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 May 12 17:18:27 UTC 2020
Hi Kevin,
in the meantime I have tried to come up with a formulation for the "Introduction to FXML"
specification about the new compile processing instruction which is brief and complete. While being
there I fixed a typo in the document and added a missing language processing instruction to an
existing script example, hope that was o.k. as I have not filed an explicit bug for it.
Also closed the PR 129 and 187, removed the WIP from PR 192, and supplied the CSR draft as a comment.
If there is anything else I should do, please let me know.
Cheers,
---rony
On 11.05.2020 14:12, Rony G. Flatscher wrote:
> Hi Kevin,
>
> On 09.05.2020 17:16, Kevin Rushforth wrote:
>> I'm finally getting back to this. I took a look at https://github.com/openjdk/jfx/pull/192 and I
>> like that as the direction for this enhancement.
>>
>> The initial CSR you have is a good start.
> Thank you!
>
>> Next steps are:
>>
>> 1. Update the "Introduction to FXML" specification (see my comment in the PR)
>> 2. Update PR 192 with the draft CSR as a comment, modifying it to include the above additions to
>> "Introduction to FXML"
>> 3. Remove WIP from the title
>>
>> You can then close the other two PRs (129 and 187).
> will do (may take a little bit).
>
> Cheers
>
> ---rony
>
>
>> On 4/28/2020 6:15 AM, Rony G. Flatscher wrote:
>>> 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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