BP-47 (task2): Add structured logger support (#3190)

* Add slogger support

* update pom.xml

* fix check style

bookkeeper-slogger/api/build.gradle

@@ -0,0 +1,33 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+plugins {
+    id 'java'
+}
+
+dependencies {
+    testImplementation depLibs.hamcrest
+    testImplementation depLibs.junit
+}
+
+jar.archiveBaseName = 'bookkeeper-slogger-api'
+
+jar {
+    dependsOn tasks.named("writeClasspath")
+}
+

bookkeeper-slogger/api/pom.xml

@@ -0,0 +1,27 @@
+<?xml version="1.0"?>
+<!--
+   Licensed to the Apache Software Foundation (ASF) under one or more
+   contributor license agreements.  See the NOTICE file distributed with
+   this work for additional information regarding copyright ownership.
+   The ASF licenses this file to You under the Apache License, Version 2.0
+   (the "License"); you may not use this file except in compliance with
+   the License.  You may obtain a copy of the License at
+       http://www.apache.org/licenses/LICENSE-2.0
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+-->
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <artifactId>bookkeeper-slogger-parent</artifactId>
+        <groupId>org.apache.bookkeeper</groupId>
+        <version>4.16.0-SNAPSHOT</version>
+        <relativePath>..</relativePath>
+    </parent>
+    <groupId>org.apache.bookkeeper</groupId>
+    <artifactId>bookkeeper-slogger-api</artifactId>
+    <name>Apache BookKeeper :: Structured Logger :: API</name>
+</project>

bookkeeper-slogger/api/src/main/java/org/apache/bookkeeper/slogger/AbstractSlogger.java

