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| library(shiny) | |
| library(bslib) | |
| library(minhub) | |
| library(magrittr) | |
| source("model-session.R") | |
| repo <- "EleutherAI/pythia-70m" | |
| #repo <- "stabilityai/stablelm-tuned-alpha-3b" | |
| repo <- Sys.getenv("MODEL_REPO", unset = repo) | |
| sess <- model_session$new() | |
| max_n_tokens <- 100 | |
| system_prompt <- "<|SYSTEM|># StableLM Tuned (Alpha version) | |
| - StableLM is a helpful and harmless open-source AI language model developed by StabilityAI. | |
| - StableLM is excited to be able to help the user, but will refuse to do anything that could be considered harmful to the user. | |
| - StableLM is more than just an information source, StableLM is also able to write poetry, short stories, and make jokes. | |
| - StableLM will refuse to participate in anything that could harm a human. | |
| " | |
| ui <- page_fillable( | |
| theme = bs_theme(bootswatch = "minty"), | |
| card( | |
| height="90%", | |
| heights_equal = "row", | |
| width = 1, | |
| fillable = FALSE, | |
| uiOutput("messages") | |
| ), | |
| layout_column_wrap( | |
| width = 1/2, | |
| textInput("prompt", label = NULL, width="100%"), | |
| uiOutput("sendButton") | |
| ) | |
| ) | |
| server <- function(input, output, session) { | |
| # context for the observers that load the model in the background session | |
| # it also handles reloads | |
| loading <- reactiveValues( | |
| model = NULL, | |
| reload = NULL | |
| ) | |
| # Observer used at app startup time to allow using the 'Send' button once the | |
| # model has been loaded. | |
| observeEvent(loading$reload, ignoreInit = FALSE, ignoreNULL = FALSE, priority = 0, { | |
| # the model is already loaded, we just make sure that we propagate this | |
| # by setting generating to FALSE | |
| if (!is.null(sess$is_loaded) && sess$is_loaded) { | |
| context$generating <- FALSE | |
| return() | |
| } | |
| # the model isn't loaded and no task is trying to load it, so we start a new | |
| # task to load it | |
| if (is.null(sess$is_loaded)) { | |
| cat("Started loading model ....", "\n") | |
| loading$model <- sess$load_model(repo) | |
| sess$is_loaded <- FALSE # not yet loaded, but loading | |
| } else { | |
| # the model is loading, but this is handled by another session. We should | |
| # come back to this observer later to enable the send button once model | |
| # is loaded. | |
| invalidateLater(100, session) | |
| return() | |
| } | |
| # this runs for the cases where sess$is_loaded was NULL | |
| # ie there was no model currently loading. | |
| m <- loading$model %>% | |
| promises::then( | |
| onFulfilled = function(x) { | |
| Sys.sleep(5) | |
| cat("Model has been loaded!", "\n") | |
| context$generating <- FALSE | |
| sess$is_loaded <- TRUE | |
| TRUE | |
| }, | |
| onRejected = function(x) { | |
| context$generating <- "error" | |
| msg <- list( | |
| role = "error", | |
| content = paste0("Error loading the model:\n", as.character(x)) | |
| ) | |
| context$messages <- append(context$messages, list(msg)) | |
| # setup for retry! | |
| sess$is_loaded <- NULL # means failure! | |
| sess$sess <- NULL | |
| if (loading$reload < 10) { | |
| Sys.sleep(5) | |
| loading$reload <- loading$reload + 1 | |
| } | |
| FALSE | |
| }) | |
| loading$model <- m | |
| }) | |
| # context for generating messages | |
| context <- reactiveValues( | |
| generating = "loading", # a flag indicating if we are still generating tokens | |
| idxs = NULL, # the current sequence of tokens | |
| n_tokens = 0, # number of tokens already generated | |
| messages = list() | |
| ) | |
| observeEvent(input$send, ignoreInit = TRUE, { | |
| # the is the observer for send message action button that triggers the rest | |
| # of the reactions. | |
| # if the prompt is empty, there's nothing to do | |
| if (is.null(input$prompt) || input$prompt == "") { | |
| return() | |
| } | |
| # the user clicked 'send' and the prompt is not empty: | |
| # we will enter in generation mode | |
| context$generating <- TRUE | |
| # we add the user message into the messages list | |
| context$messages <- append( | |
| context$messages, | |
| list(list(role = "user", content = input$prompt)) | |
| ) | |
| # ... and the start of the assistant message | |
| context$messages <- append( | |
| context$messages, | |
| list(list(role = "assistant", content = "")) | |
| ) | |
| # we also update the idxs context value with the newly added prompt | |
