November 2014 - Pharo-dev - lists.pharo.org

callback explanation
by stepharo Nov. 25, 2014

Nov. 25, 2014

Begin forwarded message: From: Eliot Miranda <eliot.miranda(a)gmail.com> Subject: Re: [Vm-dev] FFI callbacks Date: 25 Nov 2014 03:19:49 GMT+1 To: Squeak Virtual Machine Development Discussion <vm-dev(a)lists.squeakfoundation.org> Reply-To: Squeak Virtual Machine Development Discussion <vm-dev(a)lists.squeakfoundation.org> Hi Bert, On Mon, Nov 24, 2014 at 2:49 PM, Bert Freudenberg <bert(a)freudenbergs.de> wrote: How do they actually work? I want to know what information the thunk needs, and what happens when it is activated. I think SqueakJS would benefit from callback support. I'll try and write this up properly in a blog post tomorrow. But... Callback is a wrapper round a piece of executable code, a block, and a "signature" (see below). The executable code is wrapped by an FFICallbackThunk, an Alien, which is just a pointer to this code. Th code is allocated from a special pool of memory marked as executable. The address of the code is unique and is hence used as a key to identify the Callback and hence locate the block from the thunk. The FFI marshalling code should pass the address of the thunk when passing the Callback. Right now that has to be done explicitly. The thunk, when called, invokes thunkEntry, which is defined in e.g. platforms/Cross/plugins/IA32ABI/ia32abicc.c (it needs a different definition for each API). On x86 thinkEntry needs only to be invoked with the think and the stack pointer, since on x86 all arguments are accessible from the stack. On other platforms thunkEntry will need to be invoked with the register arguments. thunkEntry's job is to store the state necessary to return from the callback in an instance of either VMCallbackContext32 or VMCallbackContext64. These are aliens for the following structure: typedef struct { void *thunkp; char *stackptr; long *intRegArgs; double *floatRegArgs; void *savedCStackPointer; void *savedCFramePointer; union { long vallong; struct { int low, high; } valleint64; struct { int high, low; } valbeint64; double valflt64; struct { void *addr; long size; } valstruct; } rvs; jmp_buf trampoline; } VMCallbackContext; The structure lives in the stack frame of thunkEntry, hence one per callback. It does three things: 1. it identifies all the input arguments. These are accessible, depending on platform, through stackptr, intRegArgs and floatRegArgs. 2. it maintains the jmp_buf which can be used to longjmp back to the callback to return from it. 3. it has slots to hold the result to be returned from the callback (the union rvs). The argument to the longjmp (the value returned from the setjmp in thinkEntry) tells thunkEntry how to return the result, i.e. as a 32-bit value, a 64-bit value, a double or a struct. Once thinkEntry has packed up the state in its local VMCallbackContext, it uses if ((flags = interpreterProxy->ownVM(0)) < 0) { fprintf(stderr,"Warning; callback failed to own the VM\n"); return -1; } to "own" the VM. If the VM is single-threaded then this can check that the callback is being made on the same thread as the VM, and fail otherwise. If the VM is multi-threaded ownVM can block until the thread can enter the VM. It then calls-back into the VM using interpreterProxy->sendInvokeCallbackContext(&vmcc); which sends the message (found in the specialObjectsArray) #invokeCallbackContext: which is understood by Alien (see Alien class>>#invokeCallbackContext:). This method wraps up the input argument (the raw address of thunkEntry's VMCallbackContext) in the relevant Alien and invokes Callback's entry point: invokeCallbackContext: vmCallbackContextAddress "<Integer>" "^<FFICallbackReturnValue>" "The low-level entry-point for callbacks sent from the VM/IA32ABI plugin. Return via primReturnFromContext:through:. thisContext's sender is the call-out context." | callbackAlien type | callbackAlien := (Smalltalk wordSize = 4 ifTrue: [VMCallbackContext32] ifFalse: [VMCallbackContext64]) atAddress: vmCallbackContextAddress. [type := Callback evaluateCallbackForContext: callbackAlien] ifCurtailed: [self error: 'attempt to non-local return across a callback']. type ifNil: [type := 1. callbackAlien wordResult: -1]. callbackAlien primReturnAs: type fromContext: thisContext The sendInvokeCallbackContext machinery just constructs an activation of invokeCallbackContext: on top of the current process's stack, which is usually the process that called out through the FFI. Bit it doesn't have to be. threaded callbacks are too detailed for this brief message. Callback then locates the relevant marshalling method for the callback's signature (actually it does this when the Callback is created, but the effect is the same). Callback uses methods that identify themselves via pragmas to choose the relevant marshaller. e.g. for a qsort sort function callback the marshaller on x86 is Callback methods for signatures voidstarvoidstarRetint: callbackContext sp: spAlien <signature: #(int (*)(const void *, const void *)) abi: 'IA32'> ^callbackContext wordResult: (block value: (Alien forPointer: (spAlien unsignedLongAt: 1)) value: (Alien forPointer: (spAlien unsignedLongAt: 5))) So it fetches the arguments from the stack using Alien accessors, evaluates the block with them and then assigns the result via wordResult, and answers the type code back to invokeCallbackContext:, e.g. VMCallbackContext32 methods for accessing wordResult: anInteger "Accept any value in the -2^31 to 2^32-1 range." anInteger >= 0 ifTrue: [self unsignedLongAt: 25 put: anInteger] ifFalse: [self signedLongAt: 25 put: anInteger]. ^1 Then invokeCallbackContext: invokes the primitive to longjmp back to thunkEntry, supplying the return code that will allow thunkEntry to return the reslt correctly: VMCallbackContext32 methods for primitives primReturnAs: typeCode "<SmallInteger>" fromContext: context "<MethodContext>" <primitive: 'primReturnAsFromContextThrough' module: 'IA32ABI' error: ec> ^self primitiveFailed Then thunkEntry switches on the return code and returns to the caller. Note that sendInvokeCallbackContext and primReturnAsFromContextThrough conspire to save, set and restore the VM's notion of what the C stack is in the VMCallbackContext's savedCStackPointer & savedCFramePointer, growing the stack on callback, and cutting it back on return. There's a variable in the VM, previousCallbackContext, that primReturnAsFromContextThrough uses to make sure returns are LIFO. I imagine that somehow the VM's state needs to be saved, then the context that defined the block is activated, and then the VM would run the block until it returns (or until the return prim is called?), then the VM's state would need to be restored to what it was, and the result is passed back by the thunk returning. That's right. Am I close? Since the callback can happen at any time, and it could do anything, saving the whole VM state seems daunting. Provided that the callback occurs from the context of a callout there are no problems. Threaded callbacks take some more doing. Basically the VM needs to b sharable between threads. This is the threaded VM prototype. If you absolutely need threaded callbacks we should have a serious talk. This is not trivial to productise. HTH -- best, Eliot

