1 /*
2 * Copyright (c) 2014, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.lang.module;
27
28 import java.io.PrintStream;
29 import java.util.ArrayDeque;
30 import java.util.ArrayList;
31 import java.util.Collection;
32 import java.util.Collections;
33 import java.util.Deque;
34 import java.util.HashMap;
35 import java.util.HashSet;
36 import java.util.List;
37 import java.util.Map;
38 import java.util.Map.Entry;
39 import java.util.Objects;
40 import java.util.Optional;
41 import java.util.Set;
42 import java.util.stream.Collectors;
43 import java.util.stream.Stream;
44
45 import jdk.internal.module.ModuleReferenceImpl;
46 import jdk.internal.module.ModuleTarget;
47
48 /**
49 * A configuration that is the result of <a href="package-summary.html#resolution">
50 * resolution</a> or resolution with <a href="#service-binding">service binding</a>.
51 *
52 * <p> A configuration encapsulates the <em>readability graph</em> that is the
53 * output of resolution. A readability graph is a directed graph whose vertices
54 * are of type {@link ResolvedModule} and the edges represent the readability
55 * amongst the modules. {@code Configuration} defines the {@link #modules()
56 * modules()} method to get the set of resolved modules in the graph. {@code
57 * ResolvedModule} defines the {@link ResolvedModule#reads() reads()} method to
58 * get the set of modules that a resolved module reads. The modules that are
59 * read may be in the same configuration or may be in {@link #parents() parent}
60 * configurations. </p>
61 *
62 * <p> Configuration defines the {@link #resolve(ModuleFinder,List,ModuleFinder,Collection)
63 * resolve} method to resolve a collection of root modules, and the {@link
64 * #resolveAndBind(ModuleFinder,List,ModuleFinder,Collection) resolveAndBind}
65 * method to do resolution with service binding. There are instance and
66 * static variants of both methods. The instance methods create a configuration
67 * with the receiver as the parent configuration. The static methods are for
68 * more advanced cases where there can be more than one parent configuration. </p>
69 *
70 * <p> Each {@link java.lang.ModuleLayer layer} of modules in the Java virtual
71 * machine is created from a configuration. The configuration for the {@link
72 * java.lang.ModuleLayer#boot() boot} layer is obtained by invoking {@code
73 * ModuleLayer.boot().configuration()}. The configuration for the boot layer
74 * will often be the parent when creating new configurations. </p>
75 *
76 * <h3> Example </h3>
77 *
78 * <p> The following example uses the {@link
79 * #resolve(ModuleFinder,ModuleFinder,Collection) resolve} method to resolve a
80 * module named <em>myapp</em> with the configuration for the boot layer as the
81 * parent configuration. It prints the name of each resolved module and the
82 * names of the modules that each module reads. </p>
83 *
84 * <pre>{@code
85 * ModuleFinder finder = ModuleFinder.of(dir1, dir2, dir3);
86 *
87 * Configuration parent = ModuleLayer.boot().configuration();
88 *
89 * Configuration cf = parent.resolve(finder, ModuleFinder.of(), Set.of("myapp"));
90 * cf.modules().forEach(m -> {
91 * System.out.format("%s -> %s%n",
92 * m.name(),
93 * m.reads().stream()
94 * .map(ResolvedModule::name)
95 * .collect(Collectors.joining(", ")));
96 * });
97 * }</pre>
98 *
99 * @since 9
100 * @spec JPMS
101 * @see java.lang.ModuleLayer
102 */
103 public final class Configuration {
104
105 // @see Configuration#empty()
106 private static final Configuration EMPTY_CONFIGURATION = new Configuration();
107
108 // parent configurations, in search order
109 private final List<Configuration> parents;
110
111 private final Map<ResolvedModule, Set<ResolvedModule>> graph;
112 private final Set<ResolvedModule> modules;
113 private final Map<String, ResolvedModule> nameToModule;
114
115 // constraint on target platform
116 private final String targetPlatform;
117
118 String targetPlatform() { return targetPlatform; }
119
120 private Configuration() {
121 this.parents = Collections.emptyList();
122 this.graph = Collections.emptyMap();
123 this.modules = Collections.emptySet();
124 this.nameToModule = Collections.emptyMap();
125 this.targetPlatform = null;
126 }
127
128 private Configuration(List<Configuration> parents, Resolver resolver) {
129 Map<ResolvedModule, Set<ResolvedModule>> g = resolver.finish(this);
130
131 @SuppressWarnings(value = {"rawtypes", "unchecked"})
132 Entry<String, ResolvedModule>[] nameEntries
133 = (Entry<String, ResolvedModule>[])new Entry[g.size()];
134 ResolvedModule[] moduleArray = new ResolvedModule[g.size()];
135 int i = 0;
136 for (ResolvedModule resolvedModule : g.keySet()) {
137 moduleArray[i] = resolvedModule;
138 nameEntries[i] = Map.entry(resolvedModule.name(), resolvedModule);
139 i++;
140 }
141
142 this.parents = Collections.unmodifiableList(parents);
143 this.graph = g;
144 this.modules = Set.of(moduleArray);
145 this.nameToModule = Map.ofEntries(nameEntries);
146
147 this.targetPlatform = resolver.targetPlatform();
148 }
149
150 /**
151 * Creates the Configuration for the boot layer from a pre-generated
152 * readability graph.
