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/**
* Copyright (C) 2009-2014 MongoDB 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/>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the GNU Affero General Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
/*
PREPLOGBUFFER
we will build an output buffer ourself and then use O_DIRECT
we could be in read lock for this
for very large objects write directly to redo log in situ?
@see https://docs.google.com/drawings/edit?id=1TklsmZzm7ohIZkwgeK6rMvsdaR13KjtJYMsfLr175Zc
*/
#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kStorage
#include "mongo/platform/basic.h"
#include <boost/shared_ptr.hpp>
#include <boost/thread.hpp>
#include "mongo/db/storage/mmap_v1/aligned_builder.h"
#include "mongo/db/storage/mmap_v1/durable_mapped_file.h"
#include "mongo/db/storage/mmap_v1/dur_commitjob.h"
#include "mongo/db/storage/mmap_v1/dur_journal.h"
#include "mongo/db/storage/mmap_v1/dur_journalimpl.h"
#include "mongo/db/storage/mmap_v1/dur_stats.h"
#include "mongo/db/storage_options.h"
#include "mongo/util/log.h"
#include "mongo/util/mongoutils/str.h"
#include "mongo/util/stacktrace.h"
#include "mongo/util/timer.h"
namespace mongo {
using std::endl;
using std::min;
using std::stringstream;
namespace dur {
extern Journal j;
extern CommitJob commitJob;
const RelativePath local = RelativePath::fromRelativePath("local");
static DurableMappedFile* findMMF_inlock(void *ptr, size_t &ofs) {
DurableMappedFile *f = privateViews.find_inlock(ptr, ofs);
if( f == 0 ) {
error() << "findMMF_inlock failed " << privateViews.numberOfViews_inlock() << endl;
printStackTrace(); // we want a stack trace and the assert below didn't print a trace once in the real world - not sure why
stringstream ss;
ss << "view pointer cannot be resolved " << std::hex << (size_t) ptr;
journalingFailure(ss.str().c_str()); // asserts, which then abends
}
return f;
}
/** put the basic write operation into the buffer (bb) to be journaled */
static void prepBasicWrite_inlock(AlignedBuilder&bb, const WriteIntent *i, RelativePath& lastDbPath) {
size_t ofs = 1;
DurableMappedFile *mmf = findMMF_inlock(i->start(), /*out*/ofs);
if( MONGO_unlikely(!mmf->willNeedRemap()) ) {
// tag this mmf as needed a remap of its private view later.
// usually it will already be dirty/already set, so we do the if above first
// to avoid possibility of cpu cache line contention
mmf->setWillNeedRemap();
}
// since we have already looked up the mmf, we go ahead and remember the write view location
// so we don't have to find the DurableMappedFile again later in WRITETODATAFILES()
//
// this was for WRITETODATAFILES_Impl2 so commented out now
//
/*
dassert( i->w_ptr == 0 );
i->w_ptr = ((char*)mmf->view_write()) + ofs;
*/
JEntry e;
e.len = min(i->length(), (unsigned)(mmf->length() - ofs)); //don't write past end of file
verify( ofs <= 0x80000000 );
e.ofs = (unsigned) ofs;
e.setFileNo( mmf->fileSuffixNo() );
if( mmf->relativePath() == local ) {
e.setLocalDbContextBit();
}
else if( mmf->relativePath() != lastDbPath ) {
lastDbPath = mmf->relativePath();
JDbContext c;
bb.appendStruct(c);
bb.appendStr(lastDbPath.toString());
}
bb.appendStruct(e);
bb.appendBuf(i->start(), e.len);
if (MONGO_unlikely(e.len != (unsigned)i->length())) {
log() << "journal info splitting prepBasicWrite at boundary" << endl;
// This only happens if we write to the last byte in a file and
// the fist byte in another file that is mapped adjacently. I
// think most OSs leave at least a one page gap between
// mappings, but better to be safe.
WriteIntent next ((char*)i->start() + e.len, i->length() - e.len);
prepBasicWrite_inlock(bb, &next, lastDbPath);
}
}
/** basic write ops / write intents. note there is no particular order to these : if we have
two writes to the same location during the group commit interval, it is likely
(although not assured) that it is journaled here once.
*/
static void prepBasicWrites(AlignedBuilder& bb, const std::vector<WriteIntent>& intents) {
boost::lock_guard<boost::mutex> lk(privateViews._mutex());
// Each time write intents switch to a different database we journal a JDbContext.
// Switches will be rare as we sort by memory location first and we batch commit.
RelativePath lastDbPath;
invariant(!intents.empty());
WriteIntent last;
for (std::vector<WriteIntent>::const_iterator i = intents.begin();
i != intents.end();
i++) {
if( i->start() < last.end() ) {
// overlaps
last.absorb(*i);
}
else {
// discontinuous
if (i != intents.begin()) {
prepBasicWrite_inlock(bb, &last, lastDbPath);
}
last = *i;
}
}
prepBasicWrite_inlock(bb, &last, lastDbPath);
}
/** we will build an output buffer ourself and then use O_DIRECT
we could be in read lock for this
caller handles locking
@return partially populated sectheader and _ab set
*/
static void _PREPLOGBUFFER(JSectHeader& h, AlignedBuilder& bb) {
// Add the JSectHeader
// Invalidate the total length, we will fill it in later.
h.setSectionLen(0xffffffff);
h.seqNumber = getLastDataFileFlushTime();
h.fileId = j.curFileId();
// Ops other than basic writes (DurOp's) go first
const std::vector<boost::shared_ptr<DurOp> >& durOps = commitJob.ops();
for (std::vector<boost::shared_ptr<DurOp> >::const_iterator i = durOps.begin();
i != durOps.end();
i++) {
(*i)->serialize(bb);
}
// Write intents
const std::vector<WriteIntent>& intents = commitJob.getIntentsSorted();
if (!intents.empty()) {
prepBasicWrites(bb, intents);
}
}
void PREPLOGBUFFER(/*out*/ JSectHeader& outHeader, AlignedBuilder& outBuffer) {
Timer t;
j.assureLogFileOpen(); // so fileId is set
_PREPLOGBUFFER(outHeader, outBuffer);
stats.curr()->_prepLogBufferMicros += t.micros();
}
}
}
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