Next steps ? (Re: An attempt of a CSR draft ... (Re: A new WIP (PR # 192) (Re: WIP version with PI compile (Re: A WIP for JDK-8238080 for review/discussion (Re: "Internal review ID 9063426: "FXMLLoader: if script engines implement javax.script.Compilabel compile scripts"
Rony G. Flatscher
Rony.Flatscher at wu.ac.at
Tue Apr 28 13:15:54 UTC 2020
Hi Kevin,
what should be the next steps?
Should I remove "WIP" from the title in <https://github.com/openjdk/jfx/pull/192> and add the CSR
draft text of my last e-mail as a "CSR" comment with PR # 192, thereby requesting it to be added to
<https://bugs.java.com/bugdatabase/view_bug.do?bug_id=JDK-8238080>?
Please advise.
TIA,
---rony
P.S.: This is the RFE:
* RFE (2020-01-24): <https://bugs.java.com/bugdatabase/view_bug.do?bug_id=JDK-8238080>
These are the three versions (all with appropriate unit tests) that I came up with chronologically
to implement the RFE, would prefer the latest version (PR # 192):
* Compile if Compilable implemented (2020-02-28): <https://github.com/openjdk/jfx/pull/129>
* Compile if compile PI and Compilable is implemented (2020-04-11):
<https://github.com/openjdk/jfx/pull/187>
* Compile with fallback, if Compilable is implemented, compile PI for fine-grained control
(2020-04-14): <https://github.com/openjdk/jfx/pull/192>
On 22.04.2020 20:01, Rony G. Flatscher wrote:
> Hi Kevin,
>
> as I am not able to file a CSR with the issue you suggested to come up with a draft, so here it goes:
>
> Summary
> =======
> Have javafx.fxml.FXMLLoader compile FXML scripts before evaluating them, if the script engine
> implements the javax.script.Compilable interface to speed up execution. In case compilation
> throws a javax.script.ScriptException fall back to evaluating the uncompiled script. Allow
> control of script compilation with a "compile" PI for FXML files.
>
> Problem
> =======
> javafx.fxml.FXMLLoader is able to execute scripts in Java script languages
> (javax.script.ScriptEngine implementations) referred to or embedded in a FXML file.
>
> If a script engine implements the javax.script.Compilable interface, then such scripts could be
> compiled and the resulting javax.script.CompiledScript could be executed instead using its
> eval() methods.
>
> Evaluating the javax.script.CompiledScript objects may help speed up the execution of script
> invocations, especially for scripts defined for event attributes in FXML elements (e.g. like
> onMouseMove) which may be repetitively invoked and evaluated.
>
> Solution
> ========
> Before evaluating the script code test whether the javax.script.ScriptEngine implements
> javax.script.Compilable. If so, compile the script to a javax.script.CompiledScript object first
> and then use its eval() method to evaluate the script, otherwise continue to use the
> javax.script.ScriptEngine's eval() method instead. Should compilation of a script yield
> (unexpectedly) a javax.script.ScriptException then fall back to using the
> javax.script.ScriptEngine's eval() method. A new process instruction "compile" allows control of
> the compilation of scripts ("true" sets compilation on, "false" to set compilation off) in FXML
> files.
>
> Specification
> =============
> If a javax.script.ScriptEngine implements the javax.script.Compilable interface, then use its
> compile() method to compile the script to a javax.script.CompiledScript object and use its
> eval() method to run the script. In the case that the compilation throws (unexpectedly) a
> javax.script.ScriptException log a warning and fall back to using the
> javax.script.ScriptEngine's eval() method instead.
> To allow setting this feature off and on while processing the FXML file a "compile" process
> instruction ("<?compile false?>" or "<?compile true?>") gets defined that allows to turn
> compilation off and on throughout a FXML file.
>
> Having never seen a real CSR I hope that this matches what is expected and is helpful for
> assessment. If not please advise (got the name of these fields from [1]).
>
> ---
>
> Also added brief information about the respective test units (what they test and yield) in the WIP [2].
>
> ---rony
>
> [1] "CSR-FAQ": <https://wiki.openjdk.java.net/display/csr/CSR+FAQs>
>
> [2] "WIP: Script compilable+compile PI+fallback: 8238080: FXMLLoader: if script engines implement
> javax.script.Compilable compile scripts #192": <https://github.com/openjdk/jfx/pull/192>
>
>
> On 20.04.2020 14:58, Rony G. Flatscher wrote:
>> There is a new WIP at <https://github.com/openjdk/jfx/pull/192>:
>>
>> This WIP adds the ability for a fallback in case compilation of scripts fails, in which case a
>> warning gets issued about this fact and evaluation of the script will be done without
>> compilation. Because of the fallback scripts get compiled with this version by default. It
>> extends PR 187 #187.
