From c9d0fffb57929536535dbc66108e4491b371ea2e Mon Sep 17 00:00:00 2001
From: Krystian Fras <krystian@fras.me>
Date: Wed, 22 Jan 2025 16:15:35 +0100
Subject: [PATCH] Add gas host call (#303)

* Add gas host call

* fix conditions
---
 .../web-worker/command-handlers/host-call.ts  | 22 ++++++++++++++-----
 src/store/workers/workersSlice.ts             |  5 ++++-
 2 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/src/packages/web-worker/command-handlers/host-call.ts b/src/packages/web-worker/command-handlers/host-call.ts
index 8c9640e..3d2ca39 100644
--- a/src/packages/web-worker/command-handlers/host-call.ts
+++ b/src/packages/web-worker/command-handlers/host-call.ts
@@ -1,6 +1,6 @@
 import { HostCallIdentifiers } from "@/types/pvm";
 import { CommandStatus, PvmApiInterface, Storage } from "../types";
-import { read, Registers, write, Memory } from "@typeberry/jam-host-calls";
+import { read, Registers, write, Memory, gas } from "@typeberry/jam-host-calls";
 import { WriteAccounts } from "@/packages/host-calls/write";
 import { isInternalPvm } from "../utils";
 import { ReadAccounts } from "@/packages/host-calls/read";
@@ -146,10 +146,14 @@ const hostCall = async ({
 }: {
   pvm: PvmApiInterface;
   hostCallIdentifier: HostCallIdentifiers;
-  storage: Storage;
+  storage: Storage | null;
   serviceId: number;
 }): Promise<HostCallResponse> => {
   if (hostCallIdentifier === HostCallIdentifiers.READ) {
+    if (storage === null) {
+      throw new Error("Storage is uninitialized.");
+    }
+
     const readAccounts = new ReadAccounts(storage);
     const jamHostCall = new read.Read(readAccounts);
     // TODO the types are the same, but exported from different packages and lost track of the type
@@ -159,12 +163,22 @@ const hostCall = async ({
 
     return { hostCallIdentifier, status: CommandStatus.SUCCESS };
   } else if (hostCallIdentifier === HostCallIdentifiers.WRITE) {
+    if (storage === null) {
+      throw new Error("Storage is uninitialized.");
+    }
+
     const writeAccounts = new WriteAccounts(storage);
     const jamHostCall = new write.Write(writeAccounts);
 
     await jamHostCall.execute(getGasCounter(pvm), getRegisters(pvm), getMemory(pvm));
 
     return { hostCallIdentifier, storage, status: CommandStatus.SUCCESS };
+  } else if (hostCallIdentifier === HostCallIdentifiers.GAS) {
+    const jamHostCall = new gas.Gas();
+
+    await jamHostCall.execute(getGasCounter(pvm), getRegisters(pvm));
+
+    return { hostCallIdentifier, status: CommandStatus.SUCCESS };
   }
 
   return { hostCallIdentifier, status: CommandStatus.ERROR, error: new Error("Unknown host call identifier") };
@@ -180,10 +194,6 @@ export const runHostCall = async ({
     throw new Error("PVM is uninitialized.");
   }
 
-  if (storage === null) {
-    throw new Error("Storage is uninitialized.");
-  }
-
   if (serviceId === null) {
     throw new Error("Service ID is uninitialized.");
   }
diff --git a/src/store/workers/workersSlice.ts b/src/store/workers/workersSlice.ts
index 34478c8..03374b8 100644
--- a/src/store/workers/workersSlice.ts
+++ b/src/store/workers/workersSlice.ts
@@ -282,7 +282,10 @@ export const handleHostCall = createAsyncThunk(
   async ({ workerId }: { workerId?: string }, { getState, dispatch }) => {
     const state = getState() as RootState;
 
-    if (state.debugger.storage === null) {
+    if (
+      state.debugger.storage === null &&
+      state.workers.findIndex((worker: WorkerState) => worker.exitArg === HostCallIdentifiers.READ) !== -1
+    ) {
       return dispatch(setHasHostCallOpen(true));
     } else {
       const previousInstruction = nextInstruction(