Replace finalizer of NativeFileOutputStream.

This removes the last deprecated object finalizer from Bazel.

I created a single java.lang.ref.Cleaner instance for multiple users in Bazel.

src/main/java/com/google/devtools/build/lib/shell/BUILD

@@ -20,6 +20,7 @@ java_library(
     srcs = glob(["*.java"]),
     deps = [
         "//src/main/java/com/google/devtools/build/lib/jni",
+        "//src/main/java/com/google/devtools/build/lib/util:cleaner",
         "//src/main/java/com/google/devtools/build/lib/util:describable_execution_unit",
         "//src/main/java/com/google/devtools/build/lib/util:os",
         "//src/main/java/com/google/devtools/build/lib/util:string_encoding",

src/main/java/com/google/devtools/build/lib/shell/WindowsSubprocess.java

@@ -14,6 +14,8 @@
 
 package com.google.devtools.build.lib.shell;
 
+import static com.google.devtools.build.lib.util.BazelCleaner.CLEANER;
+
 import com.google.common.base.Throwables;
 import com.google.devtools.build.lib.windows.WindowsProcesses;
 import java.io.IOException;
@@ -29,8 +31,6 @@
 
 /** A Windows subprocess backed by a native object. */
 public class WindowsSubprocess implements Subprocess {
-  private static final Cleaner cleaner = Cleaner.create();
-
   // For debugging purposes.
   private String commandLine;
 
@@ -200,7 +200,7 @@ public void run() {
             stderrRedirected
                 ? null
                 : new ProcessInputStream(WindowsProcesses.getStderr(nativeProcess)));
-    cleanable = cleaner.register(this, nativeState);
+    cleanable = CLEANER.register(this, nativeState);
     // As per the spec of Command, we should only apply timeouts that are > 0.
     this.timeoutMillis = timeoutMillis <= 0 ? -1 : timeoutMillis;
     // Every Windows process we start consumes a thread here. This is suboptimal, but seems to be

src/main/java/com/google/devtools/build/lib/unix/BUILD

@@ -23,6 +23,7 @@ java_library(
         "//src/main/java/com/google/devtools/build/lib/jni",
         "//src/main/java/com/google/devtools/build/lib/profiler",
         "//src/main/java/com/google/devtools/build/lib/util:blocker",
+        "//src/main/java/com/google/devtools/build/lib/util:cleaner",
         "//src/main/java/com/google/devtools/build/lib/util:os",
         "//src/main/java/com/google/devtools/build/lib/util:string_encoding",
         "//src/main/java/com/google/devtools/build/lib/vfs",

src/main/java/com/google/devtools/build/lib/unix/UnixFileSystem.java

@@ -13,6 +13,8 @@
 // limitations under the License.
 package com.google.devtools.build.lib.unix;
 
+import static com.google.devtools.build.lib.util.BazelCleaner.CLEANER;
+
 import com.google.common.base.Preconditions;
 import com.google.common.collect.Lists;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
@@ -35,6 +37,8 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
+import java.io.UncheckedIOException;
+import java.lang.ref.Cleaner;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.List;
@@ -489,33 +493,45 @@ protected OutputStream createFileOutputStream(PathFragment path, boolean append,
     }
   }
 
-  private static class NativeFileOutputStream extends OutputStream {
-    private final int fd;
-    private boolean closed = false;
+  private static final class FdHolder implements Runnable {
+    private int fd;
 
-    NativeFileOutputStream(int fd) {
+    private FdHolder(int fd) {
       this.fd = fd;
     }
 
     @Override
-    protected void finalize() throws Throwable {
-      close();
-      super.finalize();
+    public void run() {
+      try {
+        NativePosixFiles.close(fd, this);
+      } catch (IOException e) {
+        throw new UncheckedIOException(e);
+      } finally {
+        fd = -1;
+      }
+    }
+  }
+
+  private static class NativeFileOutputStream extends OutputStream {
+    private final FdHolder fdHolder;
+    private final Cleaner.Cleanable cleanable;
+
+    private NativeFileOutputStream(int fd) {
+      this.fdHolder = new FdHolder(fd);
+      this.cleanable = CLEANER.register(this, fdHolder);
     }
 
     @Override
-    public synchronized void close() throws IOException {
-      if (!closed) {
+    public void close() throws IOException {
         var comp = Blocker.begin();
         try {
-          NativePosixFiles.close(fd, this);
-          closed = true;
+        cleanable.clean();
+      } catch (UncheckedIOException e) {
+        throw e.getCause();
         } finally {
           Blocker.end(comp);
         }
       }
-      super.close();
-    }
 
     @Override
     public void write(int b) throws IOException {
@@ -528,10 +544,9 @@ public void write(byte[] b) throws IOException {
     }
 
     @Override
-    @SuppressWarnings(
-        "UnsafeFinalization") // Finalizer invokes close; close and write are synchronized.
-    public synchronized void write(byte[] b, int off, int len) throws IOException {
-      if (closed) {
+    public void write(byte[] b, int off, int len) throws IOException {
+      var fd = fdHolder.fd;
+      if (fd < 0) {
         throw new IOException("attempt to write to a closed Outputstream backed by a native file");
       }
       var comp = Blocker.begin();
@@ -546,13 +561,13 @@ public synchronized void write(byte[] b, int off, int len) throws IOException {
   private static final class ProfiledNativeFileOutputStream extends NativeFileOutputStream {
     private final String name;
 
-    public ProfiledNativeFileOutputStream(int fd, String name) {
+    private ProfiledNativeFileOutputStream(int fd, String name) {
       super(fd);
       this.name = name;
     }
 
     @Override
-    public synchronized void write(byte[] b, int off, int len) throws IOException {
+    public void write(byte[] b, int off, int len) throws IOException {
       long startTime = Profiler.nanoTimeMaybe();
       try {
         super.write(b, off, len);

src/main/java/com/google/devtools/build/lib/util/BUILD

@@ -462,3 +462,8 @@ java_library(
         "//third_party:jsr305",
     ],
 )
+
+java_library(
+    name = "cleaner",
+    srcs = ["BazelCleaner.java"],
+)

src/main/java/com/google/devtools/build/lib/util/BazelCleaner.java

@@ -0,0 +1,10 @@
+package com.google.devtools.build.lib.util;
+
+import java.lang.ref.Cleaner;
+
+/** Common {@link Cleaner} for Bazel. */
+public final class BazelCleaner {
+  public static final Cleaner CLEANER = Cleaner.create();
+
+  private BazelCleaner() {}
+}