Update:Remove proper-lockfile dependency

package-lock.json

@@ -24,7 +24,6 @@
         "libgen": "^2.1.0",
         "node-ffprobe": "^3.0.0",
         "node-stream-zip": "^1.15.0",
-        "proper-lockfile": "^4.1.2",
         "recursive-readdir-async": "^1.1.8",
         "socket.io": "^4.4.1",
         "xml2js": "^0.4.23"
@@ -1488,16 +1487,6 @@
       "resolved": "https://registry.npmjs.org/process-nextick-args/-/process-nextick-args-2.0.1.tgz",
       "integrity": "sha512-3ouUOpQhtgrbOa17J7+uxOTpITYWaGP7/AhoR3+A+/1e9skrzelGi/dXzEYyvbxubEF6Wn2ypscTKiKJFFn1ag=="
     },
-    "node_modules/proper-lockfile": {
-      "version": "4.1.2",
-      "resolved": "https://registry.npmjs.org/proper-lockfile/-/proper-lockfile-4.1.2.tgz",
-      "integrity": "sha512-TjNPblN4BwAWMXU8s9AEz4JmQxnD1NNL7bNOY/AKUzyamc379FWASUhc/K1pL2noVb+XmZKLL68cjzLsiOAMaA==",
-      "dependencies": {
-        "graceful-fs": "^4.2.4",
-        "retry": "^0.12.0",
-        "signal-exit": "^3.0.2"
-      }
-    },
     "node_modules/proxy-addr": {
       "version": "2.0.7",
       "resolved": "https://registry.npmjs.org/proxy-addr/-/proxy-addr-2.0.7.tgz",
@@ -1608,14 +1597,6 @@
         "lowercase-keys": "^2.0.0"
       }
     },
-    "node_modules/retry": {
-      "version": "0.12.0",
-      "resolved": "https://registry.npmjs.org/retry/-/retry-0.12.0.tgz",
-      "integrity": "sha512-9LkiTwjUh6rT555DtE9rTX+BKByPfrMzEAtnlEtdEwr3Nkffwiihqe2bWADg+OQRjt9gl6ICdmB/ZFDCGAtSow==",
-      "engines": {
-        "node": ">= 4"
-      }
-    },
     "node_modules/safe-buffer": {
       "version": "5.2.1",
       "resolved": "https://registry.npmjs.org/safe-buffer/-/safe-buffer-5.2.1.tgz",
@@ -1713,11 +1694,6 @@
         "url": "https://github.com/sponsors/ljharb"
       }
     },
-    "node_modules/signal-exit": {
-      "version": "3.0.7",
-      "resolved": "https://registry.npmjs.org/signal-exit/-/signal-exit-3.0.7.tgz",
-      "integrity": "sha512-wnD2ZE+l+SPC/uoS0vXeE9L1+0wuaMqKlfz9AMUo38JsyLSBWSFcHR1Rri62LZc12vLr1gb3jl7iwQhgwpAbGQ=="
-    },
     "node_modules/socket.io": {
       "version": "4.5.1",
       "resolved": "https://registry.npmjs.org/socket.io/-/socket.io-4.5.1.tgz",
@@ -3084,16 +3060,6 @@
       "resolved": "https://registry.npmjs.org/process-nextick-args/-/process-nextick-args-2.0.1.tgz",
       "integrity": "sha512-3ouUOpQhtgrbOa17J7+uxOTpITYWaGP7/AhoR3+A+/1e9skrzelGi/dXzEYyvbxubEF6Wn2ypscTKiKJFFn1ag=="
     },
-    "proper-lockfile": {
-      "version": "4.1.2",
-      "resolved": "https://registry.npmjs.org/proper-lockfile/-/proper-lockfile-4.1.2.tgz",
-      "integrity": "sha512-TjNPblN4BwAWMXU8s9AEz4JmQxnD1NNL7bNOY/AKUzyamc379FWASUhc/K1pL2noVb+XmZKLL68cjzLsiOAMaA==",
-      "requires": {
-        "graceful-fs": "^4.2.4",
-        "retry": "^0.12.0",
-        "signal-exit": "^3.0.2"
-      }
-    },
     "proxy-addr": {
       "version": "2.0.7",
       "resolved": "https://registry.npmjs.org/proxy-addr/-/proxy-addr-2.0.7.tgz",
@@ -3177,11 +3143,6 @@
         "lowercase-keys": "^2.0.0"
       }
     },
-    "retry": {
-      "version": "0.12.0",
-      "resolved": "https://registry.npmjs.org/retry/-/retry-0.12.0.tgz",
-      "integrity": "sha512-9LkiTwjUh6rT555DtE9rTX+BKByPfrMzEAtnlEtdEwr3Nkffwiihqe2bWADg+OQRjt9gl6ICdmB/ZFDCGAtSow=="
-    },
     "safe-buffer": {
       "version": "5.2.1",
       "resolved": "https://registry.npmjs.org/safe-buffer/-/safe-buffer-5.2.1.tgz",
@@ -3255,11 +3216,6 @@
         "object-inspect": "^1.9.0"
       }
     },
-    "signal-exit": {
-      "version": "3.0.7",
-      "resolved": "https://registry.npmjs.org/signal-exit/-/signal-exit-3.0.7.tgz",
-      "integrity": "sha512-wnD2ZE+l+SPC/uoS0vXeE9L1+0wuaMqKlfz9AMUo38JsyLSBWSFcHR1Rri62LZc12vLr1gb3jl7iwQhgwpAbGQ=="
-    },
     "socket.io": {
       "version": "4.5.1",
       "resolved": "https://registry.npmjs.org/socket.io/-/socket.io-4.5.1.tgz",

