7393: Add vanilla Java JSON serializer for IItemCollections

Reviewed-by: hirt, jpbempel

core/org.openjdk.jmc.flightrecorder.serializers/src/main/java/org/openjdk/jmc/flightrecorder/serializers/json/IItemCollectionJsonSerializer.java

@@ -0,0 +1,172 @@
+/*
+ * Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2021, Datadog, Inc. All rights reserved.
+ *
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * The contents of this file are subject to the terms of either the Universal Permissive License
+ * v 1.0 as shown at http://oss.oracle.com/licenses/upl
+ *
+ * or the following license:
+ *
+ * Redistribution and use in source and binary forms, with or without modification, are permitted
+ * provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this list of conditions
+ * and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice, this list of
+ * conditions and the following disclaimer in the documentation and/or other materials provided with
+ * the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its contributors may be used to
+ * endorse or promote products derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
+ * WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package org.openjdk.jmc.flightrecorder.serializers.json;
+
+import java.io.IOException;
+import java.io.StringWriter;
+import java.io.Writer;
+import java.util.Map;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+import org.openjdk.jmc.common.IDescribable;
+import org.openjdk.jmc.common.IMCFrame;
+import org.openjdk.jmc.common.IMCMethod;
+import org.openjdk.jmc.common.IMCStackTrace;
+import org.openjdk.jmc.common.item.IAccessorKey;
+import org.openjdk.jmc.common.item.IItem;
+import org.openjdk.jmc.common.item.IItemCollection;
+import org.openjdk.jmc.common.item.IItemIterable;
+import org.openjdk.jmc.common.item.IMemberAccessor;
+import org.openjdk.jmc.common.item.IType;
+import org.openjdk.jmc.common.item.ItemToolkit;
+
+/**
+ * Utility methods to convert an IItemCollection to a JSON object containing the serialised array of
+ * events.
+ */
+public class IItemCollectionJsonSerializer extends JsonWriter {
+	private final static Logger LOGGER = Logger.getLogger("org.openjdk.jmc.flightrecorder.json");
+
+	public static String toJsonString(IItemCollection items) {
+		StringWriter sw = new StringWriter();
+		IItemCollectionJsonSerializer marshaller = new IItemCollectionJsonSerializer(sw);
+		try {
+			marshaller.writeRecording(items);
+		} catch (IOException e) {
+			LOGGER.log(Level.SEVERE, "Failed to serialize recording to JSON", e);
+		}
+		return sw.getBuffer().toString();
+	}
+
+	public static String toJsonString(Iterable<IItem> items) {
+		StringWriter sw = new StringWriter();
+		IItemCollectionJsonSerializer marshaller = new IItemCollectionJsonSerializer(sw);
+		try {
+			marshaller.writeEvents(items);
+		} catch (IOException e) {
+			LOGGER.log(Level.SEVERE, "Failed to serialize items to JSON", e);
+		}
+		return sw.getBuffer().toString();
+	}
+
+	private IItemCollectionJsonSerializer(Writer w) {
+		super(w);
+	}
+
+	private void writeRecording(IItemCollection recording) throws IOException {
+		writeObjectBegin();
+		nextField(true, "events");
+		writeArrayBegin();
+		int count = 0;
+		for (IItemIterable events : recording) {
+			for (IItem event : events) {
+				nextElement(count == 0);
+				writeEvent(event);
+				count++;
+			}
+		}
+		writeArrayEnd();
+		writeObjectEnd();
+		flush();
+	}
+
+	void writeEvents(Iterable<IItem> events) throws IOException {
+		writeObjectBegin();
+		nextField(true, "events");
+		writeArrayBegin();
+		int count = 0;
+		for (IItem event : events) {
+			nextElement(count == 0);
+			writeEvent(event);
+			count++;
+		}
+		writeArrayEnd();
+		writeObjectEnd();
+		flush();
+	}
+
+	private void writeEvent(IItem event) {
+		writeObjectBegin();
+		IType<?> type = event.getType();
+		writeField(true, "eventType", type.getIdentifier());
+		nextField(false, "attributes");
+		writeObjectBegin();
+		writeEventAttributes(event);
+		writeObjectEnd();
+		writeObjectEnd();
+	}
+
+	private void writeStackTrace(boolean first, IMCStackTrace trace) {
+		nextField(first, "stackTrace");
+		writeObjectBegin();
+		nextField(true, "frames");
+		writeArrayBegin();
+		boolean firstFrame = true;
+		for (IMCFrame frame : trace.getFrames()) {
+			nextElement(firstFrame);
+			writeFrame(frame); //$NON-NLS-1$
+			firstFrame = false;
+		}
+		writeArrayEnd();
+		writeObjectEnd();
+	}
+
+	private void writeFrame(IMCFrame frame) {
+		Integer lineNumber = frame.getFrameLineNumber();
+		IMCMethod method = frame.getMethod();
+
+		writeObjectBegin();
+		writeField(true, "name", method != null ? stringifyMethod(method) : null);
+		writeField(false, "line", lineNumber);
+		writeField(false, "type", frame.getType());
+		writeObjectEnd();
+	}
+
+	private void writeEventAttributes(IItem event) {
+		IType<IItem> itemType = ItemToolkit.getItemType(event);
+		boolean first = true;
+		for (Map.Entry<IAccessorKey<?>, ? extends IDescribable> e : itemType.getAccessorKeys().entrySet()) {
+			IMemberAccessor<?, IItem> accessor = itemType.getAccessor(e.getKey());
+			IAccessorKey<?> attribute = e.getKey();
+			Object value = accessor.getMember(event);
+			if (value instanceof IMCStackTrace) {
+				writeStackTrace(first, (IMCStackTrace) value);
+			} else {
+				writeField(first, attribute.getIdentifier(), value);
+			}
+			first = false;
+		}
+	}
+}

core/org.openjdk.jmc.flightrecorder.serializers/src/main/java/org/openjdk/jmc/flightrecorder/serializers/json/JsonWriter.java

