diff options
Diffstat (limited to 'src/mongo/db/s/migration_chunk_cloner_source_legacy.h')
| -rw-r--r-- | src/mongo/db/s/migration_chunk_cloner_source_legacy.h | 52 |
1 files changed, 0 insertions, 52 deletions
diff --git a/src/mongo/db/s/migration_chunk_cloner_source_legacy.h b/src/mongo/db/s/migration_chunk_cloner_source_legacy.h index 7a59f6029bc..4336a15d0c0 100644 --- a/src/mongo/db/s/migration_chunk_cloner_source_legacy.h +++ b/src/mongo/db/s/migration_chunk_cloner_source_legacy.h @@ -29,10 +29,8 @@ #pragma once -#include <deque> #include <list> #include <memory> -#include <mutex> #include <set> #include "mongo/bson/bsonobj.h" @@ -265,15 +263,6 @@ private: Status _storeCurrentLocs(OperationContext* opCtx); /** - * Returns boost::none if there are no more documents to get. - * Increments _inProgressReads if and only if return value is not none. - */ - boost::optional<Snapshotted<BSONObj>> _getNextDoc(OperationContext* opCtx, - const CollectionPtr& collection); - - void _insertOverflowDoc(Snapshotted<BSONObj> doc); - - /** * Adds the OpTime to the list of OpTimes for oplog entries that we should consider migrating as * part of session migration. */ @@ -381,47 +370,6 @@ private: // List of record ids that needs to be transferred (initial clone) std::set<RecordId> _cloneLocs; - // This iterator is a pointer into the _cloneLocs set. It allows concurrent access to - // the _cloneLocs set by allowing threads servicing _migrateClone requests to do the - // following: - // 1. Acquire mutex "_mutex" above. - // 2. Copy *_cloneRecordIdsIter into its local stack frame. - // 3. Increment _cloneRecordIdsIter - // 4. Unlock "_mutex." - // 5. Do the I/O to fetch the document corresponding to this record Id. - // - // The purpose of this algorithm, is to allow different threads to concurrently start I/O jobs - // in order to more fully saturate the disk. - // - // One issue with this algorithm, is that only 16MB worth of documents can be returned in - // response to a _migrateClone request. But, the thread does not know the size of a document - // until it does the I/O. At which point, if the document does not fit in the response to - // _migrateClone request the document must be made available to a different thread servicing a - // _migrateClone request. To solve this problem, the thread adds the document - // to the below _overflowDocs deque. - std::set<RecordId>::iterator _cloneRecordIdsIter; - - // This deque stores all documents that must be sent to the destination, but could not fit - // in the response to a particular _migrateClone request. - std::deque<Snapshotted<BSONObj>> _overflowDocs; - - // This integer represents how many documents are being "held" by threads servicing - // _migrateClone requests. Any document that is "held" by a thread may be added to the - // _overflowDocs deque if it doesn't fit in the response to a _migrateClone request. - // This integer is necessary because it gives us a condition on when all documents to be sent - // to the destination have been exhausted. - // - // If (_cloneRecordIdsIter == _cloneLocs.end() && _overflowDocs.empty() && _inProgressReads - // == 0) then all documents have been returned to the destination. - decltype(_cloneLocs.size()) _inProgressReads = 0; - - // This condition variable allows us to wait on the following condition: - // Either we're done and the above condition is satisfied, or there is some document to - // return. - stdx::condition_variable _moreDocsCV; - decltype(_cloneLocs.size()) _numRecordsCloned{0}; - decltype(_cloneLocs.size()) _numRecordsPassedOver{0}; - // The estimated average object size during the clone phase. Used for buffer size // pre-allocation (initial clone). uint64_t _averageObjectSizeForCloneLocs{0}; |