package.json

@@ -43,7 +43,6 @@
     "libgen": "^2.1.0",
     "node-ffprobe": "^3.0.0",
     "node-stream-zip": "^1.15.0",
-    "proper-lockfile": "^4.1.2",
     "recursive-readdir-async": "^1.1.8",
     "socket.io": "^4.4.1",
     "xml2js": "^0.4.23"

server/Db.js

@@ -1,6 +1,5 @@
 const Path = require('path')
-const njodb = require('./njodb')
-const jwt = require('jsonwebtoken')
+const njodb = require('./libs/njodb')
 const Logger = require('./Logger')
 const { version } = require('../package.json')
 const LibraryItem = require('./objects/LibraryItem')

server/libs/njodb/njodb.js

@@ -27,7 +27,7 @@ const {
     checkSync,
     lock,
     lockSync
-} = require("proper-lockfile");
+} = require("../properLockfile");
 
 const {
     deleteFile,

server/libs/properLockfile/index.js

@@ -0,0 +1,40 @@
+'use strict';
+
+const lockfile = require('./lib/lockfile');
+const { toPromise, toSync, toSyncOptions } = require('./lib/adapter');
+
+async function lock(file, options) {
+  const release = await toPromise(lockfile.lock)(file, options);
+
+  return toPromise(release);
+}
+
+function lockSync(file, options) {
+  const release = toSync(lockfile.lock)(file, toSyncOptions(options));
+
+  return toSync(release);
+}
+
+function unlock(file, options) {
+  return toPromise(lockfile.unlock)(file, options);
+}
+
+function unlockSync(file, options) {
+  return toSync(lockfile.unlock)(file, toSyncOptions(options));
+}
+
+function check(file, options) {
+  return toPromise(lockfile.check)(file, options);
+}
+
+function checkSync(file, options) {
+  return toSync(lockfile.check)(file, toSyncOptions(options));
+}
+
+module.exports = lock;
+module.exports.lock = lock;
+module.exports.unlock = unlock;
+module.exports.lockSync = lockSync;
+module.exports.unlockSync = unlockSync;
+module.exports.check = check;
+module.exports.checkSync = checkSync;

server/libs/properLockfile/lib/adapter.js

@@ -0,0 +1,85 @@
+'use strict';
+
+const fs = require('graceful-fs');
+
+function createSyncFs(fs) {
+    const methods = ['mkdir', 'realpath', 'stat', 'rmdir', 'utimes'];
+    const newFs = { ...fs };
+
+    methods.forEach((method) => {
+        newFs[method] = (...args) => {
+            const callback = args.pop();
+            let ret;
+
+            try {
+                ret = fs[`${method}Sync`](...args);
+            } catch (err) {
+                return callback(err);
+            }
+
+            callback(null, ret);
+        };
+    });
+
+    return newFs;
+}
+
+// ----------------------------------------------------------
+
+function toPromise(method) {
+    return (...args) => new Promise((resolve, reject) => {
+        args.push((err, result) => {
+            if (err) {
+                reject(err);
+            } else {
+                resolve(result);
+            }
+        });
+
+        method(...args);
+    });
+}
+
+function toSync(method) {
+    return (...args) => {
+        let err;
+        let result;
+
+        args.push((_err, _result) => {
+            err = _err;
+            result = _result;
+        });
+
+        method(...args);
+
+        if (err) {
+            throw err;
+        }
+
+        return result;
+    };
+}
+
+function toSyncOptions(options) {
+    // Shallow clone options because we are oging to mutate them
+    options = { ...options };
+
+    // Transform fs to use the sync methods instead
+    options.fs = createSyncFs(options.fs || fs);
+
+    // Retries are not allowed because it requires the flow to be sync
+    if (
+        (typeof options.retries === 'number' && options.retries > 0) ||
+        (options.retries && typeof options.retries.retries === 'number' && options.retries.retries > 0)
+    ) {
+        throw Object.assign(new Error('Cannot use retries with the sync api'), { code: 'ESYNC' });
+    }
+
+    return options;
+}
+
+module.exports = {
+    toPromise,
+    toSync,
+    toSyncOptions,
+};

