refactor: Make FeeFilterRounder thread safe

hebasto · hebasto · commit 877cca538b29 · 2020-06-13T18:09:34.000+03:00
diff --git a/src/net_processing.cpp b/src/net_processing.cpp
@@ -4396,7 +4396,7 @@ bool PeerLogicValidation::SendMessages(CNode* pto)
             int64_t timeNow = GetTimeMicros();
             if (timeNow > pto->m_tx_relay->nextSendTimeFeeFilter) {
                 static CFeeRate default_feerate(DEFAULT_MIN_RELAY_TX_FEE);
-                static FeeFilterRounder filterRounder(default_feerate);
+                static const FeeFilterRounder filterRounder(default_feerate);
                 CAmount filterToSend = filterRounder.round(currentFilter);
                 // We always have a fee filter of at least minRelayTxFee
                 filterToSend = std::max(filterToSend, ::minRelayTxFee.GetFeePerK());
diff --git a/src/policy/fees.cpp b/src/policy/fees.cpp
@@ -968,10 +968,11 @@ FeeFilterRounder::FeeFilterRounder(const CFeeRate& minIncrementalFee)
     }
 }
 
-CAmount FeeFilterRounder::round(CAmount currentMinFee)
+CAmount FeeFilterRounder::round(CAmount currentMinFee) const
 {
     std::set<double>::iterator it = feeset.lower_bound(currentMinFee);
-    if ((it != feeset.begin() && insecure_rand.rand32() % 3 != 0) || it == feeset.end()) {
+    const uint32_t rand = WITH_LOCK(m_random_context_mutex, return m_insecure_rand.rand32());
+    if ((it != feeset.begin() && rand % 3 != 0) || it == feeset.end()) {
         it--;
     }
     return static_cast<CAmount>(*it);
diff --git a/src/policy/fees.h b/src/policy/fees.h
@@ -281,11 +281,12 @@ class FeeFilterRounder
     explicit FeeFilterRounder(const CFeeRate& minIncrementalFee);
 
     /** Quantize a minimum fee for privacy purpose before broadcast **/
-    CAmount round(CAmount currentMinFee);
+    CAmount round(CAmount currentMinFee) const;
 
 private:
     std::set<double> feeset;
-    FastRandomContext insecure_rand;
+    mutable Mutex m_random_context_mutex;
+    mutable FastRandomContext m_insecure_rand GUARDED_BY(m_random_context_mutex);
 };
 
 #endif // BITCOIN_POLICY_FEES_H

Original file line number	Diff line number	Diff line change
`@@ -968,10 +968,11 @@ FeeFilterRounder::FeeFilterRounder(const CFeeRate& minIncrementalFee)`
`968`	`968`	`}`
`969`	`969`	`}`
`970`	`970`
`971`		`-CAmount FeeFilterRounder::round(CAmount currentMinFee)`
	`971`	`+CAmount FeeFilterRounder::round(CAmount currentMinFee) const`
`972`	`972`	`{`
`973`	`973`	`std::set<double>::iterator it = feeset.lower_bound(currentMinFee);`
`974`		`- if ((it != feeset.begin() && insecure_rand.rand32() % 3 != 0) \|\| it == feeset.end()) {`
	`974`	`+ const uint32_t rand = WITH_LOCK(m_random_context_mutex, return m_insecure_rand.rand32());`
	`975`	`+ if ((it != feeset.begin() && rand % 3 != 0) \|\| it == feeset.end()) {`
`975`	`976`	`it--;`
`976`	`977`	`}`
`977`	`978`	`return static_cast<CAmount>(*it);`