8154231: Simplify access to System properties from JDK code
Reviewed-by: rriggs, chegar, weijun
/*
* Copyright (c) 2013, 2016, 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. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* 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
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package java.lang.module;
import java.lang.module.ModuleDescriptor.Requires.Modifier;
import java.lang.reflect.Layer;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Deque;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Objects;
import java.util.Optional;
import java.util.Set;
import java.util.StringJoiner;
import java.util.stream.Collectors;
import jdk.internal.module.Hasher;
/**
* The resolver used by {@link Configuration#resolveRequires} and
* {@link Configuration#resolveRequiresAndUses}.
*/
final class Resolver {
private final ModuleFinder beforeFinder;
private final Configuration parent;
private final ModuleFinder afterFinder;
// maps module name to module reference
private final Map<String, ModuleReference> nameToReference = new HashMap<>();
Resolver(ModuleFinder beforeFinder,
Configuration parent,
ModuleFinder afterFinder) {
this.beforeFinder = beforeFinder;
this.parent = parent;
this.afterFinder = afterFinder;
}
/**
* Resolves the given named modules.
*
* @throws ResolutionException
*/
Resolver resolveRequires(Collection<String> roots) {
long start = trace_start("Resolve");
// create the visit stack to get us started
Deque<ModuleDescriptor> q = new ArrayDeque<>();
for (String root : roots) {
// find root module
ModuleReference mref = findWithBeforeFinder(root);
if (mref == null) {
if (parent.findModule(root).isPresent()) {
// in parent, nothing to do
continue;
}
mref = findWithAfterFinder(root);
if (mref == null) {
fail("Module %s not found", root);
}
}
if (TRACE) {
trace("Root module %s located", root);
if (mref.location().isPresent())
trace(" (%s)", mref.location().get());
}
assert mref.descriptor().name().equals(root);
nameToReference.put(root, mref);
q.push(mref.descriptor());
}
resolve(q);
if (TRACE) {
long duration = System.currentTimeMillis() - start;
Set<String> names = nameToReference.keySet();
trace("Resolver completed in %s ms", duration);
names.stream().sorted().forEach(name -> trace(" %s", name));
}
return this;
}
/**
* Resolve all modules in the given queue. On completion the queue will be
* empty and any resolved modules will be added to {@code nameToReference}.
*
* @return The set of module resolved by this invocation of resolve
*/
private Set<ModuleDescriptor> resolve(Deque<ModuleDescriptor> q) {
Set<ModuleDescriptor> resolved = new HashSet<>();
while (!q.isEmpty()) {
ModuleDescriptor descriptor = q.poll();
assert nameToReference.containsKey(descriptor.name());
// process dependences
for (ModuleDescriptor.Requires requires : descriptor.requires()) {
String dn = requires.name();
// find dependence
ModuleReference mref = findWithBeforeFinder(dn);
if (mref == null) {
if (parent.findModule(dn).isPresent())
continue;
mref = findWithAfterFinder(dn);
if (mref == null) {
fail("Module %s not found, required by %s",
dn, descriptor.name());
}
}
if (!nameToReference.containsKey(dn)) {
nameToReference.put(dn, mref);
q.offer(mref.descriptor());
resolved.add(mref.descriptor());
if (TRACE) {
trace("Module %s located, required by %s",
dn, descriptor.name());
if (mref.location().isPresent())
trace(" (%s)", mref.location().get());
}
}
}
resolved.add(descriptor);
}
return resolved;
}
/**
* Augments the set of resolved modules with modules induced by the
* service-use relation.
*/
Resolver resolveUses() {
long start = trace_start("Bind");
// Scan the finders for all available service provider modules. As
// java.base uses services then then module finders will be scanned
// anyway.
