java.lang.module.Resolver Maven / Gradle / Ivy
/*
* Copyright (c) 2013, 2020, 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
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package java.lang.module;
import java.io.PrintStream;
import java.lang.module.ModuleDescriptor.Provides;
import java.lang.module.ModuleDescriptor.Requires.Modifier;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Deque;
import java.util.HashMap;
import java.util.HashSet;
import java.util.HexFormat;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.Set;
import java.util.stream.Collectors;
import jdk.internal.module.ModuleHashes;
import jdk.internal.module.ModuleReferenceImpl;
import jdk.internal.module.ModuleResolution;
import jdk.internal.module.ModuleTarget;
/**
* The resolver used by {@link Configuration#resolve} and {@link
* Configuration#resolveAndBind}.
*
* @implNote The resolver is used at VM startup and so deliberately avoids
* using lambda and stream usages in code paths used during startup.
*/
final class Resolver {
private final ModuleFinder beforeFinder;
private final List parents;
private final ModuleFinder afterFinder;
private final PrintStream traceOutput;
// maps module name to module reference
private final Map nameToReference = new HashMap<>();
// true if all automatic modules have been found
private boolean haveAllAutomaticModules;
// constraint on target platform
private String targetPlatform;
String targetPlatform() { return targetPlatform; }
/**
* @throws IllegalArgumentException if there are more than one parent and
* the constraints on the target platform conflict
*/
Resolver(ModuleFinder beforeFinder,
List parents,
ModuleFinder afterFinder,
PrintStream traceOutput) {
this.beforeFinder = beforeFinder;
this.parents = parents;
this.afterFinder = afterFinder;
this.traceOutput = traceOutput;
// record constraint on target platform, checking for conflicts
for (Configuration parent : parents) {
String value = parent.targetPlatform();
if (value != null) {
if (targetPlatform == null) {
targetPlatform = value;
} else {
if (!value.equals(targetPlatform)) {
String msg = "Parents have conflicting constraints on target" +
" platform: " + targetPlatform + ", " + value;
throw new IllegalArgumentException(msg);
}
}
}
}
}
/**
* Resolves the given named modules.
*
* @throws ResolutionException
*/
Resolver resolve(Collection roots) {
// create the visit stack to get us started
Deque q = new ArrayDeque<>();
for (String root : roots) {
// find root module
ModuleReference mref = findWithBeforeFinder(root);
if (mref == null) {
if (findInParent(root) != null) {
// in parent, nothing to do
continue;
}
mref = findWithAfterFinder(root);
if (mref == null) {
findFail("Module %s not found", root);
}
}
if (isTracing()) {
trace("root %s", nameAndInfo(mref));
}
addFoundModule(mref);
q.push(mref.descriptor());
}
resolve(q);
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 resolve(Deque q) {
Set resolved = new HashSet<>();
while (!q.isEmpty()) {
ModuleDescriptor descriptor = q.poll();
assert nameToReference.containsKey(descriptor.name());
// if the module is an automatic module then all automatic
// modules need to be resolved
if (descriptor.isAutomatic() && !haveAllAutomaticModules) {
addFoundAutomaticModules().forEach(mref -> {
ModuleDescriptor other = mref.descriptor();
q.offer(other);
if (isTracing()) {
trace("%s requires %s", descriptor.name(), nameAndInfo(mref));
}
});
haveAllAutomaticModules = true;
}
// process dependences
for (ModuleDescriptor.Requires requires : descriptor.requires()) {
// only required at compile-time
if (requires.modifiers().contains(Modifier.STATIC))
continue;
String dn = requires.name();
// find dependence
ModuleReference mref = findWithBeforeFinder(dn);
if (mref == null) {
if (findInParent(dn) != null) {
// dependence is in parent
continue;
}
mref = findWithAfterFinder(dn);
if (mref == null) {
findFail("Module %s not found, required by %s",
dn, descriptor.name());
}
}
if (isTracing() && !dn.equals("java.base")) {
trace("%s requires %s", descriptor.name(), nameAndInfo(mref));
}
if (!nameToReference.containsKey(dn)) {
addFoundModule(mref);
q.offer(mref.descriptor());
}
}
resolved.add(descriptor);
}
return resolved;
}
/**
* Augments the set of resolved modules with modules induced by the
* service-use relation.
*/
Resolver bind() {
return bind(/*bindIncubatorModules*/true);
}
/**
* Augments the set of resolved modules with modules induced by the
* service-use relation.
