Imported Upstream version 1.8.0

1 files changed, 199 insertions, 0 deletions

diff --git a/db/compact.cpp b/db/compact.cpp
new file mode 100644
index 0000000..6bafd91
--- /dev/null
+++ b/db/compact.cpp
@@ -0,0 +1,199 @@
+/* @file compact.cpp
+   compaction of deleted space in pdfiles (datafiles)
+*/
+
+/* NOTE 6Oct2010 : this file PRELIMINARY, EXPERIMENTAL, NOT DONE, NOT USED YET (not in SConstruct) */
+
+/**
+*    Copyright (C) 2010 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,b
+*    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/>.
+*/
+
+#include "pch.h"
+#include "pdfile.h"
+#include "concurrency.h"
+#include "commands.h"
+#include "curop-inl.h"
+#include "../util/concurrency/task.h"
+
+namespace mongo {
+
+    class CompactJob : public task::Task {
+    public:
+        CompactJob(string ns) : _ns(ns) { }
+    private:
+        virtual string name() const { return "compact"; }
+        virtual void doWork();
+        NamespaceDetails * beginBlock();
+        void doBatch();
+        void prep();
+        const string _ns;
+        unsigned long long _nrecords;
+        unsigned long long _ncompacted;
+        DiskLoc _firstExtent;
+    };
+
+    // lock & set context first.  this checks that collection still exists, and that it hasn't
+    // morphed into a capped collection between locks (which is possible)
+    NamespaceDetails * CompactJob::beginBlock() {
+        NamespaceDetails *nsd = nsdetails(_ns.c_str());
+        if( nsd == 0 ) throw "ns no longer present";
+        if( nsd->firstExtent.isNull() )
+            throw "no first extent";
+        if( nsd->capped )
+            throw "capped collection";
+        return nsd;
+    }
+
+    void CompactJob::doBatch() {
+        unsigned n = 0;
+        {
+            /* pre-touch records in a read lock so that paging happens in read not write lock.
+               note we are only touching the records though; if indexes aren't in RAM, they will
+               page later.  So the concept is only partial.
+               */
+            readlock lk;
+            Timer t;
+            Client::Context ctx(_ns);
+            NamespaceDetails *nsd = beginBlock();
+            if( nsd->firstExtent != _firstExtent )  {
+                // TEMP DEV - stop after 1st extent
+                throw "change of first extent";
+            }
+            DiskLoc loc = nsd->firstExtent.ext()->firstRecord;
+            while( !loc.isNull() ) {
+                Record *r = loc.rec();
+                loc = r->getNext(loc);
+                if( ++n >= 100 || (n % 8 == 0 && t.millis() > 50) )
+                    break;
+            }
+        }
+        {
+            writelock lk;
+            Client::Context ctx(_ns);
+            NamespaceDetails *nsd = beginBlock();
+            for( unsigned i = 0; i < n; i++ ) {
+                if( nsd->firstExtent != _firstExtent )  {
+                    // TEMP DEV - stop after 1st extent
+                    throw "change of first extent (or it is now null)";
+                }
+                DiskLoc loc = nsd->firstExtent.ext()->firstRecord;
+                Record *rec = loc.rec();
+                BSONObj o = loc.obj().getOwned(); // todo: inefficient, double mem copy...
+                try {
+                    theDataFileMgr.deleteRecord(_ns.c_str(), rec, loc, false);
+                }
+                catch(DBException&) { throw "error deleting record"; }
+                try {
+                    theDataFileMgr.insertNoReturnVal(_ns.c_str(), o);
+                }
+                catch(DBException&) {
+                    /* todo: save the record somehow??? try again with 'avoid' logic? */
+                    log() << "compact: error re-inserting record ns:" << _ns << " n:" << _nrecords << " _id:" << o["_id"].toString() << endl;
+                    throw "error re-inserting record";
+                }
+                ++_ncompacted;
+                if( killCurrentOp.globalInterruptCheck() )
+                    throw "interrupted";
+            }
+        }
+    }
+
+    void CompactJob::prep() {
+        readlock lk;
+        Client::Context ctx(_ns);
+        NamespaceDetails *nsd = beginBlock();
+        DiskLoc L = nsd->firstExtent;
+        assert( !L.isNull() );
+        _firstExtent = L;
+        _nrecords = nsd->stats.nrecords;
+        _ncompacted = 0;
+    }
+
+    static mutex m("compact");
+    static volatile bool running;
+
+    void CompactJob::doWork() {
+        Client::initThread("compact");
+        cc().curop()->reset();
+        cc().curop()->setNS(_ns.c_str());
+        cc().curop()->markCommand();
+        sleepsecs(60);
+        try {
+            prep();
+            while( _ncompacted < _nrecords )
+                doBatch();
+        }
+        catch(const char *p) {
+            log() << "info: exception compact " << p << endl;
+        }
+        catch(...) {
+            log() << "info: exception compact" << endl;
+        }
+        mongo::running = false;
+        cc().shutdown();
+    }
+
+    /* --- CompactCmd --- */
+
+    class CompactCmd : public Command {
+    public:
+        virtual bool run(const string& db, BSONObj& cmdObj, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+            string coll = cmdObj.firstElement().valuestr();
+            if( coll.empty() || db.empty() ) {
+                errmsg = "no collection name specified";
+                return false;
+            }
+            string ns = db + '.' + coll;
+            assert( isANormalNSName(ns.c_str()) );
+            {
+                readlock lk;
+                Client::Context ctx(ns);
+                if( nsdetails(ns.c_str()) == 0 ) {
+                    errmsg = "namespace " + ns + " does not exist";
+                    return false;
+                }
+            }
+            {
+                scoped_lock lk(m);
+                if( running ) {
+                    errmsg = "a compaction is already running";
+                    return false;
+                }
+                running = true;
+                task::fork( new CompactJob(ns) );
+                return true;
+            }
+            errmsg = "not done";
+            return false;
+        }
+
+        virtual LockType locktype() const { return NONE; }
+        virtual bool adminOnly() const { return false; }
+        virtual bool slaveOk() const { return true; }
+        virtual bool logTheOp() { return false; }
+        virtual void help( stringstream& help ) const {
+            help << "compact / defragment a collection in the background, slowly, attempting to minimize disruptions to other operations\n"
+                 "{ compact : <collection> }";
+        }
+        virtual bool requiresAuth() { return true; }
+
+        /** @param webUI expose the command in the web ui as localhost:28017/<name>
+            @param oldName an optional old, deprecated name for the command
+        */
+        CompactCmd() : Command("compact") { }
+    };
+    static CompactCmd compactCmd;
+
+}