Map<String, Set<ModuleReference>> availableProviders = new HashMap<>();
for (ModuleReference mref : findAll()) {
ModuleDescriptor descriptor = mref.descriptor();
if (!descriptor.provides().isEmpty()) {
for (String sn : descriptor.provides().keySet()) {
// computeIfAbsent
Set<ModuleReference> providers = availableProviders.get(sn);
if (providers == null) {
providers = new HashSet<>();
availableProviders.put(sn, providers);
}
providers.add(mref);
}
}
}
// create the visit stack
Deque<ModuleDescriptor> q = new ArrayDeque<>();
// the initial set of modules that may use services
Set<ModuleDescriptor> candidateConsumers = new HashSet<>();
Configuration p = parent;
while (p != null) {
candidateConsumers.addAll(p.descriptors());
p = p.parent().orElse(null);
}
for (ModuleReference mref : nameToReference.values()) {
candidateConsumers.add(mref.descriptor());
}
// Where there is a consumer of a service then resolve all modules
// that provide an implementation of that service
do {
for (ModuleDescriptor descriptor : candidateConsumers) {
if (!descriptor.uses().isEmpty()) {
for (String service : descriptor.uses()) {
Set<ModuleReference> mrefs = availableProviders.get(service);
if (mrefs != null) {
for (ModuleReference mref : mrefs) {
ModuleDescriptor provider = mref.descriptor();
if (!provider.equals(descriptor)) {
trace("Module %s provides %s, used by %s",
provider.name(), service, descriptor.name());
String pn = provider.name();
if (!nameToReference.containsKey(pn)) {
if (TRACE && mref.location().isPresent())
trace(" (%s)", mref.location().get());
nameToReference.put(pn, mref);
q.push(provider);
}
}
}
}
}
}
}
candidateConsumers = resolve(q);
} while (!candidateConsumers.isEmpty());
if (TRACE) {
long duration = System.currentTimeMillis() - start;
Set<String> names = nameToReference.keySet();
trace("Bind completed in %s ms", duration);
names.stream().sorted().forEach(name -> trace(" %s", name));
}
return this;
}
/**
* Execute post-resolution checks and returns the module graph of resolved
* modules as {@code Map}. The resolved modules will be in the given
* configuration.
*/
Map<ResolvedModule, Set<ResolvedModule>> finish(Configuration cf) {
detectCycles();
checkPlatformConstraints();
checkHashes();
Map<ResolvedModule, Set<ResolvedModule>> graph = makeGraph(cf);
checkExportSuppliers(graph);
return graph;
}
/**
* Checks the given module graph for cycles.
*
* For now the implementation is a simple depth first search on the
* dependency graph. We'll replace this later, maybe with Tarjan.
*/
private void detectCycles() {
visited = new HashSet<>();
visitPath = new LinkedHashSet<>(); // preserve insertion order
for (ModuleReference mref : nameToReference.values()) {
visit(mref.descriptor());
}
visited.clear();
}
// the modules that were visited
private Set<ModuleDescriptor> visited;
// the modules in the current visit path
private Set<ModuleDescriptor> visitPath;
private void visit(ModuleDescriptor descriptor) {
if (!visited.contains(descriptor)) {
boolean added = visitPath.add(descriptor);
if (!added) {
throw new ResolutionException("Cycle detected: " +
cycleAsString(descriptor));
}
for (ModuleDescriptor.Requires requires : descriptor.requires()) {
String dn = requires.name();
ModuleReference mref = nameToReference.get(dn);
if (mref != null) {
ModuleDescriptor other = mref.descriptor();
if (other != descriptor) {
// dependency is in this configuration
visit(other);
}
}
}
visitPath.remove(descriptor);
visited.add(descriptor);
}
}
/**
* Returns a String with a list of the modules in a detected cycle.
*/
private String cycleAsString(ModuleDescriptor descriptor) {
List<ModuleDescriptor> list = new ArrayList<>(visitPath);
list.add(descriptor);
int index = list.indexOf(descriptor);
return list.stream()
.skip(index)
.map(ModuleDescriptor::name)
.collect(Collectors.joining(" -> "));
}
/**
* If there are platform specific modules then check that the OS name,
* architecture and version match.
*
* @apiNote This method does not currently check if the OS matches
* platform specific modules in parent configurations.
