Merge "Shard the waiting directory to scale better"
diff --git a/src/main/java/com/googlesource/gerrit/plugins/replication/ReplicationTasksStorage.java b/src/main/java/com/googlesource/gerrit/plugins/replication/ReplicationTasksStorage.java
index 3f3c8e8..d60bd11 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/replication/ReplicationTasksStorage.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/replication/ReplicationTasksStorage.java
@@ -47,16 +47,19 @@
* task:
*
* <p><code>
- * .../building/<tmp_name> new replication tasks under construction
- * .../running/<uri_sha1>/ lock for URI
- * .../running/<uri_sha1>/<task_sha1> running replication tasks
- * .../waiting/<task_sha1> outstanding replication tasks
+ * .../building/<tmp_name> new replication tasks under construction
+ * .../running/<uri_sha1>/ lock for URI
+ * .../running/<uri_sha1>/<task_sha1> running replication tasks
+ * .../waiting/<task_sha1_NN_shard>/<task_sha1> outstanding replication tasks
* </code>
*
* <p>The URI lock is acquired by creating the directory and released by removing it.
*
* <p>Tasks are moved atomically via a rename between those directories to indicate the current
* state of each task.
+ *
+ * <p>Note: The .../waiting/<task_sha1_NN_shard> directories are never removed. This helps prevent
+ * failures when moving tasks to and from the shard directories from different hosts concurrently.
*/
@Singleton
public class ReplicationTasksStorage {
@@ -308,7 +311,7 @@
String key = update.project + "\n" + update.ref + "\n" + update.uri + "\n" + update.remote;
taskKey = sha1(key).name();
running = lock.runningDir.resolve(taskKey);
- waiting = createDir(waitingUpdates).resolve(taskKey);
+ waiting = createDir(waitingUpdates.resolve(taskKey.substring(0, 2))).resolve(taskKey);
}
public String create() {