153 *
154 * @apiNote This method is coded for startup performance.
155 */
156 Configuration(ModuleFinder finder, Map<String, Set<String>> map) {
157 int moduleCount = map.size();
158
159 // create map of name -> ResolvedModule
160 @SuppressWarnings(value = {"rawtypes", "unchecked"})
161 Entry<String, ResolvedModule>[] nameEntries
162 = (Entry<String, ResolvedModule>[])new Entry[moduleCount];
163 ResolvedModule[] moduleArray = new ResolvedModule[moduleCount];
164 String targetPlatform = null;
165 int i = 0;
166 for (String name : map.keySet()) {
167 ModuleReference mref = finder.find(name).orElse(null);
168 assert mref != null;
169
170 if (targetPlatform == null && mref instanceof ModuleReferenceImpl) {
171 ModuleTarget target = ((ModuleReferenceImpl)mref).moduleTarget();
172 if (target != null) {
173 targetPlatform = target.targetPlatform();
174 }
175 }
176
177 ResolvedModule resolvedModule = new ResolvedModule(this, mref);
178 moduleArray[i] = resolvedModule;
179 nameEntries[i] = Map.entry(name, resolvedModule);
180 i++;
181 }
182 Map<String, ResolvedModule> nameToModule = Map.ofEntries(nameEntries);
183
184 // create entries for readability graph
185 @SuppressWarnings(value = {"rawtypes", "unchecked"})
186 Entry<ResolvedModule, Set<ResolvedModule>>[] moduleEntries
187 = (Entry<ResolvedModule, Set<ResolvedModule>>[])new Entry[moduleCount];
188 i = 0;
189 for (ResolvedModule resolvedModule : moduleArray) {
190 Set<String> names = map.get(resolvedModule.name());
191 ResolvedModule[] readsArray = new ResolvedModule[names.size()];
192 int j = 0;
193 for (String name : names) {
194 readsArray[j++] = nameToModule.get(name);
195 }
196 moduleEntries[i++] = Map.entry(resolvedModule, Set.of(readsArray));
197 }
198
199 this.parents = List.of(empty());
200 this.graph = Map.ofEntries(moduleEntries);
201 this.modules = Set.of(moduleArray);
202 this.nameToModule = nameToModule;
203 this.targetPlatform = targetPlatform;
204 }
205
206 /**
207 * Resolves a collection of root modules, with this configuration as its
208 * parent, to create a new configuration. This method works exactly as
209 * specified by the static {@link
210 * #resolve(ModuleFinder,List,ModuleFinder,Collection) resolve}
211 * method when invoked with this configuration as the parent. In other words,
212 * if this configuration is {@code cf} then this method is equivalent to
213 * invoking:
214 * <pre> {@code
215 * Configuration.resolve(before, List.of(cf), after, roots);
216 * }</pre>
217 *
218 * @param before
219 * The <em>before</em> module finder to find modules
220 * @param after
221 * The <em>after</em> module finder to locate modules when not
222 * located by the {@code before} module finder or in parent
223 * configurations
224 * @param roots
225 * The possibly-empty collection of module names of the modules
226 * to resolve
227 *
228 * @return The configuration that is the result of resolving the given
229 * root modules
230 *
231 * @throws FindException
232 * If resolution fails for any of the observability-related reasons
233 * specified by the static {@code resolve} method
234 * @throws ResolutionException
235 * If resolution fails any of the consistency checks specified by
236 * the static {@code resolve} method
237 * @throws SecurityException
238 * If locating a module is denied by the security manager
239 */
240 public Configuration resolve(ModuleFinder before,
241 ModuleFinder after,
242 Collection<String> roots)
243 {
244 return resolve(before, List.of(this), after, roots);
245 }
246
247
248 /**
249 * Resolves a collection of root modules, with service binding, and with
250 * this configuration as its parent, to create a new configuration.
