Java tutorial
/* * Copyright 2014-present Facebook, Inc. * * Licensed under the Apache License, Version 2.0 (the "License"); you may * not use this file except in compliance with the License. You may obtain * a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the * License for the specific language governing permissions and limitations * under the License. */ package com.facebook.buck.cxx; import com.facebook.buck.graph.AbstractBreadthFirstTraversal; import com.facebook.buck.graph.MutableDirectedGraph; import com.facebook.buck.graph.TopologicalSort; import com.facebook.buck.model.BuildTarget; import com.facebook.buck.parser.NoSuchBuildTargetException; import com.facebook.buck.rules.BuildRule; import com.facebook.buck.rules.SourcePath; import com.facebook.buck.util.HumanReadableException; import com.google.common.base.Preconditions; import com.google.common.base.Predicate; import com.google.common.collect.ImmutableList; import com.google.common.collect.ImmutableMap; import com.google.common.collect.ImmutableSet; import com.google.common.collect.ImmutableSortedMap; import com.google.common.collect.Iterables; import com.google.common.collect.Maps; import java.util.LinkedHashMap; import java.util.Map; import java.util.Optional; public class NativeLinkables { private NativeLinkables() { } /** * Find all {@link NativeLinkable} transitive roots reachable from the given {@link BuildRule}s. * * @param from the starting set of {@link BuildRule}s to begin the search from. * @param traverse a {@link Predicate} determining acceptable dependencies to traverse when * searching for {@link NativeLinkable}s. * @param skip Skip this {@link BuildRule} even if it is an instance of {@link NativeLinkable} * @return all the roots found as a map from {@link BuildTarget} to {@link NativeLinkable}. */ static ImmutableMap<BuildTarget, NativeLinkable> getNativeLinkableRoots(Iterable<? extends BuildRule> from, final Predicate<Object> traverse, final Predicate<Object> skip) { final ImmutableMap.Builder<BuildTarget, NativeLinkable> nativeLinkables = ImmutableMap.builder(); AbstractBreadthFirstTraversal<BuildRule> visitor = new AbstractBreadthFirstTraversal<BuildRule>(from) { @Override public ImmutableSet<BuildRule> visit(BuildRule rule) { // If this is `NativeLinkable`, we've found a root so record the rule and terminate // the search. if (rule instanceof NativeLinkable && !skip.apply(rule)) { NativeLinkable nativeLinkable = (NativeLinkable) rule; nativeLinkables.put(nativeLinkable.getBuildTarget(), nativeLinkable); return ImmutableSet.of(); } // Otherwise, make sure this rule is marked as traversable before following it's deps. if (traverse.apply(rule)) { return rule.getDeps(); } return ImmutableSet.of(); } }; visitor.start(); return nativeLinkables.build(); } /** * Find all {@link NativeLinkable} transitive roots reachable from the given {@link BuildRule}s. * * @param from the starting set of {@link BuildRule}s to begin the search from. * @param traverse a {@link Predicate} determining acceptable dependencies to traverse when * searching for {@link NativeLinkable}s. * @return all the roots found as a map from {@link BuildTarget} to {@link NativeLinkable}. */ public static ImmutableMap<BuildTarget, NativeLinkable> getNativeLinkableRoots( Iterable<? extends BuildRule> from, final Predicate<Object> traverse) { return getNativeLinkableRoots(from, traverse, x -> false); } /** * Extract from the dependency graph all the libraries which must be considered for linking. * * Traversal proceeds depending on whether each dependency is to be statically or dynamically * linked. * * @param linkStyle how dependencies should be linked, if their preferred_linkage is * {@code NativeLinkable.Linkage.ANY}. */ public static ImmutableMap<BuildTarget, NativeLinkable> getNativeLinkables(final CxxPlatform cxxPlatform, Iterable<? extends NativeLinkable> inputs, final Linker.LinkableDepType linkStyle, final Predicate<? super NativeLinkable> traverse) { final Map<BuildTarget, NativeLinkable> nativeLinkables = Maps.newHashMap(); for (NativeLinkable nativeLinkable : inputs) { nativeLinkables.put(nativeLinkable.getBuildTarget(), nativeLinkable); } final MutableDirectedGraph<BuildTarget> graph = new MutableDirectedGraph<>(); AbstractBreadthFirstTraversal<BuildTarget> visitor = new AbstractBreadthFirstTraversal<BuildTarget>( nativeLinkables.keySet()) { @Override public ImmutableSet<BuildTarget> visit(BuildTarget target) { NativeLinkable nativeLinkable = Preconditions.checkNotNull(nativeLinkables.get(target)); graph.addNode(target); // We always traverse a rule's exported native linkables. Iterable<? extends NativeLinkable> nativeLinkableDeps = nativeLinkable .getNativeLinkableExportedDepsForPlatform(cxxPlatform); boolean shouldTraverse = true; switch (nativeLinkable.getPreferredLinkage(cxxPlatform)) { case ANY: shouldTraverse = linkStyle != Linker.LinkableDepType.SHARED; break; case SHARED: shouldTraverse = false; break; case STATIC: shouldTraverse = true; break; } // If we're linking this dependency statically, we also need to traverse its deps. if (shouldTraverse) { nativeLinkableDeps = Iterables.concat(nativeLinkableDeps, nativeLinkable.getNativeLinkableDepsForPlatform(cxxPlatform)); } // Process all the traversable deps. ImmutableSet.Builder<BuildTarget> deps = ImmutableSet.builder(); for (NativeLinkable dep : nativeLinkableDeps) { if (traverse.apply(dep)) { BuildTarget depTarget = dep.getBuildTarget(); graph.addEdge(target, depTarget); deps.add(depTarget); nativeLinkables.put(depTarget, dep); } } return deps.build(); } }; visitor.start(); // Topologically sort the rules. Iterable<BuildTarget> ordered = TopologicalSort.sort(graph).reverse(); // Return a map of of the results. ImmutableMap.Builder<BuildTarget, NativeLinkable> result = ImmutableMap.builder(); for (BuildTarget target : ordered) { result.put(target, nativeLinkables.get(target)); } return result.build(); } public static ImmutableMap<BuildTarget, NativeLinkable> getNativeLinkables(final CxxPlatform cxxPlatform, Iterable<? extends NativeLinkable> inputs, final Linker.LinkableDepType linkStyle) { return getNativeLinkables(cxxPlatform, inputs, linkStyle, x -> true); } public static Linker.LinkableDepType getLinkStyle(NativeLinkable.Linkage preferredLinkage, Linker.LinkableDepType requestedLinkStyle) { Linker.LinkableDepType linkStyle; switch (preferredLinkage) { case SHARED: linkStyle = Linker.LinkableDepType.SHARED; break; case STATIC: linkStyle = requestedLinkStyle == Linker.LinkableDepType.STATIC ? Linker.LinkableDepType.STATIC : Linker.LinkableDepType.STATIC_PIC; break; case ANY: linkStyle = requestedLinkStyle; break; default: throw new IllegalStateException(); } return linkStyle; } public static NativeLinkableInput getNativeLinkableInput(CxxPlatform cxxPlatform, Linker.LinkableDepType linkStyle, NativeLinkable nativeLinkable) throws NoSuchBuildTargetException { NativeLinkable.Linkage link = nativeLinkable.getPreferredLinkage(cxxPlatform); return nativeLinkable.getNativeLinkableInput(cxxPlatform, getLinkStyle(link, linkStyle)); } /** * Collect up and merge all {@link com.facebook.buck.cxx.NativeLinkableInput} objects from * transitively traversing all unbroken dependency chains of * {@link com.facebook.buck.cxx.NativeLinkable} objects found via the passed in * {@link com.facebook.buck.rules.BuildRule} roots. */ public static NativeLinkableInput getTransitiveNativeLinkableInput(CxxPlatform cxxPlatform, Iterable<? extends BuildRule> inputs, Linker.LinkableDepType depType, Predicate<Object> traverse, Predicate<Object> skip) throws NoSuchBuildTargetException { // Get the topologically sorted native linkables. ImmutableMap<BuildTarget, NativeLinkable> roots = getNativeLinkableRoots(inputs, traverse, skip); ImmutableMap<BuildTarget, NativeLinkable> nativeLinkables = getNativeLinkables(cxxPlatform, roots.values(), depType); ImmutableList.Builder<NativeLinkableInput> nativeLinkableInputs = ImmutableList.builder(); for (NativeLinkable nativeLinkable : nativeLinkables.values()) { nativeLinkableInputs.add(getNativeLinkableInput(cxxPlatform, depType, nativeLinkable)); } return NativeLinkableInput.concat(nativeLinkableInputs.build()); } public static ImmutableMap<BuildTarget, NativeLinkable> getTransitiveNativeLinkables( final CxxPlatform cxxPlatform, Iterable<? extends NativeLinkable> inputs) { final Map<BuildTarget, NativeLinkable> nativeLinkables = Maps.newHashMap(); for (NativeLinkable nativeLinkable : inputs) { nativeLinkables.put(nativeLinkable.getBuildTarget(), nativeLinkable); } final MutableDirectedGraph<BuildTarget> graph = new MutableDirectedGraph<>(); AbstractBreadthFirstTraversal<BuildTarget> visitor = new AbstractBreadthFirstTraversal<BuildTarget>( nativeLinkables.keySet()) { @Override public ImmutableSet<BuildTarget> visit(BuildTarget target) { NativeLinkable nativeLinkable = Preconditions.checkNotNull(nativeLinkables.get(target)); graph.addNode(target); ImmutableSet.Builder<BuildTarget> deps = ImmutableSet.builder(); for (NativeLinkable dep : Iterables.concat( nativeLinkable.getNativeLinkableDepsForPlatform(cxxPlatform), nativeLinkable.getNativeLinkableExportedDepsForPlatform(cxxPlatform))) { BuildTarget depTarget = dep.getBuildTarget(); graph.addEdge(target, depTarget); deps.add(depTarget); nativeLinkables.put(depTarget, dep); } return deps.build(); } }; visitor.start(); return ImmutableMap.copyOf(nativeLinkables); } /** * Collect up and merge all {@link com.facebook.buck.cxx.NativeLinkableInput} objects from * transitively traversing all unbroken dependency chains of * {@link com.facebook.buck.cxx.NativeLinkable} objects found via the passed in * {@link com.facebook.buck.rules.BuildRule} roots. */ public static NativeLinkableInput getTransitiveNativeLinkableInput(CxxPlatform cxxPlatform, Iterable<? extends BuildRule> inputs, Linker.LinkableDepType depType, Predicate<Object> traverse) throws NoSuchBuildTargetException { return getTransitiveNativeLinkableInput(cxxPlatform, inputs, depType, traverse, x -> false); } /** * Collect all the shared libraries generated by {@link NativeLinkable}s found by transitively * traversing all unbroken dependency chains of {@link com.facebook.buck.cxx.NativeLinkable} * objects found via the passed in {@link com.facebook.buck.rules.BuildRule} roots. * * @return a mapping of library name to the library {@link SourcePath}. */ public static ImmutableSortedMap<String, SourcePath> getTransitiveSharedLibraries(CxxPlatform cxxPlatform, Iterable<? extends BuildRule> inputs, Predicate<Object> traverse, Predicate<Object> skip) throws NoSuchBuildTargetException { ImmutableMap<BuildTarget, NativeLinkable> roots = getNativeLinkableRoots(inputs, traverse, skip); ImmutableMap<BuildTarget, NativeLinkable> nativeLinkables = getTransitiveNativeLinkables(cxxPlatform, roots.values()); Map<String, SourcePath> libraries = new LinkedHashMap<>(); for (NativeLinkable nativeLinkable : nativeLinkables.values()) { NativeLinkable.Linkage linkage = nativeLinkable.getPreferredLinkage(cxxPlatform); if (linkage != NativeLinkable.Linkage.STATIC) { ImmutableMap<String, SourcePath> libs = nativeLinkable.getSharedLibraries(cxxPlatform); for (Map.Entry<String, SourcePath> lib : libs.entrySet()) { SourcePath prev = libraries.put(lib.getKey(), lib.getValue()); if (prev != null && !prev.equals(lib.getValue())) { throw new HumanReadableException("conflicting libraries for key %s: %s != %s", lib.getKey(), lib.getValue(), prev); } } } } return ImmutableSortedMap.copyOf(libraries); } /** * Collect all the shared libraries generated by {@link NativeLinkable}s found by transitively * traversing all unbroken dependency chains of {@link com.facebook.buck.cxx.NativeLinkable} * objects found via the passed in {@link com.facebook.buck.rules.BuildRule} roots. * * @return a mapping of library name to the library {@link SourcePath}. */ public static ImmutableSortedMap<String, SourcePath> getTransitiveSharedLibraries(CxxPlatform cxxPlatform, Iterable<? extends BuildRule> inputs, Predicate<Object> traverse) throws NoSuchBuildTargetException { return getTransitiveSharedLibraries(cxxPlatform, inputs, traverse, x -> false); } /** * @return the {@link NativeLinkTarget} that can be extracted from {@code object}, if any. */ public static Optional<NativeLinkTarget> getNativeLinkTarget(Object object, CxxPlatform cxxPlatform) { if (object instanceof NativeLinkTarget) { return Optional.of((NativeLinkTarget) object); } if (object instanceof CanProvideNativeLinkTarget) { return ((CanProvideNativeLinkTarget) object).getNativeLinkTarget(cxxPlatform); } return Optional.empty(); } }