@@ -0,0 +1,275 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.bookkeeper.slogger;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Optional;
+import java.util.function.BiConsumer;
+
+/**
+ * Abstract implementation of slogger. Keeps track of key value pairs.
+ */
+public abstract class AbstractSlogger implements Slogger, Iterable<Object> {
+    /**
+     * Levels at which slogger can slog.
+     */
+    public enum Level {
+        INFO,
+        WARN,
+        ERROR
+    }
+
+    private static final int MAX_DEPTH = 3;
+    private List<String> parentCtx;
+
+    private ThreadLocal<List<Object>> kvs = new ThreadLocal<List<Object>>() {
+            @Override
+            protected List<Object> initialValue() {
+                return new ArrayList<>();
+            }
+        };
+    private ThreadLocal<List<Object>> flattenedTls = ThreadLocal.withInitial(ArrayList::new);
+
+    protected AbstractSlogger(Iterable<Object> parentCtx) {
+        List<String> flattened = new ArrayList<>();
+        flattenKeyValues(parentCtx.iterator(), (k, v) -> {
+                flattened.add(k);
+                flattened.add(v);
+            });
+        this.parentCtx = Collections.unmodifiableList(flattened);
+    }
+
+    protected abstract Slogger newSlogger(Optional<Class<?>> clazz, Iterable<Object> parent);
+    protected abstract void doLog(Level level, Enum<?> event, String message,
+                                  Throwable throwable, List<Object> keyValues);
+
+    private void flattenAndLog(Level level, Enum<?> event, String message,
+                               Throwable throwable) {
+        List<Object> flattened = flattenedTls.get();
+        flattened.clear();
+
+        flattenKeyValues(this::addToFlattened);
+        doLog(level, event, message, throwable, flattened);
+    }
+
+    @Override
+    public void info(String message) {
+        flattenAndLog(Level.INFO, null, message, null);
+    }
+
+    @Override
+    public void info(String message, Throwable cause) {
+        flattenAndLog(Level.INFO, null, message, cause);
+    }
+
+    @Override
+    public void info(Enum<?> event) {
+        flattenAndLog(Level.INFO, event, null, null);
+    }
+
+    @Override
+    public void info(Enum<?> event, Throwable cause) {
+        flattenAndLog(Level.INFO, event, null, cause);
+    }
+
+    @Override
+    public void warn(String message) {
+        flattenAndLog(Level.WARN, null, message, null);
+    }
+
+    @Override
+    public void warn(String message, Throwable cause) {
+        flattenAndLog(Level.WARN, null, message, cause);
+    }
+
+    @Override
+    public void warn(Enum<?> event) {
+        flattenAndLog(Level.WARN, event, null, null);
+    }
+
+    @Override
+    public void warn(Enum<?> event, Throwable cause) {
+        flattenAndLog(Level.WARN, event, null, cause);
+    }
+
+    @Override
+    public void error(String message) {
+        flattenAndLog(Level.ERROR, null, message, null);
+    }
+
+    @Override
+    public void error(String message, Throwable cause) {
+        flattenAndLog(Level.ERROR, null, message, cause);
+    }
+
+    @Override
+    public void error(Enum<?> event) {
+        flattenAndLog(Level.ERROR, event, null, null);
+    }
+
+    @Override
+    public void error(Enum<?> event, Throwable cause) {
+        flattenAndLog(Level.ERROR, event, null, cause);
+    }
+
+    @Override
+    public Slogger ctx() {
+        try {
+            return newSlogger(Optional.empty(), this);
+        } finally {
+            kvs.get().clear();
+        }
+    }
+
+    @Override
+    public Slogger ctx(Class<?> clazz) {
+        try {
+            return newSlogger(Optional.of(clazz), this);
+        } finally {
+            kvs.get().clear();
+        }
+    }
+
+    @Override
+    public Iterator<Object> iterator() {
+        CtxIterator iterator = this.iterator.get();
+        iterator.reset();
+        return iterator;
+    }
+
+    protected void clearCurrentCtx() {
+        kvs.get().clear();
+    }
+
+    private void addToFlattened(String key, String value) {
+        flattenedTls.get().add(key);
+        flattenedTls.get().add(value);
+    }
+
+    protected void flattenKeyValues(BiConsumer<String, String> consumer) {
+        Iterator<Object> iter = iterator();
+        try {
+            flattenKeyValues(iter, consumer);
+        } finally {
+            kvs.get().clear();
+        }
+    }
+
+    public static void flattenKeyValues(Iterator<Object> iter,
+                                        BiConsumer<String, String> consumer) {
+        while (iter.hasNext()) {
+            String key = iter.next().toString();
+            if (!iter.hasNext()) {
+                return; // key without value
+            }
+            Object value = iter.next();
+
+            if (value instanceof Sloggable) {
+                addWithPrefix(key, (Sloggable) value, consumer, 0);
+            } else if (value.getClass().isArray()) {
+                consumer.accept(key, arrayToString(value));
+            } else {
+                consumer.accept(key, value.toString());
+            }
+        }
+    }
+
+    @Override
+    public Slogger kv(Object key, Object value) {
+        kvs.get().add(key);
+        kvs.get().add(value);
+        return this;
+    }
+
+    private static void addWithPrefix(String prefix, Sloggable value,
+                                      BiConsumer<String, String> consumer, int depth) {
+        value.log(new SloggableAccumulator() {
+                @Override
+                public SloggableAccumulator kv(Object key, Object value) {
+                    if (value instanceof Sloggable && depth < MAX_DEPTH) {
+                        addWithPrefix(prefix + "." + key.toString(),
+                                      (Sloggable) value, consumer, depth + 1);
+                    } else if (value.getClass().isArray()) {
+                        consumer.accept(prefix + "." + key.toString(), arrayToString(value));
+                    } else {
+                        consumer.accept(prefix + "." + key.toString(), value.toString());
+                    }
+                    return this;
+                }
+            });
+    }
+
+    private static String arrayToString(Object o) {
+        if (o instanceof long[]) {
+            return Arrays.toString((long[]) o);
+        } else if (o instanceof int[]) {
+            return Arrays.toString((int[]) o);
+        } else if (o instanceof short[]) {
+            return Arrays.toString((short[]) o);
+        } else if (o instanceof char[]) {
+            return Arrays.toString((char[]) o);
+        } else if (o instanceof byte[]) {
+            return Arrays.toString((byte[]) o);
+        } else if (o instanceof boolean[]) {
+            return Arrays.toString((boolean[]) o);
+        } else if (o instanceof float[]) {
+            return Arrays.toString((float[]) o);
+        } else if (o instanceof double[]) {
+            return Arrays.toString((double[]) o);
+        } else if (o instanceof Object[]) {
+            return Arrays.toString((Object[]) o);
+        } else {
+            return o.toString();
+        }
+    }
+
+    private final ThreadLocal<CtxIterator> iterator = new ThreadLocal<CtxIterator>() {
+            @Override
+            protected CtxIterator initialValue() {
+                return new CtxIterator();
+            }
+        };
+    class CtxIterator implements Iterator<Object> {
+        int index = 0;
+
+        private void reset() {
+            index = 0;
+        }
+
+        @Override
+        public boolean hasNext() {
+            return index < (parentCtx.size() + kvs.get().size());
+        }
+
+        @Override
+        public Object next() {
+            int i = index++;
+            if (i < parentCtx.size()) {
+                return parentCtx.get(i);
+            } else {
+                i -= parentCtx.size();
+                return kvs.get().get(i);
+            }
+        }
+    }
+}