feat: add getOutboundGateway effect and simplify VersionGraph init/uninit

Add getOutboundGateway effect across core, container-runtime, and SDK
to let services query their effective outbound gateway with callback
support. Remove preInstall/uninstall hooks from VersionGraph as they
are no longer needed.

sdk/base/lib/util/GetOutboundGateway.ts

@@ -0,0 +1,105 @@
+import { Effects } from '../Effects'
+import { DropGenerator, DropPromise } from './Drop'
+
+export class GetOutboundGateway {
+  constructor(readonly effects: Effects) {}
+
+  /**
+   * Returns the effective outbound gateway. Reruns the context from which it has been called if the underlying value changes
+   */
+  const() {
+    return this.effects.getOutboundGateway({
+      callback:
+        this.effects.constRetry &&
+        (() => this.effects.constRetry && this.effects.constRetry()),
+    })
+  }
+  /**
+   * Returns the effective outbound gateway. Does nothing if the value changes
+   */
+  once() {
+    return this.effects.getOutboundGateway({})
+  }
+
+  private async *watchGen(abort?: AbortSignal) {
+    const resolveCell = { resolve: () => {} }
+    this.effects.onLeaveContext(() => {
+      resolveCell.resolve()
+    })
+    abort?.addEventListener('abort', () => resolveCell.resolve())
+    while (this.effects.isInContext && !abort?.aborted) {
+      let callback: () => void = () => {}
+      const waitForNext = new Promise<void>((resolve) => {
+        callback = resolve
+        resolveCell.resolve = resolve
+      })
+      yield await this.effects.getOutboundGateway({
+        callback: () => callback(),
+      })
+      await waitForNext
+    }
+    return new Promise<never>((_, rej) => rej(new Error('aborted')))
+  }
+
+  /**
+   * Watches the effective outbound gateway. Returns an async iterator that yields whenever the value changes
+   */
+  watch(abort?: AbortSignal): AsyncGenerator<string, never, unknown> {
+    const ctrl = new AbortController()
+    abort?.addEventListener('abort', () => ctrl.abort())
+    return DropGenerator.of(this.watchGen(ctrl.signal), () => ctrl.abort())
+  }
+
+  /**
+   * Watches the effective outbound gateway. Takes a custom callback function to run whenever the value changes
+   */
+  onChange(
+    callback: (
+      value: string,
+      error?: Error,
+    ) => { cancel: boolean } | Promise<{ cancel: boolean }>,
+  ) {
+    ;(async () => {
+      const ctrl = new AbortController()
+      for await (const value of this.watch(ctrl.signal)) {
+        try {
+          const res = await callback(value)
+          if (res.cancel) {
+            ctrl.abort()
+            break
+          }
+        } catch (e) {
+          console.error(
+            'callback function threw an error @ GetOutboundGateway.onChange',
+            e,
+          )
+        }
+      }
+    })()
+      .catch((e) => callback('', e))
+      .catch((e) =>
+        console.error(
+          'callback function threw an error @ GetOutboundGateway.onChange',
+          e,
+        ),
+      )
+  }
+
+  /**
+   * Watches the effective outbound gateway. Returns when the predicate is true
+   */
+  waitFor(pred: (value: string) => boolean): Promise<string> {
+    const ctrl = new AbortController()
+    return DropPromise.of(
+      Promise.resolve().then(async () => {
+        for await (const next of this.watchGen(ctrl.signal)) {
+          if (pred(next)) {
+            return next
+          }
+        }
+        return ''
+      }),
+      () => ctrl.abort(),
+    )
+  }
+}

sdk/base/lib/util/index.ts

@@ -14,6 +14,7 @@ export { once } from './once'
 export { asError } from './asError'
 export * as Patterns from './patterns'
 export * from './typeHelpers'
+export { GetOutboundGateway } from './GetOutboundGateway'
 export { GetSystemSmtp } from './GetSystemSmtp'
 export { Graph, Vertex } from './graph'
 export { inMs } from './inMs'