first commit

.gitignore

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+# Logs
+logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# Runtime data
+pids
+*.pid
+*.seed
+*.pid.lock
+
+# Directory for instrumented libs generated by jscoverage/JSCover
+lib-cov
+
+# Coverage directory used by tools like istanbul
+coverage
+
+# nyc test coverage
+.nyc_output
+
+# Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files)
+.grunt
+
+# Bower dependency directory (https://bower.io/)
+bower_components
+
+# node-waf configuration
+.lock-wscript
+
+# Compiled binary addons (http://nodejs.org/api/addons.html)
+build/Release
+
+# Dependency directories
+node_modules/
+jspm_packages/
+
+# Typescript v1 declaration files
+typings/
+
+# Optional npm cache directory
+.npm
+
+# Optional eslint cache
+.eslintcache
+
+# Optional REPL history
+.node_repl_history
+
+# Output of 'npm pack'
+*.tgz
+
+# Yarn Integrity file
+.yarn-integrity
+
+# dotenv environment variables file
+.env
+
+

README.md

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+# eth-gas-json
+
+Beginnings of an API wrapper around the [ethgasstation.info](https://ethgasstation.info) oracle. Caches the Oracle JSON in memory.

app.js

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+require('dotenv').config();
+
+const fs              = require('fs');
+const cluster         = require('cluster');
+
+if (cluster.isMaster) {
+    let processes = 1; // require('os').cpus().length;
+    console.log("Spawning " + processes + " worker processes...");
+    for (let i = 0; i < processes; i += 1) {
+        cluster.fork();
+    };
+} else {
+    const express         = require('express');
+    const bodyParser      = require('body-parser');
+    const http            = require('http');
+    const path            = require('path');
+    const app             = express();
+    const helmet          = require('helmet');
+
+    app.set('port', process.env.PORT || 8080);
+    app.use(helmet());
+    app.use(bodyParser.json());
+
+    fs.readdirSync('./controllers').forEach((jsfile) => {
+        if (jsfile.substr(-3) === '.js') {
+            let controller = require('./controllers/' + jsfile);
+            controller(app);
+        }
+    });
+
+    app.get('/', (req, res) => {
+        res.json({
+            result: 'success'
+        });
+    })
+
+    http.createServer(app).listen(app.get('port'), () => {
+        console.log('Express worker process ' + cluster.worker.id + ' listening on ' + app.get('port'));
+    });
+}

controllers/gasAPI.js

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+let HttpJsonCache = require('../lib/HttpJsonCache');
+
+class GasApiController {
+
+    constructor() { 
+    }
+
+    getKey (req, res) {
+        let data = {};
+        new HttpJsonCache().getJSON('https://ethgasstation.info/json/ethgasAPI.json')
+        .then((data) => {
+            if (req.params.key in data) {
+                let ret = { result: 'success' }
+                ret[req.params.key] = data[req.params.key];
+                res.json(ret);
+            } else {
+                res.status(404).json({ result: 'error', message: 'Property not found' });
+            }
+        })
+        .catch((err) => {
+            res.status(503).json({ result: 'error', message: 'Cannot fetch from EthGasStation.' });            
+        });
+    } 
+}
+
+module.exports = (route) => {
+    var controller = new GasApiController();
+    route.get('/gasAPI/:key', controller.getKey);
+}
+

lib/HttpJsonCache.js

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+/**
+ * Cache JSON files from HTTP source to memory.
+ */
+
+const request = require('request-promise');
+const crypto  = require('crypto');
+
+let instance = null;
+
+class HttpJsonCache {
+
+    constructor(opts) {
+        if (!instance) {
+            instance = this;
+            let defaults = {
+                expiry: 60 // expiry time in seconds
+            };
+            this.options = Object.assign({}, defaults, opts);
+            this.memcache = {};
+        }
+        return instance;
+    }
+
+    async getJSON (file_uri) {
+        let key = this._hashKey(file_uri);
+
+        return new Promise((resolve, reject) => {
+            if (key in this.memcache) {
+                console.log('cache hit');
+                // cache hit
+                if (!this._isExpired(this.memcache[key])) {
+                    // still valid
+                    console.log('not expired, run from cache');
+                    resolve(this.memcache[key].data);
+                    return;
+                }
+            }
+
+            console.log('cache miss');
+            // cache miss
+            let result = null;
+            let attempts = 0;
+            request.get({
+                uri: file_uri,
+                headers: {
+                    'User-Agent': 'eth-gas-json'
+                },
+                json: true
+            })
+            .then((data) => {
+                result = data;
+                if (typeof result !== 'object') {
+                    reject('bad-data');
+                }
+                this.memcache[key] = this._makeFileObject(result);
+                resolve(result);        
+            })
+            .catch((err) => {
+                attempts += 1;
+                if (attempts >= this.options.retries) {
+                    reject('too-many-retries');
+                }
+            });
+        });
+    }
+
+    _hashKey (str) {
+        let h = crypto.createHash('sha256');
+        h.update(str);
+        return h.digest('hex');
+    }
+
+    _isExpired (fileObject) {
+        return (fileObject.expirationDate < new Date().getTime());
+    }
+
+    _makeFileObject (data, expirationDate) {
+        if (typeof expirationDate !== 'number') {
+            expirationDate = new Date().getTime() + this.options.expiry * 1000;
+            console.log('setting expiration date to ' + expirationDate);
+        }
+        return {
+            expirationDate: expirationDate,
+            data: data
+        }
+    }
+
+}
+
+module.exports = HttpJsonCache;