src/jdk.internal.vm.ci/share/classes/jdk.vm.ci.services/src/jdk/vm/ci/services/Services.java
8234681: Remove UseJVMCIClassLoader logic from JVMCI code
Reviewed-by: kvn, iignatyev
/*
* Copyright (c) 2014, 2019, 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
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package jdk.vm.ci.services;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Formatter;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.ServiceLoader;
import java.util.Set;
import jdk.internal.misc.VM;
/**
* Provides utilities needed by JVMCI clients.
*/
public final class Services {
/**
* Guards code that should be run when building an JVMCI shared library but should be excluded
* from (being compiled into) the library. Such code must be directly guarded by an {@code if}
* statement on this field - the guard cannot be behind a method call.
*/
public static final boolean IS_BUILDING_NATIVE_IMAGE = Boolean.parseBoolean(VM.getSavedProperty("jdk.vm.ci.services.aot"));
/**
* Guards code that should only be run in a JVMCI shared library. Such code must be directly
* guarded by an {@code if} statement on this field - the guard cannot be behind a method call.
*
* The value of this field in a JVMCI shared library runtime must be {@code true}.
*/
public static final boolean IS_IN_NATIVE_IMAGE;
static {
/*
* Prevents javac from constant folding use of this field. It is set to true by the process
* that builds the shared library.
*/
IS_IN_NATIVE_IMAGE = false;
}
private Services() {
}
/**
* In a native image, this field is initialized by {@link #initializeSavedProperties(byte[])}.
*/
private static volatile Map<String, String> savedProperties;
static final boolean JVMCI_ENABLED = Boolean.parseBoolean(VM.getSavedProperties().get("jdk.internal.vm.ci.enabled"));
/**
* Checks that JVMCI is enabled in the VM and throws an error if it isn't.
*/
static void checkJVMCIEnabled() {
if (!JVMCI_ENABLED) {
throw new Error("The EnableJVMCI VM option must be true (i.e., -XX:+EnableJVMCI) to use JVMCI");
}
}
/**
* Gets an unmodifiable copy of the system properties saved when {@link System} is initialized.
*/
public static Map<String, String> getSavedProperties() {
checkJVMCIEnabled();
if (IS_IN_NATIVE_IMAGE) {
if (savedProperties == null) {
throw new InternalError("Saved properties not initialized");
}
} else {
if (savedProperties == null) {
synchronized (Services.class) {
if (savedProperties == null) {
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
sm.checkPermission(new JVMCIPermission());
}
savedProperties = VM.getSavedProperties();
}
}
}
}
return savedProperties;
}
/**
* Helper method equivalent to {@link #getSavedProperties()}{@code .getOrDefault(name, def)}.
*/
public static String getSavedProperty(String name, String def) {
return Services.getSavedProperties().getOrDefault(name, def);
}
/**
* Helper method equivalent to {@link #getSavedProperties()}{@code .get(name)}.
*/
public static String getSavedProperty(String name) {
return Services.getSavedProperties().get(name);
}
/**
* Causes the JVMCI subsystem to be initialized if it isn't already initialized.
*/
public static void initializeJVMCI() {
checkJVMCIEnabled();
try {
Class.forName("jdk.vm.ci.runtime.JVMCI");
} catch (ClassNotFoundException e) {
throw new InternalError(e);
}
}
private static final Map<Class<?>, List<?>> servicesCache = IS_BUILDING_NATIVE_IMAGE ? new HashMap<>() : null;
@SuppressWarnings("unchecked")
private static <S> Iterable<S> load0(Class<S> service) {
if (IS_IN_NATIVE_IMAGE || IS_BUILDING_NATIVE_IMAGE) {
List<?> list = servicesCache.get(service);
if (list != null) {
return (Iterable<S>) list;
}
if (IS_IN_NATIVE_IMAGE) {
throw new InternalError(String.format("No %s providers found when building native image", service.getName()));
}
}
Iterable<S> providers = ServiceLoader.load(service, ClassLoader.getSystemClassLoader());
if (IS_BUILDING_NATIVE_IMAGE) {
synchronized (servicesCache) {
ArrayList<S> providersList = new ArrayList<>();
for (S provider : providers) {
providersList.add(provider);
}
servicesCache.put(service, providersList);
providers = providersList;
}
}
return providers;
}
/**
* Opens all JVMCI packages to {@code otherModule}.
*/
static void openJVMCITo(Module otherModule) {
Module jvmci = Services.class.getModule();
if (jvmci != otherModule) {
Set<String> packages = jvmci.getPackages();
for (String pkg : packages) {
boolean opened = jvmci.isOpen(pkg, otherModule);
if (!opened) {
jvmci.addOpens(pkg, otherModule);
}
}
}
}
/**
* Gets an {@link Iterable} of the JVMCI providers available for a given service.
*
* @throws SecurityException if a security manager is present and it denies <tt>
* {@link RuntimePermission}("jvmci")</tt>
*/
public static <S> Iterable<S> load(Class<S> service) {
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
sm.checkPermission(new JVMCIPermission());
}
return load0(service);
}
/**
* Gets the JVMCI provider for a given service for which at most one provider must be available.
