ipfs-cluster中rpc的使用
go-libp2p-gorpc 简介：
Package rpc is heavily inspired by Go standard net/rpc package. It aims to do the same thing, except it uses Libp2p for communication and provides context support for cancelling operations.
A server registers an object, making it visible as a service with the name of the type of the object. After registration, exported methods of the object will be accessible remotely. A server may register multiple objects (services) of different types but it is an error to register multiple objects of the same type.
rpc 方法的标准：
- the method’s type is exported.
- the method is exported.
- the method has 3 arguments.
- the method’s first argument is a context.
- the method’s second are third arguments are both exported (or builtin) types.
- the method’s second argument is a pointer.
- the method has return type error.
方法：
func (t *T) MethodName(ctx context.Context, argType T1, replyType *T2) error
The method’ first argument represents the arguments provided by the caller;
The second argument represents the result parameters to be returned to the caller.
ipfs-cluster 中示例
GoContext
API 说明1
调用 CommitOp 后2，libp2praft 会自动调用 ApplyTo. （相当于回调函数）。
cc.shutdownLock.RLock() // do not shut down while committing
_, finalErr = cc.consensus.CommitOp(op)
cc.shutdownLock.RUnlock()
1）调用GoContext
func (op *LogOp) ApplyTo(cstate consensus.State) (consensus.State, error) {
case LogOpPin:
err = state.Add(ctx, pin)
if err != nil {
logger.Error(err)
goto ROLLBACK
}
// Async, we let the PinTracker take care of any problems
op.consensus.rpcClient.GoContext(
ctx,
"",
"PinTracker",
"Track",
pin,
&struct{}{},
nil,
)
}
2）自定义RPC方法，符合标准特征
// Track runs PinTracker.Track().
func (rpcapi *PinTrackerRPCAPI) Track(ctx context.Context, in *api.Pin, out *struct{}) error {
return rpcapi.tracker.Track(ctx, in)
}