>>
>> To further ease spotting scripts that cause a ScriptException a message in the form of
>> "filename: caused ScriptException" gets added to the exception handling in either of the three
>> locations: an error message, a stack trace or a wrap-up into a RuntimeException (having three
>> different kinds of reporting ScriptExceptions may be questioned, however none of these tear down
>> the FXML GUI).
>>
>> This WIP comes with proper test units as well. As per Kevin's suggestion a warning gets logged
>> whenever a script cannot be compiled and the fallback gets used.
>>
>> It is suggested to use this WIP as it includes the compilation by default with a safe fallback to
>> evaluate the uncompiled script, if compilation (unexpectedly) fails.
>>
>> Again, any feedback, discussion welcome!
>>
>> ---rony
>>
>> P.S.: In the log history there is a commit message "Make message more pregnant.", it should have
>> read "Make messages more terse." instead|.||
>> |
>>
>>
>> On 17.04.2020 19:37, Rony G. Flatscher wrote:
>>> There is a new WIP at <https://github.com/openjdk/jfx/pull/187> which adds a compile PI (process
>>> instruction) for turning on and off script compilation if the script engine implements the
>>> Compilable interface.
>>>
>>> By default compilation is off (no compilation), such that one needs to add a compile PI
>>> ("<?compile?>") at the top to activate this feature. Supplying "true" (default) or "false" as the PI
>>> data turns this feature on and off.
>>>
>>> The WIP comes with adapted test units that test "compile on" for an entire fxml file, "compile off",
>>> alternating using "compile on and off", and alternating using "compile off and on". This will test
>>> all variants of applying the compile PI for all categories of scripts.
>>>
>>> Any feedback appreciated!
>>>
>>> ---rony
>>>
>>> P.S.: FXML files that contain unknown PIs do not cause a runtime error by FXMLLoader, they just get
>>> ignored. Therefore one could apply the compile PI to FXML files that are used in older JavaFX runtimes.
>>>
>>> P.P.S.: In the next days I will also add Kevin's idea in a separate version that will have a
>>> fallback solution in case a compilation is (unexpectedly) not successful, reverting to
>>> (interpretative) evaluation/execution of the script. In that version it is planned to have
>>> compilation on by default as in the case of a compilation failure there will be a safe backup solution.
>>>
>>>
>>> On 14.04.2020 19:52, Kevin Rushforth wrote:
>>>> Yes, I agree that enough time has gone by. Go ahead with your proposal. I would wait a bit to
>>>> create the CSR until the review is far enough along to know which direction we intend to go.
>>>>
>>>> Unless there is a real concern about possible regressions if scripts are compiled by default, I
>>>> think "enabled by default" is the way to go. Your argument that such script engines are broken
>>>> seems reasonable, since this only applies to script engines that implement javax.script.Compilable
>>>> in the first place. We still might want to add way to turn compilation off for individual scripts.
>>>> One other thing to consider is that if compilation fails, it might make sense to log a warning and
>>>> fall back to the existing interpreted mode.
>>>>
>>>> Does anyone else have any concerns with this?
>>>>
>>>> -- Kevin
>>>>
>>>>
>>>> On 4/14/2020 9:48 AM, Rony G. Flatscher wrote:
>>>>> Hi there,
>>>>>
>>>>> as there was probably enough time that has passed by I would intend to create a CSR in the next days
>>>>> with the PR as per Kevin's suggestion.
>>>>>
>>>>> (For the case that this feature should not be active by default, the CSR will suggest to define a
>>>>> new "compile" PI in the form <?compile [true|false] ?> (default, if no PI data given: true), which
>>>>> is independent of the existence of a language PI (this way it becomes also possible to allow
>>>>> compilation of external scripts denoted with the script-element, which do not need a page language
>>>>> to be set as the file's extension allows the appropriate script engine to be loaded and used for
>>>>> execution). A compile-PI would allow for turning compilation of scripts on by just adding the PI
>>>>> <?compile?> or <?compile true?> to FXML files (and <?compile false?> to turn off), which seems to
>>>>> be simple and self-documentary. In general employing such compile PIs allows for setting compilation
>>>>> of scripts on and off throughout an FXML file.)
>>>>>
>>>>> ---rony
>>>>>
>>>>>
>>>>> On 04.04.2020 18:03, Rony G. Flatscher wrote:
>>>>>
>>>>>> Hi Kevin,
>>>>>>
>>>>>> On 03.04.2020 01:21, Kevin Rushforth wrote:
>>>>>>> I see that you updated the PR and sent it for review.
>>>>>>>
>>>>>>> Before we formally review it in the PR, let's finish the discussion as to whether this is a useful
>>>>>>> feature, and if so, what form this feature should take.