*/
private void checkPlatformConstraints() {
// first module encountered that is platform specific
String savedModuleName = null;
String savedOsName = null;
String savedOsArch = null;
String savedOsVersion = null;
for (ModuleReference mref : nameToReference.values()) {
ModuleDescriptor descriptor = mref.descriptor();
String osName = descriptor.osName().orElse(null);
String osArch = descriptor.osArch().orElse(null);
String osVersion = descriptor.osVersion().orElse(null);
if (osName != null || osArch != null || osVersion != null) {
if (savedModuleName == null) {
savedModuleName = descriptor.name();
savedOsName = osName;
savedOsArch = osArch;
savedOsVersion = osVersion;
} else {
boolean matches = platformMatches(osName, savedOsName)
&& platformMatches(osArch, savedOsArch)
&& platformMatches(osVersion, savedOsVersion);
if (!matches) {
String s1 = platformAsString(savedOsName,
savedOsArch,
savedOsVersion);
String s2 = platformAsString(osName, osArch, osVersion);
fail("Mismatching constraints on target platform: "
+ savedModuleName + ": " + s1
+ ", " + descriptor.name() + ": " + s2);
}
}
}
}
}
/**
* Returns true if the s1 and s2 are equal or one of them is null.
*/
private boolean platformMatches(String s1, String s2) {
if (s1 == null || s2 == null)
return true;
else
return Objects.equals(s1, s2);
}
/**
* Return a string that encodes the OS name/arch/version.
*/
private String platformAsString(String osName,
String osArch,
String osVersion) {
return new StringJoiner("-")
.add(Objects.toString(osName, "*"))
.add(Objects.toString(osArch, "*"))
.add(Objects.toString(osVersion, "*"))
.toString();
}
/**
* Checks the hashes in the module descriptor to ensure that they match
* the hash of the dependency's module reference.
*/
private void checkHashes() {
for (ModuleReference mref : nameToReference.values()) {
ModuleDescriptor descriptor = mref.descriptor();
// get map of module names to hash
Optional<Hasher.DependencyHashes> ohashes = descriptor.hashes();
if (!ohashes.isPresent())
continue;
Hasher.DependencyHashes hashes = ohashes.get();
// check dependences
for (ModuleDescriptor.Requires d : descriptor.requires()) {
String dn = d.name();
String recordedHash = hashes.hashFor(dn);
if (recordedHash != null) {
ModuleReference other = nameToReference.get(dn);
if (other == null) {
other = parent.findModule(dn)
.map(ResolvedModule::reference)
.orElse(null);
}
if (other == null)
throw new InternalError(dn + " not found");
String actualHash = other.computeHash(hashes.algorithm());
if (actualHash == null)
fail("Unable to compute the hash of module %s", dn);
if (!recordedHash.equals(actualHash)) {
fail("Hash of %s (%s) differs to expected hash (%s)",
dn, actualHash, recordedHash);
}
}
}
}
}
/**
* Computes and sets the readability graph for the modules in the given
* Resolution object.
*
* The readability graph is created by propagating "requires" through the
* "public requires" edges of the module dependence graph. So if the module
* dependence graph has m1 requires m2 && m2 requires public m3 then the
* resulting readability graph will contain m1 reads m2, m1
* reads m3, and m2 reads m3.
*
* TODO: Use a more efficient algorithm, maybe cache the requires public
* in parent configurations.
*/
private Map<ResolvedModule, Set<ResolvedModule>> makeGraph(Configuration cf) {
// the "reads" graph starts as a module dependence graph and
// is iteratively updated to be the readability graph
Map<ResolvedModule, Set<ResolvedModule>> g1 = new HashMap<>();
// the "requires public" graph, contains requires public edges only
Map<ResolvedModule, Set<ResolvedModule>> g2 = new HashMap<>();
// need "requires public" from the modules in parent configurations as
// there may be selected modules that have a dependency on modules in
// the parent configuration.
