Java tutorial
// Copyright 2014 The Bazel Authors. All rights reserved. // // 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.google.devtools.build.lib.rules.cpp; import static java.nio.charset.StandardCharsets.UTF_8; import com.google.common.collect.ImmutableList; import com.google.common.collect.Iterables; import com.google.devtools.build.lib.actions.ActionExecutionContext; import com.google.devtools.build.lib.actions.ActionOwner; import com.google.devtools.build.lib.actions.Artifact; import com.google.devtools.build.lib.analysis.WorkspaceStatusAction; import com.google.devtools.build.lib.analysis.actions.AbstractFileWriteAction; import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable; import com.google.devtools.build.lib.util.Fingerprint; import com.google.devtools.build.lib.util.Preconditions; import java.io.IOException; import java.io.OutputStream; import java.io.OutputStreamWriter; import java.io.Writer; import java.util.Collection; import java.util.LinkedHashMap; import java.util.Map; /** * An action that creates a C++ header containing the build information in the * form of #define directives. */ @Immutable public final class WriteBuildInfoHeaderAction extends AbstractFileWriteAction { private static final String GUID = "b0798174-1352-4a54-854a-9785aaea491b"; private final ImmutableList<Artifact> valueArtifacts; private final boolean writeVolatileInfo; private final boolean writeStableInfo; /** * Creates an action that writes a C++ header with the build information. * * <p>It reads the set of build info keys from an action context that is usually contributed * to Bazel by the workspace status module, and the value associated with said keys from the * workspace status files (stable and volatile) written by the workspace status action. * * <p>Without input artifacts this action uses redacted build information. * @param inputs Artifacts that contain build information, or an empty * collection to use redacted build information * @param output the C++ header Artifact created by this action * @param writeVolatileInfo whether to write the volatile part of the build * information to the generated header * @param writeStableInfo whether to write the non-volatile part of the * build information to the generated header */ public WriteBuildInfoHeaderAction(Collection<Artifact> inputs, Artifact output, boolean writeVolatileInfo, boolean writeStableInfo) { super(ActionOwner.SYSTEM_ACTION_OWNER, inputs, output, /*makeExecutable=*/ false); valueArtifacts = ImmutableList.copyOf(inputs); if (!inputs.isEmpty()) { // With non-empty inputs we should not generate both volatile and non-volatile data // in the same header file. Preconditions.checkState(writeVolatileInfo ^ writeStableInfo); } Preconditions.checkState(output.isConstantMetadata() == (writeVolatileInfo && !inputs.isEmpty())); this.writeVolatileInfo = writeVolatileInfo; this.writeStableInfo = writeStableInfo; } @Override public DeterministicWriter newDeterministicWriter(ActionExecutionContext ctx) throws IOException { WorkspaceStatusAction.Context context = ctx.getExecutor().getContext(WorkspaceStatusAction.Context.class); final Map<String, WorkspaceStatusAction.Key> keys = new LinkedHashMap<>(); if (writeVolatileInfo) { keys.putAll(context.getVolatileKeys()); } if (writeStableInfo) { keys.putAll(context.getStableKeys()); } final Map<String, String> values = new LinkedHashMap<>(); for (Artifact valueFile : valueArtifacts) { values.putAll(WorkspaceStatusAction.parseValues(valueFile.getPath())); } final boolean redacted = valueArtifacts.isEmpty(); return new DeterministicWriter() { @Override public void writeOutputFile(OutputStream out) throws IOException { Writer writer = new OutputStreamWriter(out, UTF_8); for (Map.Entry<String, WorkspaceStatusAction.Key> key : keys.entrySet()) { if (!key.getValue().isInLanguage("C++")) { continue; } String value = redacted ? key.getValue().getRedactedValue() : values.containsKey(key.getKey()) ? values.get(key.getKey()) : key.getValue().getDefaultValue(); switch (key.getValue().getType()) { case VERBATIM: case INTEGER: break; case STRING: value = quote(value); break; default: throw new IllegalStateException(); } define(writer, key.getKey(), value); } writer.flush(); } }; } @Override protected String computeKey() { Fingerprint f = new Fingerprint(); f.addString(GUID); f.addBoolean(writeStableInfo); f.addBoolean(writeVolatileInfo); return f.hexDigestAndReset(); } @Override public boolean executeUnconditionally() { // Note: isVolatile must return true if executeUnconditionally can ever return true // for this instance. return isUnconditional(); } @Override public boolean isVolatile() { return isUnconditional(); } private boolean isUnconditional() { // Because of special handling in the MetadataHandler, changed volatile build // information does not trigger relinking of all libraries that have // linkstamps. But we do want to regenerate the header in case libraries are // relinked because of other reasons. // Without inputs the contents of the header do not change, so there is no // point in executing the action again in that case. return writeVolatileInfo && !Iterables.isEmpty(getInputs()); } /** * Quote a string with double quotes. */ private String quote(String string) { // TODO(bazel-team): This is doesn't really work if the string contains quotes. Or a newline. // Or a backslash. Or anything unusual, really. return "\"" + string + "\""; } /** * Write a preprocessor define directive to a Writer. */ private void define(Writer writer, String name, String value) throws IOException { writer.write("#define "); writer.write(name); writer.write(' '); writer.write(value); writer.write('\n'); } @Override protected String getRawProgressMessage() { return null; } }