I upgraded all plugins I could see except org.ysb33r.doxygen. 2.0 made
breaking changes, and I couldn't figure out how to migrate.
Most of the changes are for suppressing new linter purification rites.
Each client has an incoming queue of ClientMessage.
In the read callback:
- Parse and process only ping messages and a limited number of messages;
anything else will get put into the queue and not processed
- If we queued some messages, we tell the network we stopped reading; this will
result in back-pressure if we are reading too slowly. We also start an idle
handle to process the queued messages.
In the idle handle callback:
- For each client, process just a few pending messages. This is performed in
round-robin fashion across all clients with pending messages
- When a client's queue becomes empty, we re-enable the network read
- When all client queues are empty, we stop the idle handle (so we don't spin)
For local client processing, we use round-robin processing for most cases (including FlushLocal),
but still do batch processing of all local changes for explicit network Flush() calls.
This makes it easier to define schemas when the type name is non-trivial (e.g., templated structs).
This is breaking for a) custom struct implementations and b) anything calling `wpi::Struct<T>::GetTypeString(info...)` in C++ directly. In both cases, it's a simple translation: For A, rename `GetTypeString()` to `GetTypeName()` and remove the struct: at the beginning, and for B, use `wpi::GetStructTypeString<T>(info...)` instead.
Currently in the entire C API of WPILib we have ~8 different ways of handling strings. The C API actually isn't built for pure C callers (We don't actually have any of those). Instead, they're built for interop between languages like LabVIEW and C# which can talk to C API's directly.
For output parameters, the choice was fairly obvious. An output struct containing a const string pointer and a length makes the most sense. Its easy to use these from most other languages, and doesn't require special null termination handling. Freeing these is also easy, as if you ever receive one of these string structures, theres just a single function call to free it.
Input parameters are a bit more complex. To be used from pure C, and from LabVIEW, a null terminated string is the best in most cases. However, null terminated strings in general have a lot of downsides. Additionally, from LabVIEW there are other considerations around encoding that having a wrapper struct helps make a bit easier. From a language like C#, a wrapper struct is by far the easiest, as custom marshalling can make it trivial to marshal both UTF8 and UTF16 strings down.
The final consideration is its nice to have an identical concept for both input and output. It makes the rules fairly easy to understand.
WPILib will not have any APIs that manipulate a string allocated externally. This means WPI_String can be const, as across the boundary it is always const.
If a WPILib API takes a const WPI_String*, WPILib will not manipulate or attempt to free that string, and that string is treated as an input. It is up to the caller to handle that memory, WPILib will never hold onto that memory longer than the call.
If a WPILib API takes a WPI_String*, that string is an output. WPILib will allocate that API with WPI_AllocateString(), fill in the string, and return to the caller. When the caller is done with the string, they must free it with WPI_FreeString().
If an output struct contains a WPI_String member, that member is considered read only, and should not be explicitly freed. The caller should call the free function for that struct.
If an array of WPI_Strings are returned, each individual string is considered read only, and should not be explicitly freed. The free function for that array should be called by the caller.
If an input struct containing a WPI_String, or an input array of WPI_Strings is passed to WPILib, the individual strings will not be manipulated or freed by WPILib, and the caller owns and should free that memory.
Callbacks also follow these rules. The most common is a callback either getting passed a const WPI_String* or a struct containing a WPI_String. In both of these cases, the callback target should consider these strings read only, and not attempt to free them or manipulate them.
This required changing the constant values (e.g. kSize) into functions
(e.g. GetSize()).
Fixed implementations of ForEachNested to be inline (as these are actually
templates).
Also added a ntcore Struct test.
- Utilize TrySend to properly backpressure network traffic
- Split updates into reasonable sized frames using WS fragmentation
- Use WS pings for network aliveness (requires 4.1 protocol revision)
- Measure RTT only at start of connection, rather than periodically
(this avoids them being affected by other network traffic)
- Refactor network queue
- Refactor network ping, ping from server as well
- Improve meta topic performance
- Implement unified approach for network value updates (currently client and server use very different approaches) that respects requested subscriber update frequency
This adds a new protocol version (4.1) due to WS bugs in prior versions.
This works around an exit race with wpi::Now() on Rio; it was overridden
to call HAL_GetFPGATime(), which calls chipobject, but on exit, because
there was not a library dependency, the chipobject could be destroyed
prior to wpiutil/wpinet being shut down.
Previously, a setDefault() on the server could override a client doing a
real set() if the time offset between client and server was negative,
resulting in a negative timestamp from the client. This is a not
uncommon situation with robot code, as the robot code always starts at
time 0, so any clients that set values earlier (in real time) would have
negative timestamps.
Also improve special casing of 0 in the transmit side to make sure a
normal timestamp will never get sent as 0.
Previously this wouldn't send the last value on the value subscribe if a
topics only subscription already existed.
Also start adding server implementation unit tests.
These are similar, but not quite identical to, the NT3 NetworkTable
table listeners.
Also add table topic-only multi-subscriber to ensure functions like
getKeys() work properly regardless of other subscriptions.
