Merge pull request #35 from status-im/feat--survive-reorgs

feat: survive reorgs

src/database.js

@@ -33,28 +33,21 @@ class Database {
     this.db = new loki(dbFilename, {
       autoload: true,
       autoloadCallback: () => {
-        this.databaseInitialize(cb)
+        this.databaseInitialize()
       },
       autosave: true,
       env: getENV(),
       autosaveInterval: 2000
-    })
+    });
+
     this.events = events;
   }
 
   databaseInitialize(cb) {
-    let children = this.db.getCollection('children')
-    if (!children) {
-      children = this.db.addCollection('children')
-      this.db.saveDatabase()
-    }
-
     let dbChanges = fromEvent(this.events, "updateDB")
     dbChanges.subscribe(() => {
       this.db.saveDatabase()
     })
-
-    cb();
   }
 
   getLastKnownEvent(eventKey) {
@@ -71,8 +64,8 @@ class Database {
     }
     
     return {
-      firstKnownBlock, 
-      lastKnownBlock
+      firstKnownBlock: firstKnownBlock || 0, 
+      lastKnownBlock: lastKnownBlock || 0
     };
   }
 
@@ -92,6 +85,18 @@ class Database {
     children.insert(values);
   }
 
+  deleteEvent(eventKey, eventId) {
+    const collection = this.db.getCollection(eventKey);
+    if(collection)
+    collection.chain().find({ 'id': eventId }).remove();
+  }
+
+  deleteNewestBlocks(eventKey, gteBlockNum) {
+    const collection = this.db.getCollection(eventKey);
+    if(collection)
+    collection.chain().find({ 'blockNumber': {'$gte': gteBlockNum}}).remove();
+  }
+
 }
 
 export default Database;

src/eventSyncer.js

@@ -10,10 +10,12 @@ class EventSyncer {
     this.subscriptions = [];
   }
 
-  track(contractInstance, eventName, filterConditionsOrCb){
+  track(contractInstance, eventName, filterConditionsOrCb, gteBlockNum){
     const isFilterFunction = typeof filterConditionsOrCb === 'function';
     const eventKey =  hash(Object.assign({address: contractInstance.options.address}, (isFilterFunction ? {filterConditionsOrCb} : (filterConditionsOrCb || {}))));
 
+    this.db.deleteNewestBlocks(eventKey, gteBlockNum);
+
     let filterConditions = {fromBlock: 0, toBlock: "latest"};
     let filterConditionsCb;
     if (isFilterFunction) {
@@ -30,16 +32,26 @@ class EventSyncer {
     contractObserver.subscribe((e) => {
       if(!e) return;
 
+      const id = hash({eventName, blockNumber: e.blockNumber, transactionIndex: e.transactionIndex, logIndex: e.logIndex});
+        
       // TODO: would be nice if this was smart enough to understand the type of returnValues and do the needed conversions
       const eventData = {
-        id: hash({eventName, blockNumber: e.blockNumber, transactionIndex: e.transactionIndex, logIndex: e.logIndex}),
+        id,
         returnValues: {...e.returnValues},
         blockNumber: e.blockNumber, 
         transactionIndex: e.transactionIndex, 
-        logIndex: e.logIndex
+        logIndex: e.logIndex,
+        removed: e.removed
       }
 
-      sub.next({blockNumber: e.blockNumber, ...e.returnValues});
+      // TODO: test reorgs
+
+      sub.next(eventData);
+
+      if(e.removed){
+        this.db.deleteEvent(eventKey, id);
+        return;
+      }
 
       if (this.db.eventExists(eventKey, eventData.id)) return;
 

src/logSyncer.js

@@ -117,8 +117,12 @@ class LogSyncer {
   _getPastEvents(filterConditions, eventKey) {
     const cb = this._parseEventCBFactory(filterConditions, eventKey);
     this.web3.getPastLogs(options, (err, logs) => {
+      if(err) {
+        throw new Error(err);
+      }
+      
       logs.forEach(l => {
-        cb(err, l);
+        cb(null, l);
       })
     });
   }
@@ -131,8 +135,7 @@ class LogSyncer {
       
   _parseEventCBFactory = (filterConditions, eventKey) => (err, ev) => {
     if(err) {
-      console.error(err);
-      return;
+      throw new Error(err);
     }
 
     if (filterConditions) {

src/subspace.js

@@ -22,8 +22,10 @@ export default class Subspace {
     this.web3 = new Web3Eth(provider);
 
     this.options = {};
+    this.options.refreshLastNBlocks = options.refreshLastNBlocks || 12;
     this.options.callInterval = options.callInterval || 0;
     this.options.dbFilename = options.dbFilename || 'subspace.db';
+    this.latestBlockNumber = undefined;
     
     this.newBlocksSubscription = null;
     this.intervalTracker = null;
@@ -32,16 +34,21 @@ export default class Subspace {
 
   init() {
     return new Promise((resolve, reject) => {
-      this._db = new Database(this.options.dbFilename, this.events, resolve);
+      this._db = new Database(this.options.dbFilename, this.events);
       this.db = this._db.db;
       this.eventSyncer = new EventSyncer(this.web3, this.events, this._db);
       this.logSyncer = new LogSyncer(this.web3, this.events, this._db);
+
+      this.web3.getBlock('latest').then(block => {
+        this.latestBlockNumber = block.number;
+        resolve();
+      })
     })
   }
 
   // TODO: get contract abi/address instead
   trackEvent(contractInstance, eventName, filterConditionsOrCb) {
-    return this.eventSyncer.track(contractInstance, eventName, filterConditionsOrCb);
+    return this.eventSyncer.track(contractInstance, eventName, filterConditionsOrCb, this.latestBlockNumber - this.options.refreshLastNBlocks);
   }
 
   clearDB(collection) {