@@ -0,0 +1,192 @@
+/*
+ * Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2021, Datadog, Inc. All rights reserved.
+ *
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * The contents of this file are subject to the terms of either the Universal Permissive License
+ * v 1.0 as shown at http://oss.oracle.com/licenses/upl
+ *
+ * or the following license:
+ *
+ * Redistribution and use in source and binary forms, with or without modification, are permitted
+ * provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this list of conditions
+ * and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice, this list of
+ * conditions and the following disclaimer in the documentation and/or other materials provided with
+ * the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its contributors may be used to
+ * endorse or promote products derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
+ * WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package org.openjdk.jmc.flightrecorder.serializers.json;
+
+import java.io.Writer;
+
+/**
+ * This class provides a set of utility methods for serialising arbitrary objects to JSON, with
+ * special logic for stringifying JMC types and Java primitives inherited from
+ * {@link StructuredWriter}.
+ * <p/>
+ * It's a slightly modified version of the `jfr` command's JSONWriter.
+ * <p/>
+ *
+ * @see <a href=
+ *      "https://github.com/openjdk/jdk11/blob/master/src/jdk.jfr/share/classes/jdk/jfr/internal/cmd/JSONWriter.java">jdk.jfr.internal.cmd.JSONWriter</a>
+ */
+abstract class JsonWriter extends StructuredWriter {
+
+	JsonWriter(Writer p) {
+		super(p);
+	}
+
+	protected void writeField(boolean first, String fieldName, Object value) {
+		nextField(first, fieldName);
+		if (!writeIfNull(value)) {
+			if (value instanceof Boolean) {
+				writeAsString(value);
+				return;
+			}
+			if (value instanceof Double) {
+				double dValue = (Double) value;
+				if (Double.isNaN(dValue) || Double.isInfinite(dValue)) {
+					writeNull();
+					return;
+				}
+				writeAsString(value);
+				return;
+			}
+			if (value instanceof Float) {
+				float fValue = (Float) value;
+				if (Float.isNaN(fValue) || Float.isInfinite(fValue)) {
+					writeNull();
+					return;
+				}
+				writeAsString(value);
+				return;
+			}
+			if (value instanceof Number) {
+				write(stringify("", value, false));
+				return;
+			}
+			writeStringValue(stringify(value));
+		}
+	}
+
+	protected void nextElement(boolean first) {
+		if (!first) {
+			write(", ");
+		}
+	}
+
+	protected void nextField(boolean first, String fieldName) {
+		if (!first) {
+			writeln(", ");
+		}
+		writeFieldName(fieldName);
+	}
+
+	protected boolean writeIfNull(Object value) {
+		if (value == null) {
+			writeNull();
+			return true;
+		}
+		return false;
+	}
+
+	protected void writeNull() {
+		write("null");
+	}
+
+	protected void writeObjectBegin() {
+		writeln("{");
+		indent();
+	}
+
+	protected void writeObjectEnd() {
+		retract();
+		writeln();
+		writeIndent();
+		write("}");
+	}
+
+	protected void writeArrayEnd() {
+		write("]");
+	}
+
+	protected void writeArrayBegin() {
+		write("[");
+	}
+
+	protected void writeStringValue(String value) {
+		write("\"");
+		writeEscaped(value);
+		write("\"");
+	}
+
+	private void writeFieldName(String text) {
+		writeIndent();
+		write("\"");
+		write(text);
+		write("\": ");
+	}
+
+	private void writeEscaped(String text) {
+		for (int i = 0; i < text.length(); i++) {
+			writeEscaped(text.charAt(i));
+		}
+	}
+
+	private void writeEscaped(char c) {
+		if (c == '\b') {
+			write("\\b");
+			return;
+		}
+		if (c == '\n') {
+			write("\\n");
+			return;
+		}
+		if (c == '\t') {
+			write("\\t");
+			return;
+		}
+		if (c == '\f') {
+			write("\\f");
+			return;
+		}
+		if (c == '\r') {
+			write("\\r");
+			return;
+		}
+		if (c == '\"') {
+			write("\\\"");
+			return;
+		}
+		if (c == '\\') {
+			write("\\\\");
+			return;
+		}
+		/*
+		 * we don't need to escape slashes if (c == '/') { print("\\/"); return; }
+		 */
+		if (c > 0x7F || c < 32) {
+			write("\\u");
+			// 0x10000 will pad with zeros.
+			write(Integer.toHexString(0x10000 + c).substring(1));
+			return;
+		}
+		write(c);
+	}
+}