251 * This method works exactly as specified by the static {@link
252 * #resolveAndBind(ModuleFinder,List,ModuleFinder,Collection)
253 * resolveAndBind} method when invoked with this configuration
254 * as the parent. In other words, if this configuration is {@code cf} then
255 * this method is equivalent to invoking:
256 * <pre> {@code
257 * Configuration.resolveAndBind(before, List.of(cf), after, roots);
258 * }</pre>
259 *
260 *
261 * @param before
262 * The <em>before</em> module finder to find modules
263 * @param after
264 * The <em>after</em> module finder to locate modules when not
265 * located by the {@code before} module finder or in parent
266 * configurations
267 * @param roots
268 * The possibly-empty collection of module names of the modules
269 * to resolve
270 *
271 * @return The configuration that is the result of resolving, with service
272 * binding, the given root modules
273 *
274 * @throws FindException
275 * If resolution fails for any of the observability-related reasons
276 * specified by the static {@code resolve} method
277 * @throws ResolutionException
278 * If resolution fails any of the consistency checks specified by
279 * the static {@code resolve} method
280 * @throws SecurityException
281 * If locating a module is denied by the security manager
282 */
283 public Configuration resolveAndBind(ModuleFinder before,
284 ModuleFinder after,
285 Collection<String> roots)
286 {
287 return resolveAndBind(before, List.of(this), after, roots);
288 }
289
290
291 /**
292 * Resolves a collection of root modules, with service binding, and with
293 * the empty configuration as its parent.
294 *
295 * This method is used to create the configuration for the boot layer.
296 */
297 static Configuration resolveAndBind(ModuleFinder finder,
298 Collection<String> roots,
299 PrintStream traceOutput)
300 {
301 List<Configuration> parents = List.of(empty());
302 Resolver resolver = new Resolver(finder, parents, ModuleFinder.of(), traceOutput);
303 resolver.resolve(roots).bind();
304 return new Configuration(parents, resolver);
305 }
306
307 /**
308 * Resolves a collection of root modules to create a configuration.
309 *
310 * <p> Each root module is located using the given {@code before} module
311 * finder. If a module is not found then it is located in the parent
312 * configuration as if by invoking the {@link #findModule(String)
313 * findModule} method on each parent in iteration order. If not found then
314 * the module is located using the given {@code after} module finder. The
315 * same search order is used to locate transitive dependences. Root modules
316 * or dependences that are located in a parent configuration are resolved
317 * no further and are not included in the resulting configuration. </p>
318 *
319 * <p> When all modules have been enumerated then a readability graph
320 * is computed, and in conjunction with the module exports and service use,
321 * checked for consistency. </p>
322 *
323 * <p> Resolution may fail with {@code FindException} for the following
324 * <em>observability-related</em> reasons: </p>
325 *
326 * <ul>
327 *
328 * <li><p> A root module, or a direct or transitive dependency, is not
329 * found. </p></li>
330 *
331 * <li><p> An error occurs when attempting to find a module.
332 * Possible errors include I/O errors, errors detected parsing a module
333 * descriptor ({@code module-info.class}) or two versions of the same
334 * module are found in the same directory. </p></li>
335 *
336 * </ul>
337 *
338 * <p> Resolution may fail with {@code ResolutionException} if any of the
339 * following consistency checks fail: </p>
340 *
341 * <ul>
342 *
343 * <li><p> A cycle is detected, say where module {@code m1} requires
344 * module {@code m2} and {@code m2} requires {@code m1}. </p></li>
345 *
346 * <li><p> A module reads two or more modules with the same name. This
347 * includes the case where a module reads another with the same name as
348 * itself. </p></li>
349 *
350 * <li><p> Two or more modules in the configuration export the same
351 * package to a module that reads both. This includes the case where a
352 * module {@code M} containing package {@code p} reads another module
353 * that exports {@code p} to {@code M}. </p></li>
354 *
355 * <li><p> A module {@code M} declares that it "{@code uses p.S}" or
356 * "{@code provides p.S with ...}" but package {@code p} is neither in
357 * module {@code M} nor exported to {@code M} by any module that
358 * {@code M} reads. </p></li>
359 *
360 * </ul>
361 *
362 * @implNote In the implementation then observability of modules may depend
363 * on referential integrity or other checks that ensure different builds of
364 * tightly coupled modules or modules for specific operating systems or
365 * architectures are not combined in the same configuration.
