/usr/include/mongo/db/dur_commitjob.h is in mongodb-dev 1:2.4.9-1ubuntu2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 | /* @file dur_commitjob.h used by dur.cpp */
/**
* Copyright (C) 2009 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 "../util/alignedbuilder.h"
#include "../util/mongoutils/hash.h"
#include "../util/concurrency/synchronization.h"
#include "cmdline.h"
#include "durop.h"
#include "dur.h"
#include "taskqueue.h"
#include "d_concurrency.h"
namespace mongo {
namespace dur {
void assertLockedForCommitting();
/** Declaration of an intent to write to a region of a memory mapped view
* We store the end rather than the start pointer to make operator< faster
* since that is heavily used in set lookup.
*/
struct WriteIntent { /* copyable */
WriteIntent() : p(0) { }
WriteIntent(void *a, unsigned b) : p((char*)a+b), len(b) { }
void* start() const { return (char*)p - len; }
void* end() const { return p; }
unsigned length() const { return len; }
bool operator < (const WriteIntent& rhs) const { return end() < rhs.end(); }
bool overlaps(const WriteIntent& rhs) const { return (start() <= rhs.end() && end() >= rhs.start()); }
bool contains(const WriteIntent& rhs) const { return (start() <= rhs.start() && end() >= rhs.end()); }
// merge into me:
void absorb(const WriteIntent& other);
friend ostream& operator << (ostream& out, const WriteIntent& wi) {
return (out << "p: " << wi.p << " end: " << wi.end() << " len: " << wi.len);
}
private:
void *p; // intent to write up to p
unsigned len; // up to this len
};
/** try to remember things we have already marked for journaling. false negatives are ok if infrequent -
we will just log them twice.
*/
template<int Prime>
class Already : boost::noncopyable {
public:
Already() { clear(); }
void clear() { memset(this, 0, sizeof(*this)); }
/* see if we have Already recorded/indicated our write intent for this region of memory.
automatically upgrades the length if the length was shorter previously.
@return true if already indicated.
*/
bool checkAndSet(void* p, int len) {
unsigned x = mongoutils::hashPointer(p);
pair<void*, int>& nd = nodes[x % N];
if( nd.first == p ) {
if( nd.second < len ) {
nd.second = len;
return false; // haven't indicated this len yet
}
return true; // already indicated
}
nd.first = p;
nd.second = len;
return false; // a new set
}
private:
enum { N = Prime }; // this should be small the idea is that it fits in the cpu cache easily
pair<void*,int> nodes[N];
};
/** our record of pending/uncommitted write intents */
class IntentsAndDurOps : boost::noncopyable {
public:
vector<WriteIntent> _intents;
Already<127> _alreadyNoted;
vector< shared_ptr<DurOp> > _durOps; // all the ops other than basic writes
/** reset the IntentsAndDurOps structure (empties all the above) */
void clear();
void insertWriteIntent(void* p, int len) {
_intents.push_back(WriteIntent(p,len));
wassert( _intents.size() < 2000000 );
}
#if defined(DEBUG_WRITE_INTENT)
map<void*,int> _debug;
#endif
};
/** so we don't have to lock the groupCommitMutex too often */
class ThreadLocalIntents {
enum { N = 21 };
std::vector<dur::WriteIntent> intents;
bool condense();
public:
ThreadLocalIntents() : intents(N) { intents.clear(); }
~ThreadLocalIntents();
void _unspool();
void unspool();
void push(const WriteIntent& i);
int n_informational() const { return intents.size(); }
static AtomicUInt nSpooled;
};
/** A commit job object for a group commit. Currently there is one instance of this object.
concurrency: assumption is caller is appropriately locking.
for example note() invocations are from the write lock.
other uses are in a read lock from a single thread (durThread)
*/
class CommitJob : boost::noncopyable {
void _committingReset();
~CommitJob(){ verify(!"shouldn't destroy CommitJob!"); }
/** record/note an intent to write */
void note(void* p, int len);
// only called by :
friend class ThreadLocalIntents;
public:
SimpleMutex groupCommitMutex;
CommitJob();
/** note an operation other than a "basic write". threadsafe (locks in the impl) */
void noteOp(shared_ptr<DurOp> p);
vector< shared_ptr<DurOp> >& ops() {
dassert( Lock::isLocked() ); // a rather weak check, we require more than that
groupCommitMutex.dassertLocked(); // this is what really makes the below safe
return _intentsAndDurOps._durOps;
}
/** this method is safe to call outside of locks. when haswritten is false we don't do any group commit and avoid even
trying to acquire a lock, which might be helpful at times.
*/
bool hasWritten() const { return _hasWritten; }
public:
/** these called by the groupCommit code as it goes along */
void commitingBegin();
/** the commit code calls this when data reaches the journal (on disk) */
void committingNotifyCommitted() {
groupCommitMutex.dassertLocked();
_notify.notifyAll(_commitNumber);
}
/** we use the commitjob object over and over, calling reset() rather than reconstructing */
void committingReset() {
groupCommitMutex.dassertLocked();
_committingReset();
}
public:
/** we check how much written and if it is getting to be a lot, we commit sooner. */
size_t bytes() const { return _bytes; }
/** used in prepbasicwrites. sorted so that overlapping and duplicate items
* can be merged. we sort here so the caller receives something they must
* keep const from their pov. */
const vector<WriteIntent>& getIntentsSorted() {
groupCommitMutex.dassertLocked();
sort(_intentsAndDurOps._intents.begin(), _intentsAndDurOps._intents.end());
return _intentsAndDurOps._intents;
}
bool _hasWritten;
private:
NotifyAll::When _commitNumber;
IntentsAndDurOps _intentsAndDurOps;
size_t _bytes;
public:
NotifyAll _notify; // for getlasterror fsync:true acknowledgements
unsigned _nSinceCommitIfNeededCall; // for asserts and debugging
};
extern CommitJob& commitJob;
#if defined(DEBUG_WRITE_INTENT)
void assertAlreadyDeclared(void *, int len);
#else
inline void assertAlreadyDeclared(void *, int len) { }
#endif
}
}
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