+ added MDC context display feature

elf4j · Feb 14, 2024 · 4c8f44a · 4c8f44a
1 parent 3f3a7d0
commit 4c8f44a
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Showing 9 changed files with 90 additions and 15 deletions.
diff --git a/pom.xml b/pom.xml
@@ -31,7 +31,7 @@
 
     <groupId>io.github.elf4j</groupId>
     <artifactId>elf4j-engine</artifactId>
-    <version>15.0.0</version>
+    <version>15.1.0</version>
     <packaging>jar</packaging>
     <name>elf4j-engine</name>
     <description>A stand-alone Java log engine implementing the ELF4J (Easy Logging Facade for Java) API</description>
@@ -79,6 +79,11 @@
             <artifactId>dsl-json</artifactId>
             <version>2.0.2</version>
         </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-api</artifactId>
+            <version>2.0.11</version>
+        </dependency>
         <dependency>
             <groupId>org.projectlombok</groupId>
             <artifactId>lombok</artifactId>

diff --git a/src/main/java/elf4j/engine/NativeLogServiceProvider.java b/src/main/java/elf4j/engine/NativeLogServiceProvider.java
@@ -42,6 +42,7 @@
 import java.util.function.Function;
 import javax.annotation.Nullable;
 import lombok.NonNull;
+import org.slf4j.MdcAdapterInitializer;
 
 /**
  *
@@ -87,6 +88,7 @@ public NativeLogServiceProvider(@NonNull Class<?> serviceAccessClass) {
             @NonNull Level defaultLoggerLevel,
             @NonNull Class<?> serviceAccessClass,
             @NonNull NativeLogServiceProvider.NativeLoggerServiceFactory nativeLoggerServiceFactory) {
+        MdcAdapterInitializer.initialize();
         this.defaultLoggerLevel = defaultLoggerLevel;
         this.serviceAccessClass = serviceAccessClass;
         this.nativeLoggerServiceFactory = nativeLoggerServiceFactory;

diff --git a/src/main/java/elf4j/engine/service/pattern/ContextElement.java b/src/main/java/elf4j/engine/service/pattern/ContextElement.java
@@ -0,0 +1,34 @@
+package elf4j.engine.service.pattern;
+
+import elf4j.engine.service.LogEvent;
+import java.util.NoSuchElementException;
+import lombok.NonNull;
+import org.slf4j.MDC;
+
+public class ContextElement implements PatternElement {
+    final String key;
+
+    public ContextElement(String key) {
+        this.key = key;
+    }
+
+    @Override
+    public boolean includeCallerDetail() {
+        return false;
+    }
+
+    public static @NonNull ContextElement from(String patternSegment) {
+        return new ContextElement(PatternElements.getPatternElementDisplayOption(patternSegment)
+                .orElseThrow(() -> new NoSuchElementException("No key configured in 'context' pattern element")));
+    }
+    /**
+     *
+     * @param logEvent entire log content data source to render
+     * @param target logging text aggregator of the final log message
+     */
+    @Override
+    public void render(LogEvent logEvent, @NonNull StringBuilder target) {
+        String value = MDC.get(key);
+        target.append(value == null ? "" : value);
+    }
+}
diff --git a/src/main/java/elf4j/engine/service/pattern/JsonElement.java b/src/main/java/elf4j/engine/service/pattern/JsonElement.java
@@ -38,15 +38,13 @@
 import java.nio.charset.StandardCharsets;
 import java.time.OffsetDateTime;
 import java.time.ZoneId;
-import java.util.Arrays;
-import java.util.Objects;
-import java.util.Optional;
-import java.util.Set;
+import java.util.*;
 import java.util.stream.Collectors;
 import lombok.Builder;
 import lombok.NonNull;
 import lombok.ToString;
 import lombok.Value;
+import org.slf4j.MDC;
 
 /**
  *
@@ -112,11 +110,12 @@ public void render(LogEvent logEvent, @NonNull StringBuilder target) {
     @CompiledJson
     static class JsonLogEntry {
         OffsetDateTime timestamp;
-        LogEvent.ThreadValue callerThread;
         String level;
-        CharSequence message;
+        LogEvent.ThreadValue callerThread;
         String callerClass;
         LogEvent.StackFrameValue callerDetail;
+        Map<String, String> context;
+        CharSequence message;
         CharSequence exception;
 
         static JsonLogEntry from(@NonNull LogEvent logEvent, @NonNull JsonElement jsonPattern) {
@@ -128,6 +127,7 @@ static JsonLogEntry from(@NonNull LogEvent logEvent, @NonNull JsonElement jsonPa
                     .callerDetail(
                             jsonPattern.includeCallerDetail ? Objects.requireNonNull(logEvent.getCallerFrame()) : null)
                     .message(logEvent.getResolvedMessage())
+                    .context(MDC.getCopyOfContextMap())
                     .exception(
                             logEvent.getThrowable() == null
                                     ? null

diff --git a/src/main/java/elf4j/engine/service/pattern/PatternElements.java b/src/main/java/elf4j/engine/service/pattern/PatternElements.java
@@ -1,12 +1,10 @@
 package elf4j.engine.service.pattern;
 
