feat: add support for `Stream: true` to completionEndpoint (#465)

api/openai.go

@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"bytes"
 	"encoding/base64"
+	"errors"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -143,13 +144,29 @@ func defaultRequest(modelFile string) OpenAIRequest {
 
 // https://platform.openai.com/docs/api-reference/completions
 func completionEndpoint(cm *ConfigMerger, o *Option) func(c *fiber.Ctx) error {
-	return func(c *fiber.Ctx) error {
+	process := func(s string, req *OpenAIRequest, config *Config, loader *model.ModelLoader, responses chan OpenAIResponse) {
+		ComputeChoices(s, req, config, loader, func(s string, c *[]Choice) {}, func(s string) bool {
+			resp := OpenAIResponse{
+				Model:   req.Model, // we have to return what the user sent here, due to OpenAI spec.
+				Choices: []Choice{{Text: s}},
+				Object:  "text_completion",
+			}
+			log.Debug().Msgf("Sending goroutine: %s", s)
+
+			responses <- resp
+			return true
+		})
+		close(responses)
+	}
 
+	return func(c *fiber.Ctx) error {
 		model, input, err := readInput(c, o.loader, true)
 		if err != nil {
 			return fmt.Errorf("failed reading parameters from request:%w", err)
 		}
 
+		log.Debug().Msgf("`input`: %+v", input)
+
 		config, input, err := readConfig(model, input, cm, o.loader, o.debug, o.threads, o.ctxSize, o.f16)
 		if err != nil {
 			return fmt.Errorf("failed reading parameters from request:%w", err)
@@ -157,12 +174,67 @@ func completionEndpoint(cm *ConfigMerger, o *Option) func(c *fiber.Ctx) error {
 
 		log.Debug().Msgf("Parameter Config: %+v", config)
 
+		if input.Stream {
+			log.Debug().Msgf("Stream request received")
+			c.Context().SetContentType("text/event-stream")
+			//c.Response().Header.SetContentType(fiber.MIMETextHTMLCharsetUTF8)
+			//c.Set("Content-Type", "text/event-stream")
+			c.Set("Cache-Control", "no-cache")
+			c.Set("Connection", "keep-alive")
+			c.Set("Transfer-Encoding", "chunked")
+		}
+
 		templateFile := config.Model
 
 		if config.TemplateConfig.Completion != "" {
 			templateFile = config.TemplateConfig.Completion
 		}
 
+		if input.Stream {
+			if (len(config.PromptStrings) > 1) {
+				return errors.New("cannot handle more than 1 `PromptStrings` when `Stream`ing")
+			}
+
+			predInput := config.PromptStrings[0]
+
+			// A model can have a "file.bin.tmpl" file associated with a prompt template prefix
+			templatedInput, err := o.loader.TemplatePrefix(templateFile, struct {
+				Input string
+			}{Input: predInput})
+			if err == nil {
+				predInput = templatedInput
+				log.Debug().Msgf("Template found, input modified to: %s", predInput)
+			}
+
+			responses := make(chan OpenAIResponse)
+
+			go process(predInput, input, config, o.loader, responses)
+
+			c.Context().SetBodyStreamWriter(fasthttp.StreamWriter(func(w *bufio.Writer) {
+
+				for ev := range responses {
+					var buf bytes.Buffer
+					enc := json.NewEncoder(&buf)
+					enc.Encode(ev)
+
+					log.Debug().Msgf("Sending chunk: %s", buf.String())
+					fmt.Fprintf(w, "data: %v\n", buf.String())
+					w.Flush()
+				}
+
+				resp := &OpenAIResponse{
+					Model:   input.Model, // we have to return what the user sent here, due to OpenAI spec.
+					Choices: []Choice{{FinishReason: "stop"}},
+				}
+				respData, _ := json.Marshal(resp)
+
+				w.WriteString(fmt.Sprintf("data: %s\n\n", respData))
+				w.WriteString("data: [DONE]\n\n")
+				w.Flush()
+			}))
+			return nil
+		}
+
 		var result []Choice
 		for _, i := range config.PromptStrings {
 			// A model can have a "file.bin.tmpl" file associated with a prompt template prefix