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lrpc/server/context.go

115 lines
2.7 KiB
Go

/*
* lrpc allows for clients to call functions on a server remotely.
* Copyright (C) 2022 Arsen Musayelyan
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package server
import (
"context"
"time"
"go.arsenm.dev/lrpc/codec"
"github.com/gofrs/uuid"
)
// Context is a connection context for RPC calls
type Context struct {
isChannel bool
channelID string
channel chan any
codec codec.Codec
doneCh chan struct{}
canceled bool
ctx context.Context
}
func newContext(ctx context.Context, codec codec.Codec) *Context {
out := &Context{
doneCh: make(chan struct{}),
codec: codec,
ctx: ctx,
}
if ctx == nil {
out.ctx = context.Background()
}
go func() {
<-out.ctx.Done()
out.cancel()
}()
return out
}
// MakeChannel changes the function it's called in into a
// channel function, and returns a channel which can be used
// to send information to the client.
//
// This will ovewrite any return value of the function with
// a channel ID.
func (ctx *Context) MakeChannel() (chan<- any, error) {
ctx.isChannel = true
chID, err := uuid.NewV4()
ctx.channelID = chID.String()
ctx.channel = make(chan any, 5)
return ctx.channel, err
}
// GetCodec returns a codec bound to the connection
// that called this function
func (ctx *Context) GetCodec() codec.Codec {
return ctx.codec
}
// Deadline always returns the current time and false
// as this context does not support deadlines
func (ctx *Context) Deadline() (time.Time, bool) {
return time.Now(), false
}
// Value always returns nil as this context stores no values
func (ctx *Context) Value(key any) any {
return ctx.ctx.Value(key)
}
// Err returns context.Canceled if the context was canceled,
// otherwise nil
func (ctx *Context) Err() error {
if ctx.canceled {
return context.Canceled
}
return nil
}
// Done returns a channel that will be closed when
// the context is canceled, such as when ChannelDone
// is called by the client
func (ctx *Context) Done() <-chan struct{} {
return ctx.doneCh
}
// Cancel cancels the context
func (ctx *Context) cancel() {
if ctx.canceled {
return
}
ctx.canceled = true
close(ctx.doneCh)
}