Make SubmitRuleEvaluator usable for testing prolog rules.

For the purpose of testing submit rules the SubmitRuleEvaluator needs
more flexibility like skipping the submit filters and loading prolog
rules from a caller provided input stream.

This change is a preparation for refactoring of the test-submit-rule
command which currently duplicates most of the code for finding and
executing the prolog rules.

Change-Id: I54086590fa5dc5cefdd9c36ca2e8587d374bd988
Signed-off-by: Sasa Zivkov <sasa.zivkov@sap.com>

gerrit-server/src/main/java/com/google/gerrit/rules/RulesCache.java

@@ -45,7 +45,10 @@ import org.eclipse.jgit.util.RawParseUtils;
 
 import java.io.File;
 import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
 import java.io.PushbackReader;
+import java.io.Reader;
 import java.io.StringReader;
 import java.lang.ref.Reference;
 import java.lang.ref.ReferenceQueue;
@@ -146,6 +149,15 @@ public class RulesCache {
     return pcm;
   }
 
+  public PrologMachineCopy loadMachine(String name, InputStream in)
+      throws CompileException {
+    PrologMachineCopy pmc = consultRules(name, new InputStreamReader(in));
+    if (pmc == null) {
+      throw new CompileException("Cannot consult rules from the stream " + name);
+    }
+    return pmc;
+  }
+
   private void gc() {
     Reference<?> ref;
     while ((ref = dead.poll()) != null) {
@@ -172,16 +184,21 @@ public class RulesCache {
     // Dynamically consult the rules into the machine's internal database.
     //
     String rules = read(project, rulesId);
-    BufferingPrologControl ctl = newEmptyMachine(systemLoader);
-    PushbackReader in = new PushbackReader(
-        new StringReader(rules),
-        Prolog.PUSHBACK_SIZE);
+    PrologMachineCopy pmc = consultRules("rules.pl", new StringReader(rules));
+    if (pmc == null) {
+      throw new CompileException("Cannot consult rules of " + project);
+    }
+    return pmc;
+  }
 
+  private PrologMachineCopy consultRules(String name, Reader rules) {
+    BufferingPrologControl ctl = newEmptyMachine(systemLoader);
+    PushbackReader in = new PushbackReader(rules, Prolog.PUSHBACK_SIZE);
     if (!ctl.execute(
         Prolog.BUILTIN, "consult_stream",
-        SymbolTerm.intern("rules.pl"),
+        SymbolTerm.intern(name),
         new JavaObjectTerm(in))) {
-      throw new CompileException("Cannot consult rules of " + project);
+      return null;
     }
     return save(ctl);
   }

gerrit-server/src/main/java/com/google/gerrit/server/project/ProjectState.java

@@ -42,6 +42,7 @@ import org.eclipse.jgit.lib.Ref;
 import org.eclipse.jgit.lib.Repository;
 
 import java.io.IOException;
+import java.io.InputStream;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
@@ -168,6 +169,20 @@ public class ProjectState {
     return envFactory.create(pmc);
   }
 
+  /**
+   * Like {@link #newPrologEnvironment()} but instead of reading the rules.pl
+   * read the provided input stream.
+   *
+   * @param name a name of the input stream. Could be any name.
+   * @param in InputStream to read prolog rules from
+   * @throws CompileException
+   */
+  public PrologEnvironment newPrologEnvironment(String name, InputStream in)
+      throws CompileException {
+    PrologMachineCopy pmc = rulesCache.loadMachine(name, in);
+    return envFactory.create(pmc);
+  }
+
   public Project getProject() {
     return config.getProject();
   }

gerrit-server/src/main/java/com/google/gerrit/server/project/SubmitRuleEvaluator.java

@@ -29,6 +29,7 @@ import com.googlecode.prolog_cafe.lang.PrologException;
 import com.googlecode.prolog_cafe.lang.Term;
 import com.googlecode.prolog_cafe.lang.VariableTerm;
 
+import java.io.InputStream;
 import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.List;
@@ -53,6 +54,8 @@ public class SubmitRuleEvaluator {
   private final String userRuleWrapperName;
   private final String filterRuleLocatorName;
   private final String filterRuleWrapperName;
+  private final boolean skipFilters;
+  private final InputStream rulesInputStream;
 
