Adding logger wrapper.

Log backend messages to syslog.
fixes #135

backend/src/logger.ts

@@ -0,0 +1,155 @@
+import * as dgram from 'dgram';
+
+class Logger {
+  static priorities = {
+    emerg: 0,
+    alert: 1,
+    crit: 2,
+    err: 3,
+    warn: 4,
+    notice: 5,
+    info: 6,
+    debug: 7
+  };
+  static facilities = {
+    kern: 0,
+    user: 1,
+    mail: 2,
+    daemon: 3,
+    auth: 4,
+    syslog: 5,
+    lpr: 6,
+    news: 7,
+    uucp: 8,
+    local0: 16,
+    local1: 17,
+    local2: 18,
+    local3: 19,
+    local4: 20,
+    local5: 21,
+    local6: 22,
+    local7: 23
+  };
+
+  // @ts-ignore
+  public emerg: ((msg: string) => void);
+  // @ts-ignore
+  public alert: ((msg: string) => void);
+  // @ts-ignore
+  public crit: ((msg: string) => void);
+  // @ts-ignore
+  public err: ((msg: string) => void);
+  // @ts-ignore
+  public warn: ((msg: string) => void);
+  // @ts-ignore
+  public notice: ((msg: string) => void);
+  // @ts-ignore
+  public info: ((msg: string) => void);
+  // @ts-ignore
+  public debug: ((msg: string) => void);
+
+  private name = 'mempool';
+  private fac: any;
+  private loghost: string;
+  private logport: number;
+
+  constructor(fac) {
+    let prio;
+    this.fac = fac != null ? fac : Logger.facilities.local0;
+    this.loghost = '127.0.0.1';
+    this.logport = 514;
+    for (prio in Logger.priorities) {
+      if (true) {
+        this.addprio(prio);
+      }
+    }
+  }
+
+  private addprio(prio): void {
+    this[prio] = (function(_this) {
+      return function(msg) {
+        return _this.msg(prio, msg);
+      };
+    })(this);
+  }
+
+  private tag() {
+    let e, stack, stacklevel, tag;
+    stacklevel = 4;
+    try {
+      const err = new Error().stack;
+      if (err) {
+        stack = err.replace(/^\s+at\s+/gm, '').replace(/^Object.<anonymous>\s*\(/gm, '{anonymous}()@').split('\n');
+        tag = stack[stacklevel].split(' ')[1];
+        tag = '(' + tag.split('/').reverse()[0];
+      } else {
+        tag = '';
+      }
+    } catch (_error) {
+      e = _error;
+      tag = '';
+    }
+    return tag;
+  }
+
+  private msg(priority, msg) {
+    let consolemsg, prionum, syslogmsg;
+    if (typeof msg === 'string' && msg.length > 0) {
+      while (msg[msg.length - 1].charCodeAt(0) === 10) {
+        msg = msg.slice(0, msg.length - 1);
+      }
+    }
+    prionum = Logger.priorities[priority] || Logger.priorities.info;
+    const tag = this.tag();
+    syslogmsg = `<${(this.fac * 8 + prionum)}> ${this.name}[${process.pid}]: ${tag}: ${priority.toUpperCase()} ${msg}`;
+    consolemsg = `${this.ts()} [${process.pid}] ${priority.toUpperCase()}: ${msg}`;
+
+    this.syslog(syslogmsg);
+    if (priority === 'warning') {
+      priority = 'warn';
+    }
+    if (priority === 'debug') {
+      priority = 'info';
+    }
+    if (priority === 'err') {
+      priority = 'error';
+    }
+    return (console[priority] || console.error)(consolemsg);
+  }
+
+  private syslog(msg) {
+    let client, msgbuf;
+    msgbuf = Buffer.from(msg);
+    client = dgram.createSocket('udp4');
+    client.send(msgbuf, 0, msgbuf.length, this.logport, this.loghost, function(err, bytes) {
+      if (err) {
+        console.log(err);
+      }
+      client.close();
+    });
+  }
+
+  private leadZero(n: number): number | string {
+    if (n < 10) {
+      return '0' + n;
+    }
+    return n;
+  }
+
+  private ts() {
+    let day, dt, hours, minutes, month, months, seconds;
+    dt = new Date();
+    hours = this.leadZero(dt.getHours());
+    minutes = this.leadZero(dt.getMinutes());
+    seconds = this.leadZero(dt.getSeconds());
+    month = dt.getMonth();
+    day = dt.getDate();
+    if (day < 10) {
+      day = ' ' + day;
+    }
+    months = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'];
+    return months[month] + ' ' + day + ' ' + hours + ':' + minutes + ':' + seconds;
+  }
+}
+
+export default new Logger(Logger.facilities.local7);