*
* @param bindIncubatorModules true if incubator modules are candidates to
* add to the module graph
*/
Resolver bind(boolean bindIncubatorModules) {
// Scan the finders for all available service provider modules. As
// java.base uses services then the module finders will be scanned
// anyway.
Map> availableProviders = new HashMap<>();
for (ModuleReference mref : findAll()) {
ModuleDescriptor descriptor = mref.descriptor();
boolean candidate;
if (!bindIncubatorModules && (mref instanceof ModuleReferenceImpl)) {
ModuleResolution mres = ((ModuleReferenceImpl) mref).moduleResolution();
candidate = (mres == null) || (mres.hasIncubatingWarning() == false);
} else {
candidate = true;
}
if (candidate && !descriptor.provides().isEmpty()) {
for (Provides provides : descriptor.provides()) {
String sn = provides.service();
// computeIfAbsent
Set providers = availableProviders.get(sn);
if (providers == null) {
providers = new HashSet<>();
availableProviders.put(sn, providers);
}
providers.add(mref);
}
}
}
// create the visit stack
Deque q = new ArrayDeque<>();
// the initial set of modules that may use services
Set initialConsumers;
if (ModuleLayer.boot() == null) {
initialConsumers = new HashSet<>();
} else {
initialConsumers = parents.stream()
.flatMap(Configuration::configurations)
.distinct()
.flatMap(c -> c.descriptors().stream())
.collect(Collectors.toSet());
}
for (ModuleReference mref : nameToReference.values()) {
initialConsumers.add(mref.descriptor());
}
// Where there is a consumer of a service then resolve all modules
// that provide an implementation of that service
Set candidateConsumers = initialConsumers;
do {
for (ModuleDescriptor descriptor : candidateConsumers) {
if (!descriptor.uses().isEmpty()) {
// the modules that provide at least one service
Set modulesToBind = null;
if (isTracing()) {
modulesToBind = new HashSet<>();
}
for (String service : descriptor.uses()) {
Set mrefs = availableProviders.get(service);
if (mrefs != null) {
for (ModuleReference mref : mrefs) {
ModuleDescriptor provider = mref.descriptor();
if (!provider.equals(descriptor)) {
if (isTracing() && modulesToBind.add(provider)) {
trace("%s binds %s", descriptor.name(),
nameAndInfo(mref));
}
String pn = provider.name();
if (!nameToReference.containsKey(pn)) {
addFoundModule(mref);
q.push(provider);
}
}
}
}
}
}
}
candidateConsumers = resolve(q);
} while (!candidateConsumers.isEmpty());
return this;
}
/**
* Add all automatic modules that have not already been found to the
* nameToReference map.
*/
private Set addFoundAutomaticModules() {
Set result = new HashSet<>();
findAll().forEach(mref -> {
String mn = mref.descriptor().name();
if (mref.descriptor().isAutomatic() && !nameToReference.containsKey(mn)) {
addFoundModule(mref);
result.add(mref);
}
});
return result;
}
/**
* Add the module to the nameToReference map. Also check any constraints on
* the target platform with the constraints of other modules.
*/
private void addFoundModule(ModuleReference mref) {
String mn = mref.descriptor().name();
if (mref instanceof ModuleReferenceImpl) {
ModuleTarget target = ((ModuleReferenceImpl)mref).moduleTarget();
if (target != null)
checkTargetPlatform(mn, target);
}
nameToReference.put(mn, mref);
}
/**
* Check that the module's constraints on the target platform does
* conflict with the constraint of other modules resolved so far.
*/
private void checkTargetPlatform(String mn, ModuleTarget target) {
String value = target.targetPlatform();
if (value != null) {
if (targetPlatform == null) {
targetPlatform = value;
} else {
if (!value.equals(targetPlatform)) {
findFail("Module %s has constraints on target platform (%s)"
+ " that conflict with other modules: %s", mn,
value, targetPlatform);
}
}
}
}
/**
* Execute post-resolution checks and returns the module graph of resolved
* modules as a map.
*/
Map> finish(Configuration cf) {
detectCycles();
checkHashes();
Map> 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 visited;
// the modules in the current visit path
private Set visitPath;
private void visit(ModuleDescriptor descriptor) {
if (!visited.contains(descriptor)) {
boolean added = visitPath.add(descriptor);
if (!added) {
resolveFail("Cycle detected: %s", 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 list = new ArrayList<>(visitPath);
list.add(descriptor);
int index = list.indexOf(descriptor);
return list.stream()
.skip(index)
.map(ModuleDescriptor::name)
.collect(Collectors.joining(" -> "));
}
/**
* Checks the hashes in the module descriptor to ensure that they match
* any recorded hashes.
