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
|
#include "WAVM/Platform/Thread.h"
#include <stdint.h>
#include <atomic>
#include <memory>
#include <utility>
#include <vector>
#include "WAVM/IR/Types.h"
#include "WAVM/IR/Value.h"
#include "WAVM/Inline/Assert.h"
#include "WAVM/Inline/BasicTypes.h"
#include "WAVM/Inline/Errors.h"
#include "WAVM/Inline/IndexMap.h"
#include "WAVM/Inline/IntrusiveSharedPtr.h"
#include "WAVM/Platform/Mutex.h"
#include "WAVM/Runtime/Intrinsics.h"
#include "WAVM/Runtime/Runtime.h"
#include "WAVM/RuntimeABI/RuntimeABI.h"
#include "WAVM/ThreadTest/ThreadTest.h"
using namespace WAVM;
using namespace WAVM::IR;
using namespace WAVM::Runtime;
static constexpr Uptr numStackBytes = 1 * 1024 * 1024;
// Keeps track of the entry function used by a running WebAssembly-spawned thread.
// Used to find garbage collection roots.
struct Thread
{
Uptr id = UINTPTR_MAX;
std::atomic<Uptr> numRefs{0};
Platform::Thread* platformThread = nullptr;
GCPointer<Context> context;
GCPointer<Function> entryFunction;
Platform::Mutex resultMutex;
bool threwException = false;
Exception* exception = nullptr;
I64 result = -1;
I32 argument;
WAVM_FORCENOINLINE Thread(Context* inContext, Function* inEntryFunction, I32 inArgument)
: context(inContext), entryFunction(inEntryFunction), argument(inArgument)
{
}
void addRef(Uptr delta = 1) { numRefs += delta; }
void removeRef()
{
if(--numRefs == 0) { delete this; }
}
};
struct ExitThreadException
{
I64 code;
};
// A global list of running threads created by WebAssembly code.
static Platform::Mutex threadsMutex;
static IndexMap<Uptr, IntrusiveSharedPtr<Thread>> threads(1, UINTPTR_MAX);
// A shared pointer to the current thread. This is used to decrement the thread's reference count
// when the thread exits.
static thread_local IntrusiveSharedPtr<Thread> currentThread = nullptr;
// Adds the thread to the global thread array, assigning it an ID corresponding to its index in the
// array.
WAVM_FORCENOINLINE static Uptr allocateThreadId(Thread* thread)
{
Platform::Mutex::Lock threadsLock(threadsMutex);
thread->id = threads.add(0, thread);
WAVM_ERROR_UNLESS(thread->id != 0);
return thread->id;
}
// Validates that a thread ID is valid. i.e. 0 < threadId < threads.size(), and threads[threadId] !=
// null If the thread ID is invalid, throws an invalid argument exception. The caller must have
// already locked threadsMutex before calling validateThreadId.
static void validateThreadId(Uptr threadId)
{
if(threadId == 0 || !threads.contains(threadId))
{ throwException(ExceptionTypes::invalidArgument); }
}
WAVM_DEFINE_INTRINSIC_MODULE(threadTest);
static I64 threadEntry(void* threadVoid)
{
// Assign the thread reference to currentThread, and discard it the local copy.
{
Thread* thread = (Thread*)threadVoid;
currentThread = thread;
thread->removeRef();
}
catchRuntimeExceptions(
[]() {
I64 result;
try
{
UntaggedValue argumentValue{currentThread->argument};
UntaggedValue resultValue;
invokeFunction(currentThread->context,
currentThread->entryFunction,
FunctionType({ValueType::i64}, {ValueType::i32}),
&argumentValue,
&resultValue);
result = resultValue.i64;
}
catch(ExitThreadException& exitThreadException)
{
result = exitThreadException.code;
}
Platform::Mutex::Lock resultLock(currentThread->resultMutex);
currentThread->result = result;
},
[](Exception* exception) {
Platform::Mutex::Lock resultLock(currentThread->resultMutex);
if(currentThread->numRefs == 1)
{
// If the thread has already been detached, the exception is fatal.
Errors::fatalf("Runtime exception in detached thread: %s",
describeException(exception).c_str());
}
else
{
currentThread->threwException = true;
currentThread->exception = exception;
}
});
return 0;
}
WAVM_DEFINE_INTRINSIC_FUNCTION(threadTest,
"createThread",
U64,
createThread,
Function* entryFunction,
I32 entryArgument)
{
// Validate that the entry function is non-null and has the correct type (i32)->i64
if(!entryFunction
|| IR::FunctionType{entryFunction->encodedType}
!= FunctionType(TypeTuple{ValueType::i64}, TypeTuple{ValueType::i32}))
{ throwException(Runtime::ExceptionTypes::indirectCallSignatureMismatch); }
// Create a thread object that will expose its entry and error functions to the garbage
// collector as roots.
auto newContext = createContext(getCompartmentFromContextRuntimeData(contextRuntimeData));
Thread* thread = new Thread(newContext, entryFunction, entryArgument);
allocateThreadId(thread);
// Increment the Thread's reference count for the pointer passed to the thread's entry function.
// threadFunc calls the corresponding removeRef.
thread->addRef();
// Spawn and detach a platform thread that calls threadFunc.
thread->platformThread = Platform::createThread(numStackBytes, threadEntry, thread);
return thread->id;
}
WAVM_DEFINE_INTRINSIC_FUNCTION(threadTest, "exitThread", void, exitThread, I64 code)
{
if(!currentThread) { throwException(ExceptionTypes::calledAbort); }
throw ExitThreadException{code};
}
// Validates a thread ID, removes the corresponding thread from the threads array, and returns it.
static IntrusiveSharedPtr<Thread> removeThreadById(Uptr threadId)
{
IntrusiveSharedPtr<Thread> thread;
Platform::Mutex::Lock threadsLock(threadsMutex);
validateThreadId(threadId);
thread = std::move(threads[threadId]);
threads.removeOrFail(threadId);
WAVM_ASSERT(thread->id == Uptr(threadId));
thread->id = UINTPTR_MAX;
return thread;
}
WAVM_DEFINE_INTRINSIC_FUNCTION(threadTest, "joinThread", I64, joinThread, U64 threadId)
{
IntrusiveSharedPtr<Thread> thread = removeThreadById(Uptr(threadId));
Platform::joinThread(thread->platformThread);
thread->platformThread = nullptr;
Platform::Mutex::Lock resultLock(thread->resultMutex);
if(thread->threwException) { throwException(thread->exception); }
else
{
return thread->result;
}
}
WAVM_DEFINE_INTRINSIC_FUNCTION(threadTest, "detachThread", void, detachThread, U64 threadId)
{
IntrusiveSharedPtr<Thread> thread = removeThreadById(Uptr(threadId));
Platform::detachThread(thread->platformThread);
thread->platformThread = nullptr;
// If the thread threw an exception, turn it into a fatal error.
Platform::Mutex::Lock resultLock(thread->resultMutex);
if(thread->threwException)
{
Errors::fatalf("Runtime exception in detached thread: %s",
describeException(thread->exception).c_str());
}
}
Instance* ThreadTest::instantiate(Compartment* compartment)
{
return Intrinsics::instantiateModule(
compartment, {WAVM_INTRINSIC_MODULE_REF(threadTest)}, "threadTest");
}
|
