refactor: consolidate SDK Watchable with generic map/eq and rename call to fetch

sdk/base/lib/util/GetContainerIp.ts

@@ -12,7 +12,7 @@ export class GetContainerIp extends Watchable<string> {
     super(effects)
   }
 
-  protected call(callback?: () => void) {
+  protected fetch(callback?: () => void) {
     return this.effects.getContainerIp({ ...this.opts, callback })
   }
 }

sdk/base/lib/util/GetHostInfo.ts

@@ -12,7 +12,7 @@ export class GetHostInfo extends Watchable<Host | null> {
     super(effects)
   }
 
-  protected call(callback?: () => void) {
+  protected fetch(callback?: () => void) {
     return this.effects.getHostInfo({ ...this.opts, callback })
   }
 }

sdk/base/lib/util/GetOutboundGateway.ts

@@ -8,7 +8,7 @@ export class GetOutboundGateway extends Watchable<string> {
     super(effects)
   }
 
-  protected call(callback?: () => void) {
+  protected fetch(callback?: () => void) {
     return this.effects.getOutboundGateway({ callback })
   }
 }

sdk/base/lib/util/GetServiceManifest.ts

@@ -1,18 +1,47 @@
 import { Effects } from '../Effects'
 import { Manifest, PackageId } from '../osBindings'
+import { deepEqual } from './deepEqual'
 import { Watchable } from './Watchable'
 
-export class GetServiceManifest extends Watchable<Manifest> {
+export class GetServiceManifest<
+  Mapped = Manifest | null,
+> extends Watchable<Manifest | null, Mapped> {
   protected readonly label = 'GetServiceManifest'
 
   constructor(
     effects: Effects,
     readonly opts: { packageId: PackageId },
+    options?: {
+      map?: (value: Manifest | null) => Mapped
+      eq?: (a: Mapped, b: Mapped) => boolean
+    },
   ) {
-    super(effects)
+    super(effects, options)
   }
 
-  protected call(callback?: () => void) {
+  protected fetch(callback?: () => void) {
     return this.effects.getServiceManifest({ ...this.opts, callback })
   }
 }
+
+export function getServiceManifest(
+  effects: Effects,
+  packageId: PackageId,
+): GetServiceManifest<Manifest | null>
+export function getServiceManifest<Mapped>(
+  effects: Effects,
+  packageId: PackageId,
+  map: (manifest: Manifest | null) => Mapped,
+  eq?: (a: Mapped, b: Mapped) => boolean,
+): GetServiceManifest<Mapped>
+export function getServiceManifest<Mapped>(
+  effects: Effects,
+  packageId: PackageId,
+  map?: (manifest: Manifest | null) => Mapped,
+  eq?: (a: Mapped, b: Mapped) => boolean,
+): GetServiceManifest<Mapped> {
+  return new GetServiceManifest<Mapped>(effects, { packageId }, {
+    map: map ?? ((a) => a as Mapped),
+    eq: eq ?? ((a, b) => deepEqual(a, b)),
+  })
+}

sdk/base/lib/util/GetSslCertificate.ts

@@ -14,7 +14,7 @@ export class GetSslCertificate extends Watchable<[string, string, string]> {
     super(effects)
   }
 
-  protected call(callback?: () => void) {
+  protected fetch(callback?: () => void) {
     return this.effects.getSslCertificate({ ...this.opts, callback })
   }
 }

sdk/base/lib/util/GetStatus.ts

@@ -12,7 +12,7 @@ export class GetStatus extends Watchable<StatusInfo | null> {
     super(effects)
   }
 
-  protected call(callback?: () => void) {
+  protected fetch(callback?: () => void) {
     return this.effects.getStatus({ ...this.opts, callback })
   }
 }

sdk/base/lib/util/GetSystemSmtp.ts

@@ -9,7 +9,7 @@ export class GetSystemSmtp extends Watchable<T.SmtpValue | null> {
     super(effects)
   }
 
-  protected call(callback?: () => void) {
+  protected fetch(callback?: () => void) {
     return this.effects.getSystemSmtp({ callback })
   }
 }

sdk/base/lib/util/Watchable.ts

@@ -1,55 +1,124 @@
 import { Effects } from '../Effects'
 import { AbortedError } from './AbortedError'
+import { deepEqual } from './deepEqual'
 import { DropGenerator, DropPromise } from './Drop'
 
