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feat(filter): add CPU load-based request control with HTTP 429
Introduce LoadControlFilter that monitors OpenSearch CPU usage and returns HTTP 429 (Too Many Requests) when thresholds are exceeded. Web and API requests have independent configurable thresholds. - Add LoadControlFilter servlet filter with configurable CPU thresholds - Add LoadControlMonitorTarget for periodic OpenSearch CPU monitoring - Add ErrorBusyAction and busy.jsp for user-friendly 429 error page - Add web.xml filter registration and 429 error-page mapping - Add FessConfig properties: web.load.control, api.load.control, load.control.monitor.interval (disabled by default with threshold=100) - Add i18n labels for busy page across all supported languages - Add comprehensive unit tests for LoadControlFilter Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
1 parent 44093a8 commit 3b34876

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+1575
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lines changed

‎src/main/java/org/codelibs/fess/app/web/error/ErrorBusyAction.java‎

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/*
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* Copyright 2012-2025 CodeLibs Project and the Others.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
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* either express or implied. See the License for the specific language
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* governing permissions and limitations under the License.
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*/
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package org.codelibs.fess.app.web.error;
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import org.codelibs.fess.app.web.base.FessSearchAction;
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import org.lastaflute.web.Execute;
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import org.lastaflute.web.response.HtmlResponse;
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/**
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* Action class for handling HTTP 429 Too Many Requests error pages.
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* This action displays error pages when the server is under high load.
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*/
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public class ErrorBusyAction extends FessSearchAction {
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/**
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* Default constructor for ErrorBusyAction.
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*/
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public ErrorBusyAction() {
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super();
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}
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/**
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* Displays the busy error page.
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*
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* @param form the error form containing error information
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* @return HTML response for the busy error page
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*/
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@Execute
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public HtmlResponse index(final ErrorForm form) {
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return asHtml(virtualHost(path_Error_BusyJsp));
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}
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}