366 *
367 * @param before
368 * The <em>before</em> module finder to find modules
369 * @param parents
370 * The list parent configurations in search order
371 * @param after
372 * The <em>after</em> module finder to locate modules when not
373 * located by the {@code before} module finder or in parent
374 * configurations
375 * @param roots
376 * The possibly-empty collection of module names of the modules
377 * to resolve
378 *
379 * @return The configuration that is the result of resolving the given
380 * root modules
381 *
382 * @throws FindException
383 * If resolution fails for any of observability-related reasons
384 * specified above
385 * @throws ResolutionException
386 * If resolution fails for any of the consistency checks specified
387 * above
388 * @throws IllegalArgumentException
389 * If the list of parents is empty, or the list has two or more
390 * parents with modules for different target operating systems,
391 * architectures, or versions
392 *
393 * @throws SecurityException
394 * If locating a module is denied by the security manager
395 */
396 public static Configuration resolve(ModuleFinder before,
397 List<Configuration> parents,
398 ModuleFinder after,
399 Collection<String> roots)
400 {
401 Objects.requireNonNull(before);
402 Objects.requireNonNull(after);
403 Objects.requireNonNull(roots);
404
405 List<Configuration> parentList = new ArrayList<>(parents);
406 if (parentList.isEmpty())
407 throw new IllegalArgumentException("'parents' is empty");
408
409 Resolver resolver = new Resolver(before, parentList, after, null);
410 resolver.resolve(roots);
411
412 return new Configuration(parentList, resolver);
413 }
414
415 /**
416 * Resolves a collection of root modules, with service binding, to create
417 * configuration.
418 *
419 * <p> This method works exactly as specified by {@link
420 * #resolve(ModuleFinder,List,ModuleFinder,Collection)
421 * resolve} except that the graph of resolved modules is augmented
422 * with modules induced by the service-use dependence relation. </p>
423 *
424 * <p id="service-binding"> More specifically, the root modules are
425 * resolved as if by calling {@code resolve}. The resolved modules, and
426 * all modules in the parent configurations, with {@link ModuleDescriptor#uses()
427 * service dependences} are then examined. All modules found by the given
428 * module finders that {@link ModuleDescriptor#provides() provide} an
429 * implementation of one or more of the service types are added to the
430 * module graph and then resolved as if by calling the {@code
431 * resolve} method. Adding modules to the module graph may introduce new
432 * service-use dependences and so the process works iteratively until no
433 * more modules are added. </p>
434 *
435 * <p> As service binding involves resolution then it may fail with {@code
436 * FindException} or {@code ResolutionException} for exactly the same
437 * reasons specified in {@code resolve}. </p>
438 *
439 * @param before
440 * The <em>before</em> module finder to find modules
441 * @param parents
442 * The list parent configurations in search order
443 * @param after
444 * The <em>after</em> module finder to locate modules when not
445 * located by the {@code before} module finder or in parent
446 * configurations
447 * @param roots
448 * The possibly-empty collection of module names of the modules
449 * to resolve
450 *
451 * @return The configuration that is the result of resolving, with service
452 * binding, the given root modules
453 *
454 * @throws FindException
455 * If resolution fails for any of the observability-related reasons
456 * specified by the static {@code resolve} method
457 * @throws ResolutionException
458 * If resolution fails any of the consistency checks specified by
459 * the static {@code resolve} method
460 * @throws IllegalArgumentException
461 * If the list of parents is empty, or the list has two or more
462 * parents with modules for different target operating systems,
463 * architectures, or versions
464 * @throws SecurityException
465 * If locating a module is denied by the security manager
466 */
467 public static Configuration resolveAndBind(ModuleFinder before,
468 List<Configuration> parents,
469 ModuleFinder after,
470 Collection<String> roots)
471 {
472 Objects.requireNonNull(before);
473 Objects.requireNonNull(after);
474 Objects.requireNonNull(roots);
475
476 List<Configuration> parentList = new ArrayList<>(parents);
477 if (parentList.isEmpty())
478 throw new IllegalArgumentException("'parents' is empty");
479
480 Resolver resolver = new Resolver(before, parentList, after, null);
481 resolver.resolve(roots).bind();
482
483 return new Configuration(parentList, resolver);
484 }
485
486
487 /**
488 * Returns the <em>empty</em> configuration. There are no modules in the
489 * empty configuration. It has no parents.
