431 lines
16 KiB
C++
431 lines
16 KiB
C++
// @file dur_recover.cpp crash recovery via the journal
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/**
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* Copyright (C) 2009 10gen Inc.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License, version 3,
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "pch.h"
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#include "dur.h"
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#include "dur_recover.h"
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#include "dur_journal.h"
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#include "dur_journalformat.h"
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#include "durop.h"
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#include "namespace.h"
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#include "../util/mongoutils/str.h"
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#include "../util/bufreader.h"
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#include "pdfile.h"
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#include "database.h"
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#include "db.h"
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#include "../util/unittest.h"
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#include "cmdline.h"
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#include "curop.h"
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#include <sys/stat.h>
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#include <fcntl.h>
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using namespace mongoutils;
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namespace mongo {
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namespace dur {
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struct ParsedJournalEntry /*copyable*/ {
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ParsedJournalEntry() : e(0) { }
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// relative path of database for the operation.
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// might be a pointer into mmaped Journal file
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const char *dbName;
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// thse are pointers into the memory mapped journal file
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const JEntry *e; // local db sentinel is already parsed out here into dbName
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// if not one of the two simple JEntry's above, this is the operation:
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shared_ptr<DurOp> op;
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};
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void removeJournalFiles();
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path getJournalDir();
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/** get journal filenames, in order. throws if unexpected content found */
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static void getFiles(path dir, vector<path>& files) {
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map<unsigned,path> m;
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for ( filesystem::directory_iterator i( dir );
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i != filesystem::directory_iterator();
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++i ) {
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filesystem::path filepath = *i;
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string fileName = filesystem::path(*i).leaf();
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if( str::startsWith(fileName, "j._") ) {
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unsigned u = str::toUnsigned( str::after(fileName, '_') );
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if( m.count(u) ) {
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uasserted(13531, str::stream() << "unexpected files in journal directory " << dir.string() << " : " << fileName);
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}
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if( !m.empty() && !m.count(u-1) ) {
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uasserted(13532,
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str::stream() << "unexpected file in journal directory " << dir.string()
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<< " : " << fileName << " : can't find its preceeding file");
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}
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m.insert( pair<unsigned,path>(u,filepath) );
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}
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}
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for( map<unsigned,path>::iterator i = m.begin(); i != m.end(); ++i )
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files.push_back(i->second);
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}
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/** read through the memory mapped data of a journal file (journal/j._<n> file)
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throws
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*/
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class JournalSectionIterator : boost::noncopyable {
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public:
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JournalSectionIterator(const void *p, unsigned len, bool doDurOps)
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: _br(p, len)
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, _sectHead(static_cast<const JSectHeader*>(_br.skip(sizeof(JSectHeader))))
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, _lastDbName(NULL)
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, _doDurOps(doDurOps)
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{}
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bool atEof() const { return _br.atEof(); }
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unsigned long long seqNumber() const { return _sectHead->seqNumber; }
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/** get the next entry from the log. this function parses and combines JDbContext and JEntry's.
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* @return true if got an entry. false at successful end of section (and no entry returned).
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* throws on premature end of section.
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*/
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bool next(ParsedJournalEntry& e) {
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unsigned lenOrOpCode;
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_br.read(lenOrOpCode);
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if (lenOrOpCode > JEntry::OpCode_Min){
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switch( lenOrOpCode ) {
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case JEntry::OpCode_Footer:
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{
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const char* pos = (const char*) _br.pos();
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pos -= sizeof(lenOrOpCode); // rewind to include OpCode
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const JSectFooter& footer = *(const JSectFooter*)pos;
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int len = pos - (char*)_sectHead;
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if (!footer.checkHash(_sectHead, len)){
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massert(13594, str::stream() << "Journal checksum doesn't match. recorded: "
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<< toHex(footer.hash, sizeof(footer.hash))
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<< " actual: " << md5simpledigest(_sectHead, len)
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, false);
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}
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return false; // false return value denotes end of section
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}
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case JEntry::OpCode_FileCreated:
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case JEntry::OpCode_DropDb:
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{
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e.dbName = 0;
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boost::shared_ptr<DurOp> op = DurOp::read(lenOrOpCode, _br);
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if (_doDurOps) {
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e.op = op;
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}
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return true;
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}
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case JEntry::OpCode_DbContext:
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{
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_lastDbName = (const char*) _br.pos();
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const unsigned limit = std::min((unsigned)Namespace::MaxNsLen, _br.remaining());
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const unsigned len = strnlen(_lastDbName, limit);
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massert(13533, "problem processing journal file during recovery", _lastDbName[len] == '\0');
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_br.skip(len+1); // skip '\0' too
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_br.read(lenOrOpCode);
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}
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// fall through as a basic operation always follows jdbcontext, and we don't have anything to return yet
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default:
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// fall through
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;
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}
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}
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// JEntry - a basic write
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assert( lenOrOpCode && lenOrOpCode < JEntry::OpCode_Min );
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_br.rewind(4);
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e.e = (JEntry *) _br.skip(sizeof(JEntry));
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e.dbName = e.e->isLocalDbContext() ? "local" : _lastDbName;
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assert( e.e->len == lenOrOpCode );
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_br.skip(e.e->len);
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return true;
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}
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private:
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BufReader _br;
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const JSectHeader* _sectHead;
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const char *_lastDbName; // pointer into mmaped journal file
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const bool _doDurOps;
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};
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/** retrieve the file for the specified dbName plus file number.
