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
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
|
// record.cpp
#include "pch.h"
#include "pdfile.h"
#include "../util/processinfo.h"
#include "../util/net/listen.h"
namespace mongo {
namespace ps {
enum State {
In , Out, Unk
};
enum Constants {
SliceSize = 65536 ,
MaxChain = 20 , // intentionally very low
NumSlices = 10 ,
RotateTimeSecs = 90
};
int hash( size_t region ) {
return
abs( ( ( 7 + (int)(region & 0xFFFF) )
* ( 11 + (int)( ( region >> 16 ) & 0xFFFF ) )
#if defined(_WIN64) || defined(__amd64__)
* ( 13 + (int)( ( region >> 32 ) & 0xFFFF ) )
* ( 17 + (int)( ( region >> 48 ) & 0xFFFF ) )
#endif
) % SliceSize );
}
/**
* simple hash map for region -> status
* this constitures a single region of time
* it does chaining, but very short chains
*/
class Slice {
struct Entry {
size_t region;
unsigned long long value;
};
public:
Slice() {
reset();
}
void reset() {
memset( _data , 0 , SliceSize * sizeof(Entry) );
}
State get( int regionHash , size_t region , short offset ) {
DEV assert( hash( region ) == regionHash );
Entry * e = _get( regionHash , region , false );
if ( ! e )
return Unk;
return ( e->value & ( ((unsigned long long)1) << offset ) ) ? In : Out;
}
/**
* @return true if added, false if full
*/
bool in( int regionHash , size_t region , short offset ) {
DEV assert( hash( region ) == regionHash );
Entry * e = _get( regionHash , region , true );
if ( ! e )
return false;
e->value |= ((unsigned long long)1) << offset;
return true;
}
private:
Entry* _get( int start , size_t region , bool add ) {
for ( int i=0; i<MaxChain; i++ ) {
int bucket = ( start + i ) % SliceSize;
if ( _data[bucket].region == 0 ) {
if ( ! add )
return 0;
_data[bucket].region = region;
return &_data[bucket];
}
if ( _data[bucket].region == region ) {
return &_data[bucket];
}
}
return 0;
}
Entry _data[SliceSize];
};
/**
* this contains many slices of times
* the idea you put mem status in the current time slice
* and then after a certain period of time, it rolls off so we check again
*/
class Rolling {
public:
Rolling()
: _lock( "ps::Rolling" ){
_curSlice = 0;
_lastRotate = Listener::getElapsedTimeMillis();
}
/**
* after this call, we assume the page is in ram
* @param doHalf if this is a known good access, want to put in first half
* @return whether we know the page is in ram
*/
bool access( size_t region , short offset , bool doHalf ) {
int regionHash = hash(region);
SimpleMutex::scoped_lock lk( _lock );
static int rarely_count = 0;
if ( rarely_count++ % 2048 == 0 ) {
long long now = Listener::getElapsedTimeMillis();
RARELY if ( now == 0 ) {
tlog() << "warning Listener::getElapsedTimeMillis returning 0ms" << endl;
}
if ( now - _lastRotate > ( 1000 * RotateTimeSecs ) ) {
_rotate();
}
}
for ( int i=0; i<NumSlices / ( doHalf ? 2 : 1 ); i++ ) {
int pos = (_curSlice+i)%NumSlices;
State s = _slices[pos].get( regionHash , region , offset );
if ( s == In )
return true;
if ( s == Out ) {
_slices[pos].in( regionHash , region , offset );
return false;
}
}
// we weren't in any slice
// so add to cur
if ( ! _slices[_curSlice].in( regionHash , region , offset ) ) {
_rotate();
_slices[_curSlice].in( regionHash , region , offset );
}
return false;
}
private:
void _rotate() {
_curSlice = ( _curSlice + 1 ) % NumSlices;
_slices[_curSlice].reset();
_lastRotate = Listener::getElapsedTimeMillis();
}
int _curSlice;
long long _lastRotate;
Slice _slices[NumSlices];
SimpleMutex _lock;
} rolling;
}
bool Record::MemoryTrackingEnabled = true;
volatile int __record_touch_dummy = 1; // this is used to make sure the compiler doesn't get too smart on us
void Record::touch( bool entireRecrd ) {
if ( lengthWithHeaders > HeaderSize ) { // this also makes sure lengthWithHeaders is in memory
char * addr = data;
char * end = data + netLength();
for ( ; addr <= end ; addr += 2048 ) {
__record_touch_dummy += addr[0];
break; // TODO: remove this, pending SERVER-3711
if ( ! entireRecrd )
break;
}
}
}
bool Record::likelyInPhysicalMemory() {
if ( ! MemoryTrackingEnabled )
return true;
static bool blockSupported = ProcessInfo::blockCheckSupported();
const size_t page = (size_t)data >> 12;
const size_t region = page >> 6;
const size_t offset = page & 0x3f;
if ( ps::rolling.access( region , offset , false ) )
return true;
if ( ! blockSupported )
return false;
return ProcessInfo::blockInMemory( data );
}
Record* Record::accessed() {
const size_t page = (size_t)data >> 12;
const size_t region = page >> 6;
const size_t offset = page & 0x3f;
ps::rolling.access( region , offset , true );
return this;
}
}
|
