From 7292a88ea3dec00f5da48852711859586259d4cb Mon Sep 17 00:00:00 2001
From: Jon Chambers <jon@signal.org>
Date: Tue, 16 Aug 2022 11:26:42 -0400
Subject: [PATCH] Record table performance metrics around reported messages

---
 .../storage/ReportMessageDynamoDb.java        | 25 ++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/service/src/main/java/org/whispersystems/textsecuregcm/storage/ReportMessageDynamoDb.java b/service/src/main/java/org/whispersystems/textsecuregcm/storage/ReportMessageDynamoDb.java
index 7ecd7a851..611514d2c 100644
--- a/service/src/main/java/org/whispersystems/textsecuregcm/storage/ReportMessageDynamoDb.java
+++ b/service/src/main/java/org/whispersystems/textsecuregcm/storage/ReportMessageDynamoDb.java
@@ -1,5 +1,7 @@
 package org.whispersystems.textsecuregcm.storage;
 
+import io.micrometer.core.instrument.Metrics;
+import io.micrometer.core.instrument.Timer;
 import org.whispersystems.textsecuregcm.util.AttributeValues;
 import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
 import software.amazon.awssdk.services.dynamodb.model.DeleteItemRequest;
@@ -10,6 +12,8 @@ import java.time.Duration;
 import java.time.Instant;
 import java.util.Map;
 
+import static org.whispersystems.textsecuregcm.metrics.MetricsUtil.name;
+
 public class ReportMessageDynamoDb {
 
   static final String KEY_HASH = "H";
@@ -19,6 +23,9 @@ public class ReportMessageDynamoDb {
   private final String tableName;
   private final Duration ttl;
 
+  private static final String REMOVED_MESSAGE_COUNTER_NAME = name(ReportMessageDynamoDb.class, "removed");
+  private static final Timer REMOVED_MESSAGE_AGE_TIMER = Metrics.timer(name(ReportMessageDynamoDb.class, "removedMessageAge"));
+
   public ReportMessageDynamoDb(final DynamoDbClient dynamoDB, final String tableName, final Duration ttl) {
     this.db = dynamoDB;
     this.tableName = tableName;
@@ -41,6 +48,22 @@ public class ReportMessageDynamoDb {
         .key(Map.of(KEY_HASH, AttributeValues.fromByteArray(hash)))
         .returnValues(ReturnValue.ALL_OLD)
         .build());
-    return !deleteItemResponse.attributes().isEmpty();
+
+    final boolean found = !deleteItemResponse.attributes().isEmpty();
+
+    if (found) {
+      if (deleteItemResponse.attributes().containsKey(ATTR_TTL)) {
+        final Instant expiration =
+            Instant.ofEpochSecond(Long.parseLong(deleteItemResponse.attributes().get(ATTR_TTL).n()));
+
+        final Duration approximateAge = ttl.minus(Duration.between(Instant.now(), expiration));
+
+        REMOVED_MESSAGE_AGE_TIMER.record(approximateAge);
+      }
+    }
+
+    Metrics.counter(REMOVED_MESSAGE_COUNTER_NAME, "found", String.valueOf(found)).increment();
+
+    return found;
   }
 }