Add HTTP fallback mechanism

billiegoose · billiegoose · commit 11ff6f5be4fb · 2018-12-23T23:12:39.000-05:00
diff --git a/karma.conf.js b/karma.conf.js
@@ -21,7 +21,19 @@ module.exports = function (config) {
     frameworks: ['jasmine'],
     // list of files / patterns to load in the browser
     files: [
-      'src/**/*.spec.js'
+      'src/**/*.spec.js',
+      {
+        pattern: 'src/__tests__/__fixtures__/test-folder/**/*',
+        served: true,
+        watched: false,
+        included: false
+      },
+      {
+        pattern: 'src/__tests__/__fixtures__/test-folder/**/.*',
+        served: true,
+        watched: false,
+        included: false
+      },
     ],
     // list of files to exclude
     // exclude: [
diff --git a/package.json b/package.json
@@ -6,6 +6,9 @@
   "version": "0.0.0",
   "description": "A lean and fast 'fs' for the browser",
   "main": "index.js",
+  "bin": {
+    "superblocktxt": "src/superblocktxt.js"
+  },
   "scripts": {
     "test": "karma start --single-run"
   },
diff --git a/src/CacheFS.js b/src/CacheFS.js
@@ -8,12 +8,21 @@ module.exports = class CacheFS {
     const root = this._makeRoot();
     this._root = new Map([["/", root]]);
   }
-  _makeRoot() {
-    let root = new Map();
+  _makeRoot(root) {
+    root = root || new Map();
     let stat = { mode: 0o777, type: "dir", size: 0, mtimeMs: Date.now() };
     root.set(STAT, stat);
     return root
   }
+  loadSuperBlock(superblock) {
+    if (typeof superblock === 'string') {
+      let root = this.parse(superblock)
+      root = this._makeRoot(root);
+      this._root = new Map([["/", root]]);
+    } else {
+      this._root = superblock
+    }
+  }
   print(root) {
     root = root || this._root.get("/")
     let str = "";
@@ -33,7 +42,7 @@ module.exports = class CacheFS {
       }
     };
     printTree(root, 0);
-    return str.trimStart();
+    return str.trimStart() + '\n';
   }
   parse(print) {
     function mk(stat) {
diff --git a/src/HttpBackend.js b/src/HttpBackend.js
@@ -0,0 +1,11 @@
+module.exports = class IdbBackend {
+  constructor(url) {
+    this._url = url;
+  }
+  loadSuperblock() {
+    return fetch(this._url + '/.superblock.txt').then(res => res.text())
+  }
+  readFile(filepath) {
+    return fetch(this._url + filepath).then(res => res.arrayBuffer())
+  }
+}
diff --git a/src/__tests__/__fixtures__/test-folder/.superblock.txt b/src/__tests__/__fixtures__/test-folder/.superblock.txt
@@ -0,0 +1,11 @@
+0	40755
+	a.txt	100644	14	1545621303427.1333
+	b.txt	100644	14	1545621303427.2192
+	c.txt	100644	14	1545621303427.2607
+1	40755
+	d.txt	100644	14	1545621340683.4724
+	e.txt	100644	14	1545621349775.4539
+	f.txt	100644	14	1545621356008.1582
+a.txt	100644	14	1545621375109
+b.txt	100644	14	1545621255760.9512
+c.txt	100644	14	1545621290070.7742
diff --git a/src/__tests__/__fixtures__/test-folder/0/a.txt b/src/__tests__/__fixtures__/test-folder/0/a.txt
@@ -0,0 +1 @@
+Hello from "a"
diff --git a/src/__tests__/__fixtures__/test-folder/0/b.txt b/src/__tests__/__fixtures__/test-folder/0/b.txt
@@ -0,0 +1 @@
+Hello from "b"
diff --git a/src/__tests__/__fixtures__/test-folder/0/c.txt b/src/__tests__/__fixtures__/test-folder/0/c.txt
@@ -0,0 +1 @@
+Hello from "c"
diff --git a/src/__tests__/__fixtures__/test-folder/1/d.txt b/src/__tests__/__fixtures__/test-folder/1/d.txt
@@ -0,0 +1 @@
+Hello from "d"
