update sse I/O code to limit the amount of memory a single
non-terminated event can take
---------
Co-authored-by: Guglielmo Colombo <guglielmoc@google.com>
## Summary
`MemoryEventStore.After` guarded only the lower bound of the requested
index:
```go
start := index + 1
if dl.first > start { // too old → ErrEventsPurged
return nil, fmt.Errorf(... ErrEventsPurged)
}
return slices.Clone(dl.data[start-dl.first:]), nil
```
There was no *upper*-bound guard, so an `index` greater than the highest
stored event made the final slice expression panic with `slice bounds
out of range`. The boundary `start-dl.first == len(dl.data)` (resume
from the last event seen) is a valid empty replay, so only
strictly-greater indices faulted.
This is reachable from untrusted input: `parseEventID` accepts any
non-negative index from the client-supplied `Last-Event-ID` header, and
`serveGET` passes it straight to `eventStore.After`. Direct callers of
the exported `EventStore.After` API crash outright.
Fixes#1131
## Change
Return an empty replay for an index at or beyond the latest stored event
— there is nothing after it — consistent with the already-valid `index
== last` case. `ErrEventsPurged` would be misleading here, since those
events were never sent rather than purged.
## Testing
Extended `TestMemoryEventStoreAfter` with indices past the end of a
stream (`3`, `100`, and one past a second stream), asserting an empty
replay with no error.
Verified the new cases **panic on the pre-fix code** (`panic: runtime
error: slice bounds out of range [3:2]`) and **pass with the fix**. `go
vet ./mcp/` and the full `go test ./mcp/` suite pass.
---------
Co-authored-by: Yaroslav Shevchuk <yarolegovich@gmail.com>
We have a use case for messages larger than 1MB, hence making this
configurable would help.
In order to discover the source of our problems we had to spend some
time investigating, as errors were silently discarded. So we also
included changes to improving surfacing errors .
---------
Co-authored-by: Maciej Kisiel <macio92@gmail.com>
Address TODOs in code requiring go 1.24 as minimum version
mcp/logging.go: use slog.DiscardHandler, over local implementation
mcp/util.go: use rand.Text, over local implementation
Fixes#772
Add a benchmark using the streamable HTTP handler, and a more realistic input/output signature. Also expose this handler as an example (both a go example and a server in the examples/ directory).
Add a new benchmark measuring the append and purge performance of the
MemoryEventStore. This benchmark revealed that the store is orders of
magnitude slower than it should be due to conservative validation
(hugely so: 300KB/s vs 568MB/s). Turn off this validation by default.
For #190
Introduce an EventStore interface to store events for resumable streams.
Provide an in-memory implementation.
Still to do: connect to streaming transports.
For #10
Export the Event type in preparation for providing user-definable
storage for resumable streams.
Also, move event code to a separate file.
This PR is just renaming and code motion.
