initial apollo-link-dedup implementation

packages/apollo-link-dedup/package.json

@@ -0,0 +1,68 @@
+{
+  "name": "apollo-link-dedup",
+  "version": "0.0.0",
+  "description": "Deduplicates queries that are currently on the wire",
+  "author": "Evans Hauser <evanshauser@gmail.com>",
+  "contributors": [
+    "James Baxley <james@meteor.com>",
+    "Jonas Helfer <jonas@helfer.email>",
+    "jon wong <j@jnwng.com>",
+    "Sashko Stubailo <sashko@stubailo.com>"
+  ],
+  "license": "MIT",
+  "main": "./lib/dedupLink.js",
+  "typings": "./lib/dedupLink.d.ts",
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/apollographql/apollo-link.git"
+  },
+  "bugs": {
+    "url": "https://github.com/apollographql/apollo-link/issues"
+  },
+  "homepage": "https://github.com/apollographql/apollo-link#readme",
+  "scripts": {
+    "pretest": "npm run build",
+    "test": "npm run test-only --",
+    "posttest": "npm run lint",
+    "test-only": "mocha --reporter spec --full-trace dist/tests/tests.js",
+    "test-watch": "mocha --reporter spec --full-trace dist/tests/tests.js --watch",
+    "coverage": "istanbul cover ./node_modules/mocha/bin/_mocha -- --reporter dot --full-trace dist/tests/tests.js",
+    "postcoverage": "remap-istanbul --input coverage/coverage.json --type lcovonly --output coverage/lcov.info",
+    "lint": "tslint --type-check -p tsconfig.json src/*.ts && tslint --type-check -p tsconfig.json tests/*.ts",
+    "prebuild": "npm run clean:dist",
+    "build": "tsc -p .",
+    "postbuild": "cp -R ./dist/src/. ./lib",
+    "watch": "tsc -w -p .",
+    "clean": "npm run clean:dist && npm run clean:coverage",
+    "clean:dist": "rimraf dist/* && rimraf lib/*",
+    "clean:coverage": "rimraf coverage/*",
+    "prepublishOnly": "npm run clean && npm run build"
+  },
+  "dependencies": {
+    "apollo-fetch": "^0.6.0",
+    "apollo-link-core": "^0.1.1",
+    "graphql": "^0.10.5"
+  },
+  "devDependencies": {
+    "@types/chai": "^4.0.0",
+    "@types/chai-as-promised": "0.0.31",
+    "@types/mocha": "^2.2.31",
+    "@types/sinon": "^2.3.2",
+    "chai": "^4.0.2",
+    "chai-as-promised": "^7.0.0",
+    "fetch-mock": "^5.11.0",
+    "graphql-tag": "^2.2.2",
+    "istanbul": "^0.4.4",
+    "lodash": "^4.17.4",
+    "mocha": "^3.2.0",
+    "remap-istanbul": "^0.9.0",
+    "rimraf": "^2.5.4",
+    "sinon": "^2.3.4",
+    "source-map-support": "^0.4.5",
+    "tslint": "^5.0.0",
+    "typescript": "^2.2.1"
+  },
+  "optionalDependencies": {
+    "@types/graphql": "~0.9.0"
+  }
+}

packages/apollo-link-dedup/src/dedupLink.ts

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+import {
+  ApolloLink,
+  Operation,
+  NextLink,
+  FetchResult,
+  Observable,
+} from 'apollo-link-core';
+
+import { print } from 'graphql/language/printer';
+
+/*
+ * Expects context to contain the deduplicate field
+ */
+export class DedupLink extends ApolloLink {
+  private inFlightRequestPromises: { [key: string]: Observable<FetchResult> };
+
+  constructor() {
+    super();
+    this.inFlightRequestPromises = {};
+  }
+
+  public request(
+    operation: Operation,
+    forward: NextLink,
+  ): Observable<FetchResult> {
+    // sometimes we might not want to deduplicate a request, for example when we want to force fetch it.
+    if (!operation.context.deduplicate) {
+      return forward(operation);
+    }
+
+    const key = this.getKey(operation);
+    if (!this.inFlightRequestPromises[key]) {
+      this.inFlightRequestPromises[key] = forward(operation);
+    }
+    return new Observable<FetchResult>(observer => {
+      this.inFlightRequestPromises[key].subscribe({
+        next: observer.next.bind(observer),
+        error: error => {
+          observer.error(error);
+          delete this.inFlightRequestPromises[key];
+        },
+        complete: () => {
+          observer.complete();
+          delete this.inFlightRequestPromises[key];
+        },
+      });
+    });
+  }
+
+  private getKey(operation: Operation) {
+    // XXX we're assuming here that variables will be serialized in the same order.
+    // that might not always be true
+    return `${print(operation.query)}|${JSON.stringify(
+      operation.variables,
+    )}|${operation.operationName}`;
+  }
+}

