Merge bitcoin#9558: Clarify assumptions made about when BlockCheck is…

… called

c4a6929 Clarify assumptions made about when BlockCheck is called (Matt Corallo)

Tree-SHA512: 2eceb0c4f06c7fd6b290b93843bda11a4b63131559c5e8226bfec84596ed4e54ee6d8f5bc9cf789a80675be8b8079cf9234c96032df306258cb2260b9d8c7825

src/validationinterface.h

@@ -69,7 +69,12 @@ struct CMainSignals {
     boost::signals2::signal<void (const uint256 &)> Inventory;
     /** Tells listeners to broadcast their data. */
     boost::signals2::signal<void (int64_t nBestBlockTime, CConnman* connman)> Broadcast;
-    /** Notifies listeners of a block validation result */
+    /**
+     * Notifies listeners of a block validation result.
+     * If the provided CValidationState IsValid, the provided block
+     * is guaranteed to be the current best block at the time the
+     * callback was generated (not necessarily now)
+     */
     boost::signals2::signal<void (const CBlock&, const CValidationState&)> BlockChecked;
     /** Notifies listeners that a key for mining is required (coinbase) */
     boost::signals2::signal<void (boost::shared_ptr<CReserveScript>&)> ScriptForMining;