74 lines
2 KiB
Go
74 lines
2 KiB
Go
package server
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import (
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"bytes"
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"context"
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"log/slog"
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"github.com/ollama/ollama/api"
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"github.com/ollama/ollama/llm"
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"github.com/ollama/ollama/template"
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)
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type tokenizeFunc func(context.Context, string) ([]int, error)
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// chatPrompt accepts a list of messages and returns the prompt and images that should be used for the next chat turn.
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// chatPrompt truncates any messages that exceed the context window of the model, making sure to always include 1) the
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// latest message and 2) system messages
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func chatPrompt(ctx context.Context, m *Model, tokenize tokenizeFunc, opts *api.Options, msgs []api.Message, tools []api.Tool) (prompt string, images []llm.ImageData, _ error) {
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var system []api.Message
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// always include the last message
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n := len(msgs) - 1
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// in reverse, find all messages that fit into context window
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for i := n - 1; i >= 0; i-- {
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system = make([]api.Message, 0)
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for j := range i {
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if msgs[j].Role == "system" {
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system = append(system, msgs[j])
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}
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}
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var b bytes.Buffer
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if err := m.Template.Execute(&b, template.Values{Messages: append(system, msgs[i:]...), Tools: tools}); err != nil {
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return "", nil, err
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}
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s, err := tokenize(ctx, b.String())
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if err != nil {
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return "", nil, err
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}
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c := len(s)
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if m.ProjectorPaths != nil {
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for _, m := range msgs[i:] {
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// images are represented as 768 sized embeddings
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// TODO: get embedding length from project metadata
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c += 768 * len(m.Images)
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}
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}
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if c > opts.NumCtx {
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slog.Debug("truncating input messages which exceed context length", "truncated", len(msgs[i:]))
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break
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} else {
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n = i
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}
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}
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// truncate any messages that do not fit into the context window
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var b bytes.Buffer
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if err := m.Template.Execute(&b, template.Values{Messages: append(system, msgs[n:]...), Tools: tools}); err != nil {
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return "", nil, err
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}
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for _, m := range msgs[n:] {
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for _, i := range m.Images {
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images = append(images, llm.ImageData{
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ID: len(images),
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Data: i,
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})
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}
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}
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return b.String(), images, nil
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}
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