Port callbacks to promise where possible, #104

LinkedDataFragments · Apr 7, 2020 · b7b78ea · b7b78ea
1 parent 58a3946
commit b7b78ea
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Showing 5 changed files with 33 additions and 29 deletions.
diff --git a/packages/core/lib/datasources/Datasource.js b/packages/core/lib/datasources/Datasource.js
@@ -62,23 +62,22 @@ class Datasource extends EventEmitter {
 
   // Initialize the datasource asynchronously
   initialize() {
-    setImmediate(() => {
-      let done = _.once((error) => {
-        if (error)
-          this.emit('error', error);
-        else {
+    try {
+      this._initialize()
+        .then(() => {
           this.initialized = true;
           this.emit('initialized');
-        }
-      });
-      try { this._initialize(done); }
-      catch (error) { done(error); }
-    });
+        })
+        .catch((error) => this.emit('error', error));
+    }
+    catch (error) {
+      this.emit('error', error);
+    }
   }
 
   // Prepares the datasource for querying
-  _initialize(done) {
-    done();
+  async _initialize() {
+
   }
 
   // Checks whether the data source can evaluate the given query

diff --git a/packages/core/lib/datasources/MemoryDatasource.js b/packages/core/lib/datasources/MemoryDatasource.js
@@ -13,8 +13,14 @@ class MemoryDatasource extends Datasource {
 
   // Prepares the datasource for querying
   _initialize(done) {
-    let quadStore = this._quadStore = new N3Store();
-    this._getAllQuads((quad) => { quadStore.addQuad(quad); }, done);
+    return new Promise((resolve, reject) => {
+      let quadStore = this._quadStore = new N3Store();
+      this._getAllQuads((quad) => { quadStore.addQuad(quad); }, (error) => {
+        if (error)
+          return reject(error);
+        return resolve();
+      });
+    });
   }
 
   // Retrieves all quads in the datasource

diff --git a/packages/core/test/datasources/Datasource-test.js b/packages/core/test/datasources/Datasource-test.js
@@ -117,10 +117,11 @@ describe('Datasource', () => {
   });
 
   describe('A Datasource instance with an initializer', () => {
-    let datasource, initializedListener, errorListener;
+    let datasource, initializedListener, errorListener, initResolver, initSpy;
     before(() => {
       datasource = new Datasource({ dataFactory });
-      datasource._initialize = sinon.stub();
+      datasource._initialize = () => new Promise((resolve) => initResolver = resolve);
+      initSpy = sinon.spy(datasource, '_initialize');
       Object.defineProperty(datasource, 'supportedFeatures', {
         value: { all: true },
       });
@@ -131,7 +132,7 @@ describe('Datasource', () => {
 
     describe('after construction', () => {
       it('should have called the initializer', () => {
-        datasource._initialize.should.have.been.calledOnce;
+        initSpy.should.have.been.calledOnce;
       });
 
       it('should not be initialized', () => {
@@ -152,7 +153,7 @@ describe('Datasource', () => {
 
     describe('after the initializer calls the callback', () => {
       before(() => {
-        datasource._initialize.getCall(0).args[0]();
+        initResolver();
       });
 
       it('should be initialized', () => {
@@ -185,7 +186,8 @@ describe('Datasource', () => {
     before(() => {
       datasource = new Datasource({ dataFactory });
       error = new Error('initializer error');
-      datasource._initialize = sinon.stub().throws(error);
+      datasource._initialize = () => { throw error; };
+      sinon.spy(datasource, '_initialize');
       datasource.on('initialized', initializedListener = sinon.stub());
       datasource.on('error', errorListener = sinon.stub());
       datasource.initialize();
@@ -216,7 +218,8 @@ describe('Datasource', () => {
     before(() => {
       datasource = new Datasource({ dataFactory });
       error = new Error('initializer error');
-      datasource._initialize = sinon.stub().callsArgWith(0, error);
+      datasource._initialize = () => Promise.reject(error);
+      sinon.spy(datasource, '_initialize');
       datasource.on('initialized', initializedListener = sinon.stub());
       datasource.on('error', errorListener = sinon.stub());
       datasource.initialize();

diff --git a/packages/datasource-hdt/lib/datasources/ExternalHdtDatasource.js b/packages/datasource-hdt/lib/datasources/ExternalHdtDatasource.js
@@ -23,14 +23,13 @@ class ExternalHdtDatasource extends Datasource {
   }
 
   // Prepares the datasource for querying
-  _initialize(done) {
+  async _initialize() {
     if (this._options.checkFile !== false) {
       if (!fs.existsSync(this._hdtFile))
-        return done(new Error('Not an HDT file: ' + this._hdtFile));
+        throw new Error('Not an HDT file: ' + this._hdtFile);
       if (!fs.existsSync(hdtUtility))
-        return done(new Error('hdt not found: ' + hdtUtility));
+        throw new Error('hdt not found: ' + hdtUtility);
     }
-    done();
   }
 
   // Writes the results of the query to the given quad stream

diff --git a/packages/datasource-hdt/lib/datasources/HdtDatasource.js b/packages/datasource-hdt/lib/datasources/HdtDatasource.js
@@ -20,11 +20,8 @@ class HdtDatasource extends Datasource {
   }
 
   // Loads the HDT datasource
-  _initialize(done) {
-    let datasource = this;
-    hdt.fromFile(this._hdtFile).then((hdtDocument) => {
-      datasource._hdtDocument = hdtDocument;
-    }).then(done, done);
+  async _initialize() {
+    this._hdtDocument = await hdt.fromFile(this._hdtFile);
   }
 
   // Writes the results of the query to the given quad stream