Configuration p = parent;
while (p != null) {
for (ModuleDescriptor descriptor : p.descriptors()) {
ResolvedModule x = p.findModule(descriptor.name()).orElse(null);
if (x == null)
throw new InternalError();
for (ModuleDescriptor.Requires requires : descriptor.requires()) {
if (requires.modifiers().contains(Modifier.PUBLIC)) {
String dn = requires.name();
ResolvedModule y = p.findModule(dn).orElse(null);
if (y == null)
throw new InternalError(dn + " not found");
g2.computeIfAbsent(x, k -> new HashSet<>()).add(y);
}
}
}
p = p.parent().orElse(null);
}
// populate g1 and g2 with the dependences from the selected modules
for (ModuleReference mref : nameToReference.values()) {
ModuleDescriptor descriptor = mref.descriptor();
ResolvedModule x = new ResolvedModule(cf, mref);
Set<ResolvedModule> reads = new HashSet<>();
g1.put(x, reads);
Set<ResolvedModule> requiresPublic = new HashSet<>();
g2.put(x, requiresPublic);
for (ModuleDescriptor.Requires requires : descriptor.requires()) {
String dn = requires.name();
ResolvedModule y;
ModuleReference other = nameToReference.get(dn);
if (other != null) {
y = new ResolvedModule(cf, other); // cache?
} else {
y = parent.findModule(dn).orElse(null);
if (y == null)
throw new InternalError("unable to find " + dn);
}
// m requires other => m reads other
reads.add(y);
// m requires public other
if (requires.modifiers().contains(Modifier.PUBLIC)) {
requiresPublic.add(y);
}
}
// automatic modules reads all selected modules and all modules
// in parent configurations
if (descriptor.isAutomatic()) {
String name = descriptor.name();
// reads all selected modules
// requires public` all selected automatic modules
for (ModuleReference mref2 : nameToReference.values()) {
ModuleDescriptor descriptor2 = mref2.descriptor();
if (!name.equals(descriptor2.name())) {
ResolvedModule m = new ResolvedModule(cf, mref2);
reads.add(m);
if (descriptor2.isAutomatic())
requiresPublic.add(m);
}
}
// reads all modules in parent configurations
// `requires public` all automatic modules in parent configurations
p = parent;
while (p != null) {
for (ResolvedModule m : p.modules()) {
reads.add(m);
if (m.reference().descriptor().isAutomatic())
requiresPublic.add(m);
}
p = p.parent().orElse(null);
}
}
}
// Iteratively update g1 until there are no more requires public to propagate
boolean changed;
Map<ResolvedModule, Set<ResolvedModule>> changes = new HashMap<>();
do {
changed = false;
for (Entry<ResolvedModule, Set<ResolvedModule>> entry : g1.entrySet()) {
ResolvedModule m1 = entry.getKey();
Set<ResolvedModule> m1Reads = entry.getValue();
for (ResolvedModule m2 : m1Reads) {
Set<ResolvedModule> m2RequiresPublic = g2.get(m2);
if (m2RequiresPublic != null) {
for (ResolvedModule m3 : m2RequiresPublic) {
if (!m1Reads.contains(m3)) {
// computeIfAbsent
Set<ResolvedModule> s = changes.get(m1);
if (s == null) {
s = new HashSet<>();
changes.put(m1, s);
}
s.add(m3);
changed = true;
}
}
}
}
}
if (changed) {
for (Map.Entry<ResolvedModule, Set<ResolvedModule>> e :
changes.entrySet()) {
ResolvedModule m = e.getKey();
g1.get(m).addAll(e.getValue());
}
changes.clear();
}
} while (changed);
return g1;
}
/**
* Checks the readability graph to ensure that no two modules export the
* same package to a module. This includes the case where module M has
* a local package P and M reads another module that exports P to M.
* Also checks the uses/provides of module M to ensure that it reads a
* module that exports the package of the service type to M.
