| // Copyright 2024 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.common; |
| |
| import com.google.devtools.build.lib.vfs.Path; |
| import java.io.IOException; |
| import java.io.InputStream; |
| |
| /** |
| * Creates an {@link InputStream} backed by a file that isn't actually opened until the first data |
| * is read. This is useful to only have as many open file descriptors as necessary at a time to |
| * avoid running into system limits. |
| * |
| * <p>The markSupported(), mark() and reset() methods need not be overridden, as they're unsupported |
| * by the base implementation. |
| */ |
| public class LazyFileInputStream extends InputStream { |
| |
| private final Path path; |
| private InputStream in; |
| |
| public LazyFileInputStream(Path path) { |
| this.path = path; |
| } |
| |
| @Override |
| public int available() throws IOException { |
| ensureOpen(); |
| return in.available(); |
| } |
| |
| @Override |
| public int read() throws IOException { |
| ensureOpen(); |
| return in.read(); |
| } |
| |
| @Override |
| public int read(byte[] b) throws IOException { |
| ensureOpen(); |
| return in.read(b); |
| } |
| |
| @Override |
| public int read(byte[] b, int off, int len) throws IOException { |
| ensureOpen(); |
| return in.read(b, off, len); |
| } |
| |
| @Override |
| public long skip(long n) throws IOException { |
| ensureOpen(); |
| return in.skip(n); |
| } |
| |
| @Override |
| public void close() throws IOException { |
| ensureOpen(); |
| in.close(); |
| } |
| |
| private void ensureOpen() throws IOException { |
| if (in == null) { |
| in = path.getInputStream(); |
| } |
| } |
| } |