| // 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.skyframe; |
| |
| import com.google.common.annotations.VisibleForTesting; |
| import com.google.common.base.Function; |
| import com.google.common.base.Preconditions; |
| import com.google.common.collect.ImmutableList; |
| import com.google.common.collect.ImmutableSet; |
| import com.google.common.collect.Iterables; |
| import com.google.devtools.build.lib.util.OS; |
| import com.google.devtools.build.lib.vfs.ModifiedFileSet; |
| import com.google.devtools.build.lib.vfs.PathFragment; |
| import com.google.devtools.build.lib.vfs.Root; |
| import com.google.devtools.common.options.Option; |
| import com.google.devtools.common.options.OptionDocumentationCategory; |
| import com.google.devtools.common.options.OptionEffectTag; |
| import com.google.devtools.common.options.OptionsBase; |
| import java.io.IOException; |
| import java.nio.file.FileSystems; |
| import java.nio.file.Path; |
| import java.util.Set; |
| |
| /** |
| * File system watcher for local filesystems. It's able to provide a list of changed files between |
| * two consecutive calls. On Linux, uses the standard Java WatchService, which uses 'inotify' and, |
| * on OS X, uses {@link MacOSXFsEventsDiffAwareness}, which use FSEvents. |
| * |
| * <p> |
| * This is an abstract class, specialized by {@link MacOSXFsEventsDiffAwareness} and |
| * {@link WatchServiceDiffAwareness}. |
| */ |
| public abstract class LocalDiffAwareness implements DiffAwareness { |
| /** |
| * Option to enable / disable local diff awareness. |
| */ |
| public static final class Options extends OptionsBase { |
| @Option( |
| name = "watchfs", |
| defaultValue = "false", |
| documentationCategory = OptionDocumentationCategory.UNCATEGORIZED, |
| effectTags = {OptionEffectTag.UNKNOWN}, |
| help = |
| "If true, %{product} tries to use the operating system's file watch service for " |
| + "local changes instead of scanning every file for a change." |
| ) |
| public boolean watchFS; |
| } |
| |
| /** Factory for creating {@link LocalDiffAwareness} instances. */ |
| public static class Factory implements DiffAwareness.Factory { |
| private final ImmutableList<String> prefixBlacklist; |
| |
| /** |
| * Creates a new factory; the file system watcher may not work on all file systems, particularly |
| * for network file systems. The prefix blacklist can be used to blacklist known paths that |
| * point to network file systems. |
| */ |
| public Factory(ImmutableList<String> prefixBlacklist) { |
| this.prefixBlacklist = prefixBlacklist; |
| } |
| |
| @Override |
| public DiffAwareness maybeCreate(Root pathEntry) { |
| com.google.devtools.build.lib.vfs.Path resolvedPathEntry; |
| try { |
| resolvedPathEntry = pathEntry.asPath().resolveSymbolicLinks(); |
| } catch (IOException e) { |
| return null; |
| } |
| PathFragment resolvedPathEntryFragment = resolvedPathEntry.asFragment(); |
| // There's no good way to automatically detect network file systems. We rely on a blacklist |
| // for now (and maybe add a command-line option in the future?). |
| for (String prefix : prefixBlacklist) { |
| if (resolvedPathEntryFragment.startsWith(PathFragment.create(prefix))) { |
| return null; |
| } |
| } |
| // On OSX uses FsEvents due to https://bugs.openjdk.java.net/browse/JDK-7133447 |
| if (OS.getCurrent() == OS.DARWIN) { |
| return new MacOSXFsEventsDiffAwareness(resolvedPathEntryFragment.toString()); |
| } |
| |
| return new WatchServiceDiffAwareness(resolvedPathEntryFragment.toString()); |
| } |
| } |
| |
| /** |
| * A view that results in any subsequent getDiff calls returning |
