Squeak-dev January 2024

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89 discussions

Code duplication around unwinding
by Jaromir Matas 14 Jan '24

14 Jan '24

Hi all, When I started learning Squeak I wondered why so much code duplication around unwinding: Context>>#restart, #resume:through:, #resumeEvaluating:, #terminate and #unwindTo: all implementing the exact same algorithm. Kernel-jar.1499 suggests removing all this duplicity while keeping the current unwind semantics. All Process and Exceptions tests are green. This changeset is the first step in my effort to reduce the "noise" around the "collection" of resume/return methods in Context and Exception. One idea is to return calling the unwind mechanism back to the Exception class, as originally implemented in Squeak 2.x up to 3.5; please let me know if you find something fundamentally wrong with this idea. Example: I find this call sequence begging for simplification: Exception>>resume: --> resumeUnchecked: --> resumeEvaluating: --> Context>>returnEvaluating: --> resumeEvaluating: Best, Jaromir -- Jaromír Matas mail(a)jaromir.net

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The Trunk: Tests-ct.503.mcz
by commits＠source.squeak.org 13 Jan '24

13 Jan '24

Christoph Thiede uploaded a new version of Tests to project The Trunk: http://source.squeak.org/trunk/Tests-ct.503.mcz ==================== Summary ==================== Name: Tests-ct.503 Author: ct Time: 13 January 2024, 9:26:44.03906 pm UUID: 70a433e6-4b0a-fb47-9201-9a401559ca05 Ancestors: Tests-dtl.502 Complements Chronology-Core-jar.91 (fixes concurrency issue in #valueWithin:onTimeout:). =============== Diff against Tests-dtl.502 =============== Item was added: + ----- Method: TestValueWithinFix>>testValueWithinTermination (in category 'tests') ----- + testValueWithinTermination + "Regression test for synchronization issue (https://github.com/squeak-smalltalk/squeak-object-memory/issues/108)" + + | process watchdog | + process := [[100 milliSeconds wait] valueWithin: 200 milliSeconds onTimeout: []] newProcess. + "simulate a possible context switch in primitiveResume" + process runUntil: [:c | c isClosureContext and: [c size > 0 and: [(watchdog := c top) isKindOf: Process]]]. + self assert: watchdog isSuspended. + + process step. + process terminate. + + 250 milliSeconds wait. + self assert: watchdog isTerminated. + self assert: process isTerminated.!

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The Trunk: Chronology-Core-jar.91.mcz
by commits＠source.squeak.org 13 Jan '24

13 Jan '24

Christoph Thiede uploaded a new version of Chronology-Core to project The Trunk: http://source.squeak.org/trunk/Chronology-Core-jar.91.mcz ==================== Summary ==================== Name: Chronology-Core-jar.91 Author: jar Time: 7 January 2024, 1:50:33.62718 pm UUID: 449881a6-d6f2-1748-a77b-16c0a300483c Ancestors: Chronology-Core-jar.90 an alternative fix of a bug in #valueWithin:onTimeout: described in Chronology-Core-jar.90 FYI: Issue: the method starts a watchdog at high priority before entering the ensure: method. But the active process may terminate before entering the ensure: inside valueWithin:onTimeout:, and thus the cleanup ensure argument block will not be executed during the unwind. As a result the watchod will assume the active process has not completed the watched block and will erroneously signal the TimedOut exception and a failure (BCR exception) inside #signalException will follow. =============== Diff against Chronology-Core-jar.90 =============== Item was changed: ----- Method: BlockClosure>>valueWithin:onTimeout: (in category '*chronology-core') ----- valueWithin: aDuration onTimeout: timeoutBlock "Evaluate the receiver. If the evaluation does not complete in less than aDuration evaluate the timeoutBlock instead" | theProcess delay watchdog tag | aDuration <= Duration zero ifTrue: [^ timeoutBlock value ]. "the block will be executed in the current process" theProcess := Processor activeProcess. delay := aDuration asDelay. tag := self. "make a watchdog process" watchdog := [ + delay wait. "wait for timeout" + theProcess signalException: (TimedOut new tag: tag) - delay wait. "wait for timeout or completion" - theProcess ifNotNil:[ theProcess signalException: (TimedOut new tag: tag)] ] newProcess. "Watchdog needs to run at high priority to do its job (but not at timing priority)" watchdog priority: Processor timingPriority-1. "catch the timeout signal" + ^ [[watchdog resume. "start up the watchdog" + self value] ensure: [ "evaluate the receiver" + watchdog terminate. "exit the watchdog" - ^ [ [watchdog resume. "start up the watchdog" - self value] ensure:[ "evaluate the receiver" - theProcess := nil. "it has completed, so ..." - delay delaySemaphore signal. "arrange for the watchdog to exit" ]] on: TimedOut do: [ :e | e tag == tag ifTrue:[ timeoutBlock value ] ifFalse:[ e pass]].!

