Add change kind to PatchSetCreatedEvent

Pass along an extra flag in the patchset-created hook to convey
the change kind.  This is also exposed in the PatchSetCreatedEvent
as the "kind" field.  Both follow the ChangeKind enum type, where a
change can be "REWORK", "NO_CODE_CHANGE", or "TRIVIAL_REBASE".

Bug: Issue 2634
Change-Id: Ie04d0282e42ab177810fafd857e90d21999cab28

Documentation/config-hooks.txt

@@ -41,9 +41,18 @@ This is called whenever a patchset is created (this includes new
 changes and drafts).
 
 ====
-  patchset-created --change <change id> --is-draft <boolean> --change-url <change url> --change-owner <change owner> --project <project name> --branch <branch> --topic <topic> --uploader <uploader> --commit <sha1> --patchset <patchset id>
+  patchset-created --change <change id> --is-draft <boolean> --kind <change kind> --change-url <change url> --change-owner <change owner> --project <project name> --branch <branch> --topic <topic> --uploader <uploader> --commit <sha1> --patchset <patchset id>
 ====
 
+kind:: change kind represents the kind of change uploaded, also represented in link:json.html#patchSet[patchSet]
+
+  REWORK;; Nontrivial content changes.
+
+  TRIVIAL_REBASE;; Conflict-free merge between the new parent and the prior patch set.
+
+  NO_CODE_CHANGE;; No code changed; same tree and same parents.
+
+
 === draft-published
 
 This is called whenever a draft change is published.

Documentation/json.txt

@@ -115,6 +115,14 @@ was created.
 
 isDraft:: Whether or not the patch set is a draft patch set.
 
+changeKind:: Kind of change uploaded.
+
+  REWORK;; Nontrivial content changes.
+
+  TRIVIAL_REBASE;; Conflict-free merge between the new parent and the prior patch set.
+
+  NO_CODE_CHANGE;; No code changed; same tree and same parents.
+
 approvals:: The <<approval,approval attribute>> granted.
 
 comments:: All comments for this patchset in <<patchsetcomment,patchsetComment attributes>>.

gerrit-server/src/main/java/com/google/gerrit/common/ChangeHookRunner.java

@@ -30,6 +30,7 @@ import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.IdentifiedUser;
 import com.google.gerrit.server.account.AccountCache;
 import com.google.gerrit.server.account.AccountState;
+import com.google.gerrit.server.change.ChangeKindCache;
 import com.google.gerrit.server.config.AnonymousCowardName;
 import com.google.gerrit.server.config.GerritServerConfig;
 import com.google.gerrit.server.config.SitePaths;
@@ -209,6 +210,8 @@ public class ChangeHookRunner implements ChangeHooks, LifecycleListener {
 
     private final AccountCache accountCache;
 
+    private final ChangeKindCache changeKindCache;
+
     private final EventFactory eventFactory;
 
     private final SitePaths sitePaths;
@@ -236,6 +239,7 @@ public class ChangeHookRunner implements ChangeHooks, LifecycleListener {
       final SitePaths sitePath,
       final ProjectCache projectCache,
       final AccountCache accountCache,
+      final ChangeKindCache changeKindCache,
       final EventFactory eventFactory,
       final SitePaths sitePaths,
       final DynamicSet<ChangeListener> unrestrictedListeners) {
@@ -244,6 +248,7 @@ public class ChangeHookRunner implements ChangeHooks, LifecycleListener {
         this.hookQueue = queue.createQueue(1, "hook");
         this.projectCache = projectCache;
         this.accountCache = accountCache;
+        this.changeKindCache = changeKindCache;
         this.eventFactory = eventFactory;
         this.sitePaths = sitePath;
         this.unrestrictedListeners = unrestrictedListeners;
@@ -354,11 +359,13 @@ public class ChangeHookRunner implements ChangeHooks, LifecycleListener {
         event.change = eventFactory.asChangeAttribute(change);
         event.patchSet = eventFactory.asPatchSetAttribute(patchSet);
         event.uploader = eventFactory.asAccountAttribute(uploader.getAccount());
+        event.kind = changeKindCache.getChangeKind(db, change, patchSet);
         fireEvent(change, event, db);
 
         final List<String> args = new ArrayList<>();
         addArg(args, "--change", event.change.id);
-        addArg(args, "--is-draft", patchSet.isDraft() ? "true" : "false");
+        addArg(args, "--is-draft", String.valueOf(patchSet.isDraft()));
+        addArg(args, "--kind", String.valueOf(event.kind));
         addArg(args, "--change-url", event.change.url);
         addArg(args, "--change-owner", getDisplayName(owner.getAccount()));
         addArg(args, "--project", event.change.project);

gerrit-server/src/main/java/com/google/gerrit/server/change/ChangeKindCache.java

@@ -14,6 +14,9 @@
 
 package com.google.gerrit.server.change;
 
