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feat(elections): scalable vote storage with atomic MongoDB ops and multi-server safety
Replace single-document read-modify-write with per-voter documents and atomic $inc tally counters for O(1) vote reads. Add StartElection and ResolveElection endpoints for idempotent multi-server election lifecycle. Remove SaveElectionData endpoint.
1 parent 28190f5 commit 7c3ab1c

12 files changed

Lines changed: 579 additions & 166 deletions

‎commons/src/main/java/net/swofty/commons/protocol/objects/election/ResolveElectionProtocolObject.java‎

Lines changed: 64 additions & 0 deletions
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@@ -0,0 +1,64 @@
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package net.swofty.commons.protocol.objects.election;
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import net.swofty.commons.protocol.ProtocolObject;
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import net.swofty.commons.protocol.Serializer;
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import org.json.JSONObject;
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public class ResolveElectionProtocolObject
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extends ProtocolObject<ResolveElectionProtocolObject.ResolveElectionMessage,
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ResolveElectionProtocolObject.ResolveElectionResponse> {
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@Override
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public Serializer<ResolveElectionMessage> getSerializer() {
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return new Serializer<>() {
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@Override
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public String serialize(ResolveElectionMessage value) {
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JSONObject json = new JSONObject();
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json.put("year", value.year());
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return json.toString();
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}
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@Override
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public ResolveElectionMessage deserialize(String json) {
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JSONObject obj = new JSONObject(json);
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return new ResolveElectionMessage(obj.getInt("year"));
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}
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@Override
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public ResolveElectionMessage clone(ResolveElectionMessage value) {
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return value;
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}
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};
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}
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@Override
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public Serializer<ResolveElectionResponse> getReturnSerializer() {
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return new Serializer<>() {
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@Override
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public String serialize(ResolveElectionResponse value) {
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JSONObject json = new JSONObject();
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json.put("resolved", value.resolved());
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json.put("serializedData", value.serializedData());
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return json.toString();
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}
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@Override
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public ResolveElectionResponse deserialize(String json) {
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JSONObject obj = new JSONObject(json);
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return new ResolveElectionResponse(
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obj.getBoolean("resolved"),
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obj.optString("serializedData", null)
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);
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}
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@Override
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public ResolveElectionResponse clone(ResolveElectionResponse value) {
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return value;
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}
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};
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}
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public record ResolveElectionMessage(int year) {}
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public record ResolveElectionResponse(boolean resolved, String serializedData) {}
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}

‎commons/src/main/java/net/swofty/commons/protocol/objects/election/SaveElectionDataProtocolObject.java‎

Lines changed: 0 additions & 58 deletions
This file was deleted.

‎commons/src/main/java/net/swofty/commons/protocol/objects/election/StartElectionProtocolObject.java‎

Lines changed: 68 additions & 0 deletions
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package net.swofty.commons.protocol.objects.election;
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import net.swofty.commons.protocol.ProtocolObject;
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import net.swofty.commons.protocol.Serializer;
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import org.json.JSONObject;
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public class StartElectionProtocolObject
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extends ProtocolObject<StartElectionProtocolObject.StartElectionMessage,
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StartElectionProtocolObject.StartElectionResponse> {
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@Override
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public Serializer<StartElectionMessage> getSerializer() {
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return new Serializer<>() {
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@Override
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public String serialize(StartElectionMessage value) {
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JSONObject json = new JSONObject();
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json.put("year", value.year());
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json.put("candidatesJson", value.candidatesJson());
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return json.toString();
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}
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@Override
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public StartElectionMessage deserialize(String json) {
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JSONObject obj = new JSONObject(json);
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return new StartElectionMessage(
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obj.getInt("year"),
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obj.getString("candidatesJson")
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);
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}
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@Override
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public StartElectionMessage clone(StartElectionMessage value) {
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return value;
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}
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};
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}
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@Override
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public Serializer<StartElectionResponse> getReturnSerializer() {
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return new Serializer<>() {
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@Override
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public String serialize(StartElectionResponse value) {
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JSONObject json = new JSONObject();
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json.put("started", value.started());
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json.put("serializedData", value.serializedData());
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return json.toString();
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}
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@Override
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public StartElectionResponse deserialize(String json) {
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JSONObject obj = new JSONObject(json);
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return new StartElectionResponse(
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obj.getBoolean("started"),
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obj.optString("serializedData", null)
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);
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}
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@Override
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public StartElectionResponse clone(StartElectionResponse value) {
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return value;
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}
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};
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}
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public record StartElectionMessage(int year, String candidatesJson) {}
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public record StartElectionResponse(boolean started, String serializedData) {}
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}

‎service.elections/src/main/java/net/swofty/service/election/ElectionDatabase.java‎

Lines changed: 99 additions & 24 deletions
Original file line numberDiff line numberDiff line change
@@ -7,14 +7,21 @@
77
import com.mongodb.client.MongoCollection;
88
import com.mongodb.client.MongoDatabase;
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import com.mongodb.client.model.Filters;
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import com.mongodb.client.model.ReplaceOptions;
1011
import com.mongodb.client.model.Updates;
1112
import net.swofty.service.generic.MongoDB;
1213
import org.bson.Document;
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15+
import java.util.HashMap;
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import java.util.List;
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import java.util.Map;
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1419
public record ElectionDatabase(String key) implements MongoDB {
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public static MongoClient client;
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public static MongoDatabase database;
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public static MongoCollection<Document> electionCollection;
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public static MongoCollection<Document> votesCollection;
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public static MongoCollection<Document> talliesCollection;
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@Override
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public MongoDB connect(String connectionString) {
@@ -24,6 +31,8 @@ public MongoDB connect(String connectionString) {
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database = client.getDatabase("Minestom");
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electionCollection = database.getCollection("elections");
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votesCollection = database.getCollection("election-votes");
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talliesCollection = database.getCollection("election-tallies");
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return this;
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}
2938

