Refresh PR views when a push occurs

[BinaryMuse]

When a push completes in a repository, the associated PR views should automatically update.

[BinaryMuse]

I started prototyping on a way to do this, but don't love it. Thinking about dropping the decorator and just making the function body a little uglier.

diff --git a/lib/models/repository-states/present.js b/lib/models/repository-states/present.js
index b93d873a..7b7bc604 100644
--- a/lib/models/repository-states/present.js
+++ b/lib/models/repository-states/present.js
@@ -36,6 +37,29 @@ function invalidate(spec) {
   };
 }
 
+function emits(op) {
+  return function(target, name, descriptor) {
+    const original = descriptor.value;
+    descriptor.value = function(...args) {
+      return original.apply(this, args).then(
+        result => {
+          // Disabling no-unsafe-finally as we always want to return `result`.
+          // The order of operations is;
+          // 1. Evaluate the `try` block
+          // 2. Evaluate the `finally` block
+          // 3. If the result of `finally` is normal, return it
+          try {
+            this.repository.emitOperation(op);
+          } finally {
+            return result; // eslint-disable-line no-unsafe-finally
+          }
+        },
+      );
+
+    };
+  };
+}
+
 /**
  * State used when the working directory contains a valid git repository and can be interacted with. Performs
  * actual git operations, caching the results, and broadcasts `onDidUpdate` events when write actions are
@@ -297,6 +321,7 @@ export default class Present extends State {
 
     return keys;
   })
+  @emits('push')
   async push(branchName, options) {
     const remote = await this.getRemoteForBranch(branchName);
     return this.git().push(remote.getNameOr('origin'), branchName, options);
diff --git a/lib/models/repository.js b/lib/models/repository.js
index ce80973d..7d86392d 100644
--- a/lib/models/repository.js
+++ b/lib/models/repository.js
@@ -112,6 +112,14 @@ export default class Repository {
     return this.emitter.on('did-update', callback);
   }
 
+  onOperationComplete(op, callback) {
+    return this.emitter.on(`did-operation-${op}`, callback);
+  }
+
+  emitOperation(op) {
+    return this.emitter.emit(`did-operation-${op}`);
+  }
+
   // State-independent actions /////////////////////////////////////////////////////////////////////////////////////////
   // Actions that use direct filesystem access or otherwise don't need `this.git` to be available.

[smashwilson]

Thinking about dropping the decorator and just making the function body a little uglier.

As much as I ❤️ decorators I think I'm 👍 on this alternative. Doing the emit() explicitly makes it easier to find the event source with good old-fashioned grep. It also gives us more control over its timing and context - it'd let us drop a console.log or a debugger after the event broadcast if we need to, for example.

If we end up needing lifecycle events for more Repository actions, I could see abstracting it out to a decorator or a helper, and maybe even introducing separate "begin" and "end" events. I could also see wiring it up to the Switchboard to participate in the global event bus there, but honestly I'm not particularly fond of the Switchboard either.