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diff --git a/src/mongo/bson/oid.h b/src/mongo/bson/oid.h
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+++ b/src/mongo/bson/oid.h
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+// oid.h
+
+/*    Copyright 2009 10gen Inc.
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+
+#pragma once
+
+#include <boost/functional/hash.hpp>
+#include "../util/hex.h"
+
+namespace mongo {
+
+#pragma pack(1)
+    /** Object ID type.
+        BSON objects typically have an _id field for the object id.  This field should be the first
+        member of the object when present.  class OID is a special type that is a 12 byte id which
+        is likely to be unique to the system.  You may also use other types for _id's.
+        When _id field is missing from a BSON object, on an insert the database may insert one
+        automatically in certain circumstances.
+
+        Warning: You must call OID::newState() after a fork().
+
+        Typical contents of the BSON ObjectID is a 12-byte value consisting of a 4-byte timestamp (seconds since epoch),
+        a 3-byte machine id, a 2-byte process id, and a 3-byte counter. Note that the timestamp and counter fields must
+        be stored big endian unlike the rest of BSON. This is because they are compared byte-by-byte and we want to ensure
+        a mostly increasing order.
+    */
+    class OID {
+    public:
+        OID() : a(0), b(0) { }
+
+        /** init from a 24 char hex string */
+        explicit OID(const string &s) { init(s); }
+
+        /** initialize to 'null' */
+        void clear() { a = 0; b = 0; }
+
+        const unsigned char *getData() const { return data; }
+
+        bool operator==(const OID& r) const { return a==r.a && b==r.b; }
+        bool operator!=(const OID& r) const { return a!=r.a || b!=r.b; }
+        int compare( const OID& other ) const { return memcmp( data , other.data , 12 ); }
+        bool operator<( const OID& other ) const { return compare( other ) < 0; }
+        bool operator<=( const OID& other ) const { return compare( other ) <= 0; }
+
+        /** @return the object ID output as 24 hex digits */
+        string str() const { return toHexLower(data, 12); }
+        string toString() const { return str(); }
+
+        static OID gen() { OID o; o.init(); return o; }
+
+        /** sets the contents to a new oid / randomized value */
+        void init();
+
+        /** init from a 24 char hex string */
+        void init( string s );
+
+        /** Set to the min/max OID that could be generated at given timestamp. */
+        void init( Date_t date, bool max=false );
+
+        time_t asTimeT();
+        Date_t asDateT() { return asTimeT() * (long long)1000; }
+
+        bool isSet() const { return a || b; }
+
+	void hash_combine(size_t &seed) const {
+	    boost::hash_combine(seed, a);
+	    boost::hash_combine(seed, b);
+	}
+
+        /** call this after a fork to update the process id */
+        static void justForked();
+
+        static unsigned getMachineId(); // features command uses
+        static void regenMachineId(); // used by unit tests
+
+    private:
+        struct MachineAndPid {
+            unsigned char _machineNumber[3];
+            unsigned short _pid;
+            bool operator!=(const OID::MachineAndPid& rhs) const;
+        };
+        static MachineAndPid ourMachine, ourMachineAndPid;
+        union {
+            struct {
+                // 12 bytes total
+                unsigned char _time[4];
+                MachineAndPid _machineAndPid;
+                unsigned char _inc[3];
+            };
+            struct {
+                long long a;
+                unsigned b;
+            };
+            unsigned char data[12];
+        };
+
+        static unsigned ourPid();
+        static void foldInPid(MachineAndPid& x);
+        static MachineAndPid genMachineAndPid();
+    };
+#pragma pack()
+
+    ostream& operator<<( ostream &s, const OID &o );
+    inline StringBuilder& operator<< (StringBuilder& s, const OID& o) { return (s << o.str()); }
+
+    /** Formatting mode for generating JSON from BSON.
+        See <http://mongodb.onconfluence.com/display/DOCS/Mongo+Extended+JSON>
+        for details.
+    */
+    enum JsonStringFormat {
+        /** strict RFC format */
+        Strict,
+        /** 10gen format, which is close to JS format.  This form is understandable by
+            javascript running inside the Mongo server via eval() */
+        TenGen,
+        /** Javascript JSON compatible */
+        JS
+    };
+
+    inline ostream& operator<<( ostream &s, const OID &o ) {
+        s << o.str();
+        return s;
+    }
+
+}