server/libs/properLockfile/lib/lockfile.js

@@ -0,0 +1,342 @@
+'use strict';
+
+const path = require('path');
+const fs = require('graceful-fs');
+const retry = require('../../retry');
+const onExit = require('../../signalExit');
+const mtimePrecision = require('./mtime-precision');
+
+const locks = {};
+
+function getLockFile(file, options) {
+    return options.lockfilePath || `${file}.lock`;
+}
+
+function resolveCanonicalPath(file, options, callback) {
+    if (!options.realpath) {
+        return callback(null, path.resolve(file));
+    }
+
+    // Use realpath to resolve symlinks
+    // It also resolves relative paths
+    options.fs.realpath(file, callback);
+}
+
+function acquireLock(file, options, callback) {
+    const lockfilePath = getLockFile(file, options);
+
+    // Use mkdir to create the lockfile (atomic operation)
+    options.fs.mkdir(lockfilePath, (err) => {
+        if (!err) {
+            // At this point, we acquired the lock!
+            // Probe the mtime precision
+            return mtimePrecision.probe(lockfilePath, options.fs, (err, mtime, mtimePrecision) => {
+                // If it failed, try to remove the lock..
+                /* istanbul ignore if */
+                if (err) {
+                    options.fs.rmdir(lockfilePath, () => { });
+
+                    return callback(err);
+                }
+
+                callback(null, mtime, mtimePrecision);
+            });
+        }
+
+        // If error is not EEXIST then some other error occurred while locking
+        if (err.code !== 'EEXIST') {
+            return callback(err);
+        }
+
+        // Otherwise, check if lock is stale by analyzing the file mtime
+        if (options.stale <= 0) {
+            return callback(Object.assign(new Error('Lock file is already being held'), { code: 'ELOCKED', file }));
+        }
+
+        options.fs.stat(lockfilePath, (err, stat) => {
+            if (err) {
+                // Retry if the lockfile has been removed (meanwhile)
+                // Skip stale check to avoid recursiveness
+                if (err.code === 'ENOENT') {
+                    return acquireLock(file, { ...options, stale: 0 }, callback);
+                }
+
+                return callback(err);
+            }
+
+            if (!isLockStale(stat, options)) {
+                return callback(Object.assign(new Error('Lock file is already being held'), { code: 'ELOCKED', file }));
+            }
+
+            // If it's stale, remove it and try again!
+            // Skip stale check to avoid recursiveness
+            removeLock(file, options, (err) => {
+                if (err) {
+                    return callback(err);
+                }
+
+                acquireLock(file, { ...options, stale: 0 }, callback);
+            });
+        });
+    });
+}
+
+function isLockStale(stat, options) {
+    return stat.mtime.getTime() < Date.now() - options.stale;
+}
+
+function removeLock(file, options, callback) {
+    // Remove lockfile, ignoring ENOENT errors
+    options.fs.rmdir(getLockFile(file, options), (err) => {
+        if (err && err.code !== 'ENOENT') {
+            return callback(err);
+        }
+
+        callback();
+    });
+}
+
+function updateLock(file, options) {
+    const lock = locks[file];
+
+    // Just for safety, should never happen
+    /* istanbul ignore if */
+    if (lock.updateTimeout) {
+        return;
+    }
+
+    lock.updateDelay = lock.updateDelay || options.update;
+    lock.updateTimeout = setTimeout(() => {
+        lock.updateTimeout = null;
+
+        // Stat the file to check if mtime is still ours
+        // If it is, we can still recover from a system sleep or a busy event loop
+        options.fs.stat(lock.lockfilePath, (err, stat) => {
+            const isOverThreshold = lock.lastUpdate + options.stale < Date.now();
+
+            // If it failed to update the lockfile, keep trying unless
+            // the lockfile was deleted or we are over the threshold
+            if (err) {
+                if (err.code === 'ENOENT' || isOverThreshold) {
+                    return setLockAsCompromised(file, lock, Object.assign(err, { code: 'ECOMPROMISED' }));
+                }
+
+                lock.updateDelay = 1000;
+
+                return updateLock(file, options);
+            }
+
+            const isMtimeOurs = lock.mtime.getTime() === stat.mtime.getTime();
+
+            if (!isMtimeOurs) {
+                return setLockAsCompromised(
+                    file,
+                    lock,
+                    Object.assign(
+                        new Error('Unable to update lock within the stale threshold'),
+                        { code: 'ECOMPROMISED' }
+                    ));
+            }
+
+            const mtime = mtimePrecision.getMtime(lock.mtimePrecision);
+
+            options.fs.utimes(lock.lockfilePath, mtime, mtime, (err) => {
+                const isOverThreshold = lock.lastUpdate + options.stale < Date.now();
+
+                // Ignore if the lock was released
+                if (lock.released) {
+                    return;
+                }
+
+                // If it failed to update the lockfile, keep trying unless
+                // the lockfile was deleted or we are over the threshold
+                if (err) {
+                    if (err.code === 'ENOENT' || isOverThreshold) {
+                        return setLockAsCompromised(file, lock, Object.assign(err, { code: 'ECOMPROMISED' }));
+                    }
+
+                    lock.updateDelay = 1000;
+
+                    return updateLock(file, options);
