SERVER-28030 Remove writes from Chunk

(cherry picked from commit 41729cec076164077f13571e35596934477d7110)

5 files changed, 78 insertions, 111 deletions

diff --git a/src/mongo/db/s/balancer/balancer.cpp b/src/mongo/db/s/balancer/balancer.cpp
index 75973319966..75c9d5243cd 100644
--- a/src/mongo/db/s/balancer/balancer.cpp
+++ b/src/mongo/db/s/balancer/balancer.cpp
@@ -654,7 +654,23 @@ void Balancer::_splitOrMarkJumbo(OperationContext* txn,
                                                   ChunkRange(chunk->getMin(), chunk->getMax()),
                                                   splitPoints));
     } catch (const DBException& ex) {
-        chunk->markAsJumbo(txn);
+        log() << "Marking chunk " << redact(chunk->toString()) << " as jumbo.";
+
+        chunk->markAsJumbo();
+
+        const std::string chunkName = ChunkType::genID(nss.ns(), chunk->getMin());
+
+        auto status = Grid::get(txn)->catalogClient(txn)->updateConfigDocument(
+            txn,
+            ChunkType::ConfigNS,
+            BSON(ChunkType::name(chunkName)),
+            BSON("$set" << BSON(ChunkType::jumbo(true))),
+            false,
+            ShardingCatalogClient::kMajorityWriteConcern);
+        if (!status.isOK()) {
+            log() << "Couldn't set jumbo for chunk: " << redact(chunkName)
+                  << causedBy(redact(status.getStatus()));
+        }
     }
 }
 
diff --git a/src/mongo/dbtests/chunktests.cpp b/src/mongo/dbtests/chunktests.cpp
index 86a95684387..047d765e431 100644
--- a/src/mongo/dbtests/chunktests.cpp
+++ b/src/mongo/dbtests/chunktests.cpp
@@ -58,13 +58,14 @@ public:
             const string shardId = str::stream() << (i - 1);
             _shardIds.insert(shardId);
 
-            std::shared_ptr<Chunk> chunk(new Chunk(this,
-                                                   mySplitPoints[i - 1],
-                                                   mySplitPoints[i],
-                                                   shardId,
-                                                   ChunkVersion(0, 0, OID()),
-                                                   0));
-            _chunkMap[mySplitPoints[i]] = chunk;
+            ChunkType chunk;
+            chunk.setNS(getns());
+            chunk.setMin(mySplitPoints[i - 1]);
+            chunk.setMax(mySplitPoints[i]);
+            chunk.setShard(shardId);
+            chunk.setVersion(ChunkVersion(0, 0, OID()));
+
+            _chunkMap[mySplitPoints[i]] = std::make_shared<Chunk>(chunk);
         }
 
         _chunkRangeMap = _constructRanges(_chunkMap);
@@ -84,8 +85,9 @@ public:
         auto opCtx = serviceContext.makeOperationContext();
 
         ShardKeyPattern shardKeyPattern(shardKey());
-        TestableChunkManager chunkManager("", shardKeyPattern, defaultCollator(), false);
-        chunkManager.setSingleChunkForShards(splitPointsVector());
+        TestableChunkManager chunkManager(
+            "TestDB.TestColl", shardKeyPattern, defaultCollator(), false);
+        chunkManager.setSingleChunkForShards(splitPoints());
 
         set<ShardId> shardIds;
         chunkManager.getShardIdsForQuery(opCtx.get(), query(), queryCollation(), &shardIds);
@@ -106,8 +108,8 @@ protected:
         return {nullptr};
     }
 
-    virtual BSONArray splitPoints() const {
-        return BSONArray();
+    virtual std::vector<BSONObj> splitPoints() const {
+        return {};
     }
 
     virtual BSONObj query() const {
@@ -121,30 +123,21 @@ protected:
     virtual BSONArray expectedShardNames() const {
         return BSON_ARRAY("0");
     }
-
-    virtual vector<BSONObj> splitPointsVector() const {
-        vector<BSONObj> ret;
-        BSONArray a = splitPoints();
-        BSONObjIterator i(a);
-        while (i.more()) {
-            ret.push_back(i.next().Obj().getOwned());
-        }
-        return ret;
-    }
 };
 
 class EmptyQuerySingleShard : public Base {};
 