‎src/main/java/org/codelibs/fess/filter/LoadControlFilter.java‎

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/*
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* Copyright 2012-2025 CodeLibs Project and the Others.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
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* either express or implied. See the License for the specific language
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* governing permissions and limitations under the License.
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*/
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package org.codelibs.fess.filter;
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import java.io.IOException;
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import java.util.Arrays;
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import java.util.Set;
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import java.util.stream.Collectors;
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import org.apache.logging.log4j.LogManager;
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import org.apache.logging.log4j.Logger;
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import org.codelibs.fess.mylasta.direction.FessConfig;
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import org.codelibs.fess.util.ComponentUtil;
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import jakarta.servlet.Filter;
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import jakarta.servlet.FilterChain;
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import jakarta.servlet.ServletException;
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import jakarta.servlet.ServletRequest;
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import jakarta.servlet.ServletResponse;
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import jakarta.servlet.http.HttpServletRequest;
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import jakarta.servlet.http.HttpServletResponse;
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/**
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* Filter for CPU load-based request control.
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* Returns HTTP 429 (Too Many Requests) when CPU usage exceeds configurable thresholds.
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* Web and API requests have independent threshold settings.
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*/
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public class LoadControlFilter implements Filter {
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private static final Logger logger = LogManager.getLogger(LoadControlFilter.class);
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private static final int RETRY_AFTER_SECONDS = 60;
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private static final Set<String> STATIC_EXTENSIONS =
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Arrays.stream(new String[] { ".css", ".js", ".png", ".jpg", ".gif", ".ico", ".svg", ".woff", ".woff2", ".ttf", ".eot" })
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.collect(Collectors.toSet());
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/**
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* Creates a new instance of LoadControlFilter.
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*/
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public LoadControlFilter() {
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// Default constructor
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}
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@Override
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public void doFilter(final ServletRequest request, final ServletResponse response, final FilterChain chain)
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throws IOException, ServletException {
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if (!ComponentUtil.available()) {
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chain.doFilter(request, response);
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return;
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}
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final HttpServletRequest httpRequest = (HttpServletRequest) request;
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final HttpServletResponse httpResponse = (HttpServletResponse) response;
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final String path = httpRequest.getRequestURI().substring(httpRequest.getContextPath().length());
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if (isExcludedPath(path)) {
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chain.doFilter(request, response);
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return;
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}
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final boolean isApiPath = path.startsWith("/api/");
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final FessConfig fessConfig = ComponentUtil.getFessConfig();
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final int threshold = isApiPath ? fessConfig.getApiLoadControlAsInteger() : fessConfig.getWebLoadControlAsInteger();
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if (threshold >= 100) {
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chain.doFilter(request, response);
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return;
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}
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final short cpuPercent = ComponentUtil.getSystemHelper().getSearchEngineCpuPercent();
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if (cpuPercent < threshold) {
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chain.doFilter(request, response);
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return;
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}
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if (logger.isInfoEnabled()) {
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logger.info("Rejecting request due to high CPU load: path={}, cpu={}%, threshold={}%", path, cpuPercent, threshold);
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}
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if (isApiPath) {
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sendApiResponse(httpResponse);
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} else {
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httpResponse.sendError(429);
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}
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}
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/**
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* Checks if the given path should be excluded from load control.
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* @param path the request path
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* @return true if the path should be excluded
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*/
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protected boolean isExcludedPath(final String path) {
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if (path.startsWith("/admin") || path.startsWith("/error") || path.startsWith("/login")) {
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return true;
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}