+                }
+
+                // All ok, keep updating..
+                lock.mtime = mtime;
+                lock.lastUpdate = Date.now();
+                lock.updateDelay = null;
+                updateLock(file, options);
+            });
+        });
+    }, lock.updateDelay);
+
+    // Unref the timer so that the nodejs process can exit freely
+    // This is safe because all acquired locks will be automatically released
+    // on process exit
+
+    // We first check that `lock.updateTimeout.unref` exists because some users
+    // may be using this module outside of NodeJS (e.g., in an electron app),
+    // and in those cases `setTimeout` return an integer.
+    /* istanbul ignore else */
+    if (lock.updateTimeout.unref) {
+        lock.updateTimeout.unref();
+    }
+}
+
+function setLockAsCompromised(file, lock, err) {
+    // Signal the lock has been released
+    lock.released = true;
+
+    // Cancel lock mtime update
+    // Just for safety, at this point updateTimeout should be null
+    /* istanbul ignore if */
+    if (lock.updateTimeout) {
+        clearTimeout(lock.updateTimeout);
+    }
+
+    if (locks[file] === lock) {
+        delete locks[file];
+    }
+
+    lock.options.onCompromised(err);
+}
+
+// ----------------------------------------------------------
+
+function lock(file, options, callback) {
+    /* istanbul ignore next */
+    options = {
+        stale: 10000,
+        update: null,
+        realpath: true,
+        retries: 0,
+        fs,
+        onCompromised: (err) => { throw err; },
+        ...options,
+    };
+
+    options.retries = options.retries || 0;
+    options.retries = typeof options.retries === 'number' ? { retries: options.retries } : options.retries;
+    options.stale = Math.max(options.stale || 0, 2000);
+    options.update = options.update == null ? options.stale / 2 : options.update || 0;
+    options.update = Math.max(Math.min(options.update, options.stale / 2), 1000);
+
+    // Resolve to a canonical file path
+    resolveCanonicalPath(file, options, (err, file) => {
+        if (err) {
+            return callback(err);
+        }
+
+        // Attempt to acquire the lock
+        const operation = retry.operation(options.retries);
+
+        operation.attempt(() => {
+            acquireLock(file, options, (err, mtime, mtimePrecision) => {
+                if (operation.retry(err)) {
+                    return;
+                }
+
+                if (err) {
+                    return callback(operation.mainError());
+                }
+
+                // We now own the lock
+                const lock = locks[file] = {
+                    lockfilePath: getLockFile(file, options),
+                    mtime,
+                    mtimePrecision,
+                    options,
+                    lastUpdate: Date.now(),
+                };
+
+                // We must keep the lock fresh to avoid staleness
+                updateLock(file, options);
+
+                callback(null, (releasedCallback) => {
+                    if (lock.released) {
+                        return releasedCallback &&
+                            releasedCallback(Object.assign(new Error('Lock is already released'), { code: 'ERELEASED' }));
+                    }
+
+                    // Not necessary to use realpath twice when unlocking
+                    unlock(file, { ...options, realpath: false }, releasedCallback);
+                });
+            });
+        });
+    });
+}
+
+function unlock(file, options, callback) {
+    options = {
+        fs,
+        realpath: true,
+        ...options,
+    };
+
+    // Resolve to a canonical file path
+    resolveCanonicalPath(file, options, (err, file) => {
+        if (err) {
+            return callback(err);
+        }
+
+        // Skip if the lock is not acquired
+        const lock = locks[file];
+
+        if (!lock) {
+            return callback(Object.assign(new Error('Lock is not acquired/owned by you'), { code: 'ENOTACQUIRED' }));
+        }
+
+        lock.updateTimeout && clearTimeout(lock.updateTimeout); // Cancel lock mtime update
+        lock.released = true; // Signal the lock has been released
+        delete locks[file]; // Delete from locks
+
+        removeLock(file, options, callback);
+    });
+}
+
+function check(file, options, callback) {
+    options = {
+        stale: 10000,
+        realpath: true,
+        fs,
+        ...options,
+    };
+
+    options.stale = Math.max(options.stale || 0, 2000);
+
+    // Resolve to a canonical file path
+    resolveCanonicalPath(file, options, (err, file) => {
+        if (err) {
+            return callback(err);
+        }
+
+        // Check if lockfile exists
+        options.fs.stat(getLockFile(file, options), (err, stat) => {
+            if (err) {
+                // If does not exist, file is not locked. Otherwise, callback with error
+                return err.code === 'ENOENT' ? callback(null, false) : callback(err);
+            }
+
+            // Otherwise, check if lock is stale by analyzing the file mtime
+            return callback(null, !isLockStale(stat, options));
+        });
+    });
+}
+
+function getLocks() {
+    return locks;
+}
+
+// Remove acquired locks on exit
+/* istanbul ignore next */
+onExit(() => {
+    for (const file in locks) {
+        const options = locks[file].options;
+
+        try { options.fs.rmdirSync(getLockFile(file, options)); } catch (e) { /* Empty */ }
+    }
+});
+
+module.exports.lock = lock;
+module.exports.unlock = unlock;
+module.exports.check = check;
+module.exports.getLocks = getLocks;