 class MultiShardBase : public Base {
-    virtual BSONArray splitPoints() const {
-        return BSON_ARRAY(BSON("a"
-                               << "x")
-                          << BSON("a"
-                                  << "y")
-                          << BSON("a"
-                                  << "z"));
+    virtual std::vector<BSONObj> splitPoints() const {
+        return {BSON("a"
+                     << "x"),
+                BSON("a"
+                     << "y"),
+                BSON("a"
+                     << "z")};
     }
 };
+
 class EmptyQueryMultiShard : public MultiShardBase {
     virtual BSONArray expectedShardNames() const {
         return BSON_ARRAY("0"
@@ -172,6 +165,7 @@ class EqualityRangeMultiShard : public MultiShardBase {
         return BSON("a"
                     << "y");
     }
+
     virtual BSONArray expectedShardNames() const {
         return BSON_ARRAY("2");
     }
@@ -181,6 +175,7 @@ class SetRangeMultiShard : public MultiShardBase {
     virtual BSONObj query() const {
         return fromjson("{a:{$in:['u','y']}}");
     }
+
     virtual BSONArray expectedShardNames() const {
         return BSON_ARRAY("0"
                           << "2");
@@ -191,6 +186,7 @@ class GTRangeMultiShard : public MultiShardBase {
     virtual BSONObj query() const {
         return BSON("a" << GT << "x");
     }
+
     virtual BSONArray expectedShardNames() const {
         return BSON_ARRAY("1"
                           << "2"
@@ -202,6 +198,7 @@ class GTERangeMultiShard : public MultiShardBase {
     virtual BSONObj query() const {
         return BSON("a" << GTE << "x");
     }
+
     virtual BSONArray expectedShardNames() const {
         return BSON_ARRAY("1"
                           << "2"
@@ -229,6 +226,7 @@ class LTERangeMultiShard : public MultiShardBase {
     virtual BSONObj query() const {
         return BSON("a" << LTE << "y");
     }
+
     virtual BSONArray expectedShardNames() const {
         return BSON_ARRAY("0"
                           << "1"
@@ -240,6 +238,7 @@ class OrEqualities : public MultiShardBase {
     virtual BSONObj query() const {
         return fromjson("{$or:[{a:'u'},{a:'y'}]}");
     }
+
     virtual BSONArray expectedShardNames() const {
         return BSON_ARRAY("0"
                           << "2");
@@ -250,6 +249,7 @@ class OrEqualityInequality : public MultiShardBase {
     virtual BSONObj query() const {
         return fromjson("{$or:[{a:'u'},{a:{$gte:'y'}}]}");
     }
+
     virtual BSONArray expectedShardNames() const {
         return BSON_ARRAY("0"
                           << "2"
@@ -297,6 +297,7 @@ class EqualityThenUnsatisfiable : public Unsatisfiable<Base> {
     virtual BSONObj shardKey() const {
         return BSON("a" << 1 << "b" << 1);
     }
+
     virtual BSONObj query() const {
         return BSON("a" << 1 << "b" << GT << 4 << LT << 4);
     }
@@ -306,6 +307,7 @@ class InequalityThenUnsatisfiable : public Unsatisfiable<Base> {
     virtual BSONObj shardKey() const {
         return BSON("a" << 1 << "b" << 1);
     }
+
     virtual BSONObj query() const {
         return BSON("a" << GT << 1 << "b" << GT << 4 << LT << 4);
     }
@@ -328,8 +330,8 @@ class CompoundKeyBase : public Base {
         return BSON("a" << 1 << "b" << 1);
     }
 
-    virtual BSONArray splitPoints() const {
-        return BSON_ARRAY(BSON("a" << 5 << "b" << 10) << BSON("a" << 5 << "b" << 20));
+    virtual std::vector<BSONObj> splitPoints() const {
+        return {BSON("a" << 5 << "b" << 10), BSON("a" << 5 << "b" << 20)};
     }
 };
 
