[JENKINS-69853] User experimental flags (jenkinsci#7299)

* [JENKINS-69853] User experimental flags

* Applying feedbacks from Tim

* Improve default wording + padding + title

* Remove the "UI"

* Correct Spotbugs

---------

Co-authored-by: Alexander Brandes <[email protected]>
Co-authored-by: Tim Jacomb <[email protected]>

core/src/main/java/jenkins/model/experimentalflags/BooleanUserExperimentalFlag.java

@@ -0,0 +1,60 @@
+/*
+ * The MIT License
+ *
+ * Copyright (c) 2022, CloudBees, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package jenkins.model.experimentalflags;
+
+import edu.umd.cs.findbugs.annotations.NonNull;
+
+/**
+ * @since TODO
+ */
+public abstract class BooleanUserExperimentalFlag extends UserExperimentalFlag<Boolean> {
+    protected BooleanUserExperimentalFlag(@NonNull String flagKey) {
+        super(flagKey);
+    }
+
+    @Override
+    public @NonNull Boolean getDefaultValue() {
+        return false;
+    }
+
+    @Override
+    public Object serializeValue(Boolean rawValue) {
+        if (rawValue == null) {
+            return null;
+        }
+        return rawValue ? "true" : "false";
+    }
+
+    @Override
+    protected Boolean deserializeValue(Object serializedValue) {
+        if (serializedValue.equals("true")) {
+            return Boolean.TRUE;
+        }
+        if (serializedValue.equals("false")) {
+            return Boolean.FALSE;
+        }
+        return null;
+    }
+}

core/src/main/java/jenkins/model/experimentalflags/UserExperimentalFlag.java

@@ -0,0 +1,149 @@
+/*
+ * The MIT License
+ *
+ * Copyright (c) 2022, CloudBees, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package jenkins.model.experimentalflags;
+
+import edu.umd.cs.findbugs.annotations.CheckForNull;
+import edu.umd.cs.findbugs.annotations.NonNull;
+import edu.umd.cs.findbugs.annotations.Nullable;
+import hudson.ExtensionList;
+import hudson.ExtensionPoint;
+import hudson.model.User;
+
+/**
+ * User specific experimental flag to enable or disable specific behavior.
+ * As it's user specific, usually this kind of feature flag is only used for UI.
+ *
+ * @since TODO
+ */
+public abstract class UserExperimentalFlag<T> implements ExtensionPoint {
+    private final String flagKey;
+
+    protected UserExperimentalFlag(@NonNull String flagKey) {
+        this.flagKey = flagKey;
+    }
+
+    public abstract @NonNull T getDefaultValue();
+
+    /**
+     * Convert the usable value into a serializable form that can be stored in the user property.
+     * If no changes are necessary, simply returning the {@code rawValue} is fine.
+     */
+    public abstract @Nullable Object serializeValue(T rawValue);
+
+    /**
+     * Convert the serialized value into the usable instance.
+     * If the instance is invalid (like after migration),
+     * returning {@code null} will force to return the {@link #getDefaultValue()}
+     */
+    protected abstract @Nullable T deserializeValue(Object serializedValue);
+
+    /**
+     * The name that will be used in the configuration page for that flag
+     * It must be user readable
+     */
+    public abstract String getDisplayName();
+
+    /**
+     * Describe what the flag is changing depending on its value.
+     * This method is called in description.jelly, which could be overloaded by children.
+     * It could return HTML content.
+     */
+    public abstract @Nullable String getShortDescription();
+
+    /**
+     * The ID used by the machine to link the flag with its value within the user properties
+     */
+    public @NonNull String getFlagKey() {
+        return flagKey;
+    }
+
+    public @NonNull T getFlagValue() {
+        User currentUser = User.current();
+        if (currentUser == null) {
+            // the anonymous user is not expected to use flags
+            return this.getDefaultValue();
+        }
+        return this.getFlagValue(currentUser);
+    }
+
+    public @NonNull T getFlagValue(User user) {
+        UserExperimentalFlagsProperty property = user.getProperty(UserExperimentalFlagsProperty.class);
+        if (property == null) {
+            // if for whatever reason there is no such property
+            return this.getDefaultValue();
+        }
+
+        Object value = property.getFlagValue(this.flagKey);
+        if (value == null) {
+            return this.getDefaultValue();
+        }
+
+        T convertedValue = this.deserializeValue(value);
+        if (convertedValue == null) {
+            return this.getDefaultValue();
+        }
+        return convertedValue;
+    }
+
+    public String getFlagDescriptionPage() {
+        return "flagDescription.jelly";
+    }
+
+    public String getFlagConfigPage() {
+        return "flagConfig.jelly";
+    }
+
+    @NonNull
+    @SuppressWarnings("rawtypes")
+    public static ExtensionList<UserExperimentalFlag> all() {
+        return ExtensionList.lookup(UserExperimentalFlag.class);
+    }
+
+    /**
+     * From the flag class, return the value of the flag for the current user
+     * If the returned value is {@code null},
+     * it means that either the class was not found or the current user is anonymous
+     */
+    @SuppressWarnings("unchecked")
+    public static @CheckForNull <T> T getFlagValueForCurrentUser(String flagClassCanonicalName) {
+        Class<? extends UserExperimentalFlag<T>> flagClass;
+        try {
+            Class<?> clazz = Thread.currentThread().getContextClassLoader().loadClass(flagClassCanonicalName);
+            if (!UserExperimentalFlag.class.isAssignableFrom(clazz)) {
+                return null;
+            }
+            flagClass = (Class<? extends UserExperimentalFlag<T>>) clazz;
+        } catch (Exception e) {
+            return null;
+        }
+
+        UserExperimentalFlag<T> userExperimentalFlag = all().get(flagClass);
+        if (userExperimentalFlag == null) {
+            return null;
+        }
+
+        return userExperimentalFlag.getFlagValue();
+    }
+}