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The Trunk: Chronology-Core-jar.90.mcz
by commits＠source.squeak.org 13 Jan '24

13 Jan '24

Christoph Thiede uploaded a new version of Chronology-Core to project The Trunk: http://source.squeak.org/trunk/Chronology-Core-jar.90.mcz ==================== Summary ==================== Name: Chronology-Core-jar.90 Author: jar Time: 5 January 2024, 12:03:49.89018 pm UUID: 498e4b92-020c-2442-bb24-ad77536e626f Ancestors: Chronology-Core-mt.88 fix a bug in #valueWithin:onTimeout: see https://github.com/squeak-smalltalk/squeak-object-memory/issues/108 Issue: the method starts a watchdog at high priority before entering the ensure: method. But the active process may terminate before entering the ensure: inside valueWithin:onTimeout:, and thus the cleanup ensure argument block will not be executed during the unwind. As a result the watchod will assume the active process has not completed the watched block and will erroneously signal the TimedOut exception and a failure (BCR exception) inside #signalException will follow. =============== Diff against Chronology-Core-mt.88 =============== Item was changed: ----- Method: BlockClosure>>valueWithin:onTimeout: (in category '*chronology-core') ----- valueWithin: aDuration onTimeout: timeoutBlock "Evaluate the receiver. If the evaluation does not complete in less than aDuration evaluate the timeoutBlock instead" | theProcess delay watchdog tag | aDuration <= Duration zero ifTrue: [^ timeoutBlock value ]. "the block will be executed in the current process" theProcess := Processor activeProcess. delay := aDuration asDelay. tag := self. "make a watchdog process" watchdog := [ delay wait. "wait for timeout or completion" theProcess ifNotNil:[ theProcess signalException: (TimedOut new tag: tag)] ] newProcess. "Watchdog needs to run at high priority to do its job (but not at timing priority)" watchdog priority: Processor timingPriority-1. "catch the timeout signal" + ^ [ [watchdog resume. "start up the watchdog" + self value] ensure:[ "evaluate the receiver" - ^ [ watchdog resume. "start up the watchdog" - self ensure:[ "evaluate the receiver" theProcess := nil. "it has completed, so ..." delay delaySemaphore signal. "arrange for the watchdog to exit" ]] on: TimedOut do: [ :e | e tag == tag ifTrue:[ timeoutBlock value ] ifFalse:[ e pass]].!

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[ANN] TraceDebugger: A new time-travel debugger for Squeak
by christoph.thiede＠student.hpi.uni-potsdam.de 13 Jan '24