@@ -354,10 +356,12 @@ class CollationStringsMultiShard : public MultiShardBase {
         return BSON("a"
                     << "y");
     }
+
     virtual BSONObj queryCollation() const {
         return BSON("locale"
                     << "mock_reverse_string");
     }
+
     virtual BSONArray expectedShardNames() const {
         return BSON_ARRAY("0"
                           << "1"
@@ -371,11 +375,13 @@ class DefaultCollationStringsMultiShard : public MultiShardBase {
         return BSON("a"
                     << "y");
     }
+
     virtual std::unique_ptr<CollatorInterface> defaultCollator() const {
         auto collator = stdx::make_unique<CollatorInterfaceMock>(
             CollatorInterfaceMock::MockType::kReverseString);
         return {std::move(collator)};
     }
+
     virtual BSONArray expectedShardNames() const {
         return BSON_ARRAY("0"
                           << "1"
@@ -389,15 +395,18 @@ class SimpleCollationStringsMultiShard : public MultiShardBase {
         return BSON("a"
                     << "y");
     }
+
     virtual std::unique_ptr<CollatorInterface> defaultCollator() const {
         auto collator = stdx::make_unique<CollatorInterfaceMock>(
             CollatorInterfaceMock::MockType::kReverseString);
         return {std::move(collator)};
     }
+
     virtual BSONObj queryCollation() const {
         return BSON("locale"
                     << "simple");
     }
+
     virtual BSONArray expectedShardNames() const {
         return BSON_ARRAY("2");
     }
@@ -407,10 +416,12 @@ class CollationNumbersMultiShard : public MultiShardBase {
     virtual BSONObj query() const {
         return BSON("a" << 5);
     }
+
     virtual BSONObj queryCollation() const {
         return BSON("locale"
                     << "mock_reverse_string");
     }
+
     virtual BSONArray expectedShardNames() const {
         return BSON_ARRAY("0");
     }
@@ -420,11 +431,13 @@ class DefaultCollationNumbersMultiShard : public MultiShardBase {
     virtual BSONObj query() const {
         return BSON("a" << 5);
     }
+
     virtual std::unique_ptr<CollatorInterface> defaultCollator() const {
         auto collator = stdx::make_unique<CollatorInterfaceMock>(
             CollatorInterfaceMock::MockType::kReverseString);
         return {std::move(collator)};
     }
+
     virtual BSONArray expectedShardNames() const {
         return BSON_ARRAY("0");
     }
@@ -434,15 +447,18 @@ class SimpleCollationNumbersMultiShard : public MultiShardBase {
     virtual BSONObj query() const {
         return BSON("a" << 5);
     }
+
     virtual std::unique_ptr<CollatorInterface> defaultCollator() const {
         auto collator = stdx::make_unique<CollatorInterfaceMock>(
             CollatorInterfaceMock::MockType::kReverseString);
         return {std::move(collator)};
     }
+
     virtual BSONObj queryCollation() const {
         return BSON("locale"
                     << "simple");
     }
+
     virtual BSONArray expectedShardNames() const {
         return BSON_ARRAY("0");
     }
diff --git a/src/mongo/s/chunk.cpp b/src/mongo/s/chunk.cpp
index ff4341c3f7f..3c726477bc1 100644
--- a/src/mongo/s/chunk.cpp
+++ b/src/mongo/s/chunk.cpp
@@ -34,9 +34,6 @@
 
 #include "mongo/platform/random.h"
 #include "mongo/s/balancer_configuration.h"
-#include "mongo/s/catalog/sharding_catalog_client.h"
-#include "mongo/s/catalog/type_chunk.h"
-#include "mongo/s/chunk_manager.h"
 #include "mongo/s/grid.h"
 #include "mongo/util/log.h"
 
@@ -57,10 +54,8 @@ int64_t mkDataWritten() {
 
 }  // namespace
 
-Chunk::Chunk(ChunkManager* manager, const ChunkType& from)
-    : _manager(manager),
-      _min(from.getMin().getOwned()),
-      _max(from.getMax().getOwned()),
+Chunk::Chunk(const ChunkType& from)
+    : _range(from.getMin(), from.getMax()),
       _shardId(from.getShard()),
       _lastmod(from.getVersion()),
       _jumbo(from.getJumbo()),
@@ -68,20 +63,6 @@ Chunk::Chunk(ChunkManager* manager, const ChunkType& from)
     invariantOK(from.validate());
 }
 
-Chunk::Chunk(ChunkManager* manager,
-             const BSONObj& min,
-             const BSONObj& max,
-             const ShardId& shardId,
-             ChunkVersion lastmod,
-             uint64_t initialDataWritten)
-    : _manager(manager),
-      _min(min),
-      _max(max),
-      _shardId(shardId),
-      _lastmod(lastmod),
-      _jumbo(false),
-      _dataWritten(initialDataWritten) {}
-
 bool Chunk::containsKey(const BSONObj& shardKey) const {
     return getMin().woCompare(shardKey) <= 0 && shardKey.woCompare(getMax()) < 0;
 }
@@ -106,30 +87,11 @@ void Chunk::randomizeBytesWritten() {
 std::string Chunk::toString() const {
     return str::stream() << ChunkType::shard() << ": " << _shardId << ", "
                          << ChunkType::DEPRECATED_lastmod() << ": " << _lastmod.toString() << ", "
-                         << ChunkType::min() << ": " << _min << ", " << ChunkType::max() << ": "
-                         << _max;
+                         << _range.toString();
 }
 
