<style type="text/css"> .reveal p { text-align: left; padding-left: 40px; } .reveal ul { display: block; } .reveal ol { display: block; } </style> # CS4215 Project ## AY2023/24 Sem 2 - Bharath Chandra Sudheer - Hoang Trong Tan --- ### Key Object: Concurrency Concurrency Primitives: - `goroutine`, `mutex`, `semaphore`, `waitgroup`, `channel` - should not be naive busy-waiting Granularity level of concurrency: interleaved execution of VM instructions --- ### Other Objectives: - sequential logic: `for`, `if`, `func`, `func` literals, `var`, primitive types: `bool`, `str`, `int` and related operations and `*T` for any type - low-level memory management - garbage collection: cheney - visualisation of memory ---  --- ### Goose Compiler  --- ### Gosling VM  --- ### Final Result  --- ### Key Tools - [PeggyJs](peggyjs.org) generates left-recursive parser in JS - TSC: strong confidence in preventing malformed objects and ensuring safe logic in parsing, compiling and execution - Jest: CI/CD regression testing & test-driven development --- ### Compiler - recursive compiler - well-typed parsed objects -> well-typed instruction data objects - macro-like compiler directives for reusable Gosling snippets - `addGlobalEnv` to set builtins --- ### Compiler Macro Example ```typescript= updateBuiltinsFnDef( ` func testAndSetInt(ptr *int, expected, desired int) bool { return __noop(testAndSetInt_TEST_AND_SWAP) }`, { testAndSetInt_TEST_AND_SWAP: [ { op: OpCode.LD, symbol: "desired" }, { op: OpCode.LD, symbol: "expected" }, { op: OpCode.LD, symbol: "ptr" }, { op: OpCode.TEST_AND_SET }, ], } ) ``` --- ### Virtual Machine - Gosling interpreter written in Typescript - operand-stack architecture, with RTS and OS both stored in VM-managed memory - provides access to thread control and sys call (`print`, `breakpoint`, `yield`, ...) --- ### Memory Management - our heap is an ArrayBuffer split into fixed-size nodes - types: `Int`, `Bool`, `Str` and `Binary Pointer` - composite types (e.g. list, queue, stack, function ptr) are built with `Binary Pointer` - runtime stacks (incl. environment) and operands stacks are stored in the heap --- ### Garbage Collection - Stop and Copy (Cheney's) due to low memory residency - space: $O(1)$, time: $O(\text{liveNodes})$ ---- ### Without GC <img src="https://hackmd.io/_uploads/ryaptdkWC.png" height=300 /> <img src="https://hackmd.io/_uploads/rkby9uyWC.png" height=300 /> <br /> <em>Single-threaded (left), Multi-threaded (right)</em> ---- ### With aggressive GC <img src="https://hackmd.io/_uploads/Byg4c_yW0.png" height=300 /> <img src="https://hackmd.io/_uploads/SyYE9_kZ0.png" height=300 /> <br /> <em>Single-threaded (left), Multi-threaded (right)</em> --- ### Concurrency Control  --- ### Key Concurrency Instructions: - `SysCall('done')`: terminate execution (if main, terminate all) - `SysCall('yield')`: relinquish CPU control - `TestAndSet`: key atomic instruction to implement `mutex` and `semaphore`. --- ### Concurrency Constructs: - `mutex` - `semaphore`: with explicit upper-bound - `waitgroup`: bounded semaphore - `channel`: bounded semaphore & mutex --- ### Exploring call behaviour ```go= func main() { bar := "main bar" foo(1) go foo(1) } func foo(y int) { bar := "foo bar" x = x + y // breakpoint return } ``` --- ### Function Calls / Go routines - functions as first class objects - support expressions as args or as functions - applicative-order evaluation <img src="https://hackmd.io/_uploads/Hy7KKnigC.png" height="300" /> --- ### Runtime Stack (`foo()`)  --- ### Runtime Stack (`go foo()`)  --- ### Limitations & Future - Goose types: array, struct - typechecking - compile time env --- ### Demo #### [goose-liard.vercel.app](https://goose-liard.vercel.app) --- # Q & A --- ### Copyright <a href="https://www.flaticon.com/free-icons/goose" title="goose icons">Goose icons created by manshagraphics - Flaticon</a> <a href="https://daman.co.id/style-icon-ryan-gosling">Gosling photo from daman.co.id</a>