13 Jan '24

Hi all! I‘m very excited to announce a project today that we have been working on over the past two years: The TraceDebugger [1] is a new back-in-time/time-travel/omniscient debugging tool for Squeak that allows you to record past method activations and states during execution and explore them later. https://github.com/hpi-swa-lab/squeak-tracedebugger Metacello new baseline: 'TraceDebugger'; repository: 'github://hpi-swa-lab/squeak-tracedebugger'; "repository: 'github://hpi-swa-lab/squeak-tracedebugger:squeak60';" "for Squeak 6.0" get; load. *What can it do? (Features)* - Record all method activations and historic states: Normally step through a program in the debugger while automatically recording its execution. - Replay execution of a traced program: Navigate through all method invocations using the *context tree* or the *Step Back/Step Forward* buttons (to avoid these "oops, I‘ve stepped too far, let‘s start all over again" situations). - Interact with historic states: Inspect/explore snapshots of objects or send them any message. - State-centric debugging using the *History Explorer*: Gather, explore, and visualize all changes to an object/expression over the recorded time ("When did this variable/collection/screenshot change?"). - Additional navigation tools for searching and filtering the context tree. - Focus on interactivity: No hours of recording, no GBs of mem consumption - at least for common small to medium programs. - UI resembles the classic Smalltalk debugger: You'll find your familiar stepping buttons, code browsing tools, inspectors, and shortcuts - plus more. The TraceDebugger is a general-purpose tool and not tied to particular domains. In the past months, we have successfully used it to understand several bugs and interaction patterns in the Trunk (Morphic layout/rendering, compiler/decompiler, code simulation, …). The tool is also self-supporting, so you can debug a TraceDebugger from another TraceDebugger. :-) *What can‘t it do (yet)? (Limitations and future work)* - High performance: While (sufficiently) fast enough for most small to medium workloads, tracing very compute- or mem-intensive operations may require more time (ex.: compiler/decompiler invocation: <1s, HTTPS request: <10s, tool building: <5m, complex rendering: minutes up to hours). - Not a dataflow analyzer: The TraceDebugger does not track dataflow events (e.g., argument passing) but only state changes. - No tracing of external states/events for FFI/OSProcess or custom VM modules. - No support for advanced language concepts such as identity forwarding/write barriers. *How does it work? (Implementation)* In one sentence: To record message sends and side effects, we decorate the execution of certain bytecodes with tracing extensions by modifying the code simulation using SimulationStudio [2]. In one paragraph: The program is executed in a specialized code simulator that overrides instructions for sending messages (e.g., send, superSend) and for performing side-effects (e.g., popIntoRcvr, primitiveAtPut, push). All message sends are recorded in a tree and all changed object slots are stored in a sparse time-dependent memory structure before they are overwritten. For time-traveling, the tree is traversed using a cursor. For accessing historic objects, a proxy evaluates all messages sent to an object in another specialized simulator (retracing simulator) that emulates historic states for the requested point in time by forwarding read primitives (e.g., pushRcvr, primitiveAt) to the recorded memory. For gathering state changes in the History Explorer efficiently, the query is evaluated in a range retracing simulator with vectorization and fork semantics. In academic terms: We have published two papers about the TraceDebugger that provide further details about its implementation and its applications for program exploration, "Object-Centric Time-Travel Debugging: Exploring Traces of Objects" [3] and "Time-Awareness in Object Exploration Tools: Toward In Situ Omniscient Debugging" [4]. In Smalltalk: Just check out the code base and explore it by yourself! The class comments in TraceDebugger and TDBCursor should provide good starting points. *How can I use it?* Please try it out and report feedback! The TraceDebugger supports the latest Squeak Trunk and Squeak 6.0. You can either download a prepared all-in-one bundle on GitHub: https://github.com/hpi-swa-lab/squeak-tracedebugger/releases Or you can install it into your own image using Metacello: Metacello new baseline: 'TraceDebugger'; repository: 'github://hpi-swa-lab/squeak-tracedebugger'; "repository: 'github://hpi-swa-lab/squeak-tracedebugger:squeak60';" "for Squeak 6.0" get; load. To get started, just open a normal debugger (e.g., by selecting an expression and pressing Cmd+Shift+D to debug it) and then press the "Trace It" button on the right. There‘s also some pretty detailed documentation in the Help Browser that covers everything you should know. My goal is to improve convenience and provide a useful tool for the community, so I‘m very excited to hear your impressions, ideas, and thoughts. Here, on GitHub, or in a private message. Let‘s have a great discussion! :-) Best, Christoph (and Marcel) PS: Props to Eliot who brought up the original idea of "subclassing from Context" for other reasons four years ago. [5] [1] https://github.com/hpi-swa-lab/squeak-tracedebugger [2] https://github.com/LinqLover/SimulationStudio [3] Christoph Thiede, Marcel Taeumel, and Robert Hirschfeld. 2023. Object-Centric Time-Travel Debugging: Exploring Traces of Objects. In Companion Proceedings of the 7th International Conference on the Art, Science, and Engineering of Programming (<Programming>'23 Companion), March 13–17, 2023, Tokyo, Japan. ACM, New York, NY, USA, 7 pages. DOI: 10.1145/3594671.3594678. PDF: https://dl.acm.org/doi/pdf/10.1145/3594671.3594678 [4] Christoph Thiede, Marcel Taeumel, and Robert Hirschfeld. 2023. Time-Awareness in Object Exploration Tools: Toward In Situ Omniscient Debugging. In Proceedings of the 2023 ACM SIGPLAN International Symposium on New Ideas, New Paradigms, and Reflections on Programming and Software (Onward! '23), October 25–27, 2023, Cascais, Portugal. ACM, New York, NY, USA, 14 pages. DOI: 10.1145/3622758.3622892. PDF: https://dl.acm.org/doi/pdf/10.1145/3622758.3622892 [5] http://lists.squeakfoundation.org/pipermail/squeak-dev/2019-October/204803.… --- Sent from Squeak Inbox Talk