server/libs/properLockfile/lib/mtime-precision.js

@@ -0,0 +1,55 @@
+'use strict';
+
+const cacheSymbol = Symbol();
+
+function probe(file, fs, callback) {
+    const cachedPrecision = fs[cacheSymbol];
+
+    if (cachedPrecision) {
+        return fs.stat(file, (err, stat) => {
+            /* istanbul ignore if */
+            if (err) {
+                return callback(err);
+            }
+
+            callback(null, stat.mtime, cachedPrecision);
+        });
+    }
+
+    // Set mtime by ceiling Date.now() to seconds + 5ms so that it's "not on the second"
+    const mtime = new Date((Math.ceil(Date.now() / 1000) * 1000) + 5);
+
+    fs.utimes(file, mtime, mtime, (err) => {
+        /* istanbul ignore if */
+        if (err) {
+            return callback(err);
+        }
+
+        fs.stat(file, (err, stat) => {
+            /* istanbul ignore if */
+            if (err) {
+                return callback(err);
+            }
+
+            const precision = stat.mtime.getTime() % 1000 === 0 ? 's' : 'ms';
+
+            // Cache the precision in a non-enumerable way
+            Object.defineProperty(fs, cacheSymbol, { value: precision });
+
+            callback(null, stat.mtime, precision);
+        });
+    });
+}
+
+function getMtime(precision) {
+    let now = Date.now();
+
+    if (precision === 's') {
+        now = Math.ceil(now / 1000) * 1000;
+    }
+
+    return new Date(now);
+}
+
+module.exports.probe = probe;
+module.exports.getMtime = getMtime;