+import com.google.gerrit.reviewdb.client.Change;
+import com.google.gerrit.reviewdb.client.PatchSet;
+import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.project.ProjectState;
 
 import org.eclipse.jgit.lib.ObjectId;
@@ -28,4 +31,6 @@ import org.eclipse.jgit.lib.Repository;
 public interface ChangeKindCache {
   public ChangeKind getChangeKind(ProjectState project, Repository repo,
       ObjectId prior, ObjectId next);
+
+  public ChangeKind getChangeKind(ReviewDb db, Change change, PatchSet patch);
 }

gerrit-server/src/main/java/com/google/gerrit/server/change/ChangeKindCacheImpl.java

@@ -23,10 +23,17 @@ import com.google.common.base.Objects;
 import com.google.common.cache.CacheLoader;
 import com.google.common.cache.LoadingCache;
 import com.google.common.cache.Weigher;
+import com.google.gerrit.reviewdb.client.Change;
+import com.google.gerrit.reviewdb.client.PatchSet;
+import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.cache.CacheModule;
 import com.google.gerrit.server.config.GerritServerConfig;
+import com.google.gerrit.server.git.GitRepositoryManager;
 import com.google.gerrit.server.git.MergeUtil;
+import com.google.gerrit.server.project.ProjectCache;
 import com.google.gerrit.server.project.ProjectState;
+import com.google.gerrit.server.query.change.ChangeData;
+import com.google.gwtorm.server.OrmException;
 import com.google.inject.Inject;
 import com.google.inject.Module;
 import com.google.inject.Singleton;
@@ -45,6 +52,7 @@ import java.io.IOException;
 import java.io.ObjectInputStream;
 import java.io.ObjectOutputStream;
 import java.io.Serializable;
+import java.util.Collection;
 import java.util.concurrent.ExecutionException;
 
 public class ChangeKindCacheImpl implements ChangeKindCache {
@@ -69,11 +77,21 @@ public class ChangeKindCacheImpl implements ChangeKindCache {
   @VisibleForTesting
   public static class NoCache implements ChangeKindCache {
     private final boolean useRecursiveMerge;
+    private final ChangeData.Factory changeDataFactory;
+    private final ProjectCache projectCache;
+    private final GitRepositoryManager repoManager;
+
 
     @Inject
     NoCache(
-        @GerritServerConfig Config serverConfig) {
+        @GerritServerConfig Config serverConfig,
+        ChangeData.Factory changeDataFactory,
+        ProjectCache projectCache,
+        GitRepositoryManager repoManager) {
       this.useRecursiveMerge = MergeUtil.useRecursiveMerge(serverConfig);
+      this.changeDataFactory = changeDataFactory;
+      this.projectCache = projectCache;
+      this.repoManager = repoManager;
     }
 
     @Override
@@ -88,6 +106,12 @@ public class ChangeKindCacheImpl implements ChangeKindCache {
         return ChangeKind.REWORK;
       }
     }
+
+    @Override
+    public ChangeKind getChangeKind(ReviewDb db, Change change, PatchSet patch) {
+      return getChangeKindInternal(this, db, change, patch, changeDataFactory,
+          projectCache, repoManager);
+    }
   }
 
   public static class Key implements Serializable {
@@ -161,6 +185,10 @@ public class ChangeKindCacheImpl implements ChangeKindCache {
   private static class Loader extends CacheLoader<Key, ChangeKind> {
     @Override
     public ChangeKind load(Key key) throws IOException {
+      if (Objects.equal(key.prior, key.next)) {
+        return ChangeKind.NO_CODE_CHANGE;
+      }
+
       RevWalk walk = new RevWalk(key.repo);
       try {
         RevCommit prior = walk.parseCommit(key.prior);
@@ -224,13 +252,22 @@ public class ChangeKindCacheImpl implements ChangeKindCache {
 
   private final LoadingCache<Key, ChangeKind> cache;
   private final boolean useRecursiveMerge;
+  private final ChangeData.Factory changeDataFactory;
+  private final ProjectCache projectCache;
+  private final GitRepositoryManager repoManager;
 