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final int dotIndex = path.lastIndexOf('.');
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if (dotIndex >= 0) {
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final String extension = path.substring(dotIndex);
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return STATIC_EXTENSIONS.contains(extension);
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}
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return false;
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}
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/**
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* Sends a 429 JSON response for API requests.
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* @param response the HTTP response
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* @throws IOException if an I/O error occurs
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*/
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protected void sendApiResponse(final HttpServletResponse response) throws IOException {
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response.setStatus(429);
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response.setContentType("application/json;charset=UTF-8");
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response.setHeader("Retry-After", String.valueOf(RETRY_AFTER_SECONDS));
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response.getWriter()
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.write("{\"response\":{\"status\":9,\"message\":\"Server is busy. Please retry after " + RETRY_AFTER_SECONDS
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+ " seconds.\",\"retry_after\":" + RETRY_AFTER_SECONDS + "}}");
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}
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}

‎src/main/java/org/codelibs/fess/helper/SystemHelper.java‎

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import org.codelibs.core.lang.StringUtil;
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import org.codelibs.core.lang.ThreadUtil;
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import org.codelibs.core.misc.Pair;
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import org.codelibs.core.timer.TimeoutManager;
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import org.codelibs.core.timer.TimeoutTask;
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import org.codelibs.fess.Constants;
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import org.codelibs.fess.crawler.util.CharUtil;
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import org.codelibs.fess.exception.FessSystemException;
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import org.codelibs.fess.mylasta.action.FessMessages;
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import org.codelibs.fess.mylasta.action.FessUserBean;
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import org.codelibs.fess.mylasta.direction.FessConfig;
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import org.codelibs.fess.timer.LoadControlMonitorTarget;
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import org.codelibs.fess.util.ComponentUtil;
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import org.codelibs.fess.util.GsaConfigParser;
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import org.codelibs.fess.util.IpAddressUtil;
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private long systemCpuCheckInterval = 1000L;
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private volatile short searchEngineCpuPercent;
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private volatile TimeoutTask loadControlMonitorTask;
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/** A map of listeners for configuration updates. */
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protected Map<String, Supplier<String>> updateConfigListenerMap = new HashMap<>();
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return systemCpuPercent;
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}
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/**
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* Gets the current system CPU usage percentage.
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*
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* @return The system CPU usage percentage.
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*/
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public short currentSystemCpuPercent() {
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return getSystemCpuPercent();
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}
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/**
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* Gets the search engine CPU usage percentage.
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*
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* @return The search engine CPU usage percentage.
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*/
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public short getSearchEngineCpuPercent() {
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ensureLoadControlMonitorStarted();
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return searchEngineCpuPercent;
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}
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/**
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* Sets the search engine CPU usage percentage.
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*
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* @param percent The search engine CPU usage percentage.
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*/
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public void setSearchEngineCpuPercent(final short percent) {
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searchEngineCpuPercent = percent;
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}
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private void ensureLoadControlMonitorStarted() {
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if (loadControlMonitorTask == null) {
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final FessConfig fessConfig = ComponentUtil.getFessConfig();
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if (fessConfig.getWebLoadControlAsInteger() < 100 || fessConfig.getApiLoadControlAsInteger() < 100) {
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synchronized (this) {
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if (loadControlMonitorTask == null) {
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final int interval = fessConfig.getLoadControlMonitorIntervalAsInteger();
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loadControlMonitorTask =
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TimeoutManager.getInstance().addTimeoutTarget(new LoadControlMonitorTarget(this), interval, true);
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}
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}
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}
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}
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}
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/**
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* Gets a map of filtered environment variables.
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*

