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[dynamic control] Add json and keyvalue parsing and mapping (#2655)
Co-authored-by: Jay DeLuca <jaydeluca4@gmail.com>
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‎dynamic-control/src/main/java/io/opentelemetry/contrib/dynamic/policy/source/JsonSourceWrapper.java‎

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/*
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* Copyright The OpenTelemetry Authors
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* SPDX-License-Identifier: Apache-2.0
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*/
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package io.opentelemetry.contrib.dynamic.policy.source;
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import com.fasterxml.jackson.core.JsonProcessingException;
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import com.fasterxml.jackson.databind.JsonNode;
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import com.fasterxml.jackson.databind.ObjectMapper;
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import java.util.ArrayList;
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import java.util.Collections;
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import java.util.List;
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import java.util.Objects;
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import javax.annotation.Nullable;
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/** JSON-backed source wrapper for a single-policy object. */
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public final class JsonSourceWrapper implements SourceWrapper {
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private static final ObjectMapper MAPPER = new ObjectMapper();
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private final JsonNode source;
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public JsonSourceWrapper(JsonNode source) {
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this.source = Objects.requireNonNull(source, "source cannot be null");
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}
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@Override
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public SourceFormat getFormat() {
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return SourceFormat.JSON;
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}
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@Override
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@Nullable
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public String getPolicyType() {
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JsonNode node = asJsonNode();
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if (!node.isObject() || node.size() != 1) {
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return null;
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}
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return node.fieldNames().next();
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}
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public JsonNode asJsonNode() {
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return source;
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}
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/**
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* Parses JSON source into one wrapper per top-level policy object.
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*
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* @return an empty list if the source is an empty JSON array; a non-empty list of wrappers if the
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* source is a valid single-policy object or array thereof; or {@code null} if the shape is
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* unsupported or the source is not valid JSON.
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* @throws NullPointerException if source is null
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*/
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@Nullable
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public static List<SourceWrapper> parse(String source) {
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Objects.requireNonNull(source, "source cannot be null");
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try {
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JsonNode parsed = MAPPER.readTree(source);
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if (!isSupportedJsonShape(parsed)) {
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return null;
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}
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if (parsed.isObject()) {
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return Collections.singletonList(new JsonSourceWrapper(parsed));
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}
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List<SourceWrapper> wrappers = new ArrayList<>();
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for (JsonNode element : parsed) {
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wrappers.add(new JsonSourceWrapper(element));
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}
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return Collections.unmodifiableList(wrappers);
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} catch (JsonProcessingException e) {
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return null;
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}
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}
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private static boolean isSupportedJsonShape(JsonNode node) {
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if (node.isObject()) {
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return isSinglePolicyObject(node);
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}
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if (!node.isArray()) {
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return false;
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}
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for (JsonNode element : node) {
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if (!isSinglePolicyObject(element)) {
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return false;
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}
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}
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return true;
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}
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private static boolean isSinglePolicyObject(JsonNode node) {
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return node.isObject() && node.size() == 1;
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}
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}

‎dynamic-control/src/main/java/io/opentelemetry/contrib/dynamic/policy/source/KeyValueSourceWrapper.java‎

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/*
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* Copyright The OpenTelemetry Authors
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* SPDX-License-Identifier: Apache-2.0
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*/
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package io.opentelemetry.contrib.dynamic.policy.source;
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import java.util.ArrayList;
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import java.util.Collections;
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import java.util.List;
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import java.util.Objects;
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import java.util.regex.Pattern;
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import javax.annotation.Nullable;
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/** KEYVALUE-backed source wrapper for a single key/value policy entry. */
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public final class KeyValueSourceWrapper implements SourceWrapper {
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private final String key;
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private final String value;
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private static final Pattern LINE_SEPARATOR = Pattern.compile("\\R");
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public KeyValueSourceWrapper(String key, String value) {
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this.key = Objects.requireNonNull(key, "key cannot be null");
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this.value = Objects.requireNonNull(value, "value cannot be null");
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}
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@Override
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public SourceFormat getFormat() {
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return SourceFormat.KEYVALUE;
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}
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@Override
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@Nullable
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public String getPolicyType() {
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return key;
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}
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public String getKey() {
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return key;
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}
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public String getValue() {
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return value;
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}
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/**
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* Parses KEYVALUE source into one wrapper per non-empty line.
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*
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* @return an empty list if the source contains no non-blank lines; a non-empty list of wrappers
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* if all non-blank lines are valid key=value pairs; or {@code null} if any line is malformed.
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* @throws NullPointerException if source is null
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*/
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@Nullable
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public static List<SourceWrapper> parse(String source) {
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Objects.requireNonNull(source, "source cannot be null");
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String[] lines = LINE_SEPARATOR.split(source, -1);
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List<SourceWrapper> wrappers = new ArrayList<>();
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for (String rawLine : lines) {
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String trimmedLine = rawLine.trim();
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if (trimmedLine.isEmpty()) {
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continue;
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}
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KeyValueSourceWrapper wrapper = parseSingleKeyValue(trimmedLine);
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if (wrapper == null) {
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return null;
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}
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wrappers.add(wrapper);
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}
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if (wrappers.isEmpty()) {
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return Collections.emptyList();
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}
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return Collections.unmodifiableList(wrappers);
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}
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@Nullable
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private static KeyValueSourceWrapper parseSingleKeyValue(String line) {
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int separatorIndex = line.indexOf('=');
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if (separatorIndex <= 0) {
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return null;
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}
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String key = line.substring(0, separatorIndex).trim();
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String value = line.substring(separatorIndex + 1).trim();
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if (key.isEmpty()) {
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return null;
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}
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return new KeyValueSourceWrapper(key, value);
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}
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}