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The Inbox: KernelTests-jar.449.mcz
by commits＠source.squeak.org 13 Jan '24

13 Jan '24

A new version of KernelTests was added to project The Inbox: http://source.squeak.org/inbox/KernelTests-jar.449.mcz ==================== Summary ==================== Name: KernelTests-jar.449 Author: jar Time: 2 January 2024, 12:28:08.184411 pm UUID: decf5a85-87ad-5849-b692-ee28940eab41 Ancestors: KernelTests-jar.448 Test if #return:from: correctly handles returns to nil contexts =============== Diff against KernelTests-jar.448 =============== Item was added: + ----- Method: ContextTest>>testBlockCannotReturnToNil (in category 'tests') ----- + testBlockCannotReturnToNil + "Test if #return:from: correctly handles returns to dead or nil contexts." + + | context nextContext | + context := [] asContext. + + "assert p is at the last instruction, i.e. a return, and is about to return to a nil context" + self assert: context method selector = thisContext method selector. + self assert: context sender isNil. + self assert: context willReturn. + self assert: context atEnd. + + nextContext := context step. "step into a return to a nil sender" + + self assert: nextContext method selector = #cannotReturn:!

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Small but annoying change in Raspberry Pi GPIO world that affects Squeak
by Tim Rowledge 11 Jan '24

11 Jan '24

This affects a few people here, so I thought I should spread the weird. I've just discovered that for reasons the previously excellent pigpiod daemon/library does not work on a Pi 5. We are apparently meant to use libgpiod now , which means rewriting a lot of stuff that I use for NuScratch, and writing a new set of FFI classes. Oh joy. tim -- tim Rowledge; tim(a)rowledge.org; http://www.rowledge.org/tim Life would be much easier if I had the source code.

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The Trunk: Kernel-mt.1550.mcz
by commits＠source.squeak.org 10 Jan '24

10 Jan '24

Marcel Taeumel uploaded a new version of Kernel to project The Trunk: http://source.squeak.org/trunk/Kernel-mt.1550.mcz ==================== Summary ==================== Name: Kernel-mt.1550 Author: mt Time: 10 January 2024, 10:09:15.266957 am UUID: 8f04eaa3-9dff-3d40-83f5-5783afc41380 Ancestors: Kernel-ct.1549, Kernel-mt.1545 Merge Kernel-mt.1545: - Propose different fallback for mixed int-float arithmetics to use VM-backed mixed float-int arithmetics for + - * / . Speed-up is about 7x on my machine. No measurable slowdown for non-float fallback paths. =============== Diff against Kernel-ct.1549 =============== Item was changed: ----- Method: SmallInteger>>* (in category 'arithmetic') ----- * aNumber "Primitive. Multiply the receiver by the argument and answer with the result if it is a SmallInteger. Fail if the argument or the result is not a SmallInteger. Essential. No Lookup. See Object documentation whatIsAPrimitive." <primitive: 9> + ^ aNumber isFloat + ifTrue: [aNumber * self "exploit mixed arithmetic in float primitives"] + ifFalse: [super * aNumber]! - ^ super * aNumber! Item was changed: ----- Method: SmallInteger>>+ (in category 'arithmetic') ----- + aNumber "Primitive. Add the receiver to the argument and answer with the result if it is a SmallInteger. Fail if the argument or the result is not a SmallInteger Essential No Lookup. See Object documentation whatIsAPrimitive." <primitive: 1> + ^ aNumber isFloat + ifTrue: [aNumber + self "exploit mixed arithmetic in float primitives"] + ifFalse: [super + aNumber]! - ^ super + aNumber! Item was changed: ----- Method: SmallInteger>>- (in category 'arithmetic') ----- - aNumber "Primitive. Subtract the argument from the receiver and answer with the result if it is a SmallInteger. Fail if the argument or the result is not a SmallInteger. Essential. No Lookup. See Object documentation whatIsAPrimitive." <primitive: 2> + ^ aNumber isFloat + ifTrue: [aNumber negated + self "exploit mixed arithmetic in float primitives"] + ifFalse: [super - aNumber]! - ^super - aNumber! Item was changed: ----- Method: SmallInteger>>/ (in category 'arithmetic') ----- / aNumber "Primitive. This primitive (for /) divides the receiver by the argument and returns the result if the division is exact. Fail if the result is not a whole integer. Fail if the argument is 0 or is not a SmallInteger. Optional. No Lookup. See Object documentation whatIsAPrimitive." <primitive: 10> + ^ aNumber isFloat + ifTrue: [(1.0 / aNumber) * self "exploit mixed arithmetic in float primitives"] + ifFalse: [super / aNumber]! - ^super / aNumber!