   private Term submitRule;
   private String projectName;
@@ -67,12 +70,38 @@ public class SubmitRuleEvaluator {
    * @param filterRuleWrapperName The name of the rule used to evaluate the
    *        filter rule.
    */
-  SubmitRuleEvaluator(ReviewDb db, PatchSet patchSet,
+  public SubmitRuleEvaluator(ReviewDb db, PatchSet patchSet,
       ProjectControl projectControl,
       ChangeControl changeControl, Change change, @Nullable ChangeData cd,
       boolean fastEvalLabels,
       String userRuleLocatorName, String userRuleWrapperName,
       String filterRuleLocatorName, String filterRuleWrapperName) {
+    this(db, patchSet, projectControl, changeControl, change, cd,
+        fastEvalLabels, userRuleLocatorName, userRuleWrapperName,
+        filterRuleLocatorName, filterRuleWrapperName, false, null);
+  }
+
+  /**
+   * @param userRuleLocatorName The name of the rule used to locate the
+   *        user-supplied rule.
+   * @param userRuleWrapperName The name of the wrapper rule used to evaluate
+   *        the user-supplied rule.
+   * @param filterRuleLocatorName The name of the rule used to locate the filter
+   *        rule.
+   * @param filterRuleWrapperName The name of the rule used to evaluate the
+   *        filter rule.
+   * @param skipSubmitFilters if <code>true</code> submit filter will not be
+   *        applied
+   * @param rules when non-null the rules will be read from this input stream
+   *        instead of refs/meta/config:rules.pl file
+   */
+  public SubmitRuleEvaluator(ReviewDb db, PatchSet patchSet,
+      ProjectControl projectControl,
+      ChangeControl changeControl, Change change, @Nullable ChangeData cd,
+      boolean fastEvalLabels,
+      String userRuleLocatorName, String userRuleWrapperName,
+      String filterRuleLocatorName, String filterRuleWrapperName,
+      boolean skipSubmitFilters, InputStream rules) {
     this.db = db;
     this.patchSet = patchSet;
     this.projectControl = projectControl;
@@ -84,6 +113,8 @@ public class SubmitRuleEvaluator {
     this.userRuleWrapperName = userRuleWrapperName;
     this.filterRuleLocatorName = filterRuleLocatorName;
     this.filterRuleWrapperName = filterRuleWrapperName;
+    this.skipFilters = skipSubmitFilters;
+    this.rulesInputStream = rules;
   }
 
   /**
@@ -96,25 +127,10 @@ public class SubmitRuleEvaluator {
    * @return List of {@link Term} objects returned from the evaluated rules.
    * @throws RuleEvalException
    */
-  ListTerm evaluate() throws RuleEvalException {
+  public ListTerm evaluate() throws RuleEvalException {
     List<Term> results = new ArrayList<Term>();
-    ProjectState projectState = projectControl.getProjectState();
-    PrologEnvironment env;
-
+    PrologEnvironment env = getPrologEnvironment();
     try {
-      env = projectState.newPrologEnvironment();
-    } catch (CompileException err) {
-      throw new RuleEvalException("Cannot consult rules.pl for "
-          + getProjectName(), err);
-    }
-
-    try {
-      env.set(StoredValues.REVIEW_DB, db);
-      env.set(StoredValues.CHANGE, change);
-      env.set(StoredValues.CHANGE_DATA, cd);
-      env.set(StoredValues.PATCH_SET, patchSet);
-      env.set(StoredValues.CHANGE_CONTROL, changeControl);
-
       submitRule = env.once("gerrit", userRuleLocatorName, new VariableTerm());
       if (fastEvalLabels) {
         env.once("gerrit", "assume_range_from_label");
@@ -135,12 +151,44 @@ public class SubmitRuleEvaluator {
             err);
       }
 
+      Term resultsTerm = toListTerm(results);
+      if (!skipFilters) {
+        resultsTerm = runSubmitFilters(resultsTerm, env);
+      }
+      return (ListTerm) resultsTerm;
+    } finally {
+      env.close();
+    }
+  }
+
+  private PrologEnvironment getPrologEnvironment() throws RuleEvalException {
+    ProjectState projectState = projectControl.getProjectState();
+    PrologEnvironment env;
+    try {
+      if (rulesInputStream == null) {
+        env = projectState.newPrologEnvironment();
+      } else {
+        env = projectState.newPrologEnvironment("stdin", rulesInputStream);
+      }
+    } catch (CompileException err) {
+      throw new RuleEvalException("Cannot consult rules.pl for "
+          + getProjectName(), err);
+    }
+    env.set(StoredValues.REVIEW_DB, db);
+    env.set(StoredValues.CHANGE, change);
+    env.set(StoredValues.CHANGE_DATA, cd);
+    env.set(StoredValues.PATCH_SET, patchSet);
+    env.set(StoredValues.CHANGE_CONTROL, changeControl);
+    return env;
+  }
+
+  private Term runSubmitFilters(Term results, PrologEnvironment env) throws RuleEvalException {
+    ProjectState projectState = projectControl.getProjectState();
     ProjectState parentState = projectState.getParentState();
     PrologEnvironment childEnv = env;
     Set<Project.NameKey> projectsSeen = new HashSet<Project.NameKey>();
     projectsSeen.add(projectState.getProject().getNameKey());
 
-      Term resultsTerm = toListTerm(results);
     while (parentState != null) {
       if (!projectsSeen.add(parentState.getProject().getNameKey())) {
         // parent has been seen before, stop walk up inheritance tree
@@ -164,8 +212,8 @@ public class SubmitRuleEvaluator {
 
         Term[] template =
             parentEnv.once("gerrit", filterRuleWrapperName, filterRule,
-                  resultsTerm, new VariableTerm());
-          resultsTerm = template[2];
+                results, new VariableTerm());
+        results = template[2];
       } catch (PrologException err) {
         throw new RuleEvalException("Exception calling " + filterRule
             + " on change " + change.getId() + " of "
@@ -180,10 +228,7 @@ public class SubmitRuleEvaluator {
       childEnv = parentEnv;
     }
 
-      return (ListTerm) resultsTerm;
-    } finally {
-      env.close();
-    }
+    return results;
   }
 
   private static Term toListTerm(List<Term> terms) {
@@ -194,7 +239,7 @@ public class SubmitRuleEvaluator {
     return list;
   }
 
-  Term getSubmitRule() {
+  public Term getSubmitRule() {
     return submitRule;
   }