-export abstract class Watchable<T> {
-  constructor(readonly effects: Effects) {}
+export abstract class Watchable<Raw, Mapped = Raw> {
+  protected readonly mapFn: (value: Raw) => Mapped
+  protected readonly eqFn: (a: Mapped, b: Mapped) => boolean
 
-  protected abstract call(callback?: () => void): Promise<T>
+  constructor(
+    readonly effects: Effects,
+    options?: {
+      map?: (value: Raw) => Mapped
+      eq?: (a: Mapped, b: Mapped) => boolean
+    },
+  ) {
+    this.mapFn = options?.map ?? ((a) => a as unknown as Mapped)
+    this.eqFn = options?.eq ?? ((a, b) => deepEqual(a, b))
+  }
+
+  /**
+   * Fetch the current value, optionally registering a callback for change notification.
+   * The callback should be invoked when the underlying data changes.
+   */
+  protected abstract fetch(callback?: () => void): Promise<Raw>
   protected abstract readonly label: string
 
   /**
-   * Returns the value. Reruns the context from which it has been called if the underlying value changes
+   * Produce a stream of raw values. Default implementation uses fetch() with
+   * effects callback in a loop. Override for custom subscription mechanisms
+   * (e.g. fs.watch).
    */
-  const(): Promise<T> {
-    return this.call(
-      this.effects.constRetry &&
-        (() => this.effects.constRetry && this.effects.constRetry()),
-    )
-  }
-
-  /**
-   * Returns the value. Does nothing if the value changes
-   */
-  once(): Promise<T> {
-    return this.call()
-  }
-
-  private async *watchGen(abort?: AbortSignal) {
+  protected async *produce(abort: AbortSignal): AsyncGenerator<Raw, void> {
     const resolveCell = { resolve: () => {} }
     this.effects.onLeaveContext(() => {
       resolveCell.resolve()
     })
-    abort?.addEventListener('abort', () => resolveCell.resolve())
-    while (this.effects.isInContext && !abort?.aborted) {
+    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.call(() => callback())
+      yield await this.fetch(() => callback())
       await waitForNext
     }
-    return new Promise<never>((_, rej) => rej(new AbortedError()))
+  }
+
+  /**
+   * Lifecycle hook called when const() registers a subscription.
+   * Return a cleanup function to be called when the subscription ends.
+   * Override for side effects like FileHelper's consts tracking.
+   */
+  protected onConstRegistered(_value: Mapped): (() => void) | void {}
+
+  /**
+   * Internal generator that maps raw values and deduplicates using eq.
+   */
+  private async *watchGen(
+    abort: AbortSignal,
+  ): AsyncGenerator<Mapped, void, unknown> {
+    let prev: { value: Mapped } | null = null
+    for await (const raw of this.produce(abort)) {
+      if (abort.aborted) return
+      const mapped = this.mapFn(raw)
+      if (!prev || !this.eqFn(prev.value, mapped)) {
+        prev = { value: mapped }
+        yield mapped
+      }
+    }
+  }
+
+  /**
+   * Returns the value. Reruns the context from which it has been called if the underlying value changes
+   */
+  async const(): Promise<Mapped> {
+    const abort = new AbortController()
+    const gen = this.watchGen(abort.signal)
+    const res = await gen.next()
+    const value = res.value as Mapped
+    if (this.effects.constRetry) {
+      const constRetry = this.effects.constRetry
+      const cleanup = this.onConstRegistered(value)
+      gen.next().then(
+        () => {
+          abort.abort()
+          cleanup?.()
+          constRetry()
+        },
+        () => {
+          abort.abort()
+          cleanup?.()
+        },
+      )
+    } else {
+      abort.abort()
+    }
+    return value
+  }
+
+  /**
+   * Returns the value. Does nothing if the value changes
+   */
+  async once(): Promise<Mapped> {
+    return this.mapFn(await this.fetch())
   }
 
   /**
    * Watches the value. Returns an async iterator that yields whenever the value changes
    */
-  watch(abort?: AbortSignal): AsyncGenerator<T, never, unknown> {
+  watch(abort?: AbortSignal): AsyncGenerator<Mapped, never, unknown> {
     const ctrl = new AbortController()
     abort?.addEventListener('abort', () => ctrl.abort())
-    return DropGenerator.of(this.watchGen(ctrl.signal), () => ctrl.abort())
+    return DropGenerator.of(
+      (async function* (gen): AsyncGenerator<Mapped, never, unknown> {
+        yield* gen
+        throw new AbortedError()
+      })(this.watchGen(ctrl.signal)),
+      () => ctrl.abort(),
+    )
   }
 
