Imported Upstream version 1.3.1

1 files changed, 128 insertions, 0 deletions

diff --git a/s/shardkey.h b/s/shardkey.h
new file mode 100644
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+++ b/s/shardkey.h
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+// shardkey.h
+
+/**
+*    Copyright (C) 2008 10gen Inc.
+*
+*    This program is free software: you can redistribute it and/or  modify
+*    it under the terms of the GNU Affero General Public License, version 3,
+*    as published by the Free Software Foundation.
+*
+*    This program is distributed in the hope that it will be useful,
+*    but WITHOUT ANY WARRANTY; without even the implied warranty of
+*    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+*    GNU Affero General Public License for more details.
+*
+*    You should have received a copy of the GNU Affero General Public License
+*    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#pragma once
+
+#include "../client/dbclient.h"
+
+namespace mongo {
+    
+    class Chunk;
+
+    /* A ShardKeyPattern is a pattern indicating what data to extract from the object to make the shard key from.
+       Analogous to an index key pattern.
+    */
+    class ShardKeyPattern {
+    public:
+        ShardKeyPattern( BSONObj p = BSONObj() );
+        
+        /**
+           global min is the lowest possible value for this key
+		   e.g. { num : MinKey }
+         */
+        BSONObj globalMin() const { return gMin; }
+
+        /**
+           global max is the highest possible value for this key
+         */
+        BSONObj globalMax() const { return gMax; }
+
+        bool isGlobalMin( const BSONObj& k ){
+            return k.woCompare( globalMin() ) == 0;
+        }
+
+        bool isGlobalMax( const BSONObj& k ){
+            return k.woCompare( globalMax() ) == 0;
+        }
+        
+        bool isGlobal( const BSONObj& k ){
+            return isGlobalMin( k ) || isGlobalMax( k );
+        }
+
+        /** compare shard keys from the objects specified
+           l < r negative
+           l == r 0
+           l > r positive
+         */
+        int compare( const BSONObj& l , const BSONObj& r );
+        
+        /**
+           @return whether or not obj has all fields in this shard key pattern
+		   e.g. 
+		     ShardKey({num:1}).hasShardKey({ name:"joe", num:3 }) is true
+         */
+        bool hasShardKey( const BSONObj& obj );
+        
+        /**
+           returns a query that filters results only for the range desired, i.e. returns 
+             { "field" : { $gte: keyval(min), $lt: keyval(max) } }
+        */
+        void getFilter( BSONObjBuilder& b , const BSONObj& min, const BSONObj& max );
+        
+        /** @return true if shard s is relevant for query q.
+
+            Example:
+              q:     { x : 3 }
+              *this: { x : 1 }
+              s:     x:2..x:7
+               -> true
+         */
+        bool relevantForQuery( const BSONObj& q , Chunk * s );
+        
+        /**
+           Returns if the given sort pattern can be ordered by the shard key pattern.
+           Example
+            sort:   { ts: -1 }
+            *this:  { ts:1 }
+              -> -1
+
+              @return
+              0 if sort either doesn't have all the fields or has extra fields
+              < 0 if sort is descending
+              > 1 if sort is ascending
+         */
+        int canOrder( const BSONObj& sort );
+
+        BSONObj key() { return pattern; }
+
+        string toString() const;
+
+        BSONObj extractKey(const BSONObj& from) const;
+        
+        bool partOfShardKey(const string& key ) const {
+            return patternfields.count( key ) > 0;
+        }
+
+        operator string() const {
+            return pattern.toString();
+        }
+    private:
+        BSONObj pattern;
+        BSONObj gMin;
+        BSONObj gMax;
+
+        /* question: better to have patternfields precomputed or not?  depends on if we use copy contructor often. */
+        set<string> patternfields;
+        bool relevant(const BSONObj& query, const BSONObj& L, const BSONObj& R);
+    };
+
+    inline BSONObj ShardKeyPattern::extractKey(const BSONObj& from) const { 
+        return from.extractFields(pattern);
+    }
+
+}