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
|
/**
* Copyright (C) 2015 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.
*/
#pragma once
#include "vm/PosixNSPR.h"
#include "mongo/client/dbclientcursor.h"
#include "mongo/scripting/mozjs/engine.h"
#include "mongo/stdx/condition_variable.h"
#include "mongo/stdx/functional.h"
#include "mongo/stdx/mutex.h"
#include "mongo/stdx/thread.h"
namespace mongo {
namespace mozjs {
class MozJSImplScope;
/**
* Proxies all methods on the implementation scope over a side channel that
* allows the SpiderMonkey runtime to operate entirely on one thread. This
* implements the public scope interface and is the right way to talk to an
* implementation scope from multiple threads.
*
* In terms of implementation, it does most of it's heavy lifting through a
* stdx::function. The proxy scope owns an implementation scope transitively
* through the thread it owns. They communicate by setting a variable, then
* signaling each other. That communication has to work, there's no fallback
* for timing out.
*
* There are probably performance gains to be had from making
* the argument capture and method dispatch explicit, but I'll wait until we've
* measured it before bothering.
*
* See mongo::Scope for details on all of the overridden functions
*
*/
class MozJSProxyScope final : public Scope {
MONGO_DISALLOW_COPYING(MozJSProxyScope);
/**
* The FSM is fairly tight:
*
* +----------+ shutdownThread() +--------------------+
* | Shutdown | <------------------ | Idle | <+
* +----------+ +--------------------+ |
* | |
* | runOnImplThread() |
* v |
* +--------------------+ |
* | ProxyRequest | | impl -> proxy
* +--------------------+ |
* | |
* | proxy -> impl |
* v |
* +--------------------+ |
* | ImplResponse | -+
* +--------------------+
*
* The regular flow:
* - We start at Idle and on the proxy thread.
* - runOnImplThread sets ProxyRequest and notifies the impl thread
* - The impl thread wakes up, invokes _function(), sets ImplResponse and notifies the proxy
* thread
* - The proxy thread wakes up and sets Idle
*
* Shutdown:
* - On destruction, The proxy thread sets Shutdown and notifies the impl thread
* - The impl thread wakes up, breaks out of it's loop and returns
* - The proxy thread joins the impl thread
*
*/
enum class State : char {
Idle,
ProxyRequest,
ImplResponse,
Shutdown,
};
public:
MozJSProxyScope(MozJSScriptEngine* engine);
~MozJSProxyScope();
void init(const BSONObj* data) override;
void reset() override;
bool isKillPending() const override;
void registerOperation(OperationContext* txn) override;
void unregisterOperation() override;
void localConnectForDbEval(OperationContext* txn, const char* dbName) override;
void externalSetup() override;
std::string getError() override;
bool hasOutOfMemoryException() override;
void gc() override;
void advanceGeneration() override;
double getNumber(const char* field) override;
int getNumberInt(const char* field) override;
long long getNumberLongLong(const char* field) override;
Decimal128 getNumberDecimal(const char* field) override;
std::string getString(const char* field) override;
bool getBoolean(const char* field) override;
BSONObj getObject(const char* field) override;
void setNumber(const char* field, double val) override;
void setString(const char* field, StringData val) override;
void setBoolean(const char* field, bool val) override;
void setElement(const char* field, const BSONElement& e, const BSONObj& parent) override;
void setObject(const char* field, const BSONObj& obj, bool readOnly) override;
void setFunction(const char* field, const char* code) override;
int type(const char* field) override;
void rename(const char* from, const char* to) override;
int invoke(ScriptingFunction func,
const BSONObj* args,
const BSONObj* recv,
int timeoutMs = 0,
bool ignoreReturn = false,
bool readOnlyArgs = false,
bool readOnlyRecv = false) override;
bool exec(StringData code,
const std::string& name,
bool printResult,
bool reportError,
bool assertOnError,
int timeoutMs) override;
void injectNative(const char* field, NativeFunction func, void* data = 0) override;
ScriptingFunction _createFunction(const char* code,
ScriptingFunction functionNumber = 0) override;
OperationContext* getOpContext() const;
/**
* Thread safe. Kills the running operation
*/
void kill();
private:
void runOnImplThread(std::function<void()> f);
void shutdownThread();
static void implThread(void* proxy);
MozJSScriptEngine* const _engine;
MozJSImplScope* _implScope;
/**
* This mutex protects _function, _state and _status as channels for
* function invocation and exception handling
*/
stdx::mutex _mutex;
stdx::function<void()> _function;
State _state;
Status _status;
stdx::condition_variable _condvar;
PRThread* _thread;
};
} // namespace mozjs
} // namespace mongo
|
