storagemanager: When map store isn't available, fallback to keyval store [backported...

diff --git a/core/storagemanager.lua b/core/storagemanager.lua
index c312cf057bcd8bc3390f2193d13d85f7a1fe157c..39eae120eb4fd4c86f7b88b38917243e16470d6e 100644 (file)
--- a/core/storagemanager.lua
+++ b/core/storagemanager.lua
@@ -99,11 +99,47 @@ local function get_driver(host, store)
        return driver, driver_name;
 end
 
-local function open(host, store, typ)
+local map_shim_mt = {
+       __index = {
+               get = function(self, username, key)
+                       local ret, err = self.keyval_store:get(username);
+                       if ret == nil and err then return nil, err end
+                       return ret[key];
+               end;
+               set = function(self, username, key, data)
+                       local current, err = self.keyval_store:get(username);
+                       if current == nil then
+                               if err then
+                                       return nil, err;
+                               else
+                                       current = {};
+                               end
+                       end
+                       current[key] = data;
+                       return self.keyval_store:set(username, current);
+               end;
+       };
+}
+
+local open;
+
+local function create_map_shim(host, store)
+       local keyval_store, err = open(host, store, "keyval");
+       if keyval_store == nil then return nil, err end
+       return setmetatable({
+               keyval_store = keyval_store;
+       }, map_shim_mt);
+end
+
+function open(host, store, typ)
        local driver, driver_name = get_driver(host, store);
        local ret, err = driver:open(store, typ);
        if not ret then
                if err == "unsupported-store" then
+                       if typ == "map" then -- Use shim on top of keyval store
+                               log("debug", "map storage driver unavailable, using shim on top of keyval store.");
+                               return create_map_shim(host, store);
+                       end
                        log("debug", "Storage driver %s does not support store %s (%s), falling back to null driver",
                                driver_name, store, typ or "<nil>");
                        ret = null_storage_driver;