| * {@link ModifiedFileSet#EVERYTHING_MODIFIED}. Use this if --watchFs is disabled. |
| * |
| * <p>The position is set to -2 in order for {@link #areInSequence} below to always return false |
| * if this view is passed to it. Any negative number would work; we don't use -1 as the other |
| * view may have a position of 0. |
| */ |
| protected static final View EVERYTHING_MODIFIED = |
| new SequentialView(/*owner=*/null, /*position=*/-2, ImmutableSet.<Path>of()); |
| |
| public static boolean areInSequence(SequentialView oldView, SequentialView newView) { |
| // Keep this in sync with the EVERYTHING_MODIFIED View above. |
| return oldView.owner == newView.owner && (oldView.position + 1) == newView.position; |
| } |
| |
| private int numGetCurrentViewCalls = 0; |
| |
| /** Root directory to watch. This is an absolute path. */ |
| protected final Path watchRootPath; |
| |
| protected LocalDiffAwareness(String watchRoot) { |
| this.watchRootPath = FileSystems.getDefault().getPath(watchRoot); |
| } |
| |
| /** |
| * The WatchService is inherently sequential and side-effectful, so we enforce this by only |
| * supporting {@link #getDiff} calls that happen to be sequential. |
| */ |
| @VisibleForTesting |
| static class SequentialView implements DiffAwareness.View { |
| private final LocalDiffAwareness owner; |
| private final int position; |
| private final Set<Path> modifiedAbsolutePaths; |
| |
| public SequentialView(LocalDiffAwareness owner, int position, Set<Path> modifiedAbsolutePaths) { |
| this.owner = owner; |
| this.position = position; |
| this.modifiedAbsolutePaths = modifiedAbsolutePaths; |
| } |
| |
| @Override |
| public String toString() { |
| return String.format("SequentialView[owner=%s, position=%d, modifiedAbsolutePaths=%s]", owner, |
| position, modifiedAbsolutePaths); |
| } |
| } |
| |
| /** |
| * Returns true on any call before first call to {@link #newView}. |
| */ |
| protected boolean isFirstCall() { |
| return numGetCurrentViewCalls == 0; |
| } |
| |
| /** |
| * Create a new views using a list of modified absolute paths. This will increase the view |
| * counter. |
| */ |
| protected SequentialView newView(Set<Path> modifiedAbsolutePaths) { |
| numGetCurrentViewCalls++; |
| return new SequentialView(this, numGetCurrentViewCalls, modifiedAbsolutePaths); |
| } |
| |
| @Override |
| public ModifiedFileSet getDiff(View oldView, View newView) |
| throws IncompatibleViewException, BrokenDiffAwarenessException { |
| SequentialView oldSequentialView; |
| SequentialView newSequentialView; |
| try { |
| oldSequentialView = (SequentialView) oldView; |
| newSequentialView = (SequentialView) newView; |
| } catch (ClassCastException e) { |
| throw new IncompatibleViewException("Given views are not from LocalDiffAwareness"); |
| } |
| if (!areInSequence(oldSequentialView, newSequentialView)) { |
| return ModifiedFileSet.EVERYTHING_MODIFIED; |
| } |
| return ModifiedFileSet.builder() |
| .modifyAll(Iterables.transform(newSequentialView.modifiedAbsolutePaths, |
| nioAbsolutePathToPathFragment)) |
| .build(); |
| } |
| |
| @Override |
| public String name() { |
| return "local"; |
| } |
| |
| /** Converts java.nio.file.Path objects to vfs.PathFragment. */ |
| private final Function<Path, PathFragment> nioAbsolutePathToPathFragment = |
| new Function<Path, PathFragment>() { |
| @Override |
| public PathFragment apply(Path input) { |
| Preconditions.checkArgument( |
| input.startsWith(watchRootPath), "%s %s", input, watchRootPath); |
| return PathFragment.create(watchRootPath.relativize(input).toString()); |
| } |
| }; |
| } |