*/
private void checkExportSuppliers(Map<ResolvedModule, Set<ResolvedModule>> graph) {
for (Map.Entry<ResolvedModule, Set<ResolvedModule>> e : graph.entrySet()) {
ModuleDescriptor descriptor1 = e.getKey().descriptor();
// the map of packages that are local or exported to descriptor1
Map<String, ModuleDescriptor> packageToExporter = new HashMap<>();
// local packages
Set<String> packages = descriptor1.packages();
for (String pn : packages) {
packageToExporter.put(pn, descriptor1);
}
// descriptor1 reads descriptor2
Set<ResolvedModule> reads = e.getValue();
for (ResolvedModule endpoint : reads) {
ModuleDescriptor descriptor2 = endpoint.descriptor();
for (ModuleDescriptor.Exports export : descriptor2.exports()) {
if (export.isQualified()) {
if (!export.targets().contains(descriptor1.name()))
continue;
}
// source is exported to descriptor2
String source = export.source();
ModuleDescriptor other
= packageToExporter.put(source, descriptor2);
if (other != null && other != descriptor2) {
// package might be local to descriptor1
if (other == descriptor1) {
fail("Module %s contains package %s"
+ ", module %s exports package %s to %s",
descriptor1.name(),
source,
descriptor2.name(),
source,
descriptor1.name());
} else {
fail("Modules %s and %s export package %s to module %s",
descriptor2.name(),
other.name(),
source,
descriptor1.name());
}
}
}
}
// uses S
for (String service : descriptor1.uses()) {
String pn = packageName(service);
if (!packageToExporter.containsKey(pn)) {
fail("Module %s does not read a module that exports %s",
descriptor1.name(), pn);
}
}
// provides S
for (Map.Entry<String, ModuleDescriptor.Provides> entry :
descriptor1.provides().entrySet()) {
String service = entry.getKey();
ModuleDescriptor.Provides provides = entry.getValue();
String pn = packageName(service);
if (!packageToExporter.containsKey(pn)) {
fail("Module %s does not read a module that exports %s",
descriptor1.name(), pn);
}
for (String provider : provides.providers()) {
if (!packages.contains(packageName(provider))) {
fail("Provider %s not in module %s",
provider, descriptor1.name());
}
}
}
}
}
/**
* Invokes the beforeFinder to find method to find the given module.
*/
private ModuleReference findWithBeforeFinder(String mn) {
try {
return beforeFinder.find(mn).orElse(null);
} catch (FindException e) {
// unwrap
throw new ResolutionException(e.getMessage(), e.getCause());
}
}
/**
* Invokes the afterFinder to find method to find the given module.
*/
private ModuleReference findWithAfterFinder(String mn) {
try {
return afterFinder.find(mn).orElse(null);
} catch (FindException e) {
// unwrap
throw new ResolutionException(e.getMessage(), e.getCause());
}
}
/**
* Returns the set of all modules that are observable with the before
* and after ModuleFinders.
*/
private Set<ModuleReference> findAll() {
try {
Set<ModuleReference> beforeModules = beforeFinder.findAll();
Set<ModuleReference> afterModules = afterFinder.findAll();
if (afterModules.isEmpty())
return beforeModules;
if (beforeModules.isEmpty() && parent == Configuration.empty())
return afterModules;
Set<ModuleReference> result = new HashSet<>(beforeModules);
for (ModuleReference mref : afterModules) {
String name = mref.descriptor().name();
if (!beforeFinder.find(name).isPresent()
&& !parent.findModule(name).isPresent())
result.add(mref);
}
return result;
} catch (FindException e) {
// unwrap
throw new ResolutionException(e.getMessage(), e.getCause());
}
}
/**
* Returns the package name
*/
private static String packageName(String cn) {
int index = cn.lastIndexOf(".");
return (index == -1) ? "" : cn.substring(0, index);
}
/**
* Throw ResolutionException with the given format string and arguments
*/
private static void fail(String fmt, Object ... args) {
String msg = String.format(fmt, args);
throw new ResolutionException(msg);
}
/**
* Tracing support, limited to boot layer for now.
*/
private final static boolean TRACE
= Boolean.getBoolean("jdk.launcher.traceResolver")
&& (Layer.boot() == null);
private String op;
private long trace_start(String op) {
this.op = op;
return System.currentTimeMillis();
}
private void trace(String fmt, Object ... args) {
if (TRACE) {
System.out.print("[" + op + "] ");
System.out.format(fmt, args);
System.out.println();
}
}
}