- Closes#712.
- Replace synchronous `write()` calls in
`BidirectionalRelay` with non-blocking I/O
and `DispatchSourceWrite` backpressure
handling. Under concurrent vsock proxy load,
a single blocked write on the shared serial
dispatch queue would freeze all relay
connections permanently, including unrelated
new connections.
- Set relay file descriptors to `O_NONBLOCK`
and handle `EAGAIN` by suspending reads and
installing a write source to drain pending data.
- Give each `BidirectionalRelay` its own serial queue
instead of sharing one from `UnixSocketRelayManager`,
eliminating cross-connection blocking.
- Resume suspended read sources before cancelling
in `stop()` — GCD does not deliver cancel handlers
on suspended dispatch sources, which caused file
descriptor and memory leaks on teardown under
backpressure.
- Guard-unwrap `buf.baseAddress` in
`drainPendingWrite`.
This issue doesn't affect any of our existing products. This is a
preemptive fix for downstream consumers of EXT4.format where, in some
platforms, leading `//` in the path could get resolved into a FileTree
that looks like this
```sh
/
└── /
└── usr
```
This helps on binary size if we can successfully get all Foundation
imports out of our dep chain. It seems Foundation brings in a 30MiB ICU
blob, which bloats vmexec and vminitd.
- Downgrades a warning to the debug level in `BidirectionalRelay`
because the shutdown syscall isn't supported for certain socket types
- Rethrows an error if we can't start a socket relay
- Adds a public method to wait for the relay to complete when both
directions close
- Improves error handling
- Moves `UnixSocketRelayManager` into a separate file
- Renames `SocketRelay` to `UnixSocketRelay`
- Adds logs at the info level after converting other logs to the debug
level previously
Changes:
- Refactors a bidirectional relay into a new class
- Makes the unique identifier for a socket configuration public
Bug fixes:
- Fixes a bug where partial writes didn't advance the pointer
- Fixes a buffer memory leak
- Fixes error messages
- Fixes log messages
- Fixes log levels
* on glibc, swift expects that the msg_controllen is type Int
* on glibc, socket shutdown options should be an Int32
Signed-off-by: Kathryn Baldauf <k_baldauf@apple.com>
Improves https://github.com/apple/containerization/pull/245. A potential
deadlock risk was not proven. This PR moves the closing operation inside
the lock to prevent leaking an unclosed handle in case of an error.
While individual accesses were properly mutex-protected, the logical
operations were not atomic, leading to a potential inconsistency in a
multi-threaded environment. Multiple separate `state.withLock` calls
created race windows. With the proposed changes, single atomic
operations check and update the state together.
This change adds documentation to quite a few existing public types that
didn't have a blurb before.
Additionally, this fixes a couple things that I think either didn't make
sense when going to document them:
- Rename ConnectionStream to VsockConnectionStream. This type only
functions for vsock connections.
- Deletes NsLock+Closure. This was not used anywhere.
- Rename ContainerizationOCI/Config.swift to ImageConfig.swift.
Signed-off-by: Danny Canter <danny_canter@apple.com>
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