Implement injection of a forkserver into the compiler process

pmd-scm/src/main/java/net/sourceforge/pmd/scm/SourceCodeMinimizer.java

@@ -8,6 +8,7 @@
 import java.math.BigInteger;
 import java.nio.charset.Charset;
 import java.nio.file.Files;
+import java.nio.file.Path;
 import java.nio.file.StandardCopyOption;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
@@ -38,6 +39,7 @@ private static final class ExitException extends Exception { }
     private final MinimizationStrategy strategy;
     private final List<ASTCutter> cutters;
     private List<Node> currentRoots;
+    private List<SCMConfiguration.FileMapping> fileMappings;
 
     public SourceCodeMinimizer(SCMConfiguration configuration) throws IOException {
         MessageDigest md = null;
@@ -56,7 +58,8 @@ public SourceCodeMinimizer(SCMConfiguration configuration) throws IOException {
 
         Charset sourceCharset = configuration.getSourceCharset();
         cutters = new ArrayList<>();
-        for (SCMConfiguration.FileMapping mapping: configuration.getFileMappings()) {
+        fileMappings = configuration.getFileMappings();
+        for (SCMConfiguration.FileMapping mapping: fileMappings) {
             Files.copy(mapping.input, mapping.output, StandardCopyOption.REPLACE_EXISTING);
             ASTCutter cutter = new ASTCutter(parser, sourceCharset, mapping.output);
             cutters.add(cutter);
@@ -85,6 +88,15 @@ public boolean allInputsAreParseable() throws IOException {
         return true;
     }
 
+    @Override
+    public List<Path> getScratchFileNames() {
+        List<Path> result = new ArrayList<>();
+        for (SCMConfiguration.FileMapping mapping: fileMappings) {
+            result.add(mapping.output);
+        }
+        return result;
+    }
+
     @Override
     public NodeInformationProvider getNodeInformationProvider() {
         return language.getNodeInformationProvider();

pmd-scm/src/main/java/net/sourceforge/pmd/scm/invariants/AbstractExternalProcessInvariant.java

@@ -8,6 +8,7 @@
 
 import com.beust.jcommander.Parameter;
 
+import java.io.IOException;
 import java.io.PrintStream;
 
 /**
@@ -34,30 +35,40 @@ public String getName() {
         }
     }
 
-    private InvariantOperations ops;
-    private String[] commandArgs;
+    private final String compilerCommandLine;
+    protected InvariantOperations ops;
     private int spawnCount;
     private int fruitfulTests;
 
-    private static String[] createCommandLine(AbstractConfiguration configuration) {
-        if (SystemUtils.IS_OS_WINDOWS) {
-            return new String[] { "cmd.exe", "/C", configuration.compilerCommandLine };
-        } else {
-            return new String[] { "/bin/sh", "-c", configuration.compilerCommandLine };
-        }
-    }
-
     protected AbstractExternalProcessInvariant(AbstractConfiguration configuration) {
-        commandArgs = createCommandLine(configuration);
+        compilerCommandLine = configuration.compilerCommandLine;
     }
 
     @Override
-    public void initialize(InvariantOperations ops) {
+    public void initialize(InvariantOperations ops) throws IOException {
         this.ops = ops;
     }
 
     protected abstract boolean testSatisfied(ProcessBuilder pb) throws Exception;
 
+    protected String getCompilerCommandLine() {
+        return compilerCommandLine;
+    }
+
+    protected ProcessBuilder createProcessBuilder() {
+        ProcessBuilder pb = new ProcessBuilder();
+        if (SystemUtils.IS_OS_WINDOWS) {
+            pb.command("cmd.exe", "/C", compilerCommandLine);
+        } else {
+            pb.command("/bin/sh", "-c", compilerCommandLine);
+        }
+        return pb;
+    }
+
+    protected boolean testSatisfied() throws Exception {
+        return testSatisfied(createProcessBuilder());
+    }
+
     @Override
     public boolean checkIsSatisfied() throws Exception {
         // First, make a fast check that the source can be parsed at all
@@ -67,7 +78,7 @@ public boolean checkIsSatisfied() throws Exception {
 
         // then proceed to spawning subprocess
         spawnCount += 1;
-        boolean result = testSatisfied(new ProcessBuilder().command(commandArgs));
+        boolean result = testSatisfied();
         fruitfulTests += result ? 1 : 0;
 
         return result;