-void Chunk::markAsJumbo(OperationContext* txn) const {
-    log() << "Marking chunk " << toString() << " as jumbo.";
-
-    // set this first
-    // even if we can't set it in the db
-    // at least this mongos won't try and keep moving
+void Chunk::markAsJumbo() {
     _jumbo = true;
-
-    const std::string chunkName = ChunkType::genID(_manager->getns(), _min);
-
-    auto status = Grid::get(txn)->catalogClient(txn)->updateConfigDocument(
-        txn,
-        ChunkType::ConfigNS,
-        BSON(ChunkType::name(chunkName)),
-        BSON("$set" << BSON(ChunkType::jumbo(true))),
-        false,
-        ShardingCatalogClient::kMajorityWriteConcern);
-    if (!status.isOK()) {
-        warning() << "couldn't set jumbo for chunk: " << chunkName << causedBy(status.getStatus());
-    }
 }
 
 }  // namespace mongo
diff --git a/src/mongo/s/chunk.h b/src/mongo/s/chunk.h
index 4c107f0d2c2..484a1d9597c 100644
--- a/src/mongo/s/chunk.h
+++ b/src/mongo/s/chunk.h
@@ -28,38 +28,27 @@
 
 #pragma once
 
-#include "mongo/base/disallow_copying.h"
+#include "mongo/s/catalog/type_chunk.h"
 #include "mongo/s/chunk_version.h"
 #include "mongo/s/shard_id.h"
 
 namespace mongo {
 
-class ChunkManager;
-class ChunkType;
-class OperationContext;
+class BSONObj;
 
 /**
  * Represents a cache entry for a single Chunk. Owned by a ChunkManager.
  */
 class Chunk {
-    MONGO_DISALLOW_COPYING(Chunk);
-
 public:
-    Chunk(ChunkManager* manager, const ChunkType& from);
-
-    Chunk(ChunkManager* manager,
-          const BSONObj& min,
-          const BSONObj& max,
-          const ShardId& shardId,
-          ChunkVersion lastmod,
-          uint64_t initialDataWritten);
+    explicit Chunk(const ChunkType& from);
 
     const BSONObj& getMin() const {
-        return _min;
+        return _range.getMin();
     }
 
     const BSONObj& getMax() const {
-        return _max;
+        return _range.getMax();
     }
 
     const ShardId& getShardId() const {
@@ -94,18 +83,12 @@ public:
     void randomizeBytesWritten();
 
     /**
-     * marks this chunk as a jumbo chunk
-     * that means the chunk will be inelligble for migrates
+     * Marks this chunk as jumbo. Only moves from false to true once and is used by the balancer.
      */
-    void markAsJumbo(OperationContext* txn) const;
+    void markAsJumbo();
 
 private:
-    // The chunk manager, which owns this chunk. Not owned by the chunk.
-    const ChunkManager* _manager;
-
-    const BSONObj _min;
-
-    const BSONObj _max;
+    const ChunkRange _range;
 
     const ShardId _shardId;
 
diff --git a/src/mongo/s/chunk_manager.cpp b/src/mongo/s/chunk_manager.cpp
index f3a1d126ae1..8c8a03bccbc 100644
--- a/src/mongo/s/chunk_manager.cpp
+++ b/src/mongo/s/chunk_manager.cpp
@@ -102,7 +102,7 @@ public:
 
     pair<BSONObj, shared_ptr<Chunk>> rangeFor(OperationContext* txn,
                                               const ChunkType& chunk) const final {
-        return std::make_pair(chunk.getMax(), std::make_shared<Chunk>(_manager, chunk));
+        return std::make_pair(chunk.getMax(), std::make_shared<Chunk>(chunk));
     }
 
     ShardId shardFor(OperationContext* txn, const ShardId& shardId) const final {
@@ -267,19 +267,9 @@ bool ChunkManager::_load(OperationContext* txn,
         // Load a copy of the chunk map, replacing the chunk manager with our own
         const ChunkMap& oldChunkMap = oldManager->getChunkMap();
 
-        // Could be v.expensive
-        // TODO: If chunks were immutable and didn't reference the manager, we could do more
-        // interesting things here
         for (const auto& oldChunkMapEntry : oldChunkMap) {
-            shared_ptr<Chunk> oldC = oldChunkMapEntry.second;
-            shared_ptr<Chunk> newC(new Chunk(this,
-                                             oldC->getMin(),
-                                             oldC->getMax(),
-                                             oldC->getShardId(),
-                                             oldC->getLastmod(),
-                                             oldC->getBytesWritten()));
-
-            chunkMap.insert(std::make_pair(oldC->getMax(), newC));
+            const auto& oldC = oldChunkMapEntry.second;
+            chunkMap.emplace(oldC->getMax(), std::make_shared<Chunk>(*oldC));
         }
 
         LOG(2) << "loading chunk manager for collection " << _ns