From 24697530f31a6ca08a9c62c2f2ad938f30546c6b Mon Sep 17 00:00:00 2001
From: eyalkoren <41850454+eyalkoren@users.noreply.github.com>
Date: Tue, 26 Apr 2022 17:30:16 +0300
Subject: [PATCH] Remove more serialization allocations

---
 .../co/elastic/logging/EcsJsonSerializer.java | 26 ++++++++-----------
 .../java/co/elastic/logging/JsonUtils.java    | 10 ++++++-
 .../logging/EcsJsonSerializerTest.java        | 18 +++++++++++++
 3 files changed, 38 insertions(+), 16 deletions(-)

diff --git a/ecs-logging-core/src/main/java/co/elastic/logging/EcsJsonSerializer.java b/ecs-logging-core/src/main/java/co/elastic/logging/EcsJsonSerializer.java
index 1a317d00..deb77a15 100644
--- a/ecs-logging-core/src/main/java/co/elastic/logging/EcsJsonSerializer.java
+++ b/ecs-logging-core/src/main/java/co/elastic/logging/EcsJsonSerializer.java
@@ -279,11 +279,9 @@ private static void formatStackTraceAsArray(StringBuilder builder, CharSequence
                     continue;
                 }
 
-                // append line
-                CharSequence match = stackTrace.subSequence(index, matcher.start());
-                builder.append("\t\"");
-                JsonUtils.quoteAsString(match, builder);
-                builder.append("\",");
+                // append non-last line
+                appendStackTraceLine(builder, stackTrace, index, start);
+                builder.append(',');
                 builder.append(NEW_LINE);
                 index = end;
             } while (matcher.find());
@@ -291,22 +289,20 @@ private static void formatStackTraceAsArray(StringBuilder builder, CharSequence
             int length = stackTrace.length();
             if (index < length) {
                 // append remaining line
-                CharSequence remaining = stackTrace.subSequence(index, length);
-                builder.append("\t\"");
-                JsonUtils.quoteAsString(remaining, builder);
-                builder.append("\"");
+                appendStackTraceLine(builder, stackTrace, index, length);
             }
-
-            removeIfEndsWith(builder, NEW_LINE);
-            removeIfEndsWith(builder, ",");
         } else {
             // no newlines found, add entire stack trace as single element
-            builder.append("\t\"");
-            JsonUtils.quoteAsString(stackTrace, builder);
-            builder.append("\"");
+            appendStackTraceLine(builder, stackTrace, 0, stackTrace.length());
         }
     }
 
+    private static void appendStackTraceLine(StringBuilder builder, CharSequence stackTrace, int start, int end) {
+        builder.append("\t\"");
+        JsonUtils.quoteAsString(stackTrace, start, end, builder);
+        builder.append("\"");
+    }
+
     public static void removeIfEndsWith(StringBuilder sb, String ending) {
         if (endsWith(sb, ending)) {
             sb.setLength(sb.length() - ending.length());
diff --git a/ecs-logging-core/src/main/java/co/elastic/logging/JsonUtils.java b/ecs-logging-core/src/main/java/co/elastic/logging/JsonUtils.java
index d2d696c6..fc53a8ca 100644
--- a/ecs-logging-core/src/main/java/co/elastic/logging/JsonUtils.java
+++ b/ecs-logging-core/src/main/java/co/elastic/logging/JsonUtils.java
@@ -58,13 +58,21 @@ public final class JsonUtils {
     }
 
     public static void quoteAsString(CharSequence content, StringBuilder sb) {
+        if (content == null) {
+            sb.append("null");
+            return;
+        }
+        quoteAsString(content, 0, content.length(), sb);
+    }
+
+    public static void quoteAsString(CharSequence content, int start, int end, StringBuilder sb) {
         if (content == null) {
             sb.append("null");
             return;
         }
         final int[] escCodes = sOutputEscapes128;
         final int escLen = escCodes.length;
-        for (int i = 0, len = content.length(); i < len; ++i) {
+        for (int i = start; i < end; ++i) {
             char c = content.charAt(i);
             if (c >= escLen || escCodes[c] == 0) {
                 sb.append(c);
diff --git a/ecs-logging-core/src/test/java/co/elastic/logging/EcsJsonSerializerTest.java b/ecs-logging-core/src/test/java/co/elastic/logging/EcsJsonSerializerTest.java
index 73f088d2..ec851e8a 100644
--- a/ecs-logging-core/src/test/java/co/elastic/logging/EcsJsonSerializerTest.java
+++ b/ecs-logging-core/src/test/java/co/elastic/logging/EcsJsonSerializerTest.java
@@ -148,13 +148,31 @@ void serializeExceptionWithStackTraceAsArray() throws JsonProcessingException {
         jsonBuilder.append('}');
 
         JsonNode jsonNode = objectMapper.readTree(jsonBuilder.toString());
+        System.out.println(jsonNode.toPrettyString());
         assertThat(jsonNode.get(ERROR_TYPE).textValue()).isEqualTo("className");
         assertThat(jsonNode.get(ERROR_STACK_TRACE).isArray()).isTrue();
+        assertThat(jsonNode.get(ERROR_STACK_TRACE).size()).isEqualTo(2);
         assertThat(jsonNode.get(ERROR_STACK_TRACE).get(0).textValue()).isEqualTo("stacktrace");
         assertThat(jsonNode.get(ERROR_STACK_TRACE).get(1).textValue()).isEqualTo("caused by error");
         assertThat(jsonNode.get(ERROR_MESSAGE).textValue()).isEqualTo("message");
     }
 
+    @Test
+    void serializeExceptionWithSingleLineStackTraceAsArray() throws JsonProcessingException {
+        StringBuilder jsonBuilder = new StringBuilder();
+        jsonBuilder.append('{');
+        EcsJsonSerializer.serializeException(jsonBuilder, "className", "message", "caused by error", true);
+        jsonBuilder.append('}');
+        System.out.println(jsonBuilder);
+        JsonNode jsonNode = objectMapper.readTree(jsonBuilder.toString());
+        System.out.println(jsonNode.toPrettyString());
+        assertThat(jsonNode.get(ERROR_TYPE).textValue()).isEqualTo("className");
+        assertThat(jsonNode.get(ERROR_STACK_TRACE).isArray()).isTrue();
+        assertThat(jsonNode.get(ERROR_STACK_TRACE).size()).isEqualTo(1);
+        assertThat(jsonNode.get(ERROR_STACK_TRACE).get(0).textValue()).isEqualTo("caused by error");
+        assertThat(jsonNode.get(ERROR_MESSAGE).textValue()).isEqualTo("message");
+    }
+
     @Test
     void serializeExceptionWithNullMessage() throws JsonProcessingException {
         StringBuilder jsonBuilder = new StringBuilder();