IDEA-115906 Throwable ; IDEA-117401 IAE fixed

*update isFresh method for repository;
*hgVersion used for appropriate branchheads file detection;
*tests updated;
*additional checks inserted in HgRepositoryReader for migrating between hg versions

plugins/hg4idea/src/org/zmlx/hg4idea/repo/HgRepositoryReader.java

@@ -24,6 +24,7 @@ import com.intellij.vcs.log.VcsLogObjectsFactory;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.zmlx.hg4idea.HgNameWithHashInfo;
+import org.zmlx.hg4idea.HgVcs;
 
 import java.io.File;
 import java.util.*;
@@ -42,7 +43,8 @@ public class HgRepositoryReader {
   private static Pattern HASH_NAME = Pattern.compile("\\s*([0-9a-fA-F]+)\\s+(.+)");
 
   @NotNull private final File myHgDir;            // .hg
-  @NotNull private final File myBranchHeadsFile;  // .hg/cache/branchheads (does not exist before first commit)
+  @NotNull private final File myBranchHeadsFile;  // .hg/cache/branchheads
+  @NotNull private final File myCacheDir; // .hg/cache (does not exist before first commit)
   @NotNull private final File myCurrentBranch;    // .hg/branch
   @NotNull private final File myBookmarksFile; //.hg/bookmarks
   @NotNull private final File myCurrentBookmark; //.hg/bookmarks.current
@@ -53,9 +55,11 @@ public class HgRepositoryReader {
   public HgRepositoryReader(@NotNull Project project, @NotNull File hgDir) {
     myHgDir = hgDir;
     RepositoryUtil.assertFileExists(myHgDir, ".hg directory not found in " + myHgDir);
-    File branchesFile = new File(new File(myHgDir, "cache"), "branchheads-served");  //branchheads-served exist after mercurial 2.5,
+    myCacheDir = new File(myHgDir, "cache");
+    File branchesFile = new File(myCacheDir, "branchheads-served");  //branchheads-served exist after mercurial 2.5,
     //before 2.5 only branchheads exist
-    myBranchHeadsFile = branchesFile.exists() ? branchesFile : new File(new File(myHgDir, "cache"), "branchheads");
+    HgVcs vcs = HgVcs.getInstance(project);
+    myBranchHeadsFile = vcs != null && vcs.getVersion().hasBranchHeadsServed() ? branchesFile : new File(myCacheDir, "branchheads");
     myCurrentBranch = new File(myHgDir, "branch");
     myBookmarksFile = new File(myHgDir, "bookmarks");
     myCurrentBookmark = new File(myHgDir, "bookmarks.current");
@@ -71,7 +75,7 @@ public class HgRepositoryReader {
    */
   @Nullable
   public String readCurrentRevision() {
-    if (checkIsFresh()) return null;
+    if (checkIsFresh() || !myBranchHeadsFile.exists()) return null;
     String[] branchesWithHeads = RepositoryUtil.tryLoadFile(myBranchHeadsFile).split("\n");
     String head = branchesWithHeads[0];
     Matcher matcher = HASH_NAME.matcher(head);
@@ -93,7 +97,7 @@ public class HgRepositoryReader {
   public Collection<HgNameWithHashInfo> readBranches() {
     List<HgNameWithHashInfo> branches = new ArrayList<HgNameWithHashInfo>();
     // Set<String> branchNames = new HashSet<String>();
-    if (!checkIsFresh()) {
+    if (!checkIsFresh() && myBranchHeadsFile.exists()) {
       String[] branchesWithHeads = RepositoryUtil.tryLoadFile(myBranchHeadsFile).split("\n");
       // first one - is a head revision: head hash + head number;
       for (int i = 1; i < branchesWithHeads.length; ++i) {
@@ -119,7 +123,7 @@ public class HgRepositoryReader {
   }
 
   public boolean checkIsFresh() {
-    return !myBranchHeadsFile.exists();
+    return !myCacheDir.exists();
   }
 
   public boolean branchExist() {

plugins/hg4idea/src/org/zmlx/hg4idea/util/HgVersion.java

@@ -54,6 +54,7 @@ public final class HgVersion implements Comparable<HgVersion> {
   // see http://mercurial.808500.n3.nabble.com/Bug-3887-New-hg-log-template-quot-rev-join-file-copies-n-quot-prints-literal-quot-sourcename-quot-fos-td4000129.html
   public static final HgVersion BUILT_IN_FUNCTION_SUPPORTED = new HgVersion(2, 6, 0);
   public static final HgVersion PARENT_REVISION_TEMPLATES_SUPPORTED = new HgVersion(2, 4, 0);
+  public static final HgVersion BRANCH_HEADS_SERVED_FILE_EXIST = new HgVersion(2, 5, 0);
 
   //see http://selenic.com/pipermail/mercurial-devel/2013-May/051209.html  fixed since 2.7
   private static final HgVersion LARGEFILES_WITH_FOLLOW_SUPPORTED = new HgVersion(2, 7, 0);
@@ -157,6 +158,10 @@ public final class HgVersion implements Comparable<HgVersion> {
     return !isNull() && compareTo(PARENT_REVISION_TEMPLATES_SUPPORTED) >= 0;
   }
 
+  public boolean hasBranchHeadsServed() {
+    return !isNull() && compareTo(BRANCH_HEADS_SERVED_FILE_EXIST) >= 0;
+  }
+
   /**
    * Note: this class has a natural ordering that is inconsistent with equals.
    * Two HgVersions are equal if their number versions are equal.

plugins/hg4idea/testSrc/hg4idea/test/HgPlatformTest.java

@@ -55,6 +55,7 @@ public abstract class HgPlatformTest extends UsefulTestCase {
   protected VirtualFile myProjectRoot;
   protected VirtualFile myRepository;
   protected VirtualFile myChildRepo;
+  protected HgVcs myVcs;
 
   protected static final String COMMIT_MESSAGE = "text";
 
@@ -79,9 +80,10 @@ public abstract class HgPlatformTest extends UsefulTestCase {
     hg("version");
 
     createRepository(myProjectRoot);
-    HgVcs hgVcs = HgVcs.getInstance(myProject);
-    assertNotNull(hgVcs);
-    hgVcs.getGlobalSettings().setHgExecutable(HgExecutor.getHgExecutable());
+    myVcs = HgVcs.getInstance(myProject);
+    assertNotNull(myVcs);
+    myVcs.getGlobalSettings().setHgExecutable(HgExecutor.getHgExecutable());
+    myVcs.checkVersion();
     myRepository = myProjectRoot;
     setUpHgrc(myRepository);
   }

plugins/hg4idea/testSrc/hg4idea/test/repo/HgRealRepositoryReaderTest.java

@@ -19,6 +19,7 @@ import com.intellij.dvcs.repo.Repository;
 import com.intellij.openapi.vcs.VcsTestUtil;
 import hg4idea.test.HgPlatformTest;
 import org.jetbrains.annotations.NotNull;
+import org.zmlx.hg4idea.HgVcs;
 import org.zmlx.hg4idea.repo.HgRepositoryReader;
 import org.zmlx.hg4idea.util.HgUtil;