From 465ca1774ddb7078566cb2edf0408f5881d6aae3 Mon Sep 17 00:00:00 2001
From: Daniel Alabi <alabidan@gmail.com>
Date: Tue, 17 Mar 2015 13:28:52 -0400
Subject: [PATCH] SERVER-17586 Update ShardVersionMap in ChunkManager when
 shard is deleted during balancing

---
 src/mongo/s/chunk_manager.cpp | 26 +++++++++++++++++---------
 src/mongo/s/chunk_manager.h   |  2 +-
 2 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/src/mongo/s/chunk_manager.cpp b/src/mongo/s/chunk_manager.cpp
index 6e3dfe60309..9e075c4724e 100644
--- a/src/mongo/s/chunk_manager.cpp
+++ b/src/mongo/s/chunk_manager.cpp
@@ -158,7 +158,7 @@ namespace {
             ShardVersionMap shardVersions;
             Timer t;
 
-            bool success = _load(config, chunkMap, shards, shardVersions, oldManager);
+            bool success = _load(config, chunkMap, shards, &shardVersions, oldManager);
 
             if( success ){
                 {
@@ -201,7 +201,7 @@ namespace {
     bool ChunkManager::_load(const string& config,
                              ChunkMap& chunkMap,
                              set<Shard>& shards,
-                             ShardVersionMap& shardVersions,
+                             ShardVersionMap* shardVersions,
                              const ChunkManager* oldManager)
     {
 
@@ -215,7 +215,7 @@ namespace {
             // Get the old max version
             _version = oldManager->getVersion();
             // Load a copy of the old versions
-            shardVersions = oldManager->_shardVersions;
+            *shardVersions = oldManager->_shardVersions;
 
             // Load a copy of the chunk map, replacing the chunk manager with our own
             const ChunkMap& oldChunkMap = oldManager->getChunkMap();
@@ -243,7 +243,7 @@ namespace {
 
         // Attach a diff tracker for the versioned chunk data
         CMConfigDiffTracker differ( this );
-        differ.attach( _ns, chunkMap, _version, shardVersions );
+        differ.attach( _ns, chunkMap, _version, *shardVersions );
 
         // Diff tracker should *always* find at least one chunk if collection exists
         int diffsApplied = differ.calculateConfigDiff(config);
@@ -252,9 +252,17 @@ namespace {
             LOG(2) << "loaded " << diffsApplied << " chunks into new chunk manager for " << _ns
                    << " with version " << _version;
 
-            // Add all the shards we find to the shards set
-            for( ShardVersionMap::iterator it = shardVersions.begin(); it != shardVersions.end(); it++ ){
-                shards.insert( it->first );
+            // Add all existing shards we find to the shards set
+            for (ShardVersionMap::iterator it = shardVersions->begin();
+                 it != shardVersions->end();
+                ) {
+                if (Shard::findIfExists(it->first).ok()) {
+                    shards.insert(it->first);
+                    ++it;
+                }
+                else {
+                    shardVersions->erase(it++);
+                }
             }
 
             return true;
@@ -267,7 +275,7 @@ namespace {
 
             // Set all our data to empty
             chunkMap.clear();
-            shardVersions.clear();
+            shardVersions->clear();
             _version = ChunkVersion( 0, 0, OID() );
 
             return true;
@@ -291,7 +299,7 @@ namespace {
 
             // Set all our data to empty to be extra safe
             chunkMap.clear();
-            shardVersions.clear();
+            shardVersions->clear();
             _version = ChunkVersion( 0, 0, OID() );
 
             return allInconsistent;
diff --git a/src/mongo/s/chunk_manager.h b/src/mongo/s/chunk_manager.h
index c15fb7dbaa1..1e57c45d6d5 100644
--- a/src/mongo/s/chunk_manager.h
+++ b/src/mongo/s/chunk_manager.h
@@ -224,7 +224,7 @@ namespace mongo {
         bool _load(const std::string& config,
                    ChunkMap& chunks,
                    std::set<Shard>& shards,
-                   ShardVersionMap& shardVersions,
+                   ShardVersionMap* shardVersions,
                    const ChunkManager* oldManager);
         static bool _isValid(const ChunkMap& chunks);