core/src/main/java/jenkins/model/experimentalflags/UserExperimentalFlagsProperty.java

@@ -0,0 +1,88 @@
+/*
+ * The MIT License
+ *
+ * Copyright (c) 2022, CloudBees, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package jenkins.model.experimentalflags;
+
+import edu.umd.cs.findbugs.annotations.CheckForNull;
+import edu.umd.cs.findbugs.annotations.NonNull;
+import edu.umd.cs.findbugs.annotations.Nullable;
+import hudson.Extension;
+import hudson.model.User;
+import hudson.model.UserProperty;
+import hudson.model.UserPropertyDescriptor;
+import java.util.HashMap;
+import java.util.Map;
+import net.sf.json.JSONObject;
+import org.jenkinsci.Symbol;
+import org.kohsuke.stapler.DataBoundConstructor;
+import org.kohsuke.stapler.StaplerRequest;
+
+
+/**
+ * Per user experimental flags to enable features that still not completely ready to be active by default.
+ *
+ * @since TODO
+ */
+public class UserExperimentalFlagsProperty extends UserProperty {
+    private Map<String, String> flags = new HashMap<>();
+
+    @DataBoundConstructor
+    public UserExperimentalFlagsProperty() {
+    }
+
+    public UserExperimentalFlagsProperty(Map<String, String> flags) {
+        this.flags = new HashMap<>(flags);
+    }
+
+    public @CheckForNull Object getFlagValue(String flagKey) {
+        return this.flags.get(flagKey);
+    }
+
+    @Extension(ordinal = -500)
+    @Symbol("experimentalFlags")
+    public static final class DescriptorImpl extends UserPropertyDescriptor {
+        @Override
+        public @NonNull String getDisplayName() {
+            return Messages.UserExperimentalFlagsProperty_DisplayName();
+        }
+
+        @Override
+        public @NonNull UserProperty newInstance(User user) {
+            return new UserExperimentalFlagsProperty();
+        }
+
+        @Override
+        public UserProperty newInstance(@Nullable StaplerRequest req, @NonNull JSONObject formData) throws FormException {
+            JSONObject flagsObj = formData.getJSONObject("flags");
+            Map<String, String> flags = new HashMap<>();
+            for (Object key : flagsObj.keySet()) {
+                String value = (String) flagsObj.get((String) key);
+                if (!value.isEmpty()) {
+                    flags.put((String) key, value);
+                }
+            }
+            return new UserExperimentalFlagsProperty(flags);
+        }
+    }
+}

core/src/main/resources/jenkins/model/experimentalflags/BooleanUserExperimentalFlag/flagConfig.jelly

@@ -0,0 +1,35 @@
+<!--
+The MIT License
+
+Copyright (c) 2022, CloudBees, Inc.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+-->
+
+<?jelly escape-by-default='true'?>
+<j:jelly xmlns:j="jelly:core" xmlns:f="/lib/form">
+    <select class="jenkins-select__input" name="[${it.flagKey}]">
+        <f:option selected="${flagValue == null}" value="">
+            <j:if test="${it.getDefaultValue() == true}">${%Default_True}</j:if>
+            <j:if test="${it.getDefaultValue() == false}">${%Default_False}</j:if>
+        </f:option>
+        <f:option selected="${flagValue == true}" value="true">${%True}</f:option>
+        <f:option selected="${flagValue == false}" value="false">${%False}</f:option>
+    </select>
+</j:jelly>

core/src/main/resources/jenkins/model/experimentalflags/BooleanUserExperimentalFlag/flagConfig.properties

@@ -0,0 +1,25 @@
+# The MIT License
+#
+# Copyright (c) 2022, CloudBees, Inc.
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+Default_True=Default (enabled)
+Default_False=Default (disabled)
+True=Enabled
+False=Disabled

core/src/main/resources/jenkins/model/experimentalflags/Messages.properties

@@ -0,0 +1,23 @@
+# The MIT License
+# 
+# Copyright (c) 2022, CloudBees, Inc.
+# 
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+# 
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+# 
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+
+UserExperimentalFlagsProperty.DisplayName=Experiments