network/context.go

package network

import (
	"context"
	"git.hpds.cc/Component/network/hpds_err"
	"git.hpds.cc/Component/network/log"
	"sync"
	"time"

	"git.hpds.cc/Component/network/frame"
)

var ctxPool sync.Pool

// Context for Network Server.
type Context struct {
	// DataStream is the stream used for reading and writing frames.
	DataStream DataStream

	// Frame receives from client.
	Frame frame.Frame

	// mu is used to protect Keys from concurrent read and write operations.
	mu sync.RWMutex
	// Keys stores the key/value pairs in context, It is Lazy initialized.
	Keys map[string]any
}

// Set is used to store a new key/value pair exclusively for this context.
// It also lazy initializes c.Keys if it was not used previously.
func (c *Context) Set(key string, value any) {
	c.mu.Lock()
	defer c.mu.Unlock()

	if c.Keys == nil {
		c.Keys = make(map[string]any)
	}

	c.Keys[key] = value
}

// Get returns the value for the given key, ie: (value, true).
// If the value does not exist it returns (nil, false)
func (c *Context) Get(key string) (any, bool) {
	c.mu.RLock()
	defer c.mu.RUnlock()

	value, ok := c.Keys[key]
	return value, ok
}

var _ context.Context = &Context{}

// Done returns nil (chan which will wait forever) when c.Stream.Context() has no Context.
func (c *Context) Done() <-chan struct{} { return c.DataStream.Context().Done() }

// Deadline returns that there is no deadline (ok==false) when c.Stream has no Context.
func (c *Context) Deadline() (deadline time.Time, ok bool) { return c.DataStream.Context().Deadline() }

// Err returns nil when c.Request has no Context.
func (c *Context) Err() error { return c.DataStream.Context().Err() }

// Value returns the value associated with this context for key, or nil
// if no value is associated with key. Successive calls to Value with
// the same key returns the same result.
func (c *Context) Value(key any) any {
	if keyAsString, ok := key.(string); ok {
		if val, exists := c.Keys[keyAsString]; exists {
			return val
		}
	}
	// There always returns nil, because quic.Stream.Context is not be allowed modify.
	return c.DataStream.Context().Value(key)
}

// newContext returns a yomo context,
// The context implements standard library `context.Context` interface,
// The lifecycle of Context is equal to stream's that be passed in.
func newContext(dataStream DataStream) (c *Context) {
	v := ctxPool.Get()
	if v == nil {
		c = new(Context)
	} else {
		c = v.(*Context)
	}

	log.Infof("stream_id: %s; stream_name: %s; stream_type: %s;", dataStream.ID(),
		dataStream.Name(), dataStream.StreamType().String(),
	)

	c.DataStream = dataStream
	return
}

// WithFrame sets a frame to context.
//
// TODO: delete frame from context due to different lifecycle between stream and stream.
func (c *Context) WithFrame(f frame.Frame) {
	c.Frame = f
}

// CloseWithError close dataStream in se error,
// It tells controlStream which dataStream should be closed and close dataStream with
// returning error message to client side stream.
//
// TODO: ycode is not be transmitted.
func (c *Context) CloseWithError(hCode hpds_err.ErrorCode, errString string) {
	log.Warnf("Stream Close With error", "err_code", hCode.String(), "error", errString)

	err := c.DataStream.CloseWithError(errString)
	if err == nil {
		return
	}
	log.Errorf("Close DataStream error", err)
}

// Clean cleans the Context,
// Context is not available after called Clean,
//
// Warining: do not use any Context api after Clean, It maybe cause an error.
func (c *Context) Clean() {
	c.reset()
	ctxPool.Put(c)
}

func (c *Context) reset() {
	c.DataStream = nil
	c.Frame = nil
	for k := range c.Keys {
		delete(c.Keys, k)
	}
}

// StreamId gets dataStream ID.
func (c *Context) StreamId() string {
	return c.DataStream.ID()
}