*
* @param service the service whose provider is being requested
* @param required specifies if an {@link InternalError} should be thrown if no provider of
* {@code service} is available
* @throws SecurityException if a security manager is present and it denies <tt>
* {@link RuntimePermission}("jvmci")</tt>
*/
public static <S> S loadSingle(Class<S> service, boolean required) {
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
sm.checkPermission(new JVMCIPermission());
}
Iterable<S> providers = load0(service);
S singleProvider = null;
for (S provider : providers) {
if (singleProvider != null) {
throw new InternalError(String.format("Multiple %s providers found: %s, %s", service.getName(), singleProvider.getClass().getName(), provider.getClass().getName()));
}
singleProvider = provider;
}
if (singleProvider == null && required) {
String javaHome = Services.getSavedProperty("java.home");
String vmName = Services.getSavedProperty("java.vm.name");
Formatter errorMessage = new Formatter();
errorMessage.format("The VM does not expose required service %s.%n", service.getName());
errorMessage.format("Currently used Java home directory is %s.%n", javaHome);
errorMessage.format("Currently used VM configuration is: %s", vmName);
throw new UnsupportedOperationException(errorMessage.toString());
}
return singleProvider;
}
/**
* A Java {@code char} has a maximal UTF8 length of 3.
*/
private static final int MAX_UNICODE_IN_UTF8_LENGTH = 3;
/**
* {@link DataOutputStream#writeUTF(String)} only supports values whose UTF8 encoding length is
* less than 65535.
*/
private static final int MAX_UTF8_PROPERTY_STRING_LENGTH = 65535 / MAX_UNICODE_IN_UTF8_LENGTH;
/**
* Serializes the {@linkplain #getSavedProperties() saved system properties} to a byte array for
* the purpose of {@linkplain #initializeSavedProperties(byte[]) initializing} the initial
* properties in the JVMCI shared library.
*/
@VMEntryPoint
private static byte[] serializeSavedProperties() throws IOException {
if (IS_IN_NATIVE_IMAGE) {
throw new InternalError("Can only serialize saved properties in HotSpot runtime");
}
return serializeProperties(Services.getSavedProperties());
}
private static byte[] serializeProperties(Map<String, String> props) throws IOException {
// Compute size of output on the assumption that
// all system properties have ASCII names and values
int estimate = 4 + 4;
int nonUtf8Props = 0;
for (Map.Entry<String, String> e : props.entrySet()) {
String name = e.getKey();
String value = e.getValue();
estimate += (2 + (name.length())) + (2 + (value.length()));
if (name.length() > MAX_UTF8_PROPERTY_STRING_LENGTH || value.length() > MAX_UTF8_PROPERTY_STRING_LENGTH) {
nonUtf8Props++;
}
}
ByteArrayOutputStream baos = new ByteArrayOutputStream(estimate);
DataOutputStream out = new DataOutputStream(baos);
out.writeInt(props.size() - nonUtf8Props);
out.writeInt(nonUtf8Props);
for (Map.Entry<String, String> e : props.entrySet()) {
String name = e.getKey();
String value = e.getValue();
if (name.length() <= MAX_UTF8_PROPERTY_STRING_LENGTH && value.length() <= MAX_UTF8_PROPERTY_STRING_LENGTH) {
out.writeUTF(name);
out.writeUTF(value);
}
}
if (nonUtf8Props != 0) {
for (Map.Entry<String, String> e : props.entrySet()) {
String name = e.getKey();
String value = e.getValue();
if (name.length() > MAX_UTF8_PROPERTY_STRING_LENGTH || value.length() > MAX_UTF8_PROPERTY_STRING_LENGTH) {
byte[] utf8Name = name.getBytes("UTF-8");
byte[] utf8Value = value.getBytes("UTF-8");
out.writeInt(utf8Name.length);
out.write(utf8Name);
out.writeInt(utf8Value.length);
out.write(utf8Value);
}
}
}
return baos.toByteArray();
}
/**
* Initialized the {@linkplain #getSavedProperties() saved system properties} in the JVMCI
* shared library from the {@linkplain #serializeSavedProperties() serialized saved properties}
* in the HotSpot runtime.
*/
@VMEntryPoint
private static void initializeSavedProperties(byte[] serializedProperties) throws IOException {
if (!IS_IN_NATIVE_IMAGE) {
throw new InternalError("Can only initialize saved properties in JVMCI shared library runtime");
}
savedProperties = Collections.unmodifiableMap(deserializeProperties(serializedProperties));
}
private static Map<String, String> deserializeProperties(byte[] serializedProperties) throws IOException {
DataInputStream in = new DataInputStream(new ByteArrayInputStream(serializedProperties));
int utf8Props = in.readInt();
int nonUtf8Props = in.readInt();
Map<String, String> props = new HashMap<>(utf8Props + nonUtf8Props);
int index = 0;
while (in.available() != 0) {
if (index < utf8Props) {
String name = in.readUTF();
String value = in.readUTF();
props.put(name, value);
} else {
int nameLen = in.readInt();
byte[] nameBytes = new byte[nameLen];
in.read(nameBytes);
int valueLen = in.readInt();
byte[] valueBytes = new byte[valueLen];
in.read(valueBytes);
String name = new String(nameBytes, "UTF-8");
String value = new String(valueBytes, "UTF-8");
props.put(name, value);
}
index++;
}
return props;
}
}