>>>>>>>
>>>>>>> From my point of view, this does seem like a useful feature. Would other users of FXML benefit
>>>>>>> from it?
>>>>>> Script code should be executed faster after compilation, so any FXML page that hosts script code
>>>>>> may
>>>>>> benefit.
>>>>>>
>>>>>> The benefits depend on the type of script (and maybe its size and its complexity) and also on the
>>>>>> types of event handlers the scripts serve, e.g. move or drag event handlers may benefit
>>>>>> significantly. This is because repeated invocation of compiled script event handlers do not cause
>>>>>> the reparsing of that script's source and interpreting it on each invocation, which may be
>>>>>> expensive
>>>>>> depending on the script engine, but rather allows the immediate evaluation/execution of the
>>>>>> compiled
>>>>>> script by the script engine.
>>>>>>
>>>>>>> I'm not certain whether we want it to be implicit, compiling the script if the script engine in
>>>>>>> question implements Compilable, or via a new keyword or tag. What are the pros / cons?
>>>>>> In principle there are three possibilities:
>>>>>>
>>>>>> 1) If a script engine implements javax.script.Compilable, compile the script and execute the
>>>>>> compiled version. In the case of event handlers compile and buffer the compiled script and
>>>>>> execute the compiled script each time its registered event fires.
>>>>>>
>>>>>> o Pro: immediately benefits all existing FXML pages that host scripts
>>>>>> o Con: it is theoretically possible (albeit quite unlikely) that there are scripts that fail
>>>>>> compiling but have been employed successfully in interpreted mode
>>>>>>
>>>>>> 2) Introduce some form of an optional attribute (e.g. "compile={true|false}") to the FXML
>>>>>> language PI that switches on compilation of scripts hosted in FXML definitions if the script
>>>>>> engine implements the javax.script.Compilable interface. If missing it would default to
>>>>>> "false".
>>>>>> (Alternatively, add a "compile" PI, that if present causes the compilation of scripts, if the
>>>>>> script engine supports it. It would be an error if the "compile" PI was present, but the
>>>>>> "language" PI was not.)
>>>>>>
>>>>>> o Pro: compilation of FXML hosted scripts is done only, if the FXML definition of the
>>>>>> language
>>>>>> PI gets changed
>>>>>> o Con: benefit not made available automatically to existing FXML pages that host scripts
>>>>>>
>>>>>> 3) Another possibility would be to define a boolean attribute/property "compile" for script
>>>>>> and
>>>>>> node elements and only compile the scripts, if the property is set to true
>>>>>>
>>>>>> o Pro: compilation of FXML hosted scripts is done only, if the FXML definition gets changed
>>>>>> accordingly
>>>>>> o Con: potential benefit not made available automatically to existing FXML pages that
>>>>>> host scripts
>>>>>>
>>>>>> 2 and 3 could be combined, where 2 would define the default compilation behavior that then could be
>>>>>> overruled individually by 3.
>>>>>>
>>>>>> The question would be whether 2 or/and 3 are really necessary as it can be expected that
>>>>>> compilation
>>>>>> of scripts by the script engines would find the same errors as while interpreting the very same
>>>>>> scripts (if not, the script engine is badly broken and it could be argued that then the
>>>>>> interpretation part of the script engine might be expected to be broken as well which would be
>>>>>> quite
>>>>>> dangerous from an integrity POV; the same consideration applies as well if the execution of the
>>>>>> compiled script would behave differently to interpreting the very same script by the same script
>>>>>> engine).
>>>>>>
>>>>>> The current WIP implements 1 above and includes an appropriate test unit.
>>>>>>
>>>>>>> What do others think?
>>>>>>> In either case, we would need to make sure that this doesn't present any security concerns in the
>>>>>>> presence of a security manager. As long as a user-provided class is on the stack, it will be fine,
>>>>>>> but we would need to ensure that.
>>>>>> The compilation of scripts needs to be done by the Java script engines (implementing both,
>>>>>> javax.script.Engine and javax.script.Compilable) as well as controlling the execution of compiled
>>>>>> scripts ([javax.script.CompiledScript]
>>>>>> (https://docs.oracle.com/en/java/javase/14/docs/api/java.scripting/javax/script/CompiledScript.html)).
>>>>>>
>>>>>>
>>>>>> ---rony
>>>>>>
>>>>>>
>>>>>>
>>>>>>> On 4/2/2020 10:41 AM, Rony G. Flatscher wrote:
>>>>>>>> After merging master, applying some fixes and changing the title to reflect the change from
>>>>>>>> WIP to a
>>>>>>>> pull request I would kindly request a review of this pull request!
>>>>>>>>
>>>>>>>> Here the URL: <https://github.com/openjdk/jfx/pull/129>, title changed to: "8238080:
>>>>>>>> FXMLLoader: if
>>>>>>>> script engines implement javax.script.Compilable compile scripts".
