52 lines
1.7 KiB
Go
52 lines
1.7 KiB
Go
// openconn provides a basic context.Context object to be used with gaio.Watcher
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// the context carries two channels, InChan and OutChan, which are used by menuHandler
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// and doorHandler to read input from the remote connection
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// TODO: decide whether or not we'll actuallly need OutChan - possibly for maintaining
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// output writes in order and/or ensuring output is delivered exactly once
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package openconn
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import (
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"context"
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"github.com/xtaci/gaio"
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)
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// The key type is unexported to prevent collisions with context keys defined in
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// other packages.
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type key int
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const inChanKey key = 0
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const outChanKey key = 1
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// NewContext returns a new Context carrying two new channels.
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func NewContext(ctx context.Context) context.Context {
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inChan := make(chan gaio.OpResult)
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outChan := make(chan gaio.OpResult)
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ctx = context.WithValue(ctx, inChanKey, inChan)
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ctx = context.WithValue(ctx, outChanKey, outChan)
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return ctx
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}
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// FromContext extracts the two channels from ctx, if present.
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func FromContext(ctx context.Context) (chan gaio.OpResult, chan gaio.OpResult, bool) {
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// ctx.Value returns nil if ctx has no value for the key;
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// the type assertion returns ok=false for nil.
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inChan, iok := ctx.Value(inChanKey).(chan gaio.OpResult)
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outChan, ook := ctx.Value(outChanKey).(chan gaio.OpResult)
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if iok && ook {
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return inChan, outChan, iok && ook
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}
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return nil, nil, iok && ook
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}
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// FromOpResult extracts the two channels from a gaio.OpResult, if present.
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func FromOpResult(res gaio.OpResult) (chan gaio.OpResult, chan gaio.OpResult, bool) {
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ctx, ok := res.Context.(context.Context)
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if ok {
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inChan, iok := ctx.Value(inChanKey).(chan gaio.OpResult)
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outChan, ook := ctx.Value(outChanKey).(chan gaio.OpResult)
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return inChan, outChan, iok && ook
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}
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return nil, nil, ok
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}
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