diff --git a/src/__tests__/__fixtures__/test-folder/1/e.txt b/src/__tests__/__fixtures__/test-folder/1/e.txt
@@ -0,0 +1 @@
+Hello from "e"
diff --git a/src/__tests__/__fixtures__/test-folder/1/f.txt b/src/__tests__/__fixtures__/test-folder/1/f.txt
@@ -0,0 +1 @@
+Hello from "f"
diff --git a/src/__tests__/__fixtures__/test-folder/a.txt b/src/__tests__/__fixtures__/test-folder/a.txt
@@ -0,0 +1 @@
+Hello from "a"
diff --git a/src/__tests__/__fixtures__/test-folder/b.txt b/src/__tests__/__fixtures__/test-folder/b.txt
@@ -0,0 +1 @@
+Hello from "b"
diff --git a/src/__tests__/__fixtures__/test-folder/c.txt b/src/__tests__/__fixtures__/test-folder/c.txt
@@ -0,0 +1 @@
+Hello from "c"
diff --git a/src/__tests__/__fixtures__/tree.txt.js b/src/__tests__/__fixtures__/tree.txt.js
@@ -1765,4 +1765,5 @@ package.json	666	3996	1545535032598
 renovate.json	666	244	1545535032598
 rollup.config.js	666	804	1545535032598
 tsconfig.json	666	581	1545535032598
-webpack.config.js	666	1730	1545535032599`
+webpack.config.js	666	1730	1545535032599
+`
diff --git a/src/__tests__/fallback.spec.js b/src/__tests__/fallback.spec.js
@@ -0,0 +1,92 @@
+import FS from "../index.js";
+
+const fs = new FS("testfs", { wipe: true, url: 'http://localhost:9876/base/src/__tests__/__fixtures__/test-folder' });
+
+describe("http fallback", () => {
+  it("sanity check", () => {
+    expect(fs._fallback).not.toBeFalsy()
+  })
+  it("loads", (done) => {
+    fs.superblockPromise.then(() => {
+      done()
+    }).catch(err => {
+      expect(err).toBe(null)
+      done()
+    })
+  })
+  describe("readdir", () => {
+    it("read root dir", done => {
+      fs.readdir("/", (err, data) => {
+        expect(err).toBe(null);
+        expect(data).toEqual(['0', '1', 'a.txt', 'b.txt', 'c.txt'])
+        done();
+      });
+    });
+    it("read child dir /0", done => {
+      fs.readdir("/0", (err, data) => {
+        expect(err).toBe(null);
+        expect(data).toEqual(['a.txt', 'b.txt', 'c.txt'])
+        done();
+      });
+    });
+    it("read child dir /1", done => {
+      fs.readdir("/1", (err, data) => {
+        expect(err).toBe(null);
+        expect(data).toEqual(['d.txt', 'e.txt', 'f.txt'])
+        done();
+      });
+    });
+  });
+
+  describe("readFile", () => {
+    it("read non-existant file throws", done => {
+      fs.readFile("/readFile/non-existant.txt", (err, data) => {
+        expect(err).not.toBe(null);
+        done();
+      });
+    });
+    it("read file /a.txt", done => {
+      fs.readFile("/a.txt", 'utf8', (err, data) => {
+        expect(err).toBe(null);
+        expect(data).toEqual('Hello from "a"');
+        done();
+      });
+    });
+    it("read file /1/d.txt", done => {
+      fs.readFile("/1/d.txt", 'utf8', (err, data) => {
+        expect(err).toBe(null);
+        expect(data).toEqual('Hello from "d"');
+        done();
+      });
+    });
+  });
+
+  describe("writeFile", () => {
+    it("writing a file overwrites the server version", done => {
+      fs.writeFile("/a.txt", "welcome", (err) => {
+        expect(err).toBe(null)
+        fs.readFile("/a.txt", 'utf8', (err, data) => {
+          expect(err).toBe(null);
+          expect(data).toEqual('welcome');
+          done();
+        });
+      });
+    });
+  });
+
+  describe("unlink", () => {
+    it("deleting a file should make the file appear deleted", done => {
+      fs.unlink("/0/a.txt", (err) => {
