Update from Google.

--
MOE_MIGRATED_REVID=85702957

1 files changed, 131 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/PerBuildSyscallCache.java b/src/main/java/com/google/devtools/build/lib/skyframe/PerBuildSyscallCache.java
new file mode 100644
index 0000000000..5116a6ff64
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/PerBuildSyscallCache.java
@@ -0,0 +1,131 @@
+// Copyright 2014 Google Inc. 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.cache.CacheBuilder;
+import com.google.common.cache.CacheLoader;
+import com.google.common.cache.LoadingCache;
+import com.google.devtools.build.lib.util.Pair;
+import com.google.devtools.build.lib.vfs.Dirent;
+import com.google.devtools.build.lib.vfs.FileStatus;
+import com.google.devtools.build.lib.vfs.Path;
+import com.google.devtools.build.lib.vfs.Symlinks;
+import com.google.devtools.build.lib.vfs.UnixGlob;
+
+import java.io.IOException;
+import java.util.Collection;
+
+/**
+ * A per-build cache of filesystem operations for Skyframe invocations of legacy package loading.
+ */
+class PerBuildSyscallCache implements UnixGlob.FilesystemCalls {
+
+  private final LoadingCache<Pair<Path, Symlinks>, FileStatus> statCache =
+      newStatMap();
+  private final LoadingCache<Pair<Path, Symlinks>, Pair<Collection<Dirent>, IOException>>
+      readdirCache = newReaddirMap();
+
+  private static final FileStatus NO_STATUS = new FakeFileStatus();
+
+  @Override
+  public Collection<Dirent> readdir(Path path, Symlinks symlinks) throws IOException {
+    Pair<Collection<Dirent>, IOException> result =
+        readdirCache.getUnchecked(Pair.of(path, symlinks));
+    Collection<Dirent> entries = result.getFirst();
+    if (entries != null) {
+      return entries;
+    }
+    throw result.getSecond();
+  }
+
+  @Override
+  public FileStatus statNullable(Path path, Symlinks symlinks) {
+    FileStatus status = statCache.getUnchecked(Pair.of(path, symlinks));
+    return (status == NO_STATUS) ? null : status;
+  }
+
+  // This is used because the cache implementations don't allow null.
+  private static final class FakeFileStatus implements FileStatus {
+    @Override
+    public long getLastChangeTime() {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public long getNodeId() {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public long getLastModifiedTime() {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public long getSize() {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean isDirectory() {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean isFile() {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean isSymbolicLink() {
+      throw new UnsupportedOperationException();
+    }
+  }
+
+  /**
+   * A cache of stat calls.
+   * Input: (path, following_symlinks)
+   * Output: FileStatus
+   */
+  private static LoadingCache<Pair<Path, Symlinks>, FileStatus> newStatMap() {
+    return CacheBuilder.newBuilder().build(
+        new CacheLoader<Pair<Path, Symlinks>, FileStatus>() {
+          @Override
+          public FileStatus load(Pair<Path, Symlinks> p) {
+            FileStatus f = p.first.statNullable(p.second);
+            return (f == null) ? NO_STATUS : f;
+          }
+        });
+  }
+
+  /**
+   * A cache of readdir calls.
+   * Input: (path, following_symlinks)
+   * Output: A union of (Dirents, IOException).
+   */
+  private static
+  LoadingCache<Pair<Path, Symlinks>, Pair<Collection<Dirent>, IOException>> newReaddirMap() {
+    return CacheBuilder.newBuilder().build(
+        new CacheLoader<Pair<Path, Symlinks>, Pair<Collection<Dirent>, IOException>>() {
+          @Override
+          public Pair<Collection<Dirent>, IOException> load(Pair<Path, Symlinks> p) {
+            try {
+              return Pair.of(p.first.readdir(p.second), null);
+            } catch (IOException e) {
+              return Pair.of(null, e);
+            }
+          }
+        });
+  }
+}