packages/apollo-link-dedup/tests/dedupLink.ts

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+import { assert, expect } from 'chai';
+import * as sinon from 'sinon';
+import DedupLink from '../src/dedupLink';
+
+import * as Links from 'apollo-link-core';
+import { ApolloLink, execute } from 'apollo-link-core';
+
+import { createApolloFetch } from 'apollo-fetch';
+
+import { print } from 'graphql';
+import gql from 'graphql-tag';
+import * as fetchMock from 'fetch-mock';
+
+describe('DedupLink', () => {});

packages/apollo-link-dedup/tests/tests.ts

@@ -0,0 +1 @@
+import './*';

packages/apollo-link-dedup/tsconfig.json

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+{
+  "compilerOptions": {
+    "target": "es5",
+    "lib": ["es6", "dom"],
+    "module": "commonjs",
+    "moduleResolution": "node",
+    "removeComments": true,
+    "sourceMap": true,
+    "declaration": true,
+    "rootDir": ".",
+    "outDir": "dist",
+    "noImplicitAny": false,
+    "noUnusedParameters": false,
+    "noUnusedLocals": true,
+    "skipLibCheck": true
+  },
+  "include": ["src/**/*.ts", "tests/**/*.ts"]
+}

packages/apollo-link-dedup/tslint.json

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+{
+  "rules": {
+    "align": [false, "parameters", "arguments", "statements"],
+    "ban": false,
+    "class-name": true,
+    "curly": true,
+    "eofline": true,
+    "forin": true,
+    "indent": [true, "spaces", 2],
+    "interface-name": false,
+    "jsdoc-format": true,
+    "label-position": true,
+    "max-line-length": [true, 140],
+    "member-access": true,
+    "member-ordering": [
+      true,
+      "public-before-private",
+      "static-before-instance",
+      "variables-before-functions"
+    ],
+    "no-any": false,
+    "no-arg": true,
+    "no-bitwise": true,
+    "no-conditional-assignment": true,
+    "no-consecutive-blank-lines": false,
+    "no-console": [true, "log", "debug", "info", "time", "timeEnd", "trace"],
+    "no-construct": true,
+    "no-debugger": true,
+    "no-duplicate-variable": true,
+    "no-empty": true,
+    "no-eval": true,
+    "no-inferrable-types": false,
+    "no-internal-module": true,
+    "no-null-keyword": false,
+    "no-parameter-properties": false,
+    "no-require-imports": false,
+    "no-shadowed-variable": true,
+    "no-switch-case-fall-through": true,
+    "no-trailing-whitespace": true,
+    "no-unused-expression": true,
+    "no-use-before-declare": false,
+    "no-var-keyword": true,
+    "no-var-requires": true,
+    "object-literal-sort-keys": false,
+    "one-line": [
+      true,
+      "check-open-brace",
+      "check-catch",
+      "check-else",
+      "check-finally",
+      "check-whitespace"
+    ],
+    "quotemark": [true, "single", "avoid-escape"],
+    "radix": true,
+    "semicolon": [true, "always"],
+    "switch-default": true,
+    "trailing-comma": [
+      true,
+      {
+        "multiline": "always",
+        "singleline": "never"
+      }
+    ],
+    "triple-equals": [true, "allow-null-check"],
+    "typedef": [
+      false,
+      "call-signature",
+      "parameter",
+      "arrow-parameter",
+      "property-declaration",
+      "variable-declaration",
+      "member-variable-declaration"
+    ],
+    "typedef-whitespace": [
+      true,
+      {
+        "call-signature": "nospace",
+        "index-signature": "nospace",
+        "parameter": "nospace",
+        "property-declaration": "nospace",
+        "variable-declaration": "nospace"
+      },
+      {
+        "call-signature": "space",
+        "index-signature": "space",
+        "parameter": "space",
+        "property-declaration": "space",
+        "variable-declaration": "space"
+      }
+    ],
+    "variable-name": [
+      true,
+      "check-format",
+      "allow-pascal-case",
+      "allow-leading-underscore",
+      "ban-keywords"
+    ],
+    "whitespace": [
+      true,
+      "check-branch",
+      "check-decl",
+      "check-operator",
+      "check-separator",
+      "check-type"
+    ]
+  }
+}