   /**
@@ -57,13 +126,13 @@ export abstract class Watchable<T> {
    */
   onChange(
     callback: (
-      value: T | undefined,
+      value: Mapped | undefined,
       error?: Error,
     ) => { cancel: boolean } | Promise<{ cancel: boolean }>,
   ) {
     ;(async () => {
       const ctrl = new AbortController()
-      for await (const value of this.watch(ctrl.signal)) {
+      for await (const value of this.watchGen(ctrl.signal)) {
         try {
           const res = await callback(value)
           if (res.cancel) {
@@ -90,7 +159,7 @@ export abstract class Watchable<T> {
   /**
    * Watches the value. Returns when the predicate is true
    */
-  waitFor(pred: (value: T) => boolean): Promise<T> {
+  waitFor(pred: (value: Mapped) => boolean): Promise<Mapped> {
     const ctrl = new AbortController()
     return DropPromise.of(
       Promise.resolve().then(async () => {

sdk/base/lib/util/getServiceInterface.ts

@@ -8,11 +8,10 @@ import {
   HostnameInfo,
 } from '../types'
 import { Effects } from '../Effects'
-import { AbortedError } from './AbortedError'
-import { DropGenerator, DropPromise } from './Drop'
 import { IpAddress, IPV6_LINK_LOCAL } from './ip'
 import { deepEqual } from './deepEqual'
 import { once } from './once'
+import { Watchable } from './Watchable'
 
 export type UrlString = string
 export type HostId = string
@@ -440,136 +439,29 @@ const makeInterfaceFilled = async ({
   return interfaceFilled
 }
 
-export class GetServiceInterface<Mapped = ServiceInterfaceFilled | null> {
+export class GetServiceInterface<
+  Mapped = ServiceInterfaceFilled | null,
+> extends Watchable<ServiceInterfaceFilled | null, Mapped> {
+  protected readonly label = 'GetServiceInterface'
+
   constructor(
-    readonly effects: Effects,
+    effects: Effects,
     readonly opts: { id: string; packageId?: string },
-    readonly map: (interfaces: ServiceInterfaceFilled | null) => Mapped,
-    readonly eq: (a: Mapped, b: Mapped) => boolean,
-  ) {}
-
-  /**
-   * Returns the requested service interface. Reruns the context from which it has been called if the underlying value changes
-   */
-  async const() {
-    let abort = new AbortController()
-    const watch = this.watch(abort.signal)
-    const res = await watch.next()
-    if (this.effects.constRetry) {
-      watch
-        .next()
-        .then(() => {
-          abort.abort()
-          this.effects.constRetry && this.effects.constRetry()
-        })
-        .catch()
-    }
-    return res.value
-  }
-  /**
-   * Returns the requested service interface. Does nothing if the value changes
-   */
-  async once() {
-    const { id, packageId } = this.opts
-    const interfaceFilled = await makeInterfaceFilled({
-      effects: this.effects,
-      id,
-      packageId,
-    })
-
-    return this.map(interfaceFilled)
-  }
-
-  private async *watchGen(abort?: AbortSignal) {
-    let prev = null as { value: Mapped } | null
-    const { id, packageId } = this.opts
-    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
-      })
-      const next = this.map(
-        await makeInterfaceFilled({
-          effects: this.effects,
-          id,
-          packageId,
-          callback,
-        }),
-      )
-      if (!prev || !this.eq(prev.value, next)) {
-        yield next
-      }
-      await waitForNext
-    }
-    return new Promise<never>((_, rej) => rej(new AbortedError()))
-  }
-
-  /**
-   * Watches the requested service interface. Returns an async iterator that yields whenever the value changes
-   */
-  watch(abort?: AbortSignal): AsyncGenerator<Mapped, never, unknown> {
-    const ctrl = new AbortController()
-    abort?.addEventListener('abort', () => ctrl.abort())
-    return DropGenerator.of(this.watchGen(ctrl.signal), () => ctrl.abort())
-  }
-
-  /**
-   * Watches the requested service interface. Takes a custom callback function to run whenever the value changes
-   */
-  onChange(
-    callback: (
-      value: Mapped | null,
-      error?: Error,
-    ) => { cancel: boolean } | Promise<{ cancel: boolean }>,
+    options?: {
+      map?: (value: ServiceInterfaceFilled | null) => Mapped
+      eq?: (a: Mapped, b: Mapped) => 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 @ GetServiceInterface.onChange',
-            e,
-          )
-        }
-      }
-    })()
-      .catch((e) => callback(null, e))
-      .catch((e) =>
-        console.error(
-          'callback function threw an error @ GetServiceInterface.onChange',
-          e,
-        ),
-      )
+    super(effects, options)
   }
 