| # in case, this is the first send call, we also need to add the system | |
| # prompt | |
| if (is.null(context$idxs)) { | |
| context$idxs <- sess$tok$encode(system_prompt)$ids | |
| } | |
| # we now append the prompt. the prompt is wrapped around special tokens | |
| # for generation: | |
| prompt <- paste0("<|USER|>", input$prompt, "<|ASSISTANT|>") | |
| context$idxs <- c(context$idxs, sess$tok$encode(prompt)$ids) | |
| cat("Tokens in context: ", length(context$idxs), "\n") | |
| }) | |
| observeEvent(context$generating, priority = 10, { | |
| # this controls the state of the send button. | |
| # if generating is TRUE we want it to be disabled, otherwise it's enabled | |
| # if generating is `NULL`, then the model is not yet loaded | |
| # in the first startup we have to insert the send button directly, otherwise | |
| # it would exist after all observers ran, including the one that loads the | |
| # model | |
| if (context$generating == "loading") { | |
| btn <- list( | |
| class = "btn-secondary disabled", | |
| label = "Loading model ...", | |
| icon = icon("spinner", class="fa-spin") | |
| ) | |
| insertUI( | |
| "#sendButton", | |
| ui = ui_send(btn), | |
| immediate = TRUE | |
| ) | |
| msgs <- list(list( | |
| role = "info", | |
| content = "Model is loading. It might take some time." | |
| )) | |
| insertUI( | |
| "#messages", | |
| ui = ui_messages(msgs), | |
| immediate = TRUE | |
| ) | |
| return() | |
| } | |
| # now we can use the loop for everyone | |
| btn <- if (context$generating == "error") { | |
| list(class = "btn-secondary disabled", label = "Generating error ...") | |
| } else if (context$generating) { | |
| list(class = "btn-secondary disabled", label = "Generating response ...", | |
| icon = icon("spinner", class="fa-spin")) | |
| } else { | |
| list(class = "btn-primary", label = "Send") | |
| } | |
| output$sendButton <- renderUI({ | |
| actionButton("send", width = "100%", label = btn$label, class = btn$class, | |
| icon = btn$icon) | |
| }) | |
| }) | |
| observeEvent(context$messages, priority = 10, { | |
| # this observer generates and updates the messages list | |
| output$messages <- renderUI({ | |
| ui_messages(context$messages) | |
| }) | |
| }) | |
| observeEvent(context$idxs, { | |
| # this observer is responsible for actually generating text by calling the | |
| # model that is loaded in `sess`. it takes the context$idxs to generate new | |
| # text and updates it once it's done. It also appends the last message with | |
| # the newly generated token | |
| context$idxs %>% | |
| sess$generate() %>% | |
| promises::then( | |
| onFulfilled = function(id) { | |
| if (id %in% c(50278L, 50279L, 50277L, 1L, 0L)) { | |
| context$generating <- FALSE | |
| context$n_tokens <- 0 | |
| return() # special tokens that stop generation. | |
| } | |
| # update last message with the newly generated token | |
| messages <- context$messages | |
| new_msg <- paste0( | |
| messages[[length(messages)]]$content, | |
| sess$tok$decode(id) | |
| ) | |
| messages[[length(messages)]]$content <- new_msg | |
| context$messages <- messages | |
| # update the token counter | |
| context$n_tokens <- context$n_tokens + 1 | |
| if (context$n_tokens > max_n_tokens) { | |
| context$generating <- FALSE | |
| context$n_tokens <- 0 | |
| return() # we already generated enough tokens | |
| } | |
| context$idxs <- c(context$idxs, id) | |
| }, | |
| onRejected = function(x) { | |
| # if there was a generation error, we post a message in the message | |
| # list with a error role | |
| msg <- list( | |
| role = "error", | |
| content = paste0("Error generating token.", x) | |
| ) | |
| context$messages <- append(context$messages, list(msg)) | |
| # we also say that we are no longer generating, by setting another | |
| # value for the `generating` "flag" | |
| context$generating <- "error" | |
| } | |
| ) | |
| NULL | |
| }) | |
| } | |
| ui_messages <- function(messages) { | |
| emojis <- c(user = "🤗", assistant = "🤖", info = "📣", error = "😭") | |
| msg_cards <- messages %>% | |
| lapply(function(msg) { | |
| card(style="margin-bottom:5px;", card_body( | |
| p(paste0(emojis[msg$role], ": ", msg$content)) | |
| )) | |
| }) | |
| rlang::exec(card_body, !!!msg_cards, gap = 5, fillable = FALSE) | |
| } | |
| ui_send <- function(btn) { | |
| actionButton( | |
| "send", | |
| icon = btn$icon, | |
| width = "100%", | |
| label = btn$label, | |
| class = btn$class | |
| ) | |
| } | |
| shinyApp(ui, server) | |