NodeDomain

[iwehrman]

This pull request has three parts:

1. A new NodeDomain module, which is a high-level wrapper around NodeConnection. This makes it easy to open a connection and load a single domain, and then execute the domain's commands and listen for its events. The wrapper handles, in particular, connection and domain loading and reloading.
   The inline documentation gives the following usage example:

var myDomain = new NodeDomain("someDomain", "/path/to/SomeDomainDef");
      $result = myDomain.exec("someCommand", arg1, arg2);

      $result.done(function (value) {
        // the command succeeded!
      });

      $result.fail(function (err) {
        // the command failed; act accordingly!
      });

      $(myDomain).on("someEvent", someHandler);

1. A refactoring of StaticServer to use NodeDomain instead of manipulating NodeConnection directly. The previous code had been copied and pasted regularly, but had a few shortcomings, including redundant timeouts (NodeConnection handles this already), failure to handle disconnected sockets, and, in some cases, a silent fail-fast behavior on command execution where simply waiting would suffice. (If the NodeConnection isn't connected, don't abort; just wait for it to come back up!)
2. Finally, it also fixes a race condition in StaticServerDomain that was causing the LiveDevelopment unit tests to fail unpredictably.
   The problem is as follows: when StaticServerDomain receives an HTTP request for a filtered path, it emits a filterRequest event to Brackets to have the file contents at that path manipulated before sending the response. Brackets later calls the writeFilteredResponse command with the manipulated data, which triggers the HTTP response. StaticServerDomain connects these filtered responses to their original filter requests by way of a map of callbacks keyed on the requested paths. But, as a consequence, when the StaticServerDomain HTTP server receives two concurrent requests for the same path, it only stores one response callback. The second filtered response is then be dropped, no longer having any response callback at the given path, and the second request---whose response callback has been overwritten---will always time out. The problem is solved here by adding a unique identifier to each filterRequest and keying callbacks on this identifier.

[jasonsanjose]

Oops. Accidentally closed.

[jasonsanjose]

Assigned to me

[jasonsanjose]

Is this right? Looking at the usage it should be {Object.<string, {Object.<number, function>}} and A map from root paths to its request to reponse callback mapping.

[iwehrman]

Er, right, good catch. I'll fix that.

[jasonsanjose]

Did you make this change? I don't see it.

[jasonsanjose]

Interesting. I just happened to have an open live preview session in Brackets when I ran the StaticServer unit tests. I saw about half of them fail. However, the tests did pass after I closed the session.

[jasonsanjose]

Was there any reason besides time to not update the other usages of NodeConnection? Just curious if there were other gotchas that would prohibit use.

[jasonsanjose]

It doesn't seem necessary to wait for the promise here anymore. Is it?

[iwehrman]

Maybe not? I wasn't quite sure, so I opted to try to preserve the existing functionality. Everything is so delicate with live development, so when in doubt I just tried not to shake anything. If you don't think it's necessary though I could also kill that promise() method...

[jasonsanjose]

Initial review complete @iwehrman. Nice work.

[iwehrman]

The only reason I didn't convert more NodeConnection clients to NodeDomain was time. Also I didn't think you'd merge it unless I refactored at least one client :)

[jasonsanjose]

This doesn't need to land for sprint 35 right? We talked at the standup that this would land in sprint 36.

[iwehrman]

It does not need to land in Sprint 35. Ideally it would land before the file watchers/caching stuff so we can use it in AppshellFileSystemImpl.

[iwehrman]

Ready for re-review. I removed the StaticServer dependency on NodeDomain.promise() but left that method in there, thinking that it might be useful to someone else. But it's currently unused code, so I'm perfectly happy to remove that too. Whatever!

[jasonsanjose]

I'll add this to sprint 36.

[jasonsanjose]

Re-review complete. Just some minor questions.

[iwehrman]

Should be ready to go now.

[jasonsanjose]

Merging.

[peterflynn]

This is awesome btw! Great cleanup. Have we filed a spinoff bug/story for porting over our other NodeConnection usages?