@@ -42,33 +51,25 @@ public boolean exists() {
4251
@Override
4352
public Object get(String key, Object def) {
4453
Document doc = electionCollection.find(Filters.eq("_id", this.key)).first();
45-
if (doc == null) {
46-
return def;
47-
}
54+
if (doc == null) return def;
4855
return doc.get(key);
4956
}
5057

5158
@Override
5259
public void insertOrUpdate(String key, Object value) {
53-
if (exists()) {
54-
Document query = new Document("_id", this.key);
55-
Document found = electionCollection.find(query).first();
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assert found != null;
57-
electionCollection.updateOne(found, Updates.set(key, value));
58-
return;
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}
60-
Document newDoc = new Document("_id", this.key);
61-
newDoc.append(key, value);
62-
electionCollection.insertOne(newDoc);
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Document doc = new Document("_id", this.key).append(key, value);
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electionCollection.replaceOne(
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Filters.eq("_id", this.key),
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doc,
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new ReplaceOptions().upsert(true)
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);
6366
}
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6568
@Override
6669
public boolean remove(String id) {
6770
Document query = new Document("_id", id);
6871
Document found = electionCollection.find(query).first();
69-
if (found == null) {
70-
return false;
71-
}
72+
if (found == null) return false;
7273
electionCollection.deleteOne(query);
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return true;
7475
}
@@ -80,14 +81,88 @@ public static String loadElectionData() {
8081
}
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8283
public static void saveElectionData(String serializedData) {
83-
Document query = new Document("_id", "election_data");
84-
Document existing = electionCollection.find(query).first();
85-
if (existing != null) {
86-
electionCollection.updateOne(query, Updates.set("data", serializedData));
87-
} else {
88-
Document newDoc = new Document("_id", "election_data");
89-
newDoc.append("data", serializedData);
90-
electionCollection.insertOne(newDoc);
84+
Document doc = new Document("_id", "election_data").append("data", serializedData);
85+
electionCollection.replaceOne(
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Filters.eq("_id", "election_data"),
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doc,
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new ReplaceOptions().upsert(true)
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);
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}
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public static void castVote(String playerId, String candidateName, int electionYear) {
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String talliesDocId = "tallies_" + electionYear;
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Document existingVote = votesCollection.find(
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Filters.and(Filters.eq("_id", playerId), Filters.eq("electionYear", electionYear))
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).first();
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if (existingVote != null) {
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String oldCandidate = existingVote.getString("candidate");
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if (oldCandidate != null && !oldCandidate.equals(candidateName)) {
102+
talliesCollection.updateOne(
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Filters.eq("_id", talliesDocId),
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Updates.inc(oldCandidate, -1L)
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);
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}
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}
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109+
Document voteDoc = new Document("_id", playerId)
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.append("candidate", candidateName)
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.append("electionYear", electionYear);
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votesCollection.replaceOne(
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Filters.eq("_id", playerId),
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voteDoc,
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new ReplaceOptions().upsert(true)
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);
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118+
if (existingVote == null || !candidateName.equals(existingVote.getString("candidate"))) {
119+
talliesCollection.updateOne(
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Filters.eq("_id", talliesDocId),
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Updates.inc(candidateName, 1L),
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new com.mongodb.client.model.UpdateOptions().upsert(true)
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);
91124
}
92125
}
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public static String getPlayerVote(String playerId, int electionYear) {
128+
Document doc = votesCollection.find(
129+
Filters.and(Filters.eq("_id", playerId), Filters.eq("electionYear", electionYear))
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).first();
131+
if (doc == null) return null;
132+
return doc.getString("candidate");
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}
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135+
public static Map<String, Long> getTallies(int electionYear) {
136+
String talliesDocId = "tallies_" + electionYear;
137+
Document doc = talliesCollection.find(Filters.eq("_id", talliesDocId)).first();
138+
if (doc == null) return new HashMap<>();
139+
140+
Map<String, Long> tallies = new HashMap<>();
141+
for (String key : doc.keySet()) {
142+
if (key.equals("_id")) continue;
143+
Object val = doc.get(key);
144+
if (val instanceof Number num) {
145+
tallies.put(key, num.longValue());
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}
147+
}
148+
return tallies;
149+
}
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151+
public static void initTallies(int electionYear, List<String> candidateNames) {
152+
String talliesDocId = "tallies_" + electionYear;
153+
Document doc = new Document("_id", talliesDocId);
154+
for (String name : candidateNames) {
155+
doc.append(name, 0L);
156+
}
157+
talliesCollection.replaceOne(
158+
Filters.eq("_id", talliesDocId),
159+
doc,
160+
new ReplaceOptions().upsert(true)
161+
);
162+
}
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164+
public static void clearVotesForYear(int electionYear) {
165+
votesCollection.deleteMany(Filters.eq("electionYear", electionYear));
166+
talliesCollection.deleteMany(Filters.eq("_id", "tallies_" + electionYear));
167+
}
93168
}

‎service.elections/src/main/java/net/swofty/service/election/ElectionService.java‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -9,7 +9,7 @@
99

1010
public class ElectionService implements SkyBlockService {
1111

12-
static void main() {
12+
public static void main(String[] args) {
1313
String mongoUri = ConfigProvider.settings().getMongodb();
1414
new ElectionDatabase(null).connect(mongoUri);
1515
SkyBlockService.init(new ElectionService());

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