* rpc: rework timeouts to be per-method instead of global
Prior to this change, we set a 10-second global timeout for all RPC methods
using the net/http Server type's WriteTimeout. This meant that any request
whose handler did not return within that period would simply drop the
connection to the client.
This timeout is too short for a default, as evidenced by issues like [1] and
[2]. In addition, the mode of failure on the client side is confusing; it
shows up as a dropped connection (EOF) rather than a meaningful error from the
service. More importantly, various methods have diffent constraints: Some
should be able to return quickly, others may need to adjust based on the
application workload.
This is a first step toward supporting configurable timeouts. This change:
- Removes the server-wide default global timeout, and instead:
- Wires up a default context timeout for all RPC handlers.
- Increases the default timeout from 10s to 60s.
- Adds a hook to override this per-method as needed.
This does NOT expose the timeouts in the configuration file (yet).
[1] https://github.com/osmosis-labs/osmosis/issues/1391
[2] https://github.com/tendermint/tendermint/issues/8465
In #8397 I tried to remove all the cases where we needed to keep track of the
target type of parameters for JSON encoding, but there is one case still left:
When decoding parameters from URL query terms, there is no way to tell whether
or not we need base64 encoding without knowing whether the underlying type of
the target is string or []byte.
To fix this, keep track of parameters that are []byte valued when RPCFunc is
compiling its argument map, and use that when parsing URL query terms. Update
the tests accordingly.
Pass all parameters from JSON-RPC requests to their corresponding handlers
using struct types instead of positional parameters. This allows us to control
encoding of arguments using only the standard library, and to eliminate the
remaining special-purpose JSON encoding hooks in the server.
To support existing use, the server still allows arguments to be encoded in
JSON as either an array or an object.
Related changes:
- Rework the RPCFunc constructor to reduce reflection during RPC call service.
- Add request parameter wrappers for each RPC service method.
- Update the RPC Environment methods to use these types.
- Update the interfaces and shims derived from Environment to the new
signatures.
- Update and extend test cases.
Require that RPC functions take a context as their first argument, and return
an error as either their only result, or the second of two results.
This does not change how functions are dispatched, but will make it a little
easier to make more invasive changes in the near future.
Instead of taking a comma-separated string of parameter names, take each
parameter name as a separate argument. Now that we no longer have an extra flag
for caching, this fits nicely into a variadic trailer.
* Update all usage of NewRPCFunc and NewWSRPCFunc.
We should not set cache-control headers on RPC responses. HTTP caching
interacts poorly with resources that are expected to change frequently, or
whose rate of change is unpredictable.
More subtly, all calls to the POST endpoint use the same URL, which means a
cacheable response from one call may actually "hide" an uncacheable response
from a subsequent one. This is less of a problem for the GET endpoints, but
that means the behaviour of RPCs varies depending on which HTTP method your
client happens to use. Websocket requests were already marked statically
uncacheable, adding yet a third combination.
To address this:
- Stop setting cache-control headers.
- Update the tests that were checking for those headers.
- Remove the flags to request cache-control.
Apart from affecting the HTTP response headers, this change does not modify the
behaviour of any of the RPC methods.
Migrates the `rpc` package to use new JSON encoder in #4955. Branched off of that PR.
Tests pass, but I haven't done any manual testing beyond that. This should be handled as part of broader 0.34 testing.