*/
private void checkHashes() {
for (ModuleReference mref : nameToReference.values()) {
// get the recorded hashes, if any
if (!(mref instanceof ModuleReferenceImpl))
continue;
ModuleHashes hashes = ((ModuleReferenceImpl)mref).recordedHashes();
if (hashes == null)
continue;
ModuleDescriptor descriptor = mref.descriptor();
String algorithm = hashes.algorithm();
for (String dn : hashes.names()) {
ModuleReference mref2 = nameToReference.get(dn);
if (mref2 == null) {
ResolvedModule resolvedModule = findInParent(dn);
if (resolvedModule != null)
mref2 = resolvedModule.reference();
}
if (mref2 == null)
continue;
if (!(mref2 instanceof ModuleReferenceImpl)) {
findFail("Unable to compute the hash of module %s", dn);
}
ModuleReferenceImpl other = (ModuleReferenceImpl)mref2;
if (other != null) {
byte[] recordedHash = hashes.hashFor(dn);
byte[] actualHash = other.computeHash(algorithm);
if (actualHash == null)
findFail("Unable to compute the hash of module %s", dn);
if (!Arrays.equals(recordedHash, actualHash)) {
HexFormat hex = HexFormat.of();
findFail("Hash of %s (%s) differs to expected hash (%s)" +
" recorded in %s", dn, hex.formatHex(actualHash),
hex.formatHex(recordedHash), descriptor.name());
}
}
}
}
}
/**
* Computes the readability graph for the modules in the given Configuration.
*
* The readability graph is created by propagating "requires" through the
* "requires transitive" edges of the module dependence graph. So if the
* module dependence graph has m1 requires m2 && m2 requires transitive m3
* then the resulting readability graph will contain m1 reads m2, m1 reads m3,
* and m2 reads m3.
*/
private Map> makeGraph(Configuration cf) {
// initial capacity of maps to avoid resizing
int capacity = 1 + (4 * nameToReference.size())/ 3;
// the "reads" graph starts as a module dependence graph and
// is iteratively updated to be the readability graph
Map> g1 = new HashMap<>(capacity);
// the "requires transitive" graph, contains requires transitive edges only
Map> g2;
// need "requires transitive" from the modules in parent configurations
// as there may be selected modules that have a dependency on modules in
// the parent configuration.
if (ModuleLayer.boot() == null) {
g2 = new HashMap<>(capacity);
} else {
g2 = parents.stream()
.flatMap(Configuration::configurations)
.distinct()
.flatMap(c ->
c.modules().stream().flatMap(m1 ->
m1.descriptor().requires().stream()
.filter(r -> r.modifiers().contains(Modifier.TRANSITIVE))
.flatMap(r -> {
Optional m2 = c.findModule(r.name());
assert m2.isPresent()
|| r.modifiers().contains(Modifier.STATIC);
return m2.stream();
})
.map(m2 -> Map.entry(m1, m2))
)
)
// stream of m1->m2
.collect(Collectors.groupingBy(Map.Entry::getKey,
HashMap::new,
Collectors.mapping(Map.Entry::getValue, Collectors.toSet())
));
}
// populate g1 and g2 with the dependences from the selected modules
Map nameToResolved = new HashMap<>(capacity);
for (ModuleReference mref : nameToReference.values()) {
ModuleDescriptor descriptor = mref.descriptor();
String name = descriptor.name();
ResolvedModule m1 = computeIfAbsent(nameToResolved, name, cf, mref);
Set reads = new HashSet<>();
Set requiresTransitive = new HashSet<>();
for (ModuleDescriptor.Requires requires : descriptor.requires()) {
String dn = requires.name();
ResolvedModule m2;
ModuleReference mref2 = nameToReference.get(dn);
if (mref2 != null) {
// same configuration
m2 = computeIfAbsent(nameToResolved, dn, cf, mref2);
} else {
// parent configuration
m2 = findInParent(dn);
if (m2 == null) {
assert requires.modifiers().contains(Modifier.STATIC);
continue;
}
// m2 is automatic module in parent configuration => m1 reads
// all automatic modules that m2 reads.