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open if not yet open.
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*/
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File& RecoveryJob::getFile(const char *dbName, int fileNo) {
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File &file = _files[ make_pair(fileNo,dbName) ];
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if(!file.is_open()) {
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string fn;
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{
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stringstream ss;
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ss << dbName << '.';
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assert( fileNo >= 0 );
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if( fileNo == JEntry::DotNsSuffix )
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ss << "ns";
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else
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ss << fileNo;
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/* todo: do we need to create file here if DNE?
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we need to know what its length should be for that though.
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however does this happen? FileCreatedOp should have been in the journal and
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already applied if the file is new.
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*/
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fn = ss.str();
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}
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path full(dbpath);
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try {
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// relative name -> full path name
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full /= fn;
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file.open(full.string().c_str());
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}
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catch(DBException&) {
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log() << "recover error opening file " << full.string() << endl;
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throw;
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}
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uassert(13534, str::stream() << "recovery error couldn't open " << fn, file.is_open());
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if( cmdLine.durOptions & CmdLine::DurDumpJournal )
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log() << " opened " << fn << ' ' << file.len()/1024.0/1024.0 << endl;
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}
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return file;
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}
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RecoveryJob::~RecoveryJob() {
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if( !_files.empty() )
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close();
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}
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void RecoveryJob::close() {
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scoped_lock lk(_mx);
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_close();
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}
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void RecoveryJob::_close() {
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for(FileMap::iterator it(_files.begin()), end(_files.end()); it!=end; ++it){
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it->second.fsync();
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}
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_files.clear(); // closes files
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}
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void RecoveryJob::applyEntry(const ParsedJournalEntry& entry, bool apply, bool dump) {
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if( entry.e ) {
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if( dump ) {
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stringstream ss;
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ss << " BASICWRITE " << setw(20) << entry.dbName << '.';
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if( entry.e->isNsSuffix() )
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ss << "ns";
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else
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ss << setw(2) << entry.e->getFileNo();
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ss << ' ' << setw(6) << entry.e->len << ' ' << /*hex << setw(8) << (size_t) fqe.srcData << dec <<*/
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" " << hexdump(entry.e->srcData(), entry.e->len);
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log() << ss.str() << endl;
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}
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if( apply ) {
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//TODO(mathias) look into writev() on linux
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File& file = getFile(entry.dbName, entry.e->getFileNo());
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file.write(entry.e->ofs, entry.e->srcData(), entry.e->len);
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}
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}
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else if(entry.op) {
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// a DurOp subclass operation
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if( dump ) {
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log() << " OP " << entry.op->toString() << endl;
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}
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if( apply ) {
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if( entry.op->needFilesClosed() ) {
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_close(); // locked in processSection
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}
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entry.op->replay();
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}
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}
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}
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void RecoveryJob::applyEntries(const vector<ParsedJournalEntry> &entries) {
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bool apply = (cmdLine.durOptions & CmdLine::DurScanOnly) == 0;
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bool dump = cmdLine.durOptions & CmdLine::DurDumpJournal;
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if( dump )
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log() << "BEGIN section" << endl;
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for( vector<ParsedJournalEntry>::const_iterator i = entries.begin(); i != entries.end(); ++i ) {
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applyEntry(*i, apply, dump);
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}
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if( dump )
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log() << "END section" << endl;
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}
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void RecoveryJob::processSection(const void *p, unsigned len, bool doDurOps) {
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scoped_lock lk(_mx);
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vector<ParsedJournalEntry> entries;
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JournalSectionIterator i(p, len, doDurOps);
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if( _lastDataSyncedFromLastRun > i.seqNumber() + ExtraKeepTimeMs ) {
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log() << "recover skipping application of section " << i.seqNumber() << " < lsn:" << _lastDataSyncedFromLastRun << endl;
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}
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// first read all entries to make sure this section is valid
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ParsedJournalEntry e;
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while( i.next(e) ) {
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entries.push_back(e);
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}
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// got all the entries for one group commit. apply them:
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applyEntries(entries);
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}
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/** apply a specific journal file, that is already mmap'd
