perf: optimize metric processing (#6669)

- Replace stream-based processing with direct iteration in TimeBucketedMetrics
  to reduce allocations and GC pressure
- Eliminate intermediate list creation in extractAllMetrics by processing
  metrics recursively in-place
- Convert stream().anyMatch() to for-loop in isSupportedCategory for
  better performance

Author: zoewangg

.changes/next-release/feature-CloudWatchMetricPublisher-36c8c51.json

@@ -0,0 +1,6 @@
+{
+    "type": "feature",
+    "category": "CloudWatch Metric Publisher",
+    "contributor": "",
+    "description": "Optimize metric processing by replacing stream-based operations with direct iteration to reduce allocations and GC pressure."
+}

.kiro/settings/lsp.json

@@ -0,0 +1,41 @@
+{
+  "languages": {
+    "java": {
+      "name": "jdtls",
+      "command": "jdtls",
+      "args": [],
+      "file_extensions": [
+        "java"
+      ],
+      "project_patterns": [
+        "pom.xml",
+        "build.gradle",
+        "build.gradle.kts",
+        ".project"
+      ],
+      "exclude_patterns": [
+        "**/target/**",
+        "**/build/**",
+        "**/.gradle/**"
+      ],
+      "multi_workspace": false,
+      "initialization_options": {
+        "settings": {
+          "java": {
+            "compile": {
+              "nullAnalysis": {
+                "mode": "automatic"
+              }
+            },
+            "configuration": {
+              "annotationProcessing": {
+                "enabled": true
+              }
+            }
+          }
+        }
+      },
+      "request_timeout_secs": 60
+    }
+  }
+}

core/http-auth-aws/src/main/java/software/amazon/awssdk/http/auth/aws/internal/signer/util/SignerUtils.java

@@ -184,9 +184,8 @@ public static void addHostHeader(SdkHttpRequest.Builder requestBuilder) {
 
         String host = requestBuilder.host();
         if (!SdkHttpUtils.isUsingStandardPort(requestBuilder.protocol(), requestBuilder.port())) {
-            StringBuilder hostHeaderBuilder = new StringBuilder(host);
-            hostHeaderBuilder.append(":").append(requestBuilder.port());
-            requestBuilder.putHeader(SignerConstant.HOST, hostHeaderBuilder.toString());
+            String hostHeaderValue = host + ":" + requestBuilder.port();
+            requestBuilder.putHeader(SignerConstant.HOST, hostHeaderValue);
         } else {
             requestBuilder.putHeader(SignerConstant.HOST, host);
         }

metric-publishers/cloudwatch-metric-publisher/src/main/java/software/amazon/awssdk/metrics/publishers/cloudwatch/internal/transform/TimeBucketedMetrics.java

@@ -128,13 +128,23 @@ private void addMetricsToBucket(MetricCollection metrics, Instant bucketId) {
 
     private void aggregateMetrics(MetricCollection metrics, Map<MetricAggregatorKey, MetricAggregator> bucket) {
         List<Dimension> dimensions = dimensions(metrics);
-        extractAllMetrics(metrics).forEach(metricRecord -> {
+        processMetricsRecursively(metrics, dimensions, bucket);
+    }
+
+    private void processMetricsRecursively(MetricCollection metrics,
+                                           List<Dimension> dimensions,
+                                           Map<MetricAggregatorKey, MetricAggregator> bucket) {
+        for (MetricRecord<?> metricRecord : metrics) {
             MetricAggregatorKey aggregatorKey = new MetricAggregatorKey(metricRecord.metric(), dimensions);
             valueFor(metricRecord).ifPresent(metricValue -> {
                 bucket.computeIfAbsent(aggregatorKey, m -> newAggregator(aggregatorKey))
                       .addMetricValue(MetricValueNormalizer.normalize(metricValue));
             });
-        });
+        }
+
+        for (MetricCollection child : metrics.children()) {
+            processMetricsRecursively(child, dimensions, bucket);
+        }
     }
 
     private List<Dimension> dimensions(MetricCollection metricCollection) {
@@ -154,19 +164,6 @@ private List<Dimension> dimensions(MetricCollection metricCollection) {
         return result;
     }
 
-    private List<MetricRecord<?>> extractAllMetrics(MetricCollection metrics) {
-        List<MetricRecord<?>> result = new ArrayList<>();
-        extractAllMetrics(metrics, result);
-        return result;
-    }
-
-    private void extractAllMetrics(MetricCollection metrics, List<MetricRecord<?>> extractedMetrics) {
-        for (MetricRecord<?> metric : metrics) {
-            extractedMetrics.add(metric);
-        }
-        metrics.children().forEach(child -> extractAllMetrics(child, extractedMetrics));
-    }
-
     private MetricAggregator newAggregator(MetricAggregatorKey aggregatorKey) {
         SdkMetric<?> metric = aggregatorKey.metric();
         StandardUnit metricUnit = unitFor(metric);
@@ -214,11 +211,15 @@ private boolean shouldReport(MetricRecord<?> metricRecord) {
     }
 
     private boolean isSupportedCategory(MetricRecord<?> metricRecord) {
-        return metricCategoriesContainsAll ||
-               metricRecord.metric()
-                           .categories()
-                           .stream()
-                           .anyMatch(metricCategories::contains);
+        if (metricCategoriesContainsAll) {
+            return true;
+        }
+        for (MetricCategory category : metricRecord.metric().categories()) {
+            if (metricCategories.contains(category)) {
+                return true;
+            }
+        }
+        return false;
     }
 
     private boolean isSupportedLevel(MetricRecord<?> metricRecord) {