-  /**
-   * Watches the requested service interface. Returns when the predicate is true
-   */
-  waitFor(pred: (value: Mapped) => boolean): Promise<Mapped> {
-    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
-          }
-        }
-        throw new Error('context left before predicate passed')
-      }),
-      () => ctrl.abort(),
-    )
+  protected fetch(callback?: () => void) {
+    return makeInterfaceFilled({
+      effects: this.effects,
+      id: this.opts.id,
+      packageId: this.opts.packageId,
+      callback,
+    })
   }
 }
 
@@ -589,12 +481,10 @@ export function getOwnServiceInterface<Mapped>(
   map?: (interfaces: ServiceInterfaceFilled | null) => Mapped,
   eq?: (a: Mapped, b: Mapped) => boolean,
 ): GetServiceInterface<Mapped> {
-  return new GetServiceInterface(
-    effects,
-    { id },
-    map ?? ((a) => a as Mapped),
-    eq ?? ((a, b) => deepEqual(a, b)),
-  )
+  return new GetServiceInterface<Mapped>(effects, { id }, {
+    map: map ?? ((a) => a as Mapped),
+    eq: eq ?? ((a, b) => deepEqual(a, b)),
+  })
 }
 
 export function getServiceInterface(
@@ -613,10 +503,8 @@ export function getServiceInterface<Mapped>(
   map?: (interfaces: ServiceInterfaceFilled | null) => Mapped,
   eq?: (a: Mapped, b: Mapped) => boolean,
 ): GetServiceInterface<Mapped> {
-  return new GetServiceInterface(
-    effects,
-    opts,
-    map ?? ((a) => a as Mapped),
-    eq ?? ((a, b) => deepEqual(a, b)),
-  )
+  return new GetServiceInterface<Mapped>(effects, opts, {
+    map: map ?? ((a) => a as Mapped),
+    eq: eq ?? ((a, b) => deepEqual(a, b)),
+  })
 }

sdk/base/lib/util/getServiceInterfaces.ts

@@ -1,9 +1,8 @@
 import { Effects } from '../Effects'
 import { PackageId } from '../osBindings'
-import { AbortedError } from './AbortedError'
 import { deepEqual } from './deepEqual'
-import { DropGenerator, DropPromise } from './Drop'
 import { ServiceInterfaceFilled, filledAddress } from './getServiceInterface'
+import { Watchable } from './Watchable'
 
 const makeManyInterfaceFilled = async ({
   effects,
@@ -40,139 +39,34 @@ const makeManyInterfaceFilled = async ({
   return serviceInterfacesFilled
 }
 
-export class GetServiceInterfaces<Mapped = ServiceInterfaceFilled[]> {
+export class GetServiceInterfaces<
+  Mapped = ServiceInterfaceFilled[],
+> extends Watchable<ServiceInterfaceFilled[], Mapped> {
+  protected readonly label = 'GetServiceInterfaces'
+
   constructor(
-    readonly effects: Effects,
+    effects: Effects,
     readonly opts: { packageId?: string },
-    readonly map: (interfaces: ServiceInterfaceFilled[]) => Mapped,
-    readonly eq: (a: Mapped, b: Mapped) => boolean,
-  ) {}
-
-  /**
-   * Returns the service interfaces for the package. Reruns the context from which it has been called if the underlying value changes
-   */
-  async const() {
-    let abort = new AbortController()
-    const watch = this.watch(abort.signal)
-    const res = await watch.next()
-    if (this.effects.constRetry) {
-      watch
-        .next()
-        .then(() => {
-          abort.abort()
-          this.effects.constRetry && this.effects.constRetry()
-        })
-        .catch()
-    }
-    return res.value
-  }
-  /**
-   * Returns the service interfaces for the package. Does nothing if the value changes
-   */
-  async once() {
-    const { packageId } = this.opts
-    const interfaceFilled: ServiceInterfaceFilled[] =
-      await makeManyInterfaceFilled({
-        effects: this.effects,
-        packageId,
-      })
-
-    return this.map(interfaceFilled)
-  }
-
-  private async *watchGen(abort?: AbortSignal) {
-    let prev = null as { value: Mapped } | null
-    const { packageId } = this.opts
-    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
-      })
-      const next = this.map(
-        await makeManyInterfaceFilled({
-          effects: this.effects,
-          packageId,
-          callback,
-        }),
-      )
-      if (!prev || !this.eq(prev.value, next)) {
-        yield next
-      }
-      await waitForNext
-    }
-    return new Promise<never>((_, rej) => rej(new AbortedError()))
-  }
-
-  /**
-   * Watches the service interfaces for the package. Returns an async iterator that yields whenever the value changes
-   */
-  watch(abort?: AbortSignal): AsyncGenerator<Mapped, never, unknown> {
-    const ctrl = new AbortController()
-    abort?.addEventListener('abort', () => ctrl.abort())
-    return DropGenerator.of(this.watchGen(ctrl.signal), () => ctrl.abort())
-  }
-
-  /**
-   * Watches the service interfaces for the package. Takes a custom callback function to run whenever the value changes
-   */
-  onChange(
-    callback: (
-      value: Mapped | null,
-      error?: Error,
-    ) => { cancel: boolean } | Promise<{ cancel: boolean }>,
+    options?: {
+      map?: (value: ServiceInterfaceFilled[]) => Mapped
+      eq?: (a: Mapped, b: Mapped) => 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 @ GetServiceInterfaces.onChange',
-            e,
-          )
-        }
-      }
-    })()
-      .catch((e) => callback(null, e))
-      .catch((e) =>
-        console.error(
-          'callback function threw an error @ GetServiceInterfaces.onChange',
-          e,
-        ),
-      )
+    super(effects, options)
   }
 