+        fs.readFile("/0/a.txt", 'utf8', (err) => {
+          expect(err).not.toBe(null);
+          expect(err.code).toEqual('ENOENT');
+          fs.readdir("/0", (err, data) => {
+            expect(err).toBe(null)
+            expect(data).toEqual(["b.txt", "c.txt"])
+            done();
+          });
+        });
+      });
+    });
+  });
+});
diff --git a/src/index.js b/src/index.js
@@ -7,16 +7,20 @@ const Stat = require("./Stat.js");
 const CacheFS = require("./CacheFS.js");
 const { ENOENT, ENOTEMPTY } = require("./errors.js");
 const IdbBackend = require("./IdbBackend.js");
+const HttpBackend = require("./HttpBackend.js")
 const clock = require("./clock.js");
 
 export default class FS {
-  constructor(name, { wipe } = {}) {
+  constructor(name, { wipe, url } = {}) {
     this._backend = new IdbBackend(name);
     this._cache = new CacheFS(name);
     this.saveSuperblock = debounce(() => {
       console.log("saving superblock");
       this._saveSuperblock();
     }, 500);
+    if (url) {
+      this._fallback = new HttpBackend(url)
+    }
     if (wipe) {
       this.superblockPromise = this._wipe();
     } else {
@@ -43,14 +47,30 @@ export default class FS {
     return [filepath, opts, cb];
   }
   _wipe() {
-    return this._backend.wipe().then(() => this._saveSuperblock());
+    return this._backend.wipe().then(() => {
+      if (this._fallback) {
+        return this._fallback.loadSuperblock().then(text => {
+          if (text) {
+            this._cache.loadSuperBlock(text)
+          }
+        })
+      }
+     }).then(() => this._saveSuperblock());
   }
   _saveSuperblock() {
     return this._backend.saveSuperblock(this._cache._root);
   }
   _loadSuperblock() {
     return this._backend.loadSuperblock().then(root => {
-      if (root) this._cache._root = root;
+      if (root) {
+        this._cache.loadSuperBlock(root);
+      } else if (this._fallback) {
+        return this._fallback.loadSuperblock().then(text => {
+          if (text) {
+            this._cache.loadSuperBlock(text)
+          }
+        })
+      }
     });
   }
   readFile(filepath, opts, cb) {
@@ -66,6 +86,13 @@ export default class FS {
           return cb(err);
         }
         this._backend.readFile(filepath)
+          .then(data => {
+            if (data || !this._fallback) {
+              return data
+            } else {
+              return this._fallback.readFile(filepath)
+            }
+          })
           .then(data => {
             if (data) {
               if (encoding === "utf8") {
diff --git a/src/superblocktxt.js b/src/superblocktxt.js
@@ -1,3 +1,4 @@
+#! /usr/bin/env node
 var fs = require('fs')
 var path = require('path')
 var symLinks = {}
@@ -7,6 +8,9 @@ module.exports = (dirpath) => {
   const printTree = (root, indent) => {
     let files = fs.readdirSync(root)
     for (let file of files) {
+      // Ignore itself
+      if (file === '.superblock.txt') continue
+
       let fpath = `${root}/${file}`
       let lstat = fs.lstatSync(fpath)
       // Avoid infinite loops.
@@ -31,5 +35,11 @@ module.exports = (dirpath) => {
     }
   };
   printTree(dirpath, 0);
-  return str.trimStart();
-}
+  return str.trimStart() + '\n';
+}
+
+if (!module.parent) {
+  let filepath = process.cwd() + '/.superblock.txt'
+  let contents = module.exports(process.cwd())
+  fs.writeFileSync(filepath, contents)
+}
