Added option to spawn multiple sender processes

lib/db.js

@@ -2,5 +2,99 @@
 
 let config = require('config');
 let mysql = require('mysql');
+let redis = require('redis');
+let Lock = require('redfour');
 
 module.exports = mysql.createPool(config.mysql);
+if (config.redis.enabled) {
+
+    module.exports.redis = redis.createClient(config.redis);
+
+    let queueLock = new Lock({
+        redis: config.redis,
+        namespace: 'mailtrain:lock'
+    });
+
+    module.exports.getLock = (id, callback) => {
+        queueLock.waitAcquireLock(id, 60 * 1000 /* Lock expires after 60sec */ , 10 * 1000 /* Wait for lock for up to 10sec */ , (err, lock) => {
+            if (err) {
+                return callback(err);
+            }
+            if (!lock) {
+                return callback(null, false);
+            }
+            return callback(null, {
+                lock,
+                release(done) {
+                    queueLock.releaseLock(lock, done);
+                }
+            });
+        });
+    };
+
+    module.exports.clearCache = (key, callback) => {
+        module.exports.redis.del(key, err => callback(err));
+    };
+
+    module.exports.addToCache = (key, value, callback) => {
+        if (!value) {
+            return setImmediate(() => callback());
+        }
+        module.exports.redis.multi().
+        lpush('mailtrain:cache:' + key, JSON.stringify(value)).
+        expire('mailtrain:cache:' + key, 24 * 3600).
+        exec(err => callback(err));
+    };
+
+    module.exports.getFromCache = (key, callback) => {
+        module.exports.redis.rpop('mailtrain:cache:' + key, (err, value) => {
+            if (err) {
+                return callback(err);
+            }
+            try {
+                value = JSON.parse(value);
+            } catch (E) {
+                return callback(E);
+            }
+
+            return callback(null, value);
+        });
+    };
+
+} else {
+    // fakelock. does not lock anything
+    module.exports.getLock = (id, callback) => {
+        setImmediate(() => callback(null, {
+            lock: false,
+            release(done) {
+                setImmediate(done);
+            }
+        }));
+    };
+
+    let caches = new Map();
+
+    module.exports.clearCache = (key, callback) => {
+        caches.delete(key);
+        setImmediate(() => callback());
+    };
+
+    module.exports.addToCache = (key, value, callback) => {
+        if (!caches.has(key)) {
+            caches.set(key, []);
+        }
+        caches.get(key).push(value);
+        setImmediate(() => callback());
+    };
+
+    module.exports.getFromCache = (key, callback) => {
+        let value;
+        if (caches.has(key)) {
+            value = caches.get(key).shift();
+            if (!caches.get(key).length) {
+                caches.delete(key);
+            }
+        }
+        setImmediate(() => callback(null, value));
+    };
+}