Previously, we could have multiple in-flight messages from the server to a
single client. This isn't safe and can lead to message interleaving. While
write / send are atomic, they are only atomic for the N bytes which they write,
which may not be the entire buffer. Consider this writeAll function:
```
pub fn writeAll(socket: socket_t, bytes: []const u8) !void {
var index: usize = 0;
while (index < bytes.len) {
index += try posix.write(socket, bytes[index..]);
}
}
```
If we're trying to send "abc123", this could take anywhere from 1 to 6 calls
to posix.write (it would take 6 calls, for example, if every call to
posix.write only wrote a single byte). Now if you're trying to write other data
to this same socket at the same time, messages _will_ get interleaved.
In order for this to work, the client now has a send_queue (doubly linked list).
When one message is sent, it sends the next.
In addition to the above change, the Client is now self-contained with respect
to its lifetime. This is necessary so that completions which come in AFTER our
concept of its lifetime ends, can still be processed. I think all types that
receive completions need to follow this model. This relies on the fact that
kqueue (which I know for a fact) and io_uring (which people seem to imply) handle
socket shutdown properly. It's still a bit messy because of timeout and not
wanting to wait until timeout to accept new connections, but needing to wait
until timeout to cleanup the client.
The self-contained nature of Client makes it difficult to test as a generic. I
removed Client(T). Tests now use real sockets. Some tests had to be removed
because they're too difficult to test over a real connection :(
./lightpanda serve --host ...
./lightpanda fetch https://...
Makes it easier to communicate / document which command has which options.
Internally added a "usage" command for displaying the usage - removing the need
for error.NoError :|
Create UUID v4.
Create prefixed ids. To support more of the CDP protocol, we need to remove the
hard-coded IDs (session, browser context, frame, loader, ...) and be able to
dynamically create them, i.e. creating a new BrowserContextId when
Target.createBrowserContext is called.
var frame_id = id.Incremental(u16, "FRM"){};
frame_id.next() == "FRM-1"
frame_id.next() == "FRM-2"
Generation is allocation-free (the returned string is only valid until the
next call to next()). This is not thread safe, each CDP instance will have its
own generator (for each id it needs to generate).
The generated IDs are different than what Chrome uses, i.e.
BROWSERSESSIONID597D9875C664CAC0. I looked at various drivers and none have
any expectations beyond a string. Shorter IDs will be more efficient. Also, the
ID can cheeply be converted to and from an integer, allowing for lookups via
AutoHashMap(u16) instead of StringHashMap.
In debug mode, it has a more user-friendly output:
level | the log messge | ms since last message | key=value key=value
In release mode, it logs using logfmt, which is supported by most log
ingestion frameworks.
Not being used anywhere right now, keeping this PR small with no impact on
existing code.
ADD CDP testing helpers (mock Browser, Session, Page and Client). These are
placeholders until tests are added which use them.
Added a couple CDP tests.
For the time being, given that we only allow 1 client at a time, I took a
shortcut to implement this. The server has an incrementing "current_client_id"
which is part of every completion. On completion callback, we just check if
its client_id is still equal to the server's current_client_id.
