Toy examples for plot caching in Shiny

cached_example.R

library(shiny)
library(dplyr)
library(ggplot2)
library(R6)
library(redux)

ui <- fluidPage(titlePanel("Plot Caching Test"),
                
                sidebarLayout(sidebarPanel(
                  selectInput("number", choices = seq(80000, 100000, by = 10000),
                              label = "Number of points", selected = 5000)
                ),
                mainPanel(plotOutput("point_plot"))))


server <- function(input, output) {
  
  data <- reactive({
    data.frame(x = rnorm(input$number),
               y = rnorm(input$number))
  })
  
  output$point_plot <- renderCachedPlot({
    ggplot(data(), aes(x, y)) +
      geom_point(alpha = 0.8) +
      labs(title = "Random scatterplot")
  },
  cacheKeyExpr = { list(input$number) }
  )
  
  
  # Set up redis cache object
  RedisCache <- R6Class(
    "RedisCache",
    public = list(
      initialize = function(..., namespace = NULL) {
        private$r <- redux::hiredis(host = '127.0.0.1', port = 6379)
        
        # Configure 20mb cache
        private$r$CONFIG_SET("maxmemory", "20mb")
        private$r$CONFIG_SET("maxmemory-policy", "allkeys-lru")
        private$namespace <- namespace
      },
      
      get = function(key) {
        key <- paste0(private$namespace, "-", key)
        s_value <- private$r$GET(key)
        if (is.null(s_value)) {
          return(key_missing())
        }
        unserialize(s_value)
      },
      
      set = function(key, value) {
        key <- paste0(private$namespace, "-", key)
        s_value <- serialize(value, NULL)
        private$r$SET(key, s_value)
      }
    ),
    private = list(r = NULL,
                   namespace = NULL)
  )
  
  shinyOptions(cache = RedisCache$new(namespace = "example_app"))
  
}

shinyApp(ui, server)

uncached_example.R

library(shiny)
library(dplyr)
library(ggplot2)

ui <- fluidPage(titlePanel("Plot Caching Test"),
                
                sidebarLayout(sidebarPanel(
                  selectInput("number", choices = seq(80000, 100000, by = 10000),
                              label = "Number of points", selected = 5000)
                ),
                mainPanel(plotOutput("point_plot"))))


server <- function(input, output) {
  
  data <- reactive({
    data.frame(x = rnorm(input$number),
               y = rnorm(input$number))
  })
  
  output$point_plot <- renderPlot({
    ggplot(data(), aes(x, y)) +
      geom_point(alpha = 0.2) +
      labs(title = "Random scatterplot")
  })
  
}

shinyApp(ui, server)