Refactor detectMultipleHolderNames for efficient use of RAM.

[ghost]

Fixes #7006 (Out Of Memory Exception thrown)

Purpose of the method is to (a) maintain a list of flagged disputes, and (b) notify listeners if new items were added.
Using toString() on a large map of String to List caused an OOM exception.
For (b) notifying listeners it is only the change in flagged dispute count that is relevant (so the UI can display an alert icon). The same effect can be obtained by counting identified records.

Verification

User opens a dispute using a payment account that has a different holder name than in a previous dispute. Mediator clicks on the alert icon.

[alvasw]

Concept ACK

Good catch! The toString() comparison is indeed bad.

I saw that you're using a AtomicLongs to count the item. Does this imply that detectMultipleHolderNames() is called from multiple threads? If that's the case suspiciousDisputesByTraderMap shouldn't be a HashMap.

Otherwise the following change is simpler and faster:

diff --git a/core/src/main/java/bisq/core/support/dispute/agent/MultipleHolderNameDetection.java b/core/src/main/java/bisq/core/support/dispute/agent/MultipleHolderNameDetection.java
index 1be96332ef..09c722eed5 100644
--- a/core/src/main/java/bisq/core/support/dispute/agent/MultipleHolderNameDetection.java
+++ b/core/src/main/java/bisq/core/support/dispute/agent/MultipleHolderNameDetection.java
@@ -146,7 +146,10 @@ public class MultipleHolderNameDetection {
     ///////////////////////////////////////////////////////////////////////////////////////////
 
     public void detectMultipleHolderNames() {
-        String previous = suspiciousDisputesByTraderMap.toString();
+        int previous = suspiciousDisputesByTraderMap.values().stream()
+                .mapToInt(List::size)
+                .sum();
+
         getAllDisputesByTraderMap().forEach((key, value) -> {
             Set<String> userNames = value.stream()
                     .map(dispute -> {
@@ -161,8 +164,12 @@ public class MultipleHolderNameDetection {
                 suspiciousDisputesByTraderMap.put(key, value);
             }
         });
-        String updated = suspiciousDisputesByTraderMap.toString();
-        if (!previous.equals(updated)) {
+
+        int updated = suspiciousDisputesByTraderMap.values().stream()
+                .mapToInt(List::size)
+                .sum();
+
+        if (previous != updated) {
             listeners.forEach(Listener::onSuspiciousDisputeDetected);
         }
     }

[ghost]

Review change to use int applied.

[alvasw]

utACK

[alejandrogarcia83]

utACK