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
|
/** @file mongommf.h
*
* Copyright (C) 2008 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/mmap.h"
#include "../util/paths.h"
namespace mongo {
/** MongoMMF adds some layers atop memory mapped files - specifically our handling of private views & such.
if you don't care about journaling/durability (temp sort files & such) use MemoryMappedFile class,
not this.
*/
class MongoMMF : private MemoryMappedFile {
public:
MongoMMF();
virtual ~MongoMMF();
virtual void close();
/** @return true if opened ok. */
bool open(string fname, bool sequentialHint);
/** @return file length */
unsigned long long length() const { return MemoryMappedFile::length(); }
string filename() const { return MemoryMappedFile::filename(); }
void flush(bool sync) { MemoryMappedFile::flush(sync); }
/* Creates with length if DNE, otherwise uses existing file length,
passed length.
@param sequentialHint if true will be sequentially accessed
@return true for ok
*/
bool create(string fname, unsigned long long& len, bool sequentialHint);
/* Get the "standard" view (which is the private one).
@return the private view.
on _TESTINTENT, returns the readonly view
*/
void* getView();
/* switch to _view_write. normally, this is a bad idea since your changes will not
show up in _view_private if there have been changes there; thus the leading underscore
as a tad of a "warning". but useful when done with some care, such as during
initialization.
*/
static void* _switchToWritableView(void *private_ptr);
/** for _TESTINTENT build.
translates the read view pointer into a pointer to the corresponding
place in the private view.
*/
static void* switchToPrivateView(void *debug_readonly_ptr);
/** for a filename a/b/c.3
filePath() is "a/b/c"
fileSuffixNo() is 3
if the suffix is "ns", fileSuffixNo -1
*/
RelativePath relativePath() const {
DEV assert( !_p._p.empty() );
return _p;
}
int fileSuffixNo() const { return _fileSuffixNo; }
void* view_write() { return _view_write; }
/** true if we have written.
set in PREPLOGBUFFER, it is NOT set immediately on write intent declaration.
reset to false in REMAPPRIVATEVIEW
*/
bool& willNeedRemap() { return _willNeedRemap; }
void remapThePrivateView();
virtual bool isMongoMMF() { return true; }
private:
void *_view_write;
void *_view_private;
void *_view_readonly; // for _DEBUG build
bool _willNeedRemap;
RelativePath _p; // e.g. "somepath/dbname"
int _fileSuffixNo; // e.g. 3. -1="ns"
void setPath(string pathAndFileName);
bool finishOpening();
};
/** for durability support we want to be able to map pointers to specific MongoMMF objects.
*/
class PointerToMMF : boost::noncopyable {
public:
PointerToMMF();
/** register view. threadsafe */
void add(void *view, MongoMMF *f);
/** de-register view. threadsafe */
void remove(void *view);
/** find associated MMF object for a given pointer.
threadsafe
@param ofs out returns offset into the view of the pointer, if found.
@return the MongoMMF to which this pointer belongs. null if not found.
*/
MongoMMF* find(void *p, /*out*/ size_t& ofs);
/** for doing many finds in a row with one lock operation */
mutex& _mutex() { return _m; }
MongoMMF* _find(void *p, /*out*/ size_t& ofs);
private:
mutex _m;
map<void*, MongoMMF*> _views;
};
// allows a pointer into any private view of a MongoMMF to be resolved to the MongoMMF object
extern PointerToMMF privateViews;
}
|
