Buffer param file writes, significantly reducing the cost of creating many param files.

PiperOrigin-RevId: 257210434

src/main/java/com/google/devtools/build/lib/actions/ParameterFile.java

diff --git a/src/main/java/com/google/devtools/build/lib/actions/ParameterFile.java b/src/main/java/com/google/devtools/build/lib/actions/ParameterFile.java
index 6a9e61a..e15bc05 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/ParameterFile.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/ParameterFile.java
@@ -19,6 +19,7 @@
 import com.google.devtools.build.lib.util.GccParamFileEscaper;
 import com.google.devtools.build.lib.util.ShellEscaper;
 import com.google.devtools.build.lib.vfs.PathFragment;
+import java.io.BufferedOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
 import java.io.OutputStreamWriter;
@@ -42,10 +43,8 @@
  */
 public class ParameterFile {
 
-  /**
-   * Different styles of parameter files.
-   */
-  public static enum ParameterFileType {
+  /** Different styles of parameter files. */
+  public enum ParameterFileType {
     /**
      * A parameter file with every parameter on a separate line. This format
      * cannot handle newlines in parameters. It is currently used for most
@@ -96,15 +95,16 @@
   public static void writeParameterFile(
       OutputStream out, Iterable<String> arguments, ParameterFileType type, Charset charset)
       throws IOException {
+    OutputStream bufferedOut = new BufferedOutputStream(out);
     switch (type) {
       case SHELL_QUOTED:
-        writeContent(out, ShellEscaper.escapeAll(arguments), charset);
+        writeContent(bufferedOut, ShellEscaper.escapeAll(arguments), charset);
         break;
       case GCC_QUOTED:
-        writeContent(out, GccParamFileEscaper.escapeAll(arguments), charset);
+        writeContent(bufferedOut, GccParamFileEscaper.escapeAll(arguments), charset);
         break;
       case UNQUOTED:
-        writeContent(out, arguments, charset);
+        writeContent(bufferedOut, arguments, charset);
         break;
     }
   }