set options in hyperdb when new graph is made

Author: Benjamin Forster

index.js

@@ -12,6 +12,7 @@ const Variable = require('./lib/Variable')
 const HyperdbReadTransform = require('./lib/HyperdbReadTransform')
 const JoinStream = require('./lib/JoinStream')
 const planner = require('./lib/planner')
+const pkg = require('./package.json')
 const attachCreateReadStream = require('./lib/hyperdbModifier').attachCreateReadStream
 
 const Transform = stream.Transform
@@ -25,11 +26,19 @@ if (!hyperdb.createReadStream) {
 function Graph (storage, key, opts) {
   if (!(this instanceof Graph)) return new Graph(storage, key, opts)
   events.EventEmitter.call(this)
-  this.db = hyperdb(storage, key, opts)
 
-  // what are the default prefixes
-  this._prefixes = constants.DEFAULT_PREFIXES
-  this._indexes = (opts && opts.index === 'small')
+  if (typeof key === 'string') key = Buffer.from(key, 'hex')
+
+  if (!Buffer.isBuffer(key) && !opts) {
+    opts = key
+    key = null
+  }
+
+  if (!opts) opts = {}
+  this.db = hyperdb(storage, key, opts)
+  this._prefixes = opts.prefixes || constants.DEFAULT_PREFIXES
+  this._prefixes._ = opts.base || constants.DEFAULT_BASE
+  this._indexes = opts.index === 'tri'
     ? constants.HEXSTORE_INDEXES_REDUCED
     : constants.HEXSTORE_INDEXES
   this._indexKeys = Object.keys(this._indexes)
@@ -38,13 +47,33 @@ function Graph (storage, key, opts) {
     this.emit('error', e)
   })
   this.db.on('ready', (e) => {
-    this.emit('ready', e)
-    // check prefixes
+    if (utils.isNewDatabase(this.db)) {
+      this._onNew((err) => {
+        if (err) return this.emit('error', err)
+        this.emit('ready', e)
+      })
+    } else {
+      this.emit('ready', e)
+    }
   })
 }
 
 inherits(Graph, events.EventEmitter)
 
+Graph.prototype._onNew = function (cb) {
+  const metadata = [
+    ['@version', pkg.version],
+    ['@index', Object.keys(this._indexes).length === 3 ? 'tri' : 'hex'],
+    ['@name', this._prefixes._]
+  ]
+  Object.keys(this._prefixes).forEach((key) => {
+    if (key !== '_') {
+      metadata.push([prefixes.toKey(key), this._prefixes[key]])
+    }
+  })
+  utils.put(this.db, metadata, cb)
+}
+
 Graph.prototype.v = (name) => new Variable(name)
 
 Graph.prototype.listPrefixes = function (callback) {
@@ -206,9 +235,7 @@ Graph.prototype._possibleIndexes = function (types) {
       }
     })
   })
-
   result.sort()
-
   return result
 }
 

lib/constants.js

@@ -12,13 +12,14 @@ const HEXSTORE_INDEXES_REDUCED = {
   osp: HEXSTORE_INDEXES.osp
 }
 const PREFIX_KEY = '@prefix/'
+const DEFAULT_BASE = 'hg://'
 const DEFAULT_PREFIXES = {
-  _: 'hg://',
   foaf: 'http://xmlns.com/foaf/0.1/'
 }
 
 module.exports = {
   PREFIX_KEY,
+  DEFAULT_BASE,
   DEFAULT_PREFIXES,
   HEXSTORE_INDEXES,
   HEXSTORE_INDEXES_REDUCED

lib/utils.js

@@ -9,6 +9,22 @@ const tripleAliasMap = {
   o: 'object'
 }
 
+function isNewDatabase (db) {
+  return db._writers.length > 0 || db._writers[0].feed.length > 0
+}
+
+function put (db, data, callback) {
+  var i = 0
+
+  next()
+
+  function next (err) {
+    if (err) return callback(err)
+    var v = data[i++]
+    db.put(v[0], v[1], (i < data.length - 1) ? next : callback)
+  }
+}
+
 function collect (stream, cb) {
   var res = []
   stream.on('data', res.push.bind(res))
@@ -180,6 +196,8 @@ function materializer (pattern, data) {
 }
 
 module.exports = {
+  isNewDatabase,
+  put,
   escapeKeyValue,
   unescapeKeyValue,
   encodeTriple,

test/basic.spec.js

@@ -0,0 +1,86 @@
+/* eslint-env mocha */
+const expect = require('chai').expect
+const ram = require('random-access-memory')
+const hypergraph = require('../index')
+const constants = require('../lib/constants')
+
+function ramStore (filename) {
+   // filename will be one of: data, bitfield, tree, signatures, key, secret_key
+   // the data file will contain all your data concattenated.
+   // just store all files in ram by returning a random-access-memory instance
+  return ram()
+}
+
+describe('hypergraph', function () {
+  let db
+  context('when newly created it adds metadata to db', () => {
+    it('includes graph version', (done) => {
+      db = hypergraph(ramStore)
+      db.on('ready', () => {
+        db.db.get('@version', (err, node) => {
+          expect(err).to.not.be.a('error')
+          expect(node[0].value.toString()).to.match(/\d+.\d+.\d+.*/)
+          done()
+        })
+      })
+    })
+    it('includes index type (default)', (done) => {
+      db = hypergraph(ramStore)
+      db.on('ready', () => {
+        db.db.get('@index', (err, node) => {
+          expect(err).to.not.be.a('error')
+          expect(node[0].value.toString()).to.eql('hex')
+          done()
+        })
+      })
+    })
+    it('includes index type (option.index = tri)', (done) => {
+      db = hypergraph(ramStore, { index: 'tri' })
+      db.on('ready', () => {
+        db.db.get('@index', (err, node) => {
+          expect(err).to.not.be.a('error')
+          expect(node[0].value.toString()).to.eql('tri')
+          done()
+        })
+      })
+    })
+    it('includes name (default)', (done) => {
+      db = hypergraph(ramStore)
+      db.on('ready', () => {
+        db.db.get('@name', (err, node) => {
+          expect(err).to.not.be.a('error')
+          expect(node[0].value.toString()).to.eql(constants.DEFAULT_BASE)
+          done()
+        })
+      })
+    })
+    it('includes name (option.name)', (done) => {
+      db = hypergraph(ramStore, { base: 'this://' })
+      db.on('ready', () => {
+        db.db.get('@name', (err, node) => {
+          expect(err).to.not.be.a('error')
+          expect(node[0].value.toString()).to.eql('this://')
+          done()
+        })
+      })
+    })
+    it('includes default prefixes', (done) => {
+      db = hypergraph(ramStore)
+      db.on('ready', () => {
+        const stream = db.db.createReadStream('@prefix/')
+        stream.on('data', (nodes) => {
+
+        })
+        stream.on('error', done)
+        stream.on('end', () => {
+          done()
+        })
+      })
+    })
+  })
+  context('when loading db that already exists', () => {
+    it('does not add new metadata')
+    it('overrides options with metadata set in hyperdb (index)')
+    it('overrides options with metadata set in hyperdb (name)')
+  })
+})

test/triple-store.spec.js

@@ -635,7 +635,7 @@ describe('generateBatch', function () {
   })
   context('with index option set to small', () => {
     beforeEach(function () {
-      db = hypergraph(ramStore, null, { index: 'small' })
+      db = hypergraph(ramStore, null, { index: 'tri' })
     })
 
     afterEach(function (done) {