>>>>>>>>
>>>>>>>> ---rony
>>>>>>>>
>>>>>>>>
>>>>>>>> On 28.02.2020 19:22, Rony G. Flatscher wrote:
>>>>>>>>> Here is a WIP [1] implementation of [2]. The WIP is based on [3], which is currently in
>>>>>>>>> review, and
>>>>>>>>> has an appropriate test unit going with it as well, please review.
>>>>>>>>>
>>>>>>>>> There should be no compatibility issue with this implementation.
>>>>>>>>>
>>>>>>>>> Discussion: another solution could be to not compile by default. Rather compile, if some new
>>>>>>>>> information is present with the FXML file which cannot possibly be present in existing FXML
>>>>>>>>> files.
>>>>>>>>> In this scenario one possible and probably simple solution would be to only compile scripts
>>>>>>>>> if the
>>>>>>>>> language process instruction (e.g. <?language rexx?>) contains an appropriate attribute with a
>>>>>>>>> value
>>>>>>>>> indicating that compilation should be carried out (e.g.: compile="true"). This way only FXML
>>>>>>>>> with
>>>>>>>>> PIs having this attribute set to true would be affected. If desired I could try to come up
>>>>>>>>> with a
>>>>>>>>> respective solution as well.
>>>>>>>>>
>>>>>>>>> ---rony
>>>>>>>>>
>>>>>>>>> [1] "Implementation and test unit": <https://github.com/openjdk/jfx/pull/129>
>>>>>>>>>
>>>>>>>>> [2] "JDK-8238080 : FXMLLoader: if script engines implement javax.script.Compilable compile
>>>>>>>>> scripts":
>>>>>>>>> <https://bugs.java.com/bugdatabase/view_bug.do?bug_id=JDK-8238080>
>>>>>>>>>
>>>>>>>>> [3] "8234959: FXMLLoader does not populate ENGINE_SCOPE Bindings with FILENAME and ARGV":
>>>>>>>>> <https://github.com/openjdk/jfx/pull/122/commits>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On 24.01.2020 16:26, Kevin Rushforth wrote:
>>>>>>>>>
>>>>>>>>>> Thank you for filing this enhancement request. As an enhancement it should be discussed on this
>>>>>>>>>> list before proceeding with a pull request (although a "WIP" or Draft PR can be used to
>>>>>>>>>> illustrate
>>>>>>>>>> the concept).
>>>>>>>>>>
>>>>>>>>>> For my part, this seems like a reasonable enhancement, as long as there are no compatibility
>>>>>>>>>> issues, but it would be good to hear from application developers who heavily use FXML.
>>>>>>>>>>
>>>>>>>>>> -- Kevin
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On 1/24/2020 7:21 AM, Rony G. Flatscher wrote:
>>>>>>>>>>> Just filed a RFE with the following information:
>>>>>>>>>>>
>>>>>>>>>>> * Component:
>>>>>>>>>>> o JavaFX
>>>>>>>>>>>
>>>>>>>>>>> * Subcomponent:
>>>>>>>>>>> o fxml: JavaFX FXML
>>>>>>>>>>>
>>>>>>>>>>> * Synopsis:
>>>>>>>>>>> o "FXMLLoader: if script engines implement javax.script.Compilabel compile scripts"
>>>>>>>>>>>
>>>>>>>>>>> * Descriptions:
>>>>>>>>>>> o "FXMLLoader is able to execute scripts in Java script languages
>>>>>>>>>>> (javax.script.ScriptEngine
>>>>>>>>>>> implementations) if such a Java script language gets defined as the controller
>>>>>>>>>>> language in
>>>>>>>>>>> the FXML file.
>>>>>>>>>>>
>>>>>>>>>>> If a script engine implements the javax.script.Compilable interface, then such
>>>>>>>>>>> scripts
>>>>>>>>>>> could
>>>>>>>>>>> be compiled and the resulting javax.script.CompiledScript could be executed instead
>>>>>>>>>>> using
>>>>>>>>>>> its eval() methods.
>>>>>>>>>>>
>>>>>>>>>>> Evaluating the CompiledScript objects may help speed up the execution of script
>>>>>>>>>>> invocations,
>>>>>>>>>>> especially for scripts defined for event attributes in FXML elements (e.g. like
>>>>>>>>>>> onMouseMove)
>>>>>>>>>>> which may be repetitevly invoked and evaluated."
>>>>>>>>>>>
>>>>>>>>>>> * System /OS/Java Runtime Information:
>>>>>>>>>>> o "All systems."
>>>>>>>>>>>
>>>>>>>>>>> Received the internal review ID: "9063426"
>>>>>>>>>>>
>>>>>>>>>>> ---rony
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