-import java.util.EnumSet;
+import java.util.Arrays;
 import java.util.Optional;
 import lombok.NonNull;
 
 class PatternElements {
-    private static final EnumSet<PredefinedPatternElement> PREDEFINED_PATTERN_ELEMENT_TYPES =
-            EnumSet.allOf(PredefinedPatternElement.class);
 
     private PatternElements() {}
 
@@ -21,7 +19,7 @@ static Optional<String> getPatternElementDisplayOption(@NonNull String patternEl
     }
 
     static PatternElement parsePredefinedPatternELement(String predefinedPatternElement) {
-        return PREDEFINED_PATTERN_ELEMENT_TYPES.stream()
+        return Arrays.stream(PredefinedPatternElement.values())
                 .filter(type -> type.isTargetTypeOf(predefinedPatternElement))
                 .findFirst()
                 .orElseThrow(() ->
@@ -124,6 +122,12 @@ PatternElement parse(String patternElement) {
             PatternElement parse(String patternElement) {
                 return SystemEnvironmentElement.from(patternElement);
             }
+        },
+        CONTEXT {
+            @Override
+            PatternElement parse(String patternElement) {
+                return ContextElement.from(patternElement);
+            }
         };
 
         /**

diff --git a/src/main/java/elf4j/engine/service/writer/ConseqWriterGroup.java b/src/main/java/elf4j/engine/service/writer/ConseqWriterGroup.java
@@ -36,6 +36,7 @@
 import java.util.stream.Collectors;
 import lombok.NonNull;
 import lombok.ToString;
+import org.slf4j.MDC;
 
 /**
  * In general, log events are asynchronously written/rendered in parallel by multiple concurrent threads. However,
@@ -126,16 +127,27 @@ public Level getThresholdOutputLevel() {
     @Override
     public void write(@NonNull LogEvent logEvent) {
         conseqExecutor.execute(
-                () -> {
+                withMdcContext(() -> {
                     if (writers.size() == 1) {
                         writers.get(0).write(logEvent);
                         return;
                     }
                     writers.stream().parallel().forEach(writer -> writer.write(logEvent));
-                },
+                }),
                 logEvent.getCallerThread().getId());
     }
 
+    private static Runnable withMdcContext(Runnable task) {
+        Map<String, String> copyOfContextMap = MDC.getCopyOfContextMap();
+        return (copyOfContextMap == null)
+                ? task
+                : () -> {
+                    MDC.clear();
+                    MDC.setContextMap(copyOfContextMap);
+                    task.run();
+                };
+    }
+
     @Override
     public boolean includeCallerDetail() {
         if (includeCallerDetail == null) {

diff --git a/src/main/java/org/slf4j/MdcAdapterInitializer.java b/src/main/java/org/slf4j/MdcAdapterInitializer.java
@@ -0,0 +1,16 @@
+package org.slf4j;
+
+import org.slf4j.helpers.BasicMDCAdapter;
+import org.slf4j.helpers.NOPMDCAdapter;
+import org.slf4j.spi.MDCAdapter;
+
+public class MdcAdapterInitializer {
+    private MdcAdapterInitializer() {}
+
+    public static void initialize() {
+        MDCAdapter byOtherSlf4jProvider = MDC.mdcAdapter;
+        if (byOtherSlf4jProvider == null || byOtherSlf4jProvider instanceof NOPMDCAdapter) {
+            MDC.mdcAdapter = new BasicMDCAdapter();
+        }
+    }
+}
diff --git a/src/test/java/elf4j/engine/Main.java b/src/test/java/elf4j/engine/Main.java
@@ -28,11 +28,13 @@
 import elf4j.Logger;
 import elf4j.engine.service.NativeLogServiceManager;
 import java.util.function.Supplier;
+import org.slf4j.MDC;
 
 public class Main {
     static Logger logger = Logger.instance();
 
     public static void main(String[] args) {
+        MDC.put("ctx-key", "ctx-value");
         logger.log("Hello, world!");
         logger.atTrace().log("It's a beautiful day");
         Logger info = logger.atInfo();

diff --git a/src/test/resources/elf4j-test.properties b/src/test/resources/elf4j-test.properties
@@ -32,9 +32,9 @@ level@org.apache=error
 ### Writer out stream type - stdout/stderr, default to stdout
 #stream=stderr
 ### Overriding default writer pattern (optional)
-#pattern={timestamp:yyyy-MM-dd HH:mm:ss} {level} {thread} {class:full} - {message}
+#pattern={timestamp:yyyy-MM-dd HH:mm:ss} {level} {thread} {class:full} [{context:ctx-key}] - {message}
 #pattern={json:caller-thread,caller-detail,pretty}
-pattern={json:caller-thread}
+pattern={json:caller-thread,caller-detail}
 #pattern={json}
 ### Max concurrency to process log events from all caller threads
 #concurrency=20