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The Trunk: Kernel-mt.1551.mcz
by commits＠source.squeak.org 10 Jan '24

10 Jan '24

Marcel Taeumel uploaded a new version of Kernel to project The Trunk: http://source.squeak.org/trunk/Kernel-mt.1551.mcz ==================== Summary ==================== Name: Kernel-mt.1551 Author: mt Time: 10 January 2024, 6:09:51.670122 pm UUID: 61ce6dab-9cbd-df43-9d59-a0477314a163 Ancestors: Kernel-mt.1550 Revert but document the latest change for the int-float arithmetic with #/ as it changes precision but should not. =============== Diff against Kernel-mt.1550 =============== Item was changed: ----- Method: SmallInteger>>/ (in category 'arithmetic') ----- / aNumber "Primitive. This primitive (for /) divides the receiver by the argument and returns the result if the division is exact. Fail if the result is not a whole integer. Fail if the argument is 0 or is not a SmallInteger. Optional. No Lookup. See Object documentation whatIsAPrimitive." <primitive: 10> + ^ super / aNumber + + "In theory, we could also exploit mixed arithmetic speed-up through float + primitives. However, the reciprocal approach with multiplication involves + two rounding operations instead of one, which changes the resulting precision. + { 3.0 / 5.0 . 3.0 * (1.0 / 5.0) } + --> #(0.6 0.6000000000000001) + ^ aNumber isFloat + ifTrue: [(1.0 / aNumber) * self ] + ifFalse: [super / aNumber] + "! - ifTrue: [(1.0 / aNumber) * self "exploit mixed arithmetic in float primitives"] - ifFalse: [super / aNumber]!

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The Inbox: CollectionsTests-ct.404.mcz
by commits＠source.squeak.org 10 Jan '24

10 Jan '24

Christoph Thiede uploaded a new version of CollectionsTests to project The Inbox: http://source.squeak.org/inbox/CollectionsTests-ct.404.mcz ==================== Summary ==================== Name: CollectionsTests-ct.404 Author: ct Time: 10 January 2024, 5:56:25.41774 pm UUID: e767dffd-0390-684f-9eee-1dd083656838 Ancestors: CollectionsTests-mt.403 Improves branch coverage for LinkedListTest. =============== Diff against CollectionsTests-mt.403 =============== Item was changed: ----- Method: LinkedListTest>>test11removeLast (in category 'tests') ----- test11removeLast list add: link1. list add: link2. list add: link3. list add: link4. self assert: list size = 4. self assert: list first == link1. self assert: list second == link2. self assert: list third == link3. self assert: list fourth == link4. list removeLast. self assert: list size = 3. self assert: list first == link1. self assert: list second == link2. self assert: list third == link3. list removeLast. self assert: list size = 2. self assert: list first == link1. self assert: list second == link2. list removeLast. self assert: list size = 1. self assert: list first == link1. + list removeLast. - list removeFirst. self assert: list isEmpty! Item was changed: ----- Method: LinkedListTest>>testAtPut (in category 'tests - sequenceable') ----- testAtPut | ll | ll := LinkedList new. ll add: 1. + ll at: 1 put: 2. + self assert: (ll at: 1) equals: 2. + + ll add: 3. + ll at: 2 put: 1.5. + self assert: (ll at: 2) equals: 1.5. + + ll add: 4. + ll at: 2 put: 1.75. + self assert: (ll at: 2) equals: 1.75.! - self assert: (ll at: 1) equals: 2! Item was added: + ----- Method: LinkedListTest>>testSwapOutOfBounds (in category 'tests - swap') ----- + testSwapOutOfBounds + |aList| + aList := LinkedList with: 5 with: 4 with: 3 with: 2 with: 1. + + self + should: [aList swap: 1 with: 6] + raise: Error. + self + should: [aList swap: 1 with: 0] + raise: Error. + self + should: [aList swap: 0 with: 1] + raise: Error. + self + should: [aList swap: 6 with: 1] + raise: Error.!

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