‎src/main/java/org/codelibs/fess/mylasta/action/FessHtmlPath.java‎

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/** The path of the HTML: /error/badRequest.jsp */
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HtmlNext path_Error_BadRequestJsp = new HtmlNext("/error/badRequest.jsp");
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/** The path of the HTML: /error/busy.jsp */
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HtmlNext path_Error_BusyJsp = new HtmlNext("/error/busy.jsp");
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/** The path of the HTML: /error/error.jsp */
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HtmlNext path_Error_ErrorJsp = new HtmlNext("/error/error.jsp");
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‎src/main/java/org/codelibs/fess/mylasta/action/FessLabels.java‎

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/** The key of the message: Please check the URL. */
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public static final String LABELS_check_url = "{labels.check_url}";
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/** The key of the message: Service Temporarily Unavailable */
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public static final String LABELS_busy_title = "{labels.busy_title}";
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/** The key of the message: The server is currently experiencing high load. Please try again later. */
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public static final String LABELS_busy_message = "{labels.busy_message}";
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/** The key of the message: Username */
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public static final String LABELS_user_name = "{labels.user_name}";
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‎src/main/java/org/codelibs/fess/mylasta/direction/FessConfig.java‎

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/** The key of the configuration. e.g. 50 */
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String ADAPTIVE_LOAD_CONTROL = "adaptive.load.control";
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/** The key of the configuration. e.g. 100 */
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String WEB_LOAD_CONTROL = "web.load.control";
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/** The key of the configuration. e.g. 100 */
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String API_LOAD_CONTROL = "api.load.control";
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/** The key of the configuration. e.g. 1 */
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String LOAD_CONTROL_MONITOR_INTERVAL = "load.control.monitor.interval";
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/** The key of the configuration. e.g. js */
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String SUPPORTED_UPLOADED_JS_EXTENTIONS = "supported.uploaded.js.extentions";
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*/
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Integer getAdaptiveLoadControlAsInteger();
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/**
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* Get the value for the key 'web.load.control'. <br>
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* The value is, e.g. 100 <br>
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* comment: CPU threshold (%) for web request load control. Returns 429 when CPU &gt;= this value. (100: disabled)
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* @return The value of found property. (NotNull: if not found, exception but basically no way)
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*/
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String getWebLoadControl();
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/**
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* Get the value for the key 'web.load.control' as {@link Integer}. <br>
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* The value is, e.g. 100 <br>
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* comment: CPU threshold (%) for web request load control. Returns 429 when CPU &gt;= this value. (100: disabled)
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* @return The value of found property. (NotNull: if not found, exception but basically no way)
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* @throws NumberFormatException When the property is not integer.
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*/
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Integer getWebLoadControlAsInteger();
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/**
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* Get the value for the key 'api.load.control'. <br>
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* The value is, e.g. 100 <br>
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* comment: CPU threshold (%) for API request load control. Returns 429 when CPU &gt;= this value. (100: disabled)
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* @return The value of found property. (NotNull: if not found, exception but basically no way)
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*/
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String getApiLoadControl();
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/**
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* Get the value for the key 'api.load.control' as {@link Integer}. <br>
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* The value is, e.g. 100 <br>
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* comment: CPU threshold (%) for API request load control. Returns 429 when CPU &gt;= this value. (100: disabled)
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* @return The value of found property. (NotNull: if not found, exception but basically no way)
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* @throws NumberFormatException When the property is not integer.
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*/
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Integer getApiLoadControlAsInteger();
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/**
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* Get the value for the key 'load.control.monitor.interval'. <br>
2583+
* The value is, e.g. 1 <br>
2584+
* comment: Interval (seconds) for monitoring OpenSearch CPU load.
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* @return The value of found property. (NotNull: if not found, exception but basically no way)
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*/
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String getLoadControlMonitorInterval();
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/**
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* Get the value for the key 'load.control.monitor.interval' as {@link Integer}. <br>
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* The value is, e.g. 1 <br>
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* comment: Interval (seconds) for monitoring OpenSearch CPU load.
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* @return The value of found property. (NotNull: if not found, exception but basically no way)
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* @throws NumberFormatException When the property is not integer.
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*/
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Integer getLoadControlMonitorIntervalAsInteger();
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/**
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* Get the value for the key 'supported.uploaded.js.extentions'. <br>
25402600
* The value is, e.g. js <br>
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return getAsInteger(FessConfig.ADAPTIVE_LOAD_CONTROL);
97809840
}
97819841

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public String getWebLoadControl() {
9843+
return get(FessConfig.WEB_LOAD_CONTROL);
9844+
}
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9846+
public Integer getWebLoadControlAsInteger() {
9847+
return getAsInteger(FessConfig.WEB_LOAD_CONTROL);
9848+
}
9849+
9850+
public String getApiLoadControl() {
9851+
return get(FessConfig.API_LOAD_CONTROL);
9852+
}
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9854+
public Integer getApiLoadControlAsInteger() {
9855+
return getAsInteger(FessConfig.API_LOAD_CONTROL);
9856+
}
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9858+
public String getLoadControlMonitorInterval() {
9859+
return get(FessConfig.LOAD_CONTROL_MONITOR_INTERVAL);
9860+
}
9861+
9862+
public Integer getLoadControlMonitorIntervalAsInteger() {
9863+
return getAsInteger(FessConfig.LOAD_CONTROL_MONITOR_INTERVAL);
9864+
}
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97829866
public String getSupportedUploadedJsExtentions() {
97839867
return get(FessConfig.SUPPORTED_UPLOADED_JS_EXTENTIONS);
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}
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defaultMap.put(FessConfig.USE_OWN_TMP_DIR, "true");
1318913273
defaultMap.put(FessConfig.MAX_LOG_OUTPUT_LENGTH, "4000");
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defaultMap.put(FessConfig.ADAPTIVE_LOAD_CONTROL, "50");
13275+
defaultMap.put(FessConfig.WEB_LOAD_CONTROL, "100");
13276+
defaultMap.put(FessConfig.API_LOAD_CONTROL, "100");
13277+
defaultMap.put(FessConfig.LOAD_CONTROL_MONITOR_INTERVAL, "1");
1319113278
defaultMap.put(FessConfig.SUPPORTED_UPLOADED_JS_EXTENTIONS, "js");
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defaultMap.put(FessConfig.SUPPORTED_UPLOADED_CSS_EXTENTIONS, "css");
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defaultMap.put(FessConfig.SUPPORTED_UPLOADED_MEDIA_EXTENTIONS, "jpg,jpeg,gif,png,swf");

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