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How to import an icon inside Pharo
by kilon alios Nov. 24, 2014

Nov. 24, 2014

Hey guys any idea how to import a icon inside pharo and how to use it ? I have seen that pharo uses a sort of string representation of the icon image . Anyone has experience with this ?

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[pharo-project/pharo-core]
by GitHub Nov. 24, 2014

Nov. 24, 2014

Branch: refs/tags/40384 Home: https://github.com/pharo-project/pharo-core

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[pharo-project/pharo-core] 27151e: 40384
by GitHub Nov. 24, 2014

Nov. 24, 2014

Branch: refs/heads/4.0 Home: https://github.com/pharo-project/pharo-core Commit: 27151ed904db256d72e83d85722db500969b23b9 https://github.com/pharo-project/pharo-core/commit/27151ed904db256d72e83d85… Author: Jenkins Build Server <board(a)pharo-project.org> Date: 2014-11-24 (Mon, 24 Nov 2014) Changed paths: A Kernel.package/SmallInteger.class/class/class initialization/initialize.st A Kernel.package/SmallInteger.class/class/class initialization/startUp_.st M Kernel.package/SmallInteger.class/class/constants/maxVal.st M Kernel.package/SmallInteger.class/class/constants/minVal.st A ScriptLoader40.package/ScriptLoader.class/instance/pharo - scripts/script384.st A ScriptLoader40.package/ScriptLoader.class/instance/pharo - updates/update40384.st M ScriptLoader40.package/ScriptLoader.class/instance/public/commentForCurrentUpdate.st M System-Support.package/SmalltalkImage.class/class/initialization/initializeStartUpList.st Log Message: ----------- 40384 14506 Add class inst vars to hold SmallInteger class>>minVal and maxVal. https://pharo.fogbugz.com/f/cases/14506 http://files.pharo.org/image/40/40384.zip

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[ANN] OnScreenKeyboard
by Pavel Krivanek Nov. 24, 2014

