8288493: Document JDK specific system properties in jdk.httpserver

Reviewed-by: dfuchs, jpai, aefimov

src/jdk.httpserver/share/classes/module-info.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014, 2022, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -37,6 +37,59 @@
  * <p>The {@link com.sun.net.httpserver.spi} package specifies a Service Provider
  * Interface (SPI) for locating HTTP server implementations based on the
  * {@code com.sun.net.httpserver} API.
+ * <p>
+ * <b id="httpserverprops">System properties used by the HTTP server API</b>
+ * <p>
+ * The following is a list of JDK specific system properties used by the default HTTP
+ * server implementation in the JDK. Any properties below that take a numeric value
+ * assume the default value if given a string that does not parse as a number.
+ * <ul>
+ * <li><p><b>{@systemProperty sun.net.httpserver.idleInterval}</b> (default: 30 sec)<br>
+ * Maximum duration in seconds which an idle connection is kept open. This timer
+ * has an implementation specific granularity that may mean that idle connections are
+ * closed later than the specified interval. Values less than or equal to zero are mapped
+ * to the default setting.
+ * </li>
+ * <li><p><b>{@systemProperty jdk.httpserver.maxConnections}</b> (default: -1)<br>
+ * The maximum number of open connections at a time. This includes active and idle connections.
+ * If zero or negative, then no limit is enforced.
+ * </li>
+ * <li><p><b>{@systemProperty sun.net.httpserver.maxIdleConnections}</b> (default: 200)<br>
+ * The maximum number of idle connections at a time. If set to zero or a negative value
+ * then connections are closed after use.
+ * </li>
+ * <li><p><b>{@systemProperty sun.net.httpserver.drainAmount}</b> (default: 65536)<br>
+ * The maximum number of bytes that will be automatically read and discarded from a
+ * request body that has not been completely consumed by its
+ * {@link com.sun.net.httpserver.HttpHandler HttpHandler}. If the number of remaining
+ * unread bytes are less than this limit then the connection will be put in the idle connection
+ * cache. If not, then it will be closed.
+ * </li>
+ * <li><p><b>{@systemProperty sun.net.httpserver.maxReqHeaders}</b> (default: 200)<br>
+ * The maxiumum number of header fields accepted in a request. If this limit is exceeded
+ * while the headers are being read, then the connection is terminated and the request ignored.
+ * If the value is less than or equal to zero, then the default value is used.
+ * </li>
+ * <li><p><b>{@systemProperty sun.net.httpserver.maxReqTime}</b> (default: -1)<br>
+ * The maximum time in milliseconds allowed to receive a request headers and body.
+ * In practice, the actual time is a function of request size, network speed, and handler
+ * processing delays. A value less than or equal to zero means the time is not limited.
+ * If the limit is exceeded then the connection is terminated and the handler will receive a
+ * {@link java.io.IOException}. This timer has an implementation specific granularity
+ * that may mean requests are aborted later than the specified interval.
+ * </li>
+ * <li><p><b>{@systemProperty sun.net.httpserver.maxRspTime}</b> (default: -1)<br>
+ * The maximum time in milliseconds allowed to receive a response headers and body.
+ * In practice, the actual time is a function of response size, network speed, and handler
+ * processing delays. A value less than or equal to zero means the time is not limited.
+ * If the limit is exceeded then the connection is terminated and the handler will receive a
+ * {@link java.io.IOException}. This timer has an implementation specific granularity
+ * that may mean responses are aborted later than the specified interval.
+ * </li>
+ * <li><p><b>{@systemProperty sun.net.httpserver.nodelay}</b> (default: false)<br>
+ * Boolean value, which if true, sets the {@link java.net.StandardSocketOptions#TCP_NODELAY TCP_NODELAY}
+ * socket option on all incoming connections.
+ * </li></ul>
  *
  * @toolGuide jwebserver
  *

src/jdk.httpserver/share/classes/sun/net/httpserver/ServerConfig.java

@@ -103,6 +103,9 @@ class ServerConfig {
                     maxReqHeaders = Integer.getInteger(
                             "sun.net.httpserver.maxReqHeaders",
                             DEFAULT_MAX_REQ_HEADERS);
+                    if (maxReqHeaders <= 0) {
+                        maxReqHeaders = DEFAULT_MAX_REQ_HEADERS;
+                    }
 
                     maxReqTime = Long.getLong("sun.net.httpserver.maxReqTime",
                             DEFAULT_MAX_REQ_TIME);