Fix old events from being emitted at the beginning of a filter (ethers-io#3069, ethers-io#3094).

ricmoo · ricmoo · commit ea2d2453a535 · 2022-07-20T16:36:30.000-04:00
diff --git a/packages/providers/src.ts/base-provider.ts b/packages/providers/src.ts/base-provider.ts
@@ -1069,18 +1069,26 @@ export class BaseProvider extends Provider implements EnsProvider {
                     if (!event._inflight) {
                         event._inflight = true;
 
-                        // Filter from the last known event; due to load-balancing
+                        // This is the first filter for this event, so we want to
+                        // restrict events to events that happened no earlier than now
+                        if (event._lastBlockNumber === -2) {
+                            event._lastBlockNumber = blockNumber - 1;
+                        }
+
+                        // Filter from the last *known* event; due to load-balancing
                         // and some nodes returning updated block numbers before
                         // indexing events, a logs result with 0 entries cannot be
                         // trusted and we must retry a range which includes it again
                         const filter = event.filter;
                         filter.fromBlock = event._lastBlockNumber + 1;
                         filter.toBlock = blockNumber;
 
-                        // Prevent fitler ranges from growing too wild
-                        if (filter.toBlock - this._maxFilterBlockRange > filter.fromBlock) {
-                            filter.fromBlock = filter.toBlock - this._maxFilterBlockRange;
-                        }
+                        // Prevent fitler ranges from growing too wild, since it is quite
+                        // likely there just haven't been any events to move the lastBlockNumber.
+                        const minFromBlock = filter.toBlock - this._maxFilterBlockRange;
+                        if (minFromBlock > filter.fromBlock) { filter.fromBlock = minFromBlock; }
+
+                        if (filter.fromBlock < 0) { filter.fromBlock = 0; }
 
                         const runner = this.getLogs(filter).then((logs) => {
                             // Allow the next getLogs