server/libs/retry/index.js

@@ -0,0 +1,100 @@
+var RetryOperation = require('./retry_operation');
+
+exports.operation = function(options) {
+  var timeouts = exports.timeouts(options);
+  return new RetryOperation(timeouts, {
+      forever: options && options.forever,
+      unref: options && options.unref,
+      maxRetryTime: options && options.maxRetryTime
+  });
+};
+
+exports.timeouts = function(options) {
+  if (options instanceof Array) {
+    return [].concat(options);
+  }
+
+  var opts = {
+    retries: 10,
+    factor: 2,
+    minTimeout: 1 * 1000,
+    maxTimeout: Infinity,
+    randomize: false
+  };
+  for (var key in options) {
+    opts[key] = options[key];
+  }
+
+  if (opts.minTimeout > opts.maxTimeout) {
+    throw new Error('minTimeout is greater than maxTimeout');
+  }
+
+  var timeouts = [];
+  for (var i = 0; i < opts.retries; i++) {
+    timeouts.push(this.createTimeout(i, opts));
+  }
+
+  if (options && options.forever && !timeouts.length) {
+    timeouts.push(this.createTimeout(i, opts));
+  }
+
+  // sort the array numerically ascending
+  timeouts.sort(function(a,b) {
+    return a - b;
+  });
+
+  return timeouts;
+};
+
+exports.createTimeout = function(attempt, opts) {
+  var random = (opts.randomize)
+    ? (Math.random() + 1)
+    : 1;
+
+  var timeout = Math.round(random * opts.minTimeout * Math.pow(opts.factor, attempt));
+  timeout = Math.min(timeout, opts.maxTimeout);
+
+  return timeout;
+};
+
+exports.wrap = function(obj, options, methods) {
+  if (options instanceof Array) {
+    methods = options;
+    options = null;
+  }
+
+  if (!methods) {
+    methods = [];
+    for (var key in obj) {
+      if (typeof obj[key] === 'function') {
+        methods.push(key);
+      }
+    }
+  }
+
+  for (var i = 0; i < methods.length; i++) {
+    var method   = methods[i];
+    var original = obj[method];
+
+    obj[method] = function retryWrapper(original) {
+      var op       = exports.operation(options);
+      var args     = Array.prototype.slice.call(arguments, 1);
+      var callback = args.pop();
+
+      args.push(function(err) {
+        if (op.retry(err)) {
+          return;
+        }
+        if (err) {
+          arguments[0] = op.mainError();
+        }
+        callback.apply(this, arguments);
+      });
+
+      op.attempt(function() {
+        original.apply(obj, args);
+      });
+    }.bind(obj, original);
+    obj[method].options = options;
+  }
+};

server/libs/retry/retry_operation.js

@@ -0,0 +1,158 @@
+function RetryOperation(timeouts, options) {
+  // Compatibility for the old (timeouts, retryForever) signature
+  if (typeof options === 'boolean') {
+    options = { forever: options };
+  }
+
+  this._originalTimeouts = JSON.parse(JSON.stringify(timeouts));
+  this._timeouts = timeouts;
+  this._options = options || {};
+  this._maxRetryTime = options && options.maxRetryTime || Infinity;
+  this._fn = null;
+  this._errors = [];
+  this._attempts = 1;
+  this._operationTimeout = null;
+  this._operationTimeoutCb = null;
+  this._timeout = null;
+  this._operationStart = null;
+
+  if (this._options.forever) {
+    this._cachedTimeouts = this._timeouts.slice(0);
+  }
+}
+module.exports = RetryOperation;
+
+RetryOperation.prototype.reset = function() {
+  this._attempts = 1;
+  this._timeouts = this._originalTimeouts;
+}
+
+RetryOperation.prototype.stop = function() {
+  if (this._timeout) {
+    clearTimeout(this._timeout);
+  }
+
+  this._timeouts       = [];
+  this._cachedTimeouts = null;
+};
+
+RetryOperation.prototype.retry = function(err) {
+  if (this._timeout) {
+    clearTimeout(this._timeout);
+  }
+
+  if (!err) {
+    return false;
+  }
+  var currentTime = new Date().getTime();
+  if (err && currentTime - this._operationStart >= this._maxRetryTime) {
+    this._errors.unshift(new Error('RetryOperation timeout occurred'));
+    return false;
+  }
+
+  this._errors.push(err);
+
+  var timeout = this._timeouts.shift();
+  if (timeout === undefined) {
+    if (this._cachedTimeouts) {
+      // retry forever, only keep last error
+      this._errors.splice(this._errors.length - 1, this._errors.length);
+      this._timeouts = this._cachedTimeouts.slice(0);
+      timeout = this._timeouts.shift();
+    } else {
+      return false;
+    }
+  }
+
+  var self = this;
+  var timer = setTimeout(function() {
+    self._attempts++;
+
+    if (self._operationTimeoutCb) {
+      self._timeout = setTimeout(function() {
+        self._operationTimeoutCb(self._attempts);
+      }, self._operationTimeout);
+
+      if (self._options.unref) {
+          self._timeout.unref();
+      }
+    }
+
+    self._fn(self._attempts);
+  }, timeout);
+
+  if (this._options.unref) {
+      timer.unref();
+  }
+
+  return true;
+};
+
+RetryOperation.prototype.attempt = function(fn, timeoutOps) {
+  this._fn = fn;
+
+  if (timeoutOps) {
+    if (timeoutOps.timeout) {
+      this._operationTimeout = timeoutOps.timeout;
+    }
+    if (timeoutOps.cb) {
+      this._operationTimeoutCb = timeoutOps.cb;
+    }
+  }
+
+  var self = this;
+  if (this._operationTimeoutCb) {
+    this._timeout = setTimeout(function() {
+      self._operationTimeoutCb();
+    }, self._operationTimeout);
+  }
+
+  this._operationStart = new Date().getTime();
+
+  this._fn(this._attempts);
+};
+
+RetryOperation.prototype.try = function(fn) {
+  console.log('Using RetryOperation.try() is deprecated');
+  this.attempt(fn);
+};
+
+RetryOperation.prototype.start = function(fn) {
+  console.log('Using RetryOperation.start() is deprecated');
+  this.attempt(fn);
+};
+
+RetryOperation.prototype.start = RetryOperation.prototype.try;
+
+RetryOperation.prototype.errors = function() {
+  return this._errors;
+};
+
+RetryOperation.prototype.attempts = function() {
+  return this._attempts;
+};
+
+RetryOperation.prototype.mainError = function() {
+  if (this._errors.length === 0) {
+    return null;
+  }
+
+  var counts = {};
+  var mainError = null;
+  var mainErrorCount = 0;
+
+  for (var i = 0; i < this._errors.length; i++) {
+    var error = this._errors[i];
+    var message = error.message;
+    var count = (counts[message] || 0) + 1;
+
+    counts[message] = count;
+
+    if (count >= mainErrorCount) {
+      mainError = error;
+      mainErrorCount = count;
+    }
+  }
+
+  return mainError;
+};

