Expose IndexCollection in plugin guice injector

Secondary index underwent quite some evolution, by adding new fields
or turning search predicates that (uncorrectly) used database to
produce matches to use secondary index. When new index version is
added, the previous index version must still be supported because of
online reindexing feature. On very big site, reindexing may take hours,
clearly such a long offline time is non acceptable, that why online
reindexing feature was invented. To make online reindexing work, schema
version must be fetched to route the current search predicate to use
old (legacy) or new field. For that IndexCollection is accessed and
the current schema version is read.

Unfortunately, IndexCollection implements LifecycleListener and these
classes are not copied in guice plugin injector when the plugin is
loaded. This makes secondary index machinery not usable from within a
plugin listener. For the reasons explained above some search predicates
would try to retrieve the secondary index version but because singleton
IndexCollection instance wasn't made available in plugin's guice
injector, the correct instance is not found and guice injector creates
new virgin IndexCollection instance where change index (and the schema
version) is not set. As the consequence we are getting a NPE when
secondary index is tried to be used from within plugin listener.

To rectify, expose IndexCollection to plugin guice injector.

Bug: Issue 3768
Change-Id: I2f9c40aa43aa7b1b954d8fa318df54e45dffcd95

1 files changed, 3 insertions, 1 deletions

diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/plugins/PluginGuiceEnvironment.java b/gerrit-server/src/main/java/com/google/gerrit/server/plugins/PluginGuiceEnvironment.java
index 3fbbfa9b0d..5f33e387a8 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/plugins/PluginGuiceEnvironment.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/plugins/PluginGuiceEnvironment.java
@@ -553,7 +553,9 @@ public class PluginGuiceEnvironment {
       return false;
     }
     Class<?> type = key.getTypeLiteral().getRawType();
-    if (LifecycleListener.class.isAssignableFrom(type)) {
+    if (LifecycleListener.class.isAssignableFrom(type)
+        // This is needed for secondary index to work from plugin listeners
+        && !is("com.google.gerrit.server.index.IndexCollection", type)) {
       return false;
     }
     if (StartPluginListener.class.isAssignableFrom(type)) {