-  /**
-   * Watches the service interfaces for the package. Returns when the predicate is true
-   */
-  waitFor(pred: (value: Mapped) => boolean): Promise<Mapped> {
-    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
-          }
-        }
-        throw new Error('context left before predicate passed')
-      }),
-      () => ctrl.abort(),
-    )
+  protected fetch(callback?: () => void) {
+    return makeManyInterfaceFilled({
+      effects: this.effects,
+      packageId: this.opts.packageId,
+      callback,
+    })
   }
 }
 
-export function getOwnServiceInterfaces(effects: Effects): GetServiceInterfaces
+export function getOwnServiceInterfaces(
+  effects: Effects,
+): GetServiceInterfaces
 export function getOwnServiceInterfaces<Mapped>(
   effects: Effects,
   map: (interfaces: ServiceInterfaceFilled[]) => Mapped,
@@ -183,12 +77,10 @@ export function getOwnServiceInterfaces<Mapped>(
   map?: (interfaces: ServiceInterfaceFilled[]) => Mapped,
   eq?: (a: Mapped, b: Mapped) => boolean,
 ): GetServiceInterfaces<Mapped> {
-  return new GetServiceInterfaces(
-    effects,
-    {},
-    map ?? ((a) => a as Mapped),
-    eq ?? ((a, b) => deepEqual(a, b)),
-  )
+  return new GetServiceInterfaces<Mapped>(effects, {}, {
+    map: map ?? ((a) => a as Mapped),
+    eq: eq ?? ((a, b) => deepEqual(a, b)),
+  })
 }
 
 export function getServiceInterfaces(
@@ -207,10 +99,8 @@ export function getServiceInterfaces<Mapped>(
   map?: (interfaces: ServiceInterfaceFilled[]) => Mapped,
   eq?: (a: Mapped, b: Mapped) => boolean,
 ): GetServiceInterfaces<Mapped> {
-  return new GetServiceInterfaces(
-    effects,
-    opts,
-    map ?? ((a) => a as Mapped),
-    eq ?? ((a, b) => deepEqual(a, b)),
-  )
+  return new GetServiceInterfaces<Mapped>(effects, opts, {
+    map: map ?? ((a) => a as Mapped),
+    eq: eq ?? ((a, b) => deepEqual(a, b)),
+  })
 }

sdk/base/lib/util/index.ts

@@ -19,7 +19,7 @@ export { Watchable } from './Watchable'
 export { GetContainerIp } from './GetContainerIp'
 export { GetHostInfo } from './GetHostInfo'
 export { GetOutboundGateway } from './GetOutboundGateway'
-export { GetServiceManifest } from './GetServiceManifest'
+export { GetServiceManifest, getServiceManifest } from './GetServiceManifest'
 export { GetSslCertificate } from './GetSslCertificate'
 export { GetStatus } from './GetStatus'
 export { GetSystemSmtp } from './GetSystemSmtp'