if (m2.descriptor().isAutomatic()) {
m2.reads().stream()
.filter(d -> d.descriptor().isAutomatic())
.forEach(reads::add);
}
}
// m1 requires m2 => m1 reads m2
reads.add(m2);
// m1 requires transitive m2
if (requires.modifiers().contains(Modifier.TRANSITIVE)) {
requiresTransitive.add(m2);
}
}
// automatic modules read all selected modules and all modules
// in parent configurations
if (descriptor.isAutomatic()) {
// reads all selected modules
// `requires transitive` all selected automatic modules
for (ModuleReference mref2 : nameToReference.values()) {
ModuleDescriptor descriptor2 = mref2.descriptor();
String name2 = descriptor2.name();
if (!name.equals(name2)) {
ResolvedModule m2
= computeIfAbsent(nameToResolved, name2, cf, mref2);
reads.add(m2);
if (descriptor2.isAutomatic())
requiresTransitive.add(m2);
}
}
// reads all modules in parent configurations
// `requires transitive` all automatic modules in parent
// configurations
for (Configuration parent : parents) {
parent.configurations()
.map(Configuration::modules)
.flatMap(Set::stream)
.forEach(m -> {
reads.add(m);
if (m.reference().descriptor().isAutomatic())
requiresTransitive.add(m);
});
}
}
g1.put(m1, reads);
g2.put(m1, requiresTransitive);
}
// Iteratively update g1 until there are no more requires transitive
// to propagate
boolean changed;
List toAdd = new ArrayList<>();
do {
changed = false;
for (Set m1Reads : g1.values()) {
for (ResolvedModule m2 : m1Reads) {
Set m2RequiresTransitive = g2.get(m2);
if (m2RequiresTransitive != null) {
for (ResolvedModule m3 : m2RequiresTransitive) {
if (!m1Reads.contains(m3)) {
// m1 reads m2, m2 requires transitive m3
// => need to add m1 reads m3
toAdd.add(m3);
}
}
}
}
if (!toAdd.isEmpty()) {
m1Reads.addAll(toAdd);
toAdd.clear();
changed = true;
}
}
} while (changed);
return g1;
}
/**
* Equivalent to
* {@code
* map.computeIfAbsent(name, k -> new ResolvedModule(cf, mref))
* }
*/
private ResolvedModule computeIfAbsent(Map map,
String name,
Configuration cf,
ModuleReference mref)
{
ResolvedModule m = map.get(name);
if (m == null) {
m = new ResolvedModule(cf, mref);
map.put(name, m);
}
return m;
}
/**
* Checks the readability graph to ensure that
*
* A module does not read two or more modules with the same name.
* This includes the case where a module reads another module with the
* same name as itself.
Two or more modules in the configuration don't export the same
* package to a module that reads both. This includes the case where a
* module {@code M} containing package {@code p} reads another module
* that exports {@code p} to {@code M}.
A module {@code M} doesn't declare that it "{@code uses p.S}"
* or "{@code provides p.S with ...}" but package {@code p} is neither
* in module {@code M} nor exported to {@code M} by any module that
* {@code M} reads.
*/
private void checkExportSuppliers(Map> graph) {
for (Map.Entry> e : graph.entrySet()) {
ModuleDescriptor descriptor1 = e.getKey().descriptor();
String name1 = descriptor1.name();
// the names of the modules that are read (including self)
Set names = new HashSet<>();
names.add(name1);
// the map of packages that are local or exported to descriptor1
Map packageToExporter = new HashMap<>();
// local packages
Set packages = descriptor1.packages();
for (String pn : packages) {
packageToExporter.put(pn, descriptor1);
}
// descriptor1 reads descriptor2
Set reads = e.getValue();
for (ResolvedModule endpoint : reads) {
ModuleDescriptor descriptor2 = endpoint.descriptor();
String name2 = descriptor2.name();
if (descriptor2 != descriptor1 && !names.add(name2)) {
if (name2.equals(name1)) {
resolveFail("Module %s reads another module named %s",
name1, name1);
} else{
resolveFail("Module %s reads more than one module named %s",
name1, name2);
}
}
if (descriptor2.isAutomatic()) {
// automatic modules read self and export all packages
if (descriptor2 != descriptor1) {
for (String source : descriptor2.packages()) {
ModuleDescriptor supplier
= packageToExporter.putIfAbsent(source, descriptor2);
// descriptor2 and 'supplier' export source to descriptor1
if (supplier != null) {
failTwoSuppliers(descriptor1, source, descriptor2, supplier);
}
}
}
} else {
for (ModuleDescriptor.Exports export : descriptor2.exports()) {
if (export.isQualified()) {
if (!export.targets().contains(descriptor1.name()))
continue;
}
// source is exported by descriptor2
String source = export.source();
ModuleDescriptor supplier
= packageToExporter.putIfAbsent(source, descriptor2);
// descriptor2 and 'supplier' export source to descriptor1
if (supplier != null) {
failTwoSuppliers(descriptor1, source, descriptor2, supplier);
}
}
}
}
// uses/provides checks not applicable to automatic modules
if (!descriptor1.isAutomatic()) {
// uses S
for (String service : descriptor1.uses()) {
String pn = packageName(service);
if (!packageToExporter.containsKey(pn)) {
resolveFail("Module %s does not read a module that exports %s",
descriptor1.name(), pn);
}
}
// provides S
for (ModuleDescriptor.Provides provides : descriptor1.provides()) {
String pn = packageName(provides.service());
if (!packageToExporter.containsKey(pn)) {
resolveFail("Module %s does not read a module that exports %s",
descriptor1.name(), pn);
}
}
}
}
}
/**
* Fail because a module in the configuration exports the same package to
* a module that reads both. This includes the case where a module M
* containing a package p reads another module that exports p to at least
* module M.
