jsl data refactor

packages/api/src/utility/DatastoreProxy.js

@@ -0,0 +1,55 @@
+const { fork } = require('child_process');
+const uuidv1 = require('uuid/v1');
+
+class DatastoreProxy {
+  constructor(file) {
+    this.subprocess = null;
+    this.disconnected = false;
+    this.file = file;
+    this.requests = {};
+    this.handle_response = this.handle_response.bind(this);
+    this.handle_ping = this.handle_ping.bind(this);
+  }
+
+  // handle_response({ msgid, rows }) {
+  handle_response({ msgid, rows }) {
+    const [resolve, reject] = this.requests[msgid];
+    resolve(rows);
+    delete this.requests[msgid];
+  }
+
+  handle_ping() {}
+
+
+  async ensureSubprocess() {
+    if (!this.subprocess) {
+      this.subprocess = fork(process.argv[1], ['jslDatastoreProcess']);
+
+      // @ts-ignore
+      this.subprocess.on('message', ({ msgtype, ...message }) => {
+        // if (this.disconnected) return;
+        this[`handle_${msgtype}`](message);
+      });
+      this.subprocess.on('exit', () => {
+        // if (this.disconnected) return;
+        this.subprocess = null;
+      });
+      this.subprocess.send({ msgtype: 'open', file: this.file });
+    }
+    return this.subprocess;
+  }
+
+  async getRows(offset, limit) {
+    await this.ensureSubprocess();
+    const msgid = uuidv1();
+    const promise = new Promise((resolve, reject) => {
+      this.requests[msgid] = [resolve, reject];
+      this.subprocess.send({ msgtype: 'read', msgid, offset, limit });
+    });
+    return promise;
+  }
+
+  async notifyChanged() {}
+}
+
+module.exports = DatastoreProxy;