490 *
491 * @return The empty configuration
492 */
493 public static Configuration empty() {
494 return EMPTY_CONFIGURATION;
495 }
496
497
498 /**
499 * Returns an unmodifiable list of this configuration's parents, in search
500 * order. If this is the {@linkplain #empty empty configuration} then an
501 * empty list is returned.
502 *
503 * @return A possibly-empty unmodifiable list of this parent configurations
504 */
505 public List<Configuration> parents() {
506 return parents;
507 }
508
509
510 /**
511 * Returns an immutable set of the resolved modules in this configuration.
512 *
513 * @return A possibly-empty unmodifiable set of the resolved modules
514 * in this configuration
515 */
516 public Set<ResolvedModule> modules() {
517 return modules;
518 }
519
520
521 /**
522 * Finds a resolved module in this configuration, or if not in this
523 * configuration, the {@linkplain #parents parent} configurations.
524 * Finding a module in parent configurations is equivalent to invoking
525 * {@code findModule} on each parent, in search order, until the module
526 * is found or all parents have been searched. In a <em>tree of
527 * configurations</em> then this is equivalent to a depth-first search.
528 *
529 * @param name
530 * The module name of the resolved module to find
531 *
532 * @return The resolved module with the given name or an empty {@code
533 * Optional} if there isn't a module with this name in this
534 * configuration or any parent configurations
535 */
536 public Optional<ResolvedModule> findModule(String name) {
537 Objects.requireNonNull(name);
538 ResolvedModule m = nameToModule.get(name);
539 if (m != null)
540 return Optional.of(m);
541
542 if (!parents.isEmpty()) {
543 return configurations()
544 .skip(1) // skip this configuration
545 .map(cf -> cf.nameToModule)
546 .filter(map -> map.containsKey(name))
547 .map(map -> map.get(name))
548 .findFirst();
549 }
550
551 return Optional.empty();
552 }
553
554
555 Set<ModuleDescriptor> descriptors() {
556 if (modules.isEmpty()) {
557 return Collections.emptySet();
558 } else {
559 return modules.stream()
560 .map(ResolvedModule::reference)
561 .map(ModuleReference::descriptor)
562 .collect(Collectors.toSet());
563 }
564 }
565
566 Set<ResolvedModule> reads(ResolvedModule m) {
567 return Collections.unmodifiableSet(graph.get(m));
568 }
569
570 /**
571 * Returns an ordered stream of configurations. The first element is this
572 * configuration, the remaining elements are the parent configurations
573 * in DFS order.
574 *
575 * @implNote For now, the assumption is that the number of elements will
576 * be very low and so this method does not use a specialized spliterator.
577 */
578 Stream<Configuration> configurations() {
579 List<Configuration> allConfigurations = this.allConfigurations;
580 if (allConfigurations == null) {
581 allConfigurations = new ArrayList<>();
582 Set<Configuration> visited = new HashSet<>();
583 Deque<Configuration> stack = new ArrayDeque<>();
584 visited.add(this);
585 stack.push(this);
586 while (!stack.isEmpty()) {
587 Configuration layer = stack.pop();
588 allConfigurations.add(layer);
589
590 // push in reverse order
591 for (int i = layer.parents.size() - 1; i >= 0; i--) {
592 Configuration parent = layer.parents.get(i);
593 if (!visited.contains(parent)) {
594 visited.add(parent);
595 stack.push(parent);
596 }
597 }
598 }
599 this.allConfigurations = Collections.unmodifiableList(allConfigurations);
600 }
601 return allConfigurations.stream();
602 }
603
604 private volatile List<Configuration> allConfigurations;
605
606
607 /**
608 * Returns a string describing this configuration.
609 *
610 * @return A possibly empty string describing this configuration
611 */
612 @Override
613 public String toString() {
614 return modules().stream()
615 .map(ResolvedModule::name)
616 .collect(Collectors.joining(", "));
617 }
618 }