SERVER-21186 Fix chunk version handling in ChunkType

On read, the parsing code was preferring the old 'version' field, which is
not being written since version 2.4 and on write it was writing both the
old 'version' field and the somewhat newer 'lastmod'.

Made it to only look for 'lastmod' and to never write 'version'.

1 files changed, 11 insertions, 59 deletions

diff --git a/src/mongo/s/chunk_version.h b/src/mongo/s/chunk_version.h
index fc2f637be10..7aa8c4ee138 100644
--- a/src/mongo/s/chunk_version.h
+++ b/src/mongo/s/chunk_version.h
@@ -111,13 +111,6 @@ public:
         _minor++;
     }
 
-    // Incrementing an epoch creates a new, randomly generated identifier
-    void incEpoch() {
-        _epoch = OID::gen();
-        _major = 0;
-        _minor = 0;
-    }
-
     // Note: this shouldn't be used as a substitute for version except in specific cases -
     // epochs make versions more complex
     unsigned long long toLong() const {
@@ -128,24 +121,14 @@ public:
         return _combined > 0;
     }
 
-    bool isEpochSet() const {
-        return _epoch.isSet();
-    }
-
-    std::string toString() const {
-        std::stringstream ss;
-        // Similar to month/day/year.  For the most part when debugging, we care about major
-        // so it's first
-        ss << _major << "|" << _minor << "||" << _epoch;
-        return ss.str();
-    }
-
     int majorVersion() const {
         return _major;
     }
+
     int minorVersion() const {
         return _minor;
     }
+
     OID epoch() const {
         return _epoch;
     }
@@ -237,17 +220,6 @@ public:
     // { version : <TS> } and { version : [<TS>,<OID>] } format
     //
 
-    static bool canParseBSON(const BSONElement& el, const std::string& prefix = "") {
-        bool canParse;
-        fromBSON(el, prefix, &canParse);
-        return canParse;
-    }
-
-    static ChunkVersion fromBSON(const BSONElement& el, const std::string& prefix = "") {
-        bool canParse;
-        return fromBSON(el, prefix, &canParse);
-    }
-
     static ChunkVersion fromBSON(const BSONElement& el, const std::string& prefix, bool* canParse) {
         *canParse = true;
 
@@ -314,17 +286,6 @@ public:
     // { version : [<TS>, <OID>] } format
     //
 
-    static bool canParseBSON(const BSONArray& arr) {
-        bool canParse;
-        fromBSON(arr, &canParse);
-        return canParse;
-    }
-
-    static ChunkVersion fromBSON(const BSONArray& arr) {
-        bool canParse;
-        return fromBSON(arr, &canParse);
-    }
-
     static ChunkVersion fromBSON(const BSONArray& arr, bool* canParse) {
         *canParse = false;
 
@@ -356,19 +317,16 @@ public:
     // versions that know nothing about epochs.
     //
 
-    BSONObj toBSONWithPrefix(const std::string& prefixIn) const {
-        BSONObjBuilder b;
-
-        std::string prefix = prefixIn;
-        if (prefix == "")
-            prefix = "version";
+    BSONObj toBSONWithPrefix(const std::string& prefix) const {
+        invariant(!prefix.empty());
 
+        BSONObjBuilder b;
         b.appendTimestamp(prefix, _combined);
         b.append(prefix + "Epoch", _epoch);
         return b.obj();
     }
 
-    void addToBSON(BSONObjBuilder& b, const std::string& prefix = "") const {
+    void addToBSON(BSONObjBuilder& b, const std::string& prefix) const {
         b.appendElements(toBSONWithPrefix(prefix));
     }
 
@@ -383,19 +341,13 @@ public:
      */
     void appendForCommands(BSONObjBuilder* builder) const;
 
-    BSONObj toBSON() const {
-        // ChunkVersion wants to be an array.
-        BSONArrayBuilder b;
-        b.appendTimestamp(_combined);
-        b.append(_epoch);
-        return b.arr();
+    std::string toString() const {
+        StringBuilder sb;
+        sb << _major << "|" << _minor << "||" << _epoch;
+        return sb.str();
     }
 
-    void clear() {
-        _minor = 0;
-        _major = 0;
-        _epoch = OID();
-    }
+    BSONObj toBSON() const;
 
 private:
     union {