server/libs/signalExit/index.js

@@ -0,0 +1,202 @@
+// Note: since nyc uses this module to output coverage, any lines
+// that are in the direct sync flow of nyc's outputCoverage are
+// ignored, since we can never get coverage for them.
+// grab a reference to node's real process object right away
+var process = global.process
+
+const processOk = function (process) {
+  return process &&
+    typeof process === 'object' &&
+    typeof process.removeListener === 'function' &&
+    typeof process.emit === 'function' &&
+    typeof process.reallyExit === 'function' &&
+    typeof process.listeners === 'function' &&
+    typeof process.kill === 'function' &&
+    typeof process.pid === 'number' &&
+    typeof process.on === 'function'
+}
+
+// some kind of non-node environment, just no-op
+/* istanbul ignore if */
+if (!processOk(process)) {
+  module.exports = function () {
+    return function () {}
+  }
+} else {
+  var assert = require('assert')
+  var signals = require('./signals.js')
+  var isWin = /^win/i.test(process.platform)
+
+  var EE = require('events')
+  /* istanbul ignore if */
+  if (typeof EE !== 'function') {
+    EE = EE.EventEmitter
+  }
+
+  var emitter
+  if (process.__signal_exit_emitter__) {
+    emitter = process.__signal_exit_emitter__
+  } else {
+    emitter = process.__signal_exit_emitter__ = new EE()
+    emitter.count = 0
+    emitter.emitted = {}
+  }
+
+  // Because this emitter is a global, we have to check to see if a
+  // previous version of this library failed to enable infinite listeners.
+  // I know what you're about to say.  But literally everything about
+  // signal-exit is a compromise with evil.  Get used to it.
+  if (!emitter.infinite) {
+    emitter.setMaxListeners(Infinity)
+    emitter.infinite = true
+  }
+
+  module.exports = function (cb, opts) {
+    /* istanbul ignore if */
+    if (!processOk(global.process)) {
+      return function () {}
+    }
+    assert.equal(typeof cb, 'function', 'a callback must be provided for exit handler')
+
+    if (loaded === false) {
+      load()
+    }
+
+    var ev = 'exit'
+    if (opts && opts.alwaysLast) {
+      ev = 'afterexit'
+    }
+
+    var remove = function () {
+      emitter.removeListener(ev, cb)
+      if (emitter.listeners('exit').length === 0 &&
+          emitter.listeners('afterexit').length === 0) {
+        unload()
+      }
+    }
+    emitter.on(ev, cb)
+
+    return remove
+  }
+
+  var unload = function unload () {
+    if (!loaded || !processOk(global.process)) {
+      return
+    }
+    loaded = false
+
+    signals.forEach(function (sig) {
+      try {
+        process.removeListener(sig, sigListeners[sig])
+      } catch (er) {}
+    })
+    process.emit = originalProcessEmit
+    process.reallyExit = originalProcessReallyExit
+    emitter.count -= 1
+  }
+  module.exports.unload = unload
+
+  var emit = function emit (event, code, signal) {
+    /* istanbul ignore if */
+    if (emitter.emitted[event]) {
+      return
+    }
+    emitter.emitted[event] = true
+    emitter.emit(event, code, signal)
+  }
+
+  // { <signal>: <listener fn>, ... }
+  var sigListeners = {}
+  signals.forEach(function (sig) {
+    sigListeners[sig] = function listener () {
+      /* istanbul ignore if */
+      if (!processOk(global.process)) {
+        return
+      }
+      // If there are no other listeners, an exit is coming!
+      // Simplest way: remove us and then re-send the signal.
+      // We know that this will kill the process, so we can
+      // safely emit now.
+      var listeners = process.listeners(sig)
+      if (listeners.length === emitter.count) {
+        unload()
+        emit('exit', null, sig)
+        /* istanbul ignore next */
+        emit('afterexit', null, sig)
+        /* istanbul ignore next */
+        if (isWin && sig === 'SIGHUP') {
+          // "SIGHUP" throws an `ENOSYS` error on Windows,
+          // so use a supported signal instead
+          sig = 'SIGINT'
+        }
+        /* istanbul ignore next */
+        process.kill(process.pid, sig)
+      }
+    }
+  })
+
+  module.exports.signals = function () {
+    return signals
+  }
+
+  var loaded = false
+
+  var load = function load () {
+    if (loaded || !processOk(global.process)) {
+      return
+    }
+    loaded = true
+
+    // This is the number of onSignalExit's that are in play.
+    // It's important so that we can count the correct number of
+    // listeners on signals, and don't wait for the other one to
+    // handle it instead of us.
+    emitter.count += 1
+
+    signals = signals.filter(function (sig) {
+      try {
+        process.on(sig, sigListeners[sig])
+        return true
+      } catch (er) {
+        return false
+      }
+    })
+
+    process.emit = processEmit
+    process.reallyExit = processReallyExit
+  }
+  module.exports.load = load
+
+  var originalProcessReallyExit = process.reallyExit
+  var processReallyExit = function processReallyExit (code) {
+    /* istanbul ignore if */
+    if (!processOk(global.process)) {
+      return
+    }
+    process.exitCode = code || /* istanbul ignore next */ 0
+    emit('exit', process.exitCode, null)
+    /* istanbul ignore next */
+    emit('afterexit', process.exitCode, null)
+    /* istanbul ignore next */
+    originalProcessReallyExit.call(process, process.exitCode)
+  }
+
+  var originalProcessEmit = process.emit
+  var processEmit = function processEmit (ev, arg) {
+    if (ev === 'exit' && processOk(global.process)) {
+      /* istanbul ignore else */
+      if (arg !== undefined) {
+        process.exitCode = arg
+      }
+      var ret = originalProcessEmit.apply(this, arguments)
+      /* istanbul ignore next */
+      emit('exit', process.exitCode, null)
+      /* istanbul ignore next */
+      emit('afterexit', process.exitCode, null)
+      /* istanbul ignore next */
+      return ret
+    } else {
+      return originalProcessEmit.apply(this, arguments)
+    }
+  }
+}

