[DDW-812] Remove tail dependency and copy only the necessary code from it

Author: Lucas Araujo

package.json

@@ -271,7 +271,6 @@
     "shasum": "1.0.2",
     "source-map-support": "0.5.19",
     "spectron-fake-dialog": "0.0.1",
-    "tail": "2.2.4",
     "tcp-port-used": "1.0.1",
     "trezor-connect": "8.2.4-extended",
     "unorm": "1.6.0",

source/main/utils/handleCheckBlockReplayProgress.ts

@@ -2,7 +2,7 @@ import { BrowserWindow } from 'electron';
 import fs from 'fs';
 import moment from 'moment';
 import path from 'path';
-import { Tail } from 'tail';
+import { Tail } from './tail';
 import { getBlockSyncProgressChannel } from '../ipc/get-block-sync-progress';
 import type { GetBlockSyncProgressType } from '../../common/ipc/api';
 import { BlockSyncType } from '../../common/types/cardano-node.types';

source/main/utils/tail.ts

@@ -0,0 +1,183 @@
+import events from 'events';
+import fs from 'fs';
+import path from 'path';
+import { logger as defaultLogger } from './logging';
+import type { Logger } from '../../common/types/logging.types';
+
+const ENCODING = 'utf-8';
+
+export class Tail extends events.EventEmitter {
+  filename: string;
+  buffer: string;
+  internalDispatcher: events.EventEmitter;
+  queue: { start: number; end: number }[];
+  isWatching: boolean;
+  currentCursorPos: number;
+  watcher: fs.FSWatcher;
+  rewatchId: NodeJS.Timeout;
+  logger: Logger;
+
+  constructor(filename: string, logger: Logger = defaultLogger) {
+    super();
+    this.filename = filename;
+    this.logger = logger;
+
+    this.logger.info(`Tail starting...`);
+    this.logger.info(`filename: ${this.filename}`);
+
+    try {
+      fs.accessSync(this.filename, fs.constants.F_OK);
+    } catch (err) {
+      if (err.code === 'ENOENT') {
+        throw err;
+      }
+    }
+
+    this.buffer = '';
+    this.internalDispatcher = new events.EventEmitter();
+    this.queue = [];
+    this.isWatching = false;
+
+    this.internalDispatcher.on('next', () => {
+      this.readBlock();
+    });
+
+    try {
+      this.watch(this.latestPosition());
+    } catch (err) {
+      this.logger.error(`watch for ${this.filename} failed: ${err}`);
+      this.emit('error', `watch for ${this.filename} failed: ${err}`);
+    }
+  }
+
+  latestPosition() {
+    try {
+      return fs.statSync(this.filename).size;
+    } catch (err) {
+      this.logger.error(`size check for ${this.filename} failed: ${err}`);
+      this.emit('error', `size check for ${this.filename} failed: ${err}`);
+      throw err;
+    }
+  }
+
+  readBlock() {
+    if (this.queue.length >= 1) {
+      const block = this.queue[0];
+      if (block.end > block.start) {
+        const stream = fs.createReadStream(this.filename, {
+          start: block.start,
+          end: block.end - 1,
+          encoding: ENCODING,
+        });
+        stream.on('error', (error) => {
+          this.logger.error(`Tail error: ${error}`);
+          this.emit('error', error);
+        });
+        stream.on('end', () => {
+          this.queue.shift();
+          if (this.queue.length > 0) {
+            this.internalDispatcher.emit('next');
+          }
+        });
+        stream.on('data', (d) => {
+          this.buffer += d;
+          const parts = this.buffer.split(/[\r]{0,1}\n/);
+          this.buffer = parts.pop();
+          for (const chunk of parts) {
+            this.emit('line', chunk);
+          }
+        });
+      }
+    }
+  }
+
+  change() {
+    const p = this.latestPosition();
+    if (p < this.currentCursorPos) {
+      this.currentCursorPos = p;
+    } else if (p > this.currentCursorPos) {
+      this.queue.push({ start: this.currentCursorPos, end: p });
+      this.currentCursorPos = p;
+      if (this.queue.length === 1) {
+        this.internalDispatcher.emit('next');
+      }
+    }
+  }
+
+  watch(startingCursor) {
+    if (this.isWatching) return;
+    this.logger.info(`filesystem.watch present? ${fs.watch !== undefined}`);
+
+    this.isWatching = true;
+    this.currentCursorPos = startingCursor;
+
+    if (fs.watch) {
+      this.logger.info(`watch strategy: watch`);
+      this.watcher = fs.watch(this.filename, {}, (e, filename) => {
+        this.watchEvent(e, filename);
+      });
+    } else {
+      this.logger.info(`watch strategy: watchFile`);
+      fs.watchFile(this.filename, {}, (curr, prev) => {
+        this.watchFileEvent(curr, prev);
+      });
+    }
+  }
+
+  rename(filename) {
+    if (filename === undefined || filename !== this.filename) {
+      this.unwatch();
+      this.filename = path.join(path.dirname(this.filename), filename);
+      this.rewatchId = setTimeout(() => {
+        try {
+          this.watch(this.currentCursorPos);
+        } catch (ex) {
+          this.logger.error(
+            `'rename' event for ${this.filename}. File not available anymore.`
+          );
+          this.emit('error', ex);
+        }
+      }, 1000);
+    } else {
+      this.logger.info('rename event but same filename');
+    }
+  }
+
+  watchEvent(e, evtFilename) {
+    try {
+      if (e === 'change') {
+        this.change();
+      } else if (e === 'rename') {
+        this.rename(evtFilename);
+      }
+    } catch (err) {
+      this.logger.error(`watchEvent for ${this.filename} failed: ${err}`);
+      this.emit('error', `watchEvent for ${this.filename} failed: ${err}`);
+    }
+  }
+
+  watchFileEvent(curr, prev) {
+    if (curr.size > prev.size) {
+      this.currentCursorPos = curr.size;
+      this.queue.push({ start: prev.size, end: curr.size });
+      if (this.queue.length === 1) {
+        this.internalDispatcher.emit('next');
+      }
+    }
+  }
+
+  unwatch() {
+    if (this.watcher) {
+      this.watcher.close();
+    } else {
+      fs.unwatchFile(this.filename);
+    }
+    if (this.rewatchId) {
+      clearTimeout(this.rewatchId);
+      this.rewatchId = undefined;
+    }
+    this.isWatching = false;
+    this.queue = [];
+    this.logger.info(`Unwatch ${this.filename}`);
+  }
+}

yarn.lock

@@ -16456,10 +16456,6 @@ table@^6.0.1:
     slice-ansi "^4.0.0"
     string-width "^4.2.0"
 
-[email protected]:
-  version "2.2.4"
-  resolved "https://registry.yarnpkg.com/tail/-/tail-2.2.4.tgz#90dd4c5a174a3fa39dcb65a1df1950a4a0093a41"
-
 tapable@^0.1.8:
   version "0.1.10"
   resolved "https://registry.yarnpkg.com/tapable/-/tapable-0.1.10.tgz#29c35707c2b70e50d07482b5d202e8ed446dafd4"