*/
private void failTwoSuppliers(ModuleDescriptor descriptor,
String source,
ModuleDescriptor supplier1,
ModuleDescriptor supplier2) {
if (supplier2 == descriptor) {
ModuleDescriptor tmp = supplier1;
supplier1 = supplier2;
supplier2 = tmp;
}
if (supplier1 == descriptor) {
resolveFail("Module %s contains package %s"
+ ", module %s exports package %s to %s",
descriptor.name(),
source,
supplier2.name(),
source,
descriptor.name());
} else {
resolveFail("Modules %s and %s export package %s to module %s",
supplier1.name(),
supplier2.name(),
source,
descriptor.name());
}
}
/**
* Find a module of the given name in the parent configurations
*/
private ResolvedModule findInParent(String mn) {
for (Configuration parent : parents) {
Optional om = parent.findModule(mn);
if (om.isPresent())
return om.get();
}
return null;
}
/**
* Invokes the beforeFinder to find method to find the given module.
*/
private ModuleReference findWithBeforeFinder(String mn) {
return beforeFinder.find(mn).orElse(null);
}
/**
* Invokes the afterFinder to find method to find the given module.
*/
private ModuleReference findWithAfterFinder(String mn) {
return afterFinder.find(mn).orElse(null);
}
/**
* Returns the set of all modules that are observable with the before
* and after ModuleFinders.
*/
private Set findAll() {
Set beforeModules = beforeFinder.findAll();
Set afterModules = afterFinder.findAll();
if (afterModules.isEmpty())
return beforeModules;
if (beforeModules.isEmpty()
&& parents.size() == 1
&& parents.get(0) == Configuration.empty())
return afterModules;
Set result = new HashSet<>(beforeModules);
for (ModuleReference mref : afterModules) {
String name = mref.descriptor().name();
if (!beforeFinder.find(name).isPresent()
&& findInParent(name) == null) {
result.add(mref);
}
}
return result;
}
/**
* Returns the package name
*/
private static String packageName(String cn) {
int index = cn.lastIndexOf(".");
return (index == -1) ? "" : cn.substring(0, index);
}
/**
* Throw FindException with the given format string and arguments
*/
private static void findFail(String fmt, Object ... args) {
String msg = String.format(fmt, args);
throw new FindException(msg);
}
/**
* Throw ResolutionException with the given format string and arguments
*/
private static void resolveFail(String fmt, Object ... args) {
String msg = String.format(fmt, args);
throw new ResolutionException(msg);
}
/**
* Tracing support
*/
private boolean isTracing() {
return traceOutput != null;
}
private void trace(String fmt, Object ... args) {
if (traceOutput != null) {
traceOutput.format(fmt, args);
traceOutput.println();
}
}
private String nameAndInfo(ModuleReference mref) {
ModuleDescriptor descriptor = mref.descriptor();
StringBuilder sb = new StringBuilder(descriptor.name());
mref.location().ifPresent(uri -> sb.append(" " + uri));
if (descriptor.isAutomatic())
sb.append(" automatic");
return sb.toString();
}
}
© 2015 - 2025 Weber Informatics LLC | Privacy Policy