diff --git a/R/cache.R b/R/cache.R
index ab32d7a7a..e9c1216c2 100644
--- a/R/cache.R
+++ b/R/cache.R
@@ -95,6 +95,8 @@ DiskCache <- R6Class("DiskCache",
       private$prune_ <- list(prune)
     },
 
+    # TODO: Should call has() and return some sentinal object if not present
+    # Should be atomic ot avoid race conditions.
     get = function(key) {
       if (!self$has(key)) {
         stop("Key not available: ", key)
@@ -104,6 +106,12 @@ DiskCache <- R6Class("DiskCache",
       value
     },
 
+    mget = function(keys) {
+    },
+
+    mset = function(..., .list = NULL) {
+    },
+
     set = function(key, value) {
       # TODO: Make sure key is a safe string
       self$prune()
@@ -115,6 +123,11 @@ DiskCache <- R6Class("DiskCache",
       file.exists(private$key_to_filename(key))
     },
 
+    # Return all keys in the cache
+    keys = function() {
+
+    },
+
     remove = function(key) {
       file.remove(private$key_to_filename(key))
       invisible(self)
@@ -130,6 +143,14 @@ DiskCache <- R6Class("DiskCache",
       invisible(self)
     },
 
+    size = function() {
+    },
+
+    # Resets the cache and destroys the containing folder so that no
+    # one else who shares the data back end can use it anymore.
+    destroy = function() {
+    },
+
     finalize = function() {
       if (private$reset_on_finalize) {
         self$reset()
@@ -154,6 +175,13 @@ DiskCache <- R6Class("DiskCache",
   )
 )
 
+# Safely hash an object. If it has any weird things in it that might change, like
+# functions or xptrs (?), throw an error.
+safe_hash <- function(x) {
+
+}
+
+
 disk_pruner <- function(max_size = 5 * 1024^2, max_age = Inf,
                         discard = c("oldest", "newest"),
                         timetype = c("ctime", "atime", "mtime"))
diff --git a/R/render-cached-plot.R b/R/render-cached-plot.R
index 29f5b0d7d..89d9fb14b 100644
--- a/R/render-cached-plot.R
+++ b/R/render-cached-plot.R
@@ -220,14 +220,17 @@ renderCachedPlot <- function(expr, cacheKeyExpr,
       return()
 
     } else if (identical(cache, "app")) {
+      getShinyOption("appCacheFun")()
       cacheDir <- file.path(tempdir(),
-        paste0("shinyapp-", getShinyOption("appToken"), "-", outputName)
+        paste0("shinyapp-", getShinyOption("appToken"))
       )
       cache <<- DiskCache$new(cacheDir, prune = disk_pruner(max_size = 5*1024^2), reset_on_finalize = FALSE)
 
     } else if (identical(cache, "session")) {
+      session$getCache()
+
       cacheDir <- file.path(tempdir(),
-        paste0("shinyapp-", getShinyOption("appToken"), "-", session$token, "-", outputName)
+        paste0("shinyapp-", getShinyOption("appToken"), "-", session$token)
       )
       cache <<- DiskCache$new(cacheDir, prune = disk_pruner(max_size = 5*1024^2), reset_on_finalize = TRUE)