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@param p start of the memory mapped file
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@return true if this is detected to be the last file (ends abruptly)
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*/
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bool RecoveryJob::processFileBuffer(const void *p, unsigned len) {
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try {
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BufReader br(p,len);
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{ // read file header
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JHeader h;
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br.read(h);
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if( !h.versionOk() ) {
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log() << "journal file version number mismatch. recover with old version of mongod, terminate cleanly, then upgrade." << endl;
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uasserted(13536, str::stream() << "journal version number mismatch " << h._version);
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}
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uassert(13537, "journal header invalid", h.valid());
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}
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// read sections
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while ( !br.atEof() ) {
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JSectHeader h;
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br.peek(h);
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processSection(br.skip(h.len), h.len, /*doDurOps*/true);
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// ctrl c check
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killCurrentOp.checkForInterrupt(false);
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}
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}
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catch( BufReader::eof& ) {
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if( cmdLine.durOptions & CmdLine::DurDumpJournal )
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log() << "ABRUPT END" << endl;
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return true; // abrupt end
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}
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return false; // non-abrupt end
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}
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/** apply a specific journal file */
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bool RecoveryJob::processFile(path journalfile) {
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log() << "recover " << journalfile.string() << endl;
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MemoryMappedFile f;
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void *p = f.mapWithOptions(journalfile.string().c_str(), MongoFile::READONLY | MongoFile::SEQUENTIAL);
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massert(13544, str::stream() << "recover error couldn't open " << journalfile.string(), p);
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return processFileBuffer(p, (unsigned) f.length());
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}
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/** @param files all the j._0 style files we need to apply for recovery */
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void RecoveryJob::go(vector<path>& files) {
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log() << "recover begin" << endl;
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// load the last sequence number synced to the datafiles on disk before the last crash
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_lastDataSyncedFromLastRun = journalReadLSN();
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log() << "recover lsn: " << _lastDataSyncedFromLastRun << endl;
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for( unsigned i = 0; i != files.size(); ++i ) {
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bool abruptEnd = processFile(files[i]);
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if( abruptEnd && i+1 < files.size() ) {
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log() << "recover error: abrupt end to file " << files[i].string() << ", yet it isn't the last journal file" << endl;
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close();
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uasserted(13535, "recover abrupt journal file end");
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}
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}
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close();
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if( cmdLine.durOptions & CmdLine::DurScanOnly ) {
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uasserted(13545, str::stream() << "--durOptions " << (int) CmdLine::DurScanOnly << " (scan only) specified");
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}
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log() << "recover cleaning up" << endl;
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removeJournalFiles();
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log() << "recover done" << endl;
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okToCleanUp = true;
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}
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void _recover() {
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assert( cmdLine.dur );
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filesystem::path p = getJournalDir();
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if( !exists(p) ) {
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log() << "directory " << p.string() << " does not exist, there will be no recovery startup step" << endl;
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okToCleanUp = true;
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return;
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}
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vector<path> journalFiles;
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getFiles(p, journalFiles);
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if( journalFiles.empty() ) {
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log() << "recover : no journal files present, no recovery needed" << endl;
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okToCleanUp = true;
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return;
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}
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RecoveryJob::get().go(journalFiles);
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}
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/** recover from a crash
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throws on error
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*/
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void recover() {
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// we use a lock so that exitCleanly will wait for us
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// to finish (or at least to notice what is up and stop)
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readlock lk;
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_recover(); // throws on interruption
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}
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struct BufReaderY { int a,b; };
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class BufReaderUnitTest : public UnitTest {
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public:
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void run() {
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BufReader r((void*) "abcdabcdabcd", 12);
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char x;
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BufReaderY y;
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r.read(x); //cout << x; // a
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assert( x == 'a' );
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r.read(y);
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r.read(x);
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assert( x == 'b' );
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}
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} brunittest;
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RecoveryJob RecoveryJob::_instance;
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} // namespace dur
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} // namespace mongo
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