InstanceOf, to ensure that obj
is a Script object.
- Don't ape java.lang.String's bogo-sampling hash function for "long" (>=16
char) strings.
- Theory and practice comment in jsdhash.h helps analyze when to use double
hashing (most of the time) vs. when to use chaining.
- Subroutine ChangeTable from JS_DHashTableOperate so it can be called from
JS_DHashTableEnumerate, if the latter finds that enough entries have been
removed to be worth a shrink or compress cycle.
pschwartau%netscape.com
nboyd%atg.com
beard%netscape.com
jband%netscape.com
dbaron%fas.harvard.edu
jst%netscape.com
brendan%mozilla.org
kandrot%netscape.com
rginda%netscape.com
peterv%netscape.com
cls%seawood.org
shaver%mozilla.org
darin%netscape.com
dprice%netscape.com
rickg%netscape.com
scc%mozilla.org
pinkerton%netscape.com
mkaply%us.ibm.com
waterson%netscape.com
disttsc%bart.nl
dmose%netscape.com
Peter.VanderBeken%pandora.be