introduce CxxSquidProfiler for CxxSquidSensor

* if property set, print duration of each SquidCheck to `sonar.cxx.squidprofiler.out=<abs path>`
* currently only duration is logged
* for parallel execution we can log start/stop time also, in order to check
  the utilization level (see SonarOpenCommunity#1493)

* output: semi-JSON format for later python analysis (e.g. in http://jupyter.org/)
  `{ "visitor": "%s", "source_file": "%s", "duration_ms": "%d" }`

cxx-sensors/src/main/java/org/sonar/cxx/sensors/squid/CxxSquidProfiler.java

@@ -0,0 +1,142 @@
+/*
+ * Sonar C++ Plugin (Community)
+ * Copyright (C) 2010-2018 SonarOpenCommunity
+ * http://github.com/SonarOpenCommunity/sonar-cxx
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.cxx.sensors.squid;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.charset.Charset;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+
+import javax.annotation.Nullable;
+
+import org.apache.commons.io.FileUtils;
+import org.sonar.api.utils.log.Logger;
+import org.sonar.api.utils.log.Loggers;
+import org.sonar.squidbridge.SquidAstVisitor;
+import org.sonar.squidbridge.SquidAstVisitorContext;
+
+import com.sonar.sslr.api.AstAndTokenVisitor;
+import com.sonar.sslr.api.AstNode;
+import com.sonar.sslr.api.AstNodeType;
+import com.sonar.sslr.api.Grammar;
+import com.sonar.sslr.api.Token;
+
+public class CxxSquidProfiler {
+  private static final Logger LOG = Loggers.get(CxxSquidProfiler.class);
+
+  public static class CxxProfilerDecorator_AstVisitor extends SquidAstVisitor<Grammar> {
+    protected SquidAstVisitor<Grammar> v;
+    private long startTimestamp = 0;
+    private File outFile;
+
+    public CxxProfilerDecorator_AstVisitor(SquidAstVisitor<Grammar> visitor, File outF) {
+      v = visitor;
+      outFile = outF;
+    }
+
+    @Override
+    public void setContext(SquidAstVisitorContext<Grammar> context) {
+      v.setContext(context);
+    }
+
+    @Override
+    public SquidAstVisitorContext<Grammar> getContext() {
+      return v.getContext();
+    }
+
+    @Override
+    public void init() {
+      v.init();
+    }
+
+    @Override
+    public void destroy() {
+      v.destroy();
+    }
+
+    @Override
+    public List<AstNodeType> getAstNodeTypesToVisit() {
+      return v.getAstNodeTypesToVisit();
+    }
+
+    protected void writeEvent(long nanoDuration) {
+      String path = "null";
+      if (getContext() != null && getContext().getFile() != null) {
+        path = getContext().getFile().getAbsolutePath();
+      }
+      String classname = v.getClass().getName();
+      String entry = String.format("{ \"visitor\": \"%s\", \"source_file\": \"%s\", \"duration_ms\": \"%d\" }\n",
+          classname, path,
+          TimeUnit.NANOSECONDS.toMillis(nanoDuration));
+
+      try {
+        FileUtils.writeStringToFile(outFile, entry, Charset.defaultCharset(), true);
+      } catch (IOException e) {
+        LOG.debug("Cannot write bench information: {}", e);
+      }
+    }
+
+    @Override
+    public void visitFile(@Nullable AstNode ast) {
+      startTimestamp = System.nanoTime();
+      v.visitFile(ast);
+    }
+
+    @Override
+    public void leaveFile(@Nullable AstNode ast) {
+      v.leaveFile(ast);
+      long nanoDuration = System.nanoTime() - startTimestamp;
+      writeEvent(nanoDuration);
+    }
+
+    @Override
+    public void visitNode(AstNode ast) {
+      v.visitNode(ast);
+    }
+
+    @Override
+    public void leaveNode(AstNode ast) {
+      v.leaveNode(ast);
+    }
+  }
+
+  public static class CxxProfilerDecorator_AstAndTokenVisitor extends CxxProfilerDecorator_AstVisitor
+      implements AstAndTokenVisitor {
+
+    public CxxProfilerDecorator_AstAndTokenVisitor(SquidAstVisitor<Grammar> visitor, File outFile) {
+      super(visitor, outFile);
+    }
+
+    @Override
+    public void visitToken(Token token) {
+      ((AstAndTokenVisitor) v).visitToken(token);
+    }
+  }
+
+  public static SquidAstVisitor<Grammar> decorate(SquidAstVisitor<Grammar> v, File outFile) {
+    if (v instanceof AstAndTokenVisitor) {
+      return new CxxProfilerDecorator_AstAndTokenVisitor(v, outFile);
+    } else {
+      return new CxxProfilerDecorator_AstVisitor(v, outFile);
+    }
+  }
+
+}

cxx-sensors/src/main/java/org/sonar/cxx/sensors/squid/CxxSquidSensor.java

@@ -26,6 +26,7 @@
 import java.util.Collection;
 import java.util.List;
 import java.util.Locale;
+import java.util.Optional;
 import javax.annotation.Nullable;
 import org.sonar.api.batch.fs.FileSystem;
 import org.sonar.api.batch.fs.InputFile;
@@ -158,6 +159,17 @@ public void execute(SensorContext context) {
     }
 
     CxxConfiguration cxxConf = createConfiguration(context.fileSystem(), context);
+
+    Optional<String> squidProfilerOutOption = this.language.getStringOption("squidprofiler.out");
+    if (squidProfilerOutOption.isPresent()) {
+      File outputPath = new File(squidProfilerOutOption.get());
+      List<SquidAstVisitor<Grammar>> decoratedVisitors = new ArrayList<>();
+      for (SquidAstVisitor<Grammar> originalVisitor : visitors) {
+        decoratedVisitors.add(CxxSquidProfiler.decorate(originalVisitor, outputPath));
+      }
+      visitors = decoratedVisitors;
+    }
+
     AstScanner<Grammar> scanner = CxxAstScanner.create(this.language, cxxConf,
       visitors.toArray(new SquidAstVisitor[visitors.size()]));