Index start/activate command: fix unknown name use

Before this fix, using the IndexStartCommand [1] while passing an
invalid or unknown index name with the --force option led to an NPE in
the log, thus a fatal error in user's console. Also, using an unknown
index name either without --force or through the sibling
IndexActivateCommand [2] used to display an inaccurate console message.

This fix always shows a clearer message to the user, upon passing an
unknown index name to either [1] or [2]. It also now prevents that NPE.

[1] https://gerrit-review.googlesource.com/Documentation/cmd-index-start.html
[2] https://gerrit-review.googlesource.com/Documentation/cmd-index-activate.html

Bug: Issue 8715
Change-Id: I16cb800fbe9af00e47bb22105d1c4d4bf044fdc5

3 files changed, 24 insertions, 6 deletions

diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/index/AbstractVersionManager.java b/gerrit-server/src/main/java/com/google/gerrit/server/index/AbstractVersionManager.java
index a0273ce220..8d0f55016b 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/index/AbstractVersionManager.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/index/AbstractVersionManager.java
@@ -121,6 +121,16 @@ public abstract class AbstractVersionManager implements LifecycleListener {
     return false;
   }
 
+  /**
+   * Tells if an index with this name is currently known or not.
+   *
+   * @param name index name
+   * @return true if index is known and can be used, otherwise false.
+   */
+  public boolean isKnownIndex(String name) {
+    return defs.get(name) != null;
+  }
+
   protected <K, V, I extends Index<K, V>> void initIndex(
       IndexDefinition<K, V, I> def, GerritIndexStatus cfg) {
     TreeMap<Integer, Version<V>> versions = scanVersions(def, cfg);
diff --git a/gerrit-sshd/src/main/java/com/google/gerrit/sshd/commands/IndexActivateCommand.java b/gerrit-sshd/src/main/java/com/google/gerrit/sshd/commands/IndexActivateCommand.java
index 5db515eaab..ee19a48b36 100644
--- a/gerrit-sshd/src/main/java/com/google/gerrit/sshd/commands/IndexActivateCommand.java
+++ b/gerrit-sshd/src/main/java/com/google/gerrit/sshd/commands/IndexActivateCommand.java
@@ -35,10 +35,14 @@ public class IndexActivateCommand extends SshCommand {
   @Override
   protected void run() throws UnloggedFailure {
     try {
-      if (versionManager.activateLatestIndex(name)) {
-        stdout.println("Activated latest index version");
+      if (versionManager.isKnownIndex(name)) {
+        if (versionManager.activateLatestIndex(name)) {
+          stdout.println("Activated latest index version");
+        } else {
+          stdout.println("Not activating index, already using latest version");
+        }
       } else {
-        stdout.println("Not activating index, already using latest version");
+        stderr.println("Cannot activate index, unknown based on this name");
       }
     } catch (ReindexerAlreadyRunningException e) {
       throw die("Failed to activate latest index: " + e.getMessage());
diff --git a/gerrit-sshd/src/main/java/com/google/gerrit/sshd/commands/IndexStartCommand.java b/gerrit-sshd/src/main/java/com/google/gerrit/sshd/commands/IndexStartCommand.java
index 20fe211d4f..736478b81a 100644
--- a/gerrit-sshd/src/main/java/com/google/gerrit/sshd/commands/IndexStartCommand.java
+++ b/gerrit-sshd/src/main/java/com/google/gerrit/sshd/commands/IndexStartCommand.java
@@ -39,10 +39,14 @@ public class IndexStartCommand extends SshCommand {
   @Override
   protected void run() throws UnloggedFailure {
     try {
-      if (versionManager.startReindexer(name, force)) {
-        stdout.println("Reindexer started");
+      if (versionManager.isKnownIndex(name)) {
+        if (versionManager.startReindexer(name, force)) {
+          stdout.println("Reindexer started");
+        } else {
+          stdout.println("Nothing to reindex, index is already the latest version");
+        }
       } else {
-        stdout.println("Nothing to reindex, index is already the latest version");
+        stderr.println("Cannot reindex, index is unknown based on this name");
       }
     } catch (ReindexerAlreadyRunningException e) {
       throw die("Failed to start reindexer: " + e.getMessage());