using cartodb-redis for rate limit

lib/cartodb/api/user_limits_api.js

@@ -1,8 +1,5 @@
 var step = require('step');
 
-
-const RATE_LIMIT_REDIS_DB = 8;
-
 /**
  *
  * @param metadataBackend
@@ -14,11 +11,6 @@ function UserLimitsApi(metadataBackend, options) {
     this.metadataBackend = metadataBackend;
     this.options = options || {};
     this.options.limits = this.options.limits || {};
-    this.rateLimits = {
-        redisCommand: 'EVAL',
-        sha: null,
-        lua: getRateLimitLuaScript()
-    };
 
     this.preprareRateLimit();
 }
@@ -89,139 +81,11 @@ UserLimitsApi.prototype.getTimeoutRenderLimit = function (username, apiKey, call
 };
 
 UserLimitsApi.prototype.preprareRateLimit = function () {
-    var self = this;
-
     if (this.options.limits.rateLimitsEnabled) {
-        this.metadataBackend.redisCmd(
-            RATE_LIMIT_REDIS_DB,
-            'SCRIPT',
-            ['LOAD', getRateLimitLuaScript()],
-            function (err, sha) {
-                if (!err && sha) {
-                    self.rateLimits.sha = sha;
-                    self.rateLimits.redisCommand = 'EVALSHA';
-                }
-            }
-        );
+        this.metadataBackend.loadRateLimitsScript();
     }
 };
 
 UserLimitsApi.prototype.getRateLimit = function (user, endpointGroup, callback) {
-    var self = this;
-
-    let redisParams = [
-        this.rateLimits.redisCommand === 'EVAL' ? this.rateLimits.lua : this.rateLimits.sha,
-        2,
-        getStoreKey(user, endpointGroup),   // KEY[1] 
-        getStatusKey(user, endpointGroup)   // KEY[2]
-    ];
-
-    this.metadataBackend.redisCmd(
-        RATE_LIMIT_REDIS_DB,
-        this.rateLimits.redisCommand,
-        redisParams,
-        function (err, rateLimits) {
-            if (err) {
-                if (err.name === 'ReplyError' && err.message === 'NOSCRIPT No matching script. Please use EVAL.') {
-                    self.rateLimits.redisCommand = 'EVAL';
-                    return self.getRateLimit(user, endpointGroup, callback);
-                } else {
-                    callback(err);
-                }
-            }
-
-            callback(null, getLowerRateLimit(rateLimits));
-        }
-    );
+    this.metadataBackend.getRateLimit(user, 'maps', endpointGroup, callback);
 };
-
-/**
- * Returns Redis key where the limits are saved by user and endpoint
- * The value is a Redis hash:
- *    maxBurst (b): Integer (as string)
- *    countPerPeriod (c): Integer (as string)
- *    period (p): Integer (as string)
- * @param {string} user 
- * @param {string} endpointGroup 
- */
-function getStoreKey(user, endpointGroup) {
-    return `limits:rate:store:${user}:maps:${endpointGroup}`;
-}
-
-/**
- * Returns Redis key where the current state of the limit by user and endpoint 
- * This key is managed by redis-cell (CL.THROTTLE command)
- * @param {string} user 
- * @param {string} endpointGroup 
- */
-function getStatusKey(user, endpointGroup) {
-    return `limits:rate:status:${user}:maps:${endpointGroup}`;
-}
-
-function getRateLimitLuaScript() {
-    return `
-        local results = {}
-        local resultsCounter = 0
-    
-        local limits = {}
-        local limitsArray = redis.call("LRANGE", KEYS[1], 0, -1)
-        
-        for i, v in ipairs(limitsArray) do
-            local rest = i % 3
-            if rest ~= 0 then
-                limits[rest] = v
-            else
-                resultsCounter = resultsCounter + 1
-                results[resultsCounter] = redis.call("CL.THROTTLE", KEYS[2], limits[1], limits[2], v)
-            end
-        end
-
-        return results
-    `;
-}
-
-/**
- * Returns the inner rateLimit what is the strictest one
- * @param {Array} rateLimits Each inner array has 5 integers indicating: 
- *      isBloqued, limit, remaining, retry, reset
- */
-function getLowerRateLimit(rateLimits) {
-    /*jshint maxcomplexity:10 */
-    if (!Array.isArray(rateLimits) || !rateLimits.length) {
-        return;
-    }
-
-    let minIndex;
-    let minRemainingValue;
-    for (let currentIndex = 0; currentIndex < rateLimits.length; currentIndex++) {
-        const rateLimit = rateLimits[currentIndex];
-        if (!validateRatelimit(rateLimit)) {
-            continue;
-        }
-
-        const [isBlocked, , remaining] = rateLimit;
-
-        if (isBlocked === 1) {
-            minIndex = currentIndex;
-            break;
-        }
-
-        if (minRemainingValue === undefined || remaining < minRemainingValue) {
-            minIndex = currentIndex;
-            minRemainingValue = remaining;
-        }
-    }
-
-    if (rateLimits[minIndex]) {
-        return rateLimits[minIndex];
-    } else {
-        return;
-    }
-}
-
-function validateRatelimit(rateLimit) {
-    return rateLimit.length === 5;
-}
-
-module.exports.getStoreKey = getStoreKey;
-module.exports.getLowerRateLimit = getLowerRateLimit;