From 4a316bb7cac70666c7b64d5b5742c42966afce3e Mon Sep 17 00:00:00 2001
From: Kuba Orlik <kontakt@kuba-orlik.name>
Date: Sun, 28 Mar 2021 08:34:45 +0200
Subject: [PATCH] Better DeadlyRace

---
 src/index.ts  | 115 ++++++++++++++++++++++++++++++++------------------
 tsconfig.json |   2 +-
 2 files changed, 75 insertions(+), 42 deletions(-)

diff --git a/src/index.ts b/src/index.ts
index 16aec37..8020c9f 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -11,17 +11,20 @@ class AbortableEmittery extends Emittery {
   }
 }
 
-export default class AbortablePromise<T> implements PromiseLike<T> {
+export default class AbortablePromise<T> implements Promise<T | null> {
   private emitter: AbortableEmittery;
 
   private result_promise: Promise<T>;
+  private fulfilled = false;
+  private result: T;
 
   constructor(
     make_generator: (
       await_or_abort: <L>(
         promise: Promise<L> | AbortablePromise<L>,
         on_abort?: () => Promise<unknown> | void
-      ) => Promise<L>
+      ) => Promise<L>,
+      resolve?: Function
     ) => AsyncGenerator
   ) {
     const emitter = new AbortableEmittery();
@@ -31,6 +34,7 @@ export default class AbortablePromise<T> implements PromiseLike<T> {
       promise: Promise<L> | AbortablePromise<L>,
       on_abort?: () => Promise<unknown> | void
     ): Promise<L> {
+      console.log("await_or_abort", promise);
       if (promise instanceof AbortablePromise && !on_abort) {
         on_abort = async () => promise.abort();
       }
@@ -44,7 +48,7 @@ export default class AbortablePromise<T> implements PromiseLike<T> {
         emitter.on("abort", () => {
           if (!resolved) {
             (on_abort as Function)();
-            reject(null);
+            resolve(null);
             resolved = true;
           }
         });
@@ -55,18 +59,15 @@ export default class AbortablePromise<T> implements PromiseLike<T> {
               resolved = true;
             }
           })
-          .catch(reject);
+          .catch((err) => {
+            reject(err);
+          });
       });
     }
     this.result_promise = new Promise(async (resolve, reject) => {
       let step_value;
       const generator = make_generator(await_or_abort);
-      console.log("generator:", generator, make_generator);
       const e = new Error();
-      if (!generator) {
-        console.error(e.stack);
-        console.log("generator:", generator);
-      }
       do {
         if (emitter.aborted) {
           resolve(null);
@@ -75,6 +76,8 @@ export default class AbortablePromise<T> implements PromiseLike<T> {
         step_value = await generator.next();
       } while (!step_value.done);
       resolve(step_value.value);
+      this.fulfilled = true;
+      this.result = step_value.value;
     });
     this.emitter = emitter;
   }
@@ -83,24 +86,6 @@ export default class AbortablePromise<T> implements PromiseLike<T> {
     this.emitter.abort();
   }
 
-  static deadlyRace<L>(promises: AbortablePromise<L>[]): Promise<L> {
-    return new Promise((resolve) => {
-      let resolved = false;
-      const callback = (arg: L) => {
-        if (resolved) return;
-        resolved = true;
-        for (const promise of promises) {
-          console.log("one of the promises resolved! killing the others");
-          promise.abort();
-        }
-        resolve(arg);
-      };
-      for (const promise of promises) {
-        promise.then(callback);
-      }
-    });
-  }
-
   then<TResult1 = T, TResult2 = never>(
     onfulfilled?:
       | ((value: T) => TResult1 | PromiseLike<TResult1>)
@@ -110,9 +95,13 @@ export default class AbortablePromise<T> implements PromiseLike<T> {
       | ((reason: any) => TResult2 | PromiseLike<TResult2>)
       | undefined
       | null
-  ): PromiseLike<TResult1 | TResult2> {
+  ): AbortablePromise<TResult1 | TResult2> {
     const self = this;
     return new AbortablePromise(async function* (await_or_abort) {
+      if (self.fulfilled) {
+        onfulfilled(self.result);
+        return;
+      }
       const ret = await await_or_abort(self.result_promise, () => {
         self.abort();
       });
@@ -122,6 +111,50 @@ export default class AbortablePromise<T> implements PromiseLike<T> {
       }
     });
   }
+
+  catch<TResult = never>(
+    onrejected?:
+      | ((reason: any) => TResult | PromiseLike<TResult>)
+      | undefined
+      | null
+  ): AbortablePromise<T | TResult> {
+    const self = this;
+    return new AbortablePromise(async function* (await_or_abort) {
+      await await_or_abort(self.result_promise, () => {
+        self.abort();
+      }).catch(onrejected);
+      yield;
+    });
+  }
+
+  static deadlyRace<L>(
+    promises: AbortablePromise<L>[],
+    should_kill_others: (arg: L) => Promise<boolean> = async () => true
+  ): Promise<L> {
+    return new AbortablePromise(async function* (await_or_abort) {
+      return await_or_abort(
+        new Promise((resolve, reject) => {
+          let resolved = false;
+          const callback = async (arg: L) => {
+            if (resolved) return;
+            if (arg === null) return;
+            resolved = await should_kill_others(arg);
+            if (!resolved) return;
+            for (const promise of promises) {
+              promise.abort();
+            }
+            resolve(arg);
+          };
+          for (const promise of promises) {
+            promise.then(callback);
+          }
+        }),
+        () => {
+          promises.forEach((promise) => promise.abort());
+        }
+      );
+    });
+  }
 }
 
 const sleep = promisify((timeout: number, callback: (...args: any[]) => void) =>
@@ -146,19 +179,19 @@ const sleep = promisify((timeout: number, callback: (...args: any[]) => void) =>
 //   console.log("awaited 300");
 // });
 
-function abortableSleep(ms: number): AbortablePromise<void> {
-  return new AbortablePromise(async function* () {
-    await sleep(ms);
-    yield;
-    console.log(`Slept ${ms}.`);
-  });
-}
-
-const b = AbortablePromise.deadlyRace([
-  abortableSleep(1000),
-  abortableSleep(2000),
-  abortableSleep(3000),
-]);
+// function abortableSleep(ms: number): AbortablePromise<void> {
+//   return new AbortablePromise(async function* () {
+//     await sleep(ms);
+//     yield;
+//     console.log(`Slept ${ms}.`);
+//   });
+// }
+
+// const b = AbortablePromise.deadlyRace([
+//   abortableSleep(1000),
+//   abortableSleep(2000),
+//   abortableSleep(3000),
+// ]);
 
 // setTimeout(() => a.abort(), 1500);
 
diff --git a/tsconfig.json b/tsconfig.json
index 8fa566d..41ac8e9 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -5,7 +5,7 @@
     "noImplicitAny": true,
     "noImplicitThis": true,
     "strictNullChecks": true,
-    "target": "ES6",
+    "target": "ES2019",
     "declaration": true,
     "esModuleInterop": true,
     "lib": ["es6", "esnext"],