MISC: Make spawn able to have 0 delay (#1333)

This eliminates a hole where spawn was unrelaible, because other scripts
could jump in and steal the RAM. It's not an API break, because 0 used
to be an invalid value.

markdown/bitburner.ns.spawn.md

@@ -30,6 +30,8 @@ RAM cost: 2 GB
 
 Terminates the current script, and then after a defined delay it will execute the newly-specified script. The purpose of this function is to execute a new script without being constrained by the RAM usage of the current one. This function can only be used to run scripts on the local server.
 
+The delay specified can be 0; in this case the new script will synchronously replace the old one. (There will not be any opportunity for other scripts to use up the RAM in-between.)
+
 Because this function immediately terminates the script, it does not have a return value.
 
 Running this function with 0 or fewer threads will cause a runtime error.

markdown/bitburner.spawnoptions.md

@@ -16,5 +16,5 @@ interface SpawnOptions extends RunOptions
 
 |  Property | Modifiers | Type | Description |
 |  --- | --- | --- | --- |
-|  [spawnDelay?](./bitburner.spawnoptions.spawndelay.md) |  | number | _(Optional)_ Number of milliseconds to delay before spawning script, defaults to 10000 (10s). Must be a positive integer. |
+|  [spawnDelay?](./bitburner.spawnoptions.spawndelay.md) |  | number | _(Optional)_ Number of milliseconds to delay before spawning script, defaults to 10000 (10s). Must be a non-negative integer. If 0, the script will be spawned synchronously. |
 

markdown/bitburner.spawnoptions.spawndelay.md

@@ -4,7 +4,7 @@
 
 ## SpawnOptions.spawnDelay property
 
-Number of milliseconds to delay before spawning script, defaults to 10000 (10s). Must be a positive integer.
+Number of milliseconds to delay before spawning script, defaults to 10000 (10s). Must be a non-negative integer. If 0, the script will be spawned synchronously.
 
 **Signature:**
 

src/Netscript/NetscriptHelpers.tsx

@@ -93,7 +93,7 @@ export interface CompleteRunOptions {
 }
 /** SpawnOptions with non-optional, type-validated members, for passing between internal functions. */
 export interface CompleteSpawnOptions extends CompleteRunOptions {
-  spawnDelay: PositiveInteger;
+  spawnDelay: number;
 }
 /** HGWOptions with non-optional, type-validated members, for passing between internal functions. */
 export interface CompleteHGWOptions {
@@ -189,11 +189,16 @@ function runOptions(ctx: NetscriptContext, threadOrOption: unknown): CompleteRun
 }
 
 function spawnOptions(ctx: NetscriptContext, threadOrOption: unknown): CompleteSpawnOptions {
-  const result: CompleteSpawnOptions = { spawnDelay: 10000 as PositiveInteger, ...runOptions(ctx, threadOrOption) };
+  const result: CompleteSpawnOptions = { spawnDelay: 10000, ...runOptions(ctx, threadOrOption) };
   if (typeof threadOrOption !== "object" || !threadOrOption) return result;
   // Safe assertion since threadOrOption type has been narrowed to a non-null object
   const { spawnDelay } = threadOrOption as Unknownify<CompleteSpawnOptions>;
-  if (spawnDelay !== undefined) result.spawnDelay = positiveInteger(ctx, "spawnDelayMsec", spawnDelay);
+  if (spawnDelay !== undefined) {
+    result.spawnDelay = number(ctx, "spawnDelay", spawnDelay);
+    if (result.spawnDelay < 0) {
+      throw errorMessage(ctx, `spawnDelay must be non-negative, got ${spawnDelay}`);
+    }
+  }
   return result;
 }
 

src/NetscriptFunctions.ts

@@ -737,23 +737,36 @@ export const ns: InternalAPI<NSFull> = {
       const path = helpers.scriptPath(ctx, "scriptname", _scriptname);
       const runOpts = helpers.spawnOptions(ctx, _thread_or_opt);
       const args = helpers.scriptArgs(ctx, _args);
-      setTimeout(() => {
+      const spawnCb = () => {
         if (Router.page() === Page.BitVerse) {
           helpers.log(ctx, () => `Script execution is canceled because you are in Bitverse.`);
           return;
         }
         const scriptServer = GetServer(ctx.workerScript.hostname);
-        if (scriptServer === null) {
+        if (scriptServer == null) {
           throw helpers.errorMessage(ctx, `Cannot find server ${ctx.workerScript.hostname}`);
         }
 
-        runScriptFromScript("spawn", scriptServer, path, args, ctx.workerScript, runOpts);
-      }, runOpts.spawnDelay);
+        return runScriptFromScript("spawn", scriptServer, path, args, ctx.workerScript, runOpts);
+      };
 
+      if (runOpts.spawnDelay !== 0) {
+        setTimeout(spawnCb, runOpts.spawnDelay);
         helpers.log(ctx, () => `Will execute '${path}' in ${runOpts.spawnDelay} milliseconds`);
+      }
 
-      if (killWorkerScript(ctx.workerScript)) {
-        helpers.log(ctx, () => "Exiting...");
+      helpers.log(ctx, () => "About to exit...");
+      const killed = killWorkerScript(ctx.workerScript);
+
+      if (runOpts.spawnDelay === 0) {
+        helpers.log(ctx, () => `Executing '${path}' immediately`);
+        spawnCb();
+      }
+
+      if (killed) {
+        // This prevents error messages about statements after the spawn()
+        // trying to be executed when the script is dead.
+        throw new ScriptDeath(ctx.workerScript);
       }
     },
   kill:

src/ScriptEditor/NetscriptDefinitions.d.ts

@@ -283,7 +283,10 @@ interface RunOptions {
 
 /** @public */
 interface SpawnOptions extends RunOptions {
-  /** Number of milliseconds to delay before spawning script, defaults to 10000 (10s). Must be a positive integer. */
+  /**
+   * Number of milliseconds to delay before spawning script, defaults to 10000 (10s).
+   * Must be a non-negative integer. If 0, the script will be spawned synchronously.
+   */
   spawnDelay?: number;
 }
 
@@ -6261,6 +6264,9 @@ export interface NS {
    * constrained by the RAM usage of the current one. This function can only be used to run scripts
    * on the local server.
    *
+   * The delay specified can be 0; in this case the new script will synchronously replace
+   * the old one. (There will not be any opportunity for other scripts to use up the RAM in-between.)
+   *
    * Because this function immediately terminates the script, it does not have a return value.
    *
    * Running this function with 0 or fewer threads will cause a runtime error.