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August 29, 2015 14:12
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Git-like in-memory object store
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| // db | |
| var crypto = require("crypto"), | |
| zlib = require("zlib"), | |
| fs = require("fs"); | |
| var Oddball = function(hash, digest) { | |
| this.hash = hash; | |
| this.digest = digest; | |
| this.data = {}; | |
| this.refs = {}; | |
| } | |
| Oddball.prototype.hashfn = function(data) { | |
| return crypto.createHash(this.hash).update(data).digest(this.digest); | |
| } | |
| Oddball.prototype.store = function(str) { | |
| var hash = this.hashfn(str); | |
| this.data[hash] = str; | |
| return hash; | |
| }; | |
| Oddball.prototype.storeObject = function(obj) { | |
| return this.store(JSON.stringify(obj)); | |
| } | |
| Oddball.prototype.retrieve = function(hash) { | |
| return hash ? this.data[hash] || this.data[this.refs[hash]] : null; | |
| } | |
| Oddball.prototype.retrieveObject = function(hash) { | |
| return JSON.parse(this.retrieve(hash)); | |
| } | |
| Oddball.prototype.write = function(filename, cb) { | |
| zlib.gzip(JSON.stringify(this), function(err, res) { | |
| if(err) throw err; | |
| fs.writeFile(filename, res, cb); | |
| }); | |
| } | |
| Oddball.read = function(filename, cb) { | |
| fs.readFile(filename, null, function(err, data) { | |
| if(err) throw err; | |
| zlib.gunzip(data, function(err, data) { | |
| var o = JSON.parse(data.toString()) | |
| o.__proto__ = Oddball.prototype; | |
| if(cb) cb(o); | |
| }); | |
| }); | |
| } | |
| // usage | |
| var odb = new Oddball("sha1", "hex"); | |
| odb.refs.head = odb.storeObject( {parent: null, timestamp:Date.now(), body:odb.store("first")} ); | |
| odb.refs.head = odb.storeObject( {parent: odb.refs.head, timestamp:Date.now(), body:odb.store("second")} ); | |
| odb.refs.head = odb.storeObject( {parent: odb.refs.head, timestamp:Date.now(), body:odb.store("third")} ); | |
| var o = odb.retrieveObject("head"); | |
| while(o) { | |
| console.log(odb.retrieve(o.body)); | |
| o = odb.retrieveObject(o.parent); | |
| } | |
| console.log(JSON.stringify(odb)) | |
| odb.write("foo.odd", function() { | |
| Oddball.read("foo.odd", function(odb) { | |
| console.log(odb.retrieveObject("head")); | |
| var o = odb.retrieveObject("head"); | |
| while(o) { | |
| console.log(odb.retrieve(o.body)); | |
| o = odb.retrieveObject(o.parent); | |
| } | |
| }); | |
| }); |
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