Nov. 24, 2014

Hi, I created the first version of a virtual keyboard morph for Pharo. To try it, evaluate: Gofer it url: 'http://www.smalltalkhub.com/mc/PavelKrivanek/OnScreenKeyboard/main'; package: 'OnScreenKeyboard'; load. OnScreenKeyboard new open. Currently it doesn't work well together with completion morphs so please disable code completion. Features: - splitted int two parts - compact look - swipe up to write uppercase letter - swipe left to do backspace - swipe down to write special character - swipe right to write numbers and other special characters - swipe up right to press combination with ctrl (e.g. ctrl+p) - swipe down right to press combination with alt - press Kb button to move the keyboard up and down on the screen - press shift/alt/ctrl keys to hold them (e.g. for selecting text with cursor keys and shift) Feel free to send patches and improvements directly to the project repository :-) Cheers, -- Pavel

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Listening for shift key pressed
by Aliaksei Syrel Nov. 24, 2014

Nov. 24, 2014

Hi, In our project we would like to trigger some actions when user presses down/up Shift button. But we didn't find how to do it. It seems that such keys as Shift, Capslock, Ctrl are event modifiers in Pharo, that apply on already existing events (in HandMorph>>generateKeyboardEvent: evtBuf). Do you have any ideas or maybe have experience concerning described problem? Thanks in advance. Cheers, Alex

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[pharo-project/pharo-core]
by GitHub Nov. 24, 2014

Nov. 24, 2014

Branch: refs/tags/40383 Home: https://github.com/pharo-project/pharo-core

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[pharo-project/pharo-core] 04945b: 40383
by GitHub Nov. 24, 2014

Nov. 24, 2014

Branch: refs/heads/4.0 Home: https://github.com/pharo-project/pharo-core Commit: 04945b033abdc10ba786b45ac9b9b2bc820cb989 https://github.com/pharo-project/pharo-core/commit/04945b033abdc10ba786b45a… Author: Jenkins Build Server <board(a)pharo-project.org> Date: 2014-11-24 (Mon, 24 Nov 2014) Changed paths: A Collections-Sequenceable.package/OrderedCollection.class/instance/converting/asOrderedCollection.st A CollectionsTests.package/ArrayTest.class/instance/tests - converting/testAsArrayKeepsIdentity.st A CollectionsTests.package/OrderedCollectionTest.class/instance/tests - converting/testAsOrderedCollectionKeepsIdentity.st A CollectionsTests.package/OrderedCollectionTest.class/instance/tests - converting/testAsOrderedCollectionReturnsOrderedCollection.st A ScriptLoader40.package/ScriptLoader.class/instance/pharo - scripts/script383.st A ScriptLoader40.package/ScriptLoader.class/instance/pharo - updates/update40383.st M ScriptLoader40.package/ScriptLoader.class/instance/public/commentForCurrentUpdate.st Log Message: ----------- 40383 14498 Unnecessary instance creation in OrderedCollection>>#asOrderedCollection? https://pharo.fogbugz.com/f/cases/14498 http://files.pharo.org/image/40/40383.zip

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Something strange with fileOut
by Hilaire Nov. 24, 2014

Nov. 24, 2014

Hi, We write code and comment in English, so only ascii characters are used. For string we also use English, and when translation is needed we use catalog of messages as gettext, where the non ascii strings are externally represented. So most of the time we only use ascii characters in our code. However, if a developer writes non ascii character in a method, fileout may just break. The problem is described and related to MultiByteFileStream: https://pharo.fogbugz.com/f/cases/14462 I check with Squeak4.5, although I cannot enter non-ascii character (but that's another problem, probably related to the VM I am using not suited to Squeak) I have no error when fileout the same class with non-ascii character in method body. The MultiByteFileStream seems quite different, I don't know the history of changes in these two method versions but changed in Squeak version seems a bit newer. The changes may not be trivial because it involves the whole class hierarchy. Hilaire -- Dr. Geo - http://drgeo.eu iStoa - http://istoa.drgeo.eu

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Re: [Pharo-dev] [smalltalk-research] Re: Julia vs Pharo
by Serge Stinckwich Nov. 24, 2014

Nov. 24, 2014

On Mon, Nov 17, 2014 at 8:13 PM, Lukas Renggli <renggli(a)gmail.com> wrote: > > On Mon, Nov 17, 2014 at 5:05 PM, Serge Stinckwich > <serge.stinckwich(a)gmail.com> wrote: >> >> On Mon, Nov 17, 2014 at 5:01 PM, werner kassens <wernerk740(a)gmail.com> >> wrote: >> >>I never heard about this one. >> > >> > no wonder<g>, i got the name wrong, it was helvetia >> >> Ok, this is about domain-specific languages not multiple dispatch. > > > It actually included an example of multiple dispatch :-) Hi Lukas, I was not aware of that ;-) I will have a look. Thanks, -- Serge Stinckwich UCBN & UMI UMMISCO 209 (IRD/UPMC) Help fight Ebola by joining the Computing for Ebola Challenge http://bit.ly/1oEdBag

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