Add an on-disk storage option for the remote worker

I'm planning to switch the remote worker over to the on-disk storage system,
and delete the in-memory option. Currently, running a Bazel build with the
in-memory storage system uses up over 50% of the total available memory on my
machine (I only have 32 GB total), and grinds it to a complete halt (unless I
close most of my apps) on a simple build of //src:bazel.

PiperOrigin-RevId: 160877546

1 files changed, 57 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/remote/blobstore/OnDiskBlobStore.java b/src/main/java/com/google/devtools/build/lib/remote/blobstore/OnDiskBlobStore.java
new file mode 100644
index 0000000000..8f2ee0790e
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/remote/blobstore/OnDiskBlobStore.java
@@ -0,0 +1,57 @@
+// Copyright 2017 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.remote.blobstore;
+
+import com.google.devtools.build.lib.vfs.FileSystemUtils;
+import com.google.devtools.build.lib.vfs.Path;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.util.UUID;
+
+/** A on-disk store for the remote action cache. */
+public final class OnDiskBlobStore implements SimpleBlobStore {
+  private final Path root;
+
+  public OnDiskBlobStore(Path root) {
+    this.root = root;
+  }
+
+  @Override
+  public boolean containsKey(String key) {
+    return toPath(key).exists();
+  }
+
+  @Override
+  public byte[] get(String key) throws IOException {
+    Path f = toPath(key);
+    return f.exists() ? FileSystemUtils.readContent(f) : null;
+  }
+
+  @Override
+  public void put(String key, byte[] value) throws IOException {
+    Path temp = toPath(UUID.randomUUID().toString());
+    try (OutputStream out = temp.getOutputStream()) {
+      out.write(value);
+    }
+    Path f = toPath(key);
+    temp.renameTo(f);
+  }
+
+  @Override
+  public void close() {}
+
+  private Path toPath(String key) {
+    return root.getChild(key);
+  }
+}
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