| Commit message (Collapse) | Author | Age |
|---|
| |\ |
|
| | |
| |
| |
| |
| |
| |
| |
| | |
The changes introduced in the previous commit make it possible to detect lost connections and restart them, so do so. The process is pretty simple - a new remote state is spun up using `/api/boot`, swapped in for the existing state, and a `new EventSource` is started from that new remote state to consume events.
This can induce some anomalies. For example, messages that arrive on the server between the loss of one connection and the creation of the next one just "show up" in boot, without ever appearing in the event stream. (This is technically also true on client startup, but it's easier to expect in that situation.) This is something we'll need to consider when implementing things like notifications or unread flags, though the ones we have today, which are state-based, do work fine.
By design, this _does not_ retry either the `/api/boot` call or the new event source setup. Event sources will try to reconnect on their own, up to a point, so that's fine, but we need to build something more robust for `/api/boot`. I want to tackle that separately from detecting lost connections and reacting to them, but that does mean that this is not a complete solution to client reconnects.
|
| |/
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
A heartbeat is an event that the server synthesizes any time an event stream has been idle for longer than some timeout. They allow clients to detect disconnection and network problems, which would otherwise go unnoticed because event streams are a one-way channel. Most network problems only become clear when the offended party tries to _send_ something, and subscribing to an event stream only sends something during the request phase.
Technically, Pilcrow has always sent these, since we started using Axum's SSE support: it defaults to sending a dummy event after 15 seconds (consisting of `":\n\n"`, which is then ignored). I've built Pilcrow's heartbeat support out of that, by customizing the event sent back. The results _mostly_ look like existing events, but there are two key differences:
* Heartbeats don't have `id` fields in the event stream. They're synthetic, and they don't participate in either the "resume at" sequence management, or the last-event-id header-based resumption management.
* Heartbeats have an `event` but no `type` field in the message body. There are no subtypes.
To make it less likely that clients will race with the server on expiring timeouts, heartbeats are sent about five seconds early. In this change, heartbeats are due after 20 seconds, but are sent after 15. If it takes longer than five seconds for a heartbeat to arrive, a client can and should treat that as a network problem and reconnect, but I'd really like to avoid that happening over differences smaller than a second, so I've left a margin.
I originally sketched this out in conversation with @wlonk as having each event carry a deadline for the next one. I ultimately opted not to do that for a few reasons. First, Axum makes it hard - the built-in keep-alive support only works with a static event, and cannot make dynamic ones whose payloads might vary (for example if the deadline is variable). Second, it's complex, to no apparent gain, and adds deadline information to _every_ event type.
This implementation, instead, sends deadline information as part of boot, as a fixed interval in seconds. Clients are responsible for working out deadlines based on message arrivals. This is fine; heartbeat-based connection management is best effort at the best of times, so a few milliseconds of slop in either direction won't hurt anything.
The existing client ignores these events entirely, which is convenient.
The new heartbeat event type is defined alongside the main event type, to make it less likely that we'll inadvertently make changes to one but not the other. We can still do so advertently, I just don't want it to be an accident.
|
| | |
|
| |\ |
|
| | | |
|
| | |
| |
| |
| |
| |
| | |
357116366c1307bedaac6a3dfe9c5ed8e0e0c210 wasn't updated (and wasn't quite correct then, either).
I haven't found a way to derive it from the name of the type.
|
| |\ \ |
|
| | | | |
|
| | | | |
|
| | | | |
|
| | | | |
|
| | | | |
|
| | | | |
|
| | |/ |
|
| |/ |
|
| |
|
|
| |
In a discussion with wlonk, we both agreed that 15 days is _too_ aggressive, but also that it's not quite time to implement configurable expiry.
|
| |\ |
|
| | |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| | |
Sorry about the thousand-line omnibus change; this is functionally a rewrite of the client's state tracking, flavoured to resemble the existing code as far as is possible, rather than something that can be parted out and committed in pieces.
Highlights:
* No more `store.writeable()`s. All state is now tracked using state runs or derivatives. State is still largely structured the way it was, but several bits of nested state have been rewritten to ensure that their properties are reactive just as much as their containers are.
* State is no longer global. `(app)/+layout` manages a stateful session, created via its load hook and started/stopped via component mount and destroy events. The session also tracks an event source for the current state, and feeds events into the state, broadly along the same lines as the previous stores-based approach.
Together these two changes fix up several rough spots integrating state with Svelte, and allow for the possibility of multiple states. This is a major step towards restartable states, and thus towards better connection management, which will require the ability to "start over" once a connection is restored.
|
| |/ |
|
| |\ |
|
| | |
| |
| |
| | |
Only once on load, then once per new message.
|
| |/ |
|
| |\ |
|
| | | |
|
| | | |
|
| | | |
|
| | |\ |
|
| | | |
| | |
| | |
| | |
| | |
| | | |
the DOM.
Prevents this from breaking during DOM unmounting, when leaving a channel.
|
| | | |
| | |
| | |
| | | |
That no longer vitally pertains.
|
| | | |
| | |
| | |
| | | |
To facilitate PWA behaviour.
|
| | | |
| | |
| | |
| | |
| | |
| | |
| | |
| | | |
This is stored locally, and, while parallel to channel info, is not the
same as.
Eventually, this may hold info about moot/decayed channels, and grow
unbounded. That'll need to be addressed.
|
| | | |
| | |
| | |
| | |
| | |
| | |
| | |
| | |
| | | |
When we hit the boot endpoint, we get the server's view of things. If we
just setChannels with that, we overwrite all our locally-stored info in
on things like lastReadAt. So we need to merge data.
Eventually, this might militate for a `meta` key containing an object of
locally stored data, rather than having to handle each key specially.
|
| |\ \ \
| |_|/
|/| | |
|
| |/ /
| |
| |
| |
| |
| |
| |
| | |
Access to "global" (maybe "external?") state is now handled at the top level of the component hierarchy, in `+page.svelte`, `+layout.svelte`, and their associated scripts. State is otherwise passed down through props, and changes are passed up through callbacks.
This is - hopefully - groundwork for refactoring state management a bit. I wanted to move access to state out to a smaller number of places, so that I have fewer places to update to implement reconnect logic. My broader goal is to make it easier to refactor these kinds of external side effects, as well, though no such changes are in this branch.
This change also makes testing a mile easier, since tests can interact with props and callbacks instead of emulating the whole HTTP request stack and the Pilcrow API. This change removes do-very-little tests.
|
| | | |
|
| | | |
|
| | | |
|
| | | |
|
| | | |
|
| | | |
|
| | | |
|
| | |
| |
| |
| | |
Browsers cope with weird nestings mostly fine, but there's no upside for us in testing that.
|
| | | |
|
| | |
| |
| |
| |
| |
| | |
According to <https://stackoverflow.com/a/6803278>, this was needed for old versions of Safari. However, since at least 2022, Safari has supported `content: none` just fine.
Related Safari bug (still open as of this writing, comments relevnat): <https://bugs.webkit.org/show_bug.cgi?id=20032>
|
| | | |
|
| | | |
|
| | | |
|
| | | |
|
| | | |
|