‎dynamic-control/src/main/java/io/opentelemetry/contrib/dynamic/policy/source/SourceFormat.java‎

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/*
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* Copyright The OpenTelemetry Authors
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* SPDX-License-Identifier: Apache-2.0
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*/
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package io.opentelemetry.contrib.dynamic.policy.source;
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import com.google.errorprone.annotations.Immutable;
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import java.util.List;
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import java.util.Objects;
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import javax.annotation.Nullable;
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/** Supported source formats and their parser dispatch. */
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public enum SourceFormat {
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KEYVALUE("keyvalue", KeyValueSourceWrapper::parse),
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JSON("json", JsonSourceWrapper::parse);
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private final String configValue;
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private final SourceParser parser;
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SourceFormat(String configValue, SourceParser parser) {
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this.configValue = configValue;
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this.parser = parser;
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}
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public String configValue() {
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return configValue;
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}
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/**
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* Parses source text into normalized wrappers for this format.
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*
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* @return an empty list if the source is valid but contains no policies; a non-empty list of
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* wrappers if one or more policies were parsed successfully; or {@code null} if the source is
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* malformed or does not conform to the expected shape for this format.
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* @throws NullPointerException if source is null
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*/
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@Nullable
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public List<SourceWrapper> parse(String source) {
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Objects.requireNonNull(source, "source cannot be null");
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return parser.parse(source);
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}
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@Immutable
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@FunctionalInterface
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private interface SourceParser {
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@Nullable
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List<SourceWrapper> parse(String source);
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}
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}

‎dynamic-control/src/main/java/io/opentelemetry/contrib/dynamic/policy/source/SourceWrapper.java‎

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/*
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* Copyright The OpenTelemetry Authors
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* SPDX-License-Identifier: Apache-2.0
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*/
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package io.opentelemetry.contrib.dynamic.policy.source;
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import javax.annotation.Nullable;
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/** Parsed source payload paired with its source format. */
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public interface SourceWrapper {
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SourceFormat getFormat();
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@Nullable
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String getPolicyType();
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}

‎dynamic-control/src/test/java/io/opentelemetry/contrib/dynamic/policy/source/JsonSourceWrapperTest.java‎

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/*
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* Copyright The OpenTelemetry Authors
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* SPDX-License-Identifier: Apache-2.0
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*/
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package io.opentelemetry.contrib.dynamic.policy.source;
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import static org.assertj.core.api.Assertions.assertThat;
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import static org.assertj.core.api.Assertions.assertThatThrownBy;
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import com.fasterxml.jackson.databind.ObjectMapper;
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import java.util.List;
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import org.junit.jupiter.api.Test;
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class JsonSourceWrapperTest {
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private static final ObjectMapper MAPPER = new ObjectMapper();
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@Test
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void parseSupportsSingleObject() {
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List<SourceWrapper> parsed = JsonSourceWrapper.parse("{\"trace-sampling\": 0.5}");
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assertThat(parsed).hasSize(1);
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assertThat(parsed.get(0)).isInstanceOf(JsonSourceWrapper.class);
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assertThat(parsed.get(0).getPolicyType()).isEqualTo("trace-sampling");
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}
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@Test
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void parseSupportsArrayOfObjects() {
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List<SourceWrapper> parsed =
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JsonSourceWrapper.parse("[{\"other-policy\": 1}, {\"trace-sampling\": 0.5}]");
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assertThat(parsed).hasSize(2);
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assertThat(parsed.get(0).getPolicyType()).isEqualTo("other-policy");
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assertThat(parsed.get(1).getPolicyType()).isEqualTo("trace-sampling");
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}
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@Test
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void parseSupportsEmptyArray() {
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assertThat(JsonSourceWrapper.parse("[]")).isEmpty();
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}
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@Test
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void parseArrayResultIsImmutable() {
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List<SourceWrapper> parsed = JsonSourceWrapper.parse("[{\"trace-sampling\": 0.5}]");
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assertThatThrownBy(() -> parsed.add(new JsonSourceWrapper(MAPPER.readTree("{\"x\":1}"))))
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.isInstanceOf(UnsupportedOperationException.class);
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}
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@Test
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void getPolicyTypeReturnsNullWhenObjectHasMultipleFields() throws Exception {
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JsonSourceWrapper wrapper = new JsonSourceWrapper(MAPPER.readTree("{\"a\": 1, \"b\": 2}"));
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assertThat(wrapper.getPolicyType()).isNull();
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}
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@Test
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void parseRejectsUnsupportedJsonShapes() {
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assertThat(JsonSourceWrapper.parse("{}")).isNull();
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assertThat(JsonSourceWrapper.parse("{\"a\": 1, \"b\": 2}")).isNull();
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assertThat(JsonSourceWrapper.parse("[1, 2, 3]")).isNull();
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assertThat(JsonSourceWrapper.parse("[{\"trace-sampling\": 0.5}, {}]")).isNull();
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assertThat(JsonSourceWrapper.parse("[{\"a\": 1, \"b\": 2}]")).isNull();
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assertThat(JsonSourceWrapper.parse("\"text\"")).isNull();
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assertThat(JsonSourceWrapper.parse("{invalid-json")).isNull();
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}
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@Test
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void parseRejectsNullInput() {
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assertThatThrownBy(() -> JsonSourceWrapper.parse(null))
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.isInstanceOf(NullPointerException.class)
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.hasMessage("source cannot be null");
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}
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}

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