server/libs/signalExit/signals.js

@@ -0,0 +1,53 @@
+// This is not the set of all possible signals.
+//
+// It IS, however, the set of all signals that trigger
+// an exit on either Linux or BSD systems.  Linux is a
+// superset of the signal names supported on BSD, and
+// the unknown signals just fail to register, so we can
+// catch that easily enough.
+//
+// Don't bother with SIGKILL.  It's uncatchable, which
+// means that we can't fire any callbacks anyway.
+//
+// If a user does happen to register a handler on a non-
+// fatal signal like SIGWINCH or something, and then
+// exit, it'll end up firing `process.emit('exit')`, so
+// the handler will be fired anyway.
+//
+// SIGBUS, SIGFPE, SIGSEGV and SIGILL, when not raised
+// artificially, inherently leave the process in a
+// state from which it is not safe to try and enter JS
+// listeners.
+module.exports = [
+  'SIGABRT',
+  'SIGALRM',
+  'SIGHUP',
+  'SIGINT',
+  'SIGTERM'
+]
+
+if (process.platform !== 'win32') {
+  module.exports.push(
+    'SIGVTALRM',
+    'SIGXCPU',
+    'SIGXFSZ',
+    'SIGUSR2',
+    'SIGTRAP',
+    'SIGSYS',
+    'SIGQUIT',
+    'SIGIOT'
+    // should detect profiler and enable/disable accordingly.
+    // see #21
+    // 'SIGPROF'
+  )
+}
+
+if (process.platform === 'linux') {
+  module.exports.push(
+    'SIGIO',
+    'SIGPOLL',
+    'SIGPWR',
+    'SIGSTKFLT',
+    'SIGUNUSED'
+  )
+}

server/utils/dbMigration.js

@@ -1,6 +1,6 @@
 const Path = require('path')
 const fs = require('fs-extra')
-const njodb = require('../njodb')
+const njodb = require('../libs/njodb')
 
 const { SupportedEbookTypes } = require('./globals')
 const { PlayMethod } = require('./constants')