   @Inject
   ChangeKindCacheImpl(
       @GerritServerConfig Config serverConfig,
-      @Named(ID_CACHE) LoadingCache<Key, ChangeKind> cache) {
+      @Named(ID_CACHE) LoadingCache<Key, ChangeKind> cache,
+      ChangeData.Factory changeDataFactory,
+      ProjectCache projectCache,
+      GitRepositoryManager repoManager) {
     this.cache = cache;
     this.useRecursiveMerge = MergeUtil.useRecursiveMerge(serverConfig);
+    this.changeDataFactory = changeDataFactory;
+    this.projectCache = projectCache;
+    this.repoManager = repoManager;
   }
 
   @Override
@@ -244,4 +281,64 @@ public class ChangeKindCacheImpl implements ChangeKindCache {
       return ChangeKind.REWORK;
     }
   }
+
+  @Override
+  public ChangeKind getChangeKind(ReviewDb db, Change change, PatchSet patch) {
+    return getChangeKindInternal(this, db, change, patch, changeDataFactory,
+        projectCache, repoManager);
+  }
+
+  private static ChangeKind getChangeKindInternal(
+      ChangeKindCache cache,
+      ReviewDb db,
+      Change change,
+      PatchSet patch,
+      ChangeData.Factory changeDataFactory,
+      ProjectCache projectCache,
+      GitRepositoryManager repoManager) {
+    Repository repo = null;
+    // TODO - dborowitz: add NEW_CHANGE type for default.
+    ChangeKind kind = ChangeKind.REWORK;
+    // Trivial case: if we're on the first patch, we don't need to open
+    // the repository.
+    if (patch.getId().get() > 1) {
+      try {
+        ProjectState projectState = projectCache.checkedGet(change.getProject());
+
+        repo = repoManager.openRepository(change.getProject());
+
+        ChangeData cd = changeDataFactory.create(db, change);
+        Collection<PatchSet> patchSetCollection = cd.patches();
+        PatchSet priorPs = patch;
+        for (PatchSet ps : patchSetCollection) {
+          if (ps.getId().get() < patch.getId().get() &&
+              (ps.getId().get() > priorPs.getId().get() ||
+                  priorPs == patch)) {
+            // We only want the previous patch set, so walk until the last one
+            priorPs = ps;
+          }
+        }
+
+        // If we still think the previous patch is the current patch,
+        // we only have one patch set.  Return the default.
+        // This can happen if a user creates a draft, uploads a second patch,
+        // and deletes the draft.
+        if (priorPs != patch) {
+          kind =
+              cache.getChangeKind(projectState, repo,
+                  ObjectId.fromString(priorPs.getRevision().get()),
+                  ObjectId.fromString(patch.getRevision().get()));
+        }
+      } catch (IOException | OrmException e) {
+        // Do nothing; assume we have a complex change
+        log.warn("Unable to get change kind for patchSet " + patch.getPatchSetId() +
+            "of change " + change.getChangeId(), e);
+      } finally {
+        if (repo != null) {
+          repo.close();
+        }
+      }
+    }
+    return kind;
+  }
 }

gerrit-server/src/main/java/com/google/gerrit/server/events/PatchSetCreatedEvent.java

@@ -14,6 +14,7 @@
 
 package com.google.gerrit.server.events;
 
+import com.google.gerrit.server.change.ChangeKind;
 import com.google.gerrit.server.data.AccountAttribute;
 import com.google.gerrit.server.data.ChangeAttribute;
 import com.google.gerrit.server.data.PatchSetAttribute;
@@ -23,4 +24,5 @@ public class PatchSetCreatedEvent extends ChangeEvent {
     public ChangeAttribute change;
     public PatchSetAttribute patchSet;
     public AccountAttribute uploader;
+    public ChangeKind kind;
 }