Merge pull request #141 from bancorprotocol/support-max-block-age

user can specify maxBlockAge to force skipping logs

README.md

@@ -42,6 +42,7 @@ let sdkCache: ChainCache;
 let carbonSDK: Toolkit;
 let isInitialized = false;
 let isInitializing = false;
+const MAX_BLOCK_AGE = 2000; // past this many blocks, the SDK won't attempt to catch up by processing events and instead call the contracts for strategy info.
 
 const init = async (
   rpcUrl: string,
@@ -56,7 +57,7 @@ const init = async (
     1
   );
   api = new ContractsApi(provider, config);
-  const { cache, startDataSync } = initSyncedCache(api.reader, cachedData);
+  const { cache, startDataSync } = initSyncedCache(api.reader, cachedData, MAX_BLOCK_AGE);
   sdkCache = cache;
   carbonSDK = new Toolkit(
     api,
@@ -80,22 +81,23 @@ const init = async (
 ## Notes
 
 ### 1. The SDK Logger supports 3 verbosity levels:
-  - `0` (default) only prints errors and important logs.
-  - `1` (debug) prints highly verbose logs.
-  - `2` (debug readable) is same as `1` but also converts any BigNumber to an easy to read string (impacting performance).
-
-  To use it in Node, set the environment variable `CARBON_DEFI_SDK_VERBOSITY` to the desired level.
-  To use it from a browser app do, before importing the SDK:
 
-  ```js
-  window.CARBON_DEFI_SDK_VERBOSITY = 2;
-  ```
+- `0` (default) only prints errors and important logs.
+- `1` (debug) prints highly verbose logs.
+- `2` (debug readable) is same as `1` but also converts any BigNumber to an easy to read string (impacting performance).
+
+To use it in Node, set the environment variable `CARBON_DEFI_SDK_VERBOSITY` to the desired level.
+To use it from a browser app do, before importing the SDK:
+
+```js
+window.CARBON_DEFI_SDK_VERBOSITY = 2;
+```
 
 ### 2. For usage with contracts version < 5, without the enhanced range for trade by source:
 
-  ```js
-  window.LEGACY_TRADE_BY_SOURCE_RANGE = true;
-  ```
+```js
+window.LEGACY_TRADE_BY_SOURCE_RANGE = true;
+```
 
 ## Authors
 

package.json

@@ -2,7 +2,7 @@
   "name": "@bancor/carbon-sdk",
   "type": "module",
   "source": "src/index.ts",
-  "version": "0.0.97-DEV",
+  "version": "0.0.98-DEV",
   "description": "The SDK is a READ-ONLY tool, intended to facilitate working with Carbon contracts. It's a convenient wrapper around our matching algorithm, allowing programs and users get a ready to use transaction data that will allow them to manage strategies and fulfill trades",
   "main": "dist/index.cjs",
   "module": "dist/index.js",

src/chain-cache/ChainCache.ts

@@ -174,7 +174,7 @@ export class ChainCache extends (EventEmitter as new () => TypedEventEmitter<Cac
     logger.debug('Cache miss for pair', token0, token1, 'resolved');
   }
 
-  public clear(): void {
+  public clear(silent: boolean = false): void {
     const pairs = Object.keys(this._strategiesByPair).map(fromPairKey);
     this._strategiesByPair = {};
     this._strategiesById = {};
@@ -183,7 +183,9 @@ export class ChainCache extends (EventEmitter as new () => TypedEventEmitter<Cac
     this._latestTradesByPair = {};
     this._latestTradesByDirectedPair = {};
     this._blocksMetadata = [];
-    this.emit('onPairDataChanged', pairs);
+    if (!silent) {
+      this.emit('onPairDataChanged', pairs);
+    }
   }
 
   //#region public getters

src/chain-cache/ChainSync.ts

@@ -22,10 +22,12 @@ export class ChainSync {
   // keep the time stamp of last fetch
   private _lastFetch: number = Date.now();
   private _initialSyncDone: boolean = false;
+  private _maxBlockAge?: number;
 
-  constructor(fetcher: Fetcher, chainCache: ChainCache) {
+  constructor(fetcher: Fetcher, chainCache: ChainCache, maxBlockAge?: number) {
     this._fetcher = fetcher;
     this._chainCache = chainCache;
+    this._maxBlockAge = maxBlockAge;
   }
 
   public async startDataSync(): Promise<void> {
@@ -35,10 +37,23 @@ export class ChainSync {
     }
     this._syncCalled = true;
     const blockNumber = await this._fetcher.getBlockNumber();
-    if (this._chainCache.getLatestBlockNumber() === 0) {
+    const latestBlockInCache = this._chainCache.getLatestBlockNumber();
+
+    if (latestBlockInCache === 0) {
       logger.debug('startDataSync - cache is new', arguments);
       // cache starts from scratch so we want to avoid getting events from the beginning of time
       this._chainCache.applyBatchedUpdates(blockNumber, [], [], [], [], []);
+    } else if (
+      this._maxBlockAge !== undefined &&
+      blockNumber - latestBlockInCache > this._maxBlockAge
+    ) {
+      logger.debug(
+        `startDataSync - cache is too old: current block ${blockNumber}, cache block ${latestBlockInCache}`,
+        arguments
+      );
+      // cache is too old so we want to clear it and avoid getting events from the beginning of time
+      this._chainCache.clear(true);
+      this._chainCache.applyBatchedUpdates(blockNumber, [], [], [], [], []);
     }
 
     // let's fetch all pairs from the chain and set them to the cache - to be used by the following syncs

src/chain-cache/index.ts

@@ -19,7 +19,8 @@ export * from './types';
  */
 export const initSyncedCache = (
   fetcher: Fetcher,
-  cachedData?: string
+  cachedData?: string,
+  maxBlockAge?: number
 ): { cache: ChainCache; startDataSync: () => Promise<void> } => {
   let cache: ChainCache | undefined;
   if (cachedData) {
@@ -30,7 +31,7 @@ export const initSyncedCache = (
     cache = new ChainCache();
   }
 
-  const syncer = new ChainSync(fetcher, cache);
+  const syncer = new ChainSync(fetcher, cache, maxBlockAge);
   cache.setCacheMissHandler(syncer.syncPairData.bind(syncer));
   return { cache, startDataSync: syncer.startDataSync.bind(syncer) };
 };