Add expunge host call

packages/jam/in-core/externalities/refine.test.ts

@@ -274,4 +274,72 @@ describe("RefineExternalitiesImpl", () => {
       assert.strictEqual(result.isOk, true);
     });
   });
+
+  describe("machineExpunge", () => {
+    it("should remove machine and return its program counter (0)", async () => {
+      const ext = createExt();
+      const code = BytesBlob.blobFrom(MINIMAL_PROGRAM);
+      const initResult = await ext.machineInit(code, tryAsProgramCounter(0));
+      assert.strictEqual(initResult.isOk, true);
+
+      const machineId = initResult.ok;
+      const result = await ext.machineExpunge(machineId);
+
+      assert.strictEqual(result.isOk, true);
+      // PC should be 0 since we initialized with PC=0
+      assert.strictEqual(result.ok, tryAsProgramCounter(0));
+    });
+
+    it("should remove machine and return its program counter (10)", async () => {
+      const ext = createExt();
+      const code = BytesBlob.blobFrom(MINIMAL_PROGRAM);
+      const initResult = await ext.machineInit(code, tryAsProgramCounter(10));
+      assert.strictEqual(initResult.isOk, true);
+
+      const machineId = initResult.ok;
+      const result = await ext.machineExpunge(machineId);
+
+      assert.strictEqual(result.isOk, true);
+      // PC should be 10 since we initialized with PC=10
+      assert.strictEqual(result.ok, tryAsProgramCounter(10));
+    });
+
+    it("should return NoMachineError for non-existent machine", async () => {
+      const ext = createExt();
+      const result = await ext.machineExpunge(tryAsMachineId(999));
+
+      assert.strictEqual(result.isError, true);
+    });
+
+    it("should not allow double expunge", async () => {
+      const ext = createExt();
+      const code = BytesBlob.blobFrom(MINIMAL_PROGRAM);
+      const initResult = await ext.machineInit(code, tryAsProgramCounter(0));
+
+      assert.strictEqual(initResult.isOk, true);
+      const machineId = initResult.ok;
+
+      const r1 = await ext.machineExpunge(machineId);
+      assert.strictEqual(r1.isOk, true);
+
+      const r2 = await ext.machineExpunge(machineId);
+      assert.strictEqual(r2.isError, true);
+    });
+
+    it("should remove exact machine from multiple and return its program counter (10)", async () => {
+      const ext = createExt();
+      const code = BytesBlob.blobFrom(MINIMAL_PROGRAM);
+      await ext.machineInit(code, tryAsProgramCounter(0));
+      const initResult = await ext.machineInit(code, tryAsProgramCounter(10));
+      await ext.machineInit(code, tryAsProgramCounter(20));
+      assert.strictEqual(initResult.isOk, true);
+
+      const machineId = initResult.ok;
+      const result = await ext.machineExpunge(machineId);
+
+      assert.strictEqual(result.isOk, true);
+      // PC should be 10 since we initialized with PC=10
+      assert.strictEqual(result.ok, tryAsProgramCounter(10));
+    });
+  });
 });

packages/jam/in-core/externalities/refine.ts

@@ -13,13 +13,14 @@ import {
   type MachineId,
   type MachineResult,
   type MemoryOperation,
-  type NoMachineError,
+  NoMachineError,
   type PagesError,
   type PeekPokeError,
   type ProgramCounter,
   type RefineExternalities,
   SegmentExportError,
   tryAsMachineId,
+  tryAsProgramCounter,
   type ZeroVoidError,
 } from "@typeberry/jam-host-calls";
 import type { U64 } from "@typeberry/numbers";
@@ -88,8 +89,15 @@ export class RefineExternalitiesImpl implements RefineExternalities {
     return this.exportedSegments;
   }
 
-  machineExpunge(_machineIndex: MachineId): Promise<Result<ProgramCounter, NoMachineError>> {
-    throw new Error("Method not implemented.");
+  machineExpunge(machineIndex: MachineId): Promise<Result<ProgramCounter, NoMachineError>> {
+    // We just care about machineIndex
+    const entry = this.machines.findExact([machineIndex, undefined as unknown as IPvmInterpreter]);
+    if (entry === undefined) {
+      return Promise.resolve(Result.error(NoMachineError, () => `Machine not found (id: ${machineIndex})`));
+    }
+    const pc = tryAsProgramCounter(entry[1].getPC());
+    this.machines.removeOne(entry);
+    return Promise.resolve(Result.ok(pc));
   }
 
   machinePages(

packages/jam/jam-host-calls/externalities/refine-externalities.ts

@@ -110,7 +110,7 @@ export interface RefineExternalities {
   /** Get the segments exported during this work item's refinement. */
   getExportedSegments(): readonly Segment[];
 
-  /** Forget a previously started nested VM. */
+  /** Forget a previously started nested VM. Return its current program counter.*/
   machineExpunge(machineIndex: MachineId): Promise<Result<ProgramCounter, NoMachineError>>;
 
   /** Set given range of pages as non-accessible and re-initialize them with zeros. */