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[WebAssembly] Add no-op MutexWASI.h implementation #29459

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Merged
merged 2 commits into from
Jan 29, 2020
Merged

[WebAssembly] Add no-op MutexWASI.h implementation #29459

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ab15f84
[WebAssembly] Add no-op MutexWASI.h implementation
MaxDesiatov Jan 26, 2020
fbb9062
Update wording of header comment in MutexWASI.h
MaxDesiatov Jan 26, 2020
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2 changes: 2 additions & 0 deletions include/swift/Runtime/Mutex.h
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,8 @@
#include "swift/Runtime/MutexPThread.h"
#elif defined(_WIN32)
#include "swift/Runtime/MutexWin32.h"
#elif defined(__wasi__)
#include "swift/Runtime/MutexWASI.h"
#else
#error "Implement equivalent of MutexPThread.h/cpp for your platform."
#endif
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67 changes: 67 additions & 0 deletions include/swift/Runtime/MutexWASI.h
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@@ -0,0 +1,67 @@
//===--- MutexWASI.h - -----------------------------------------*- C++ -*-===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2020 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
//
// Stub implementation of Mutex, ConditionVariable, Read/Write lock, and Scoped
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s/stub/no-op/

I wouldn't say "no concrete implementation is provided" because it is a concrete implementation, it just does not perform locking.

"No-op implementation of locks for the WebAssembly System Interface. The implementation does not need to perform locking, because as of <insert WebAssembly spec version, or today's date> WebAssembly does not support threads."

// lock for WASI. No concrete implementation is provided as WebAssembly doesn't
// currently support threading.
//
//===----------------------------------------------------------------------===//

#ifndef SWIFT_RUNTIME_MUTEX_WASI_H
#define SWIFT_RUNTIME_MUTEX_WASI_H

namespace swift {

typedef void* ConditionHandle;
typedef void* MutexHandle;
typedef void* ReadWriteLockHandle;

#define SWIFT_CONDITION_SUPPORTS_CONSTEXPR 1
#define SWIFT_MUTEX_SUPPORTS_CONSTEXPR 1
#define SWIFT_READWRITELOCK_SUPPORTS_CONSTEXPR 1

struct ConditionPlatformHelper {
static constexpr ConditionHandle staticInit() {
return nullptr;
};
static void init(ConditionHandle &condition) {}
static void destroy(ConditionHandle &condition) {}
static void notifyOne(ConditionHandle &condition) {}
static void notifyAll(ConditionHandle &condition) {}
static void wait(ConditionHandle &condition, MutexHandle &mutex);
};

struct MutexPlatformHelper {
static constexpr MutexHandle staticInit() { return nullptr; }
static void init(MutexHandle &mutex, bool checked = false) {}
static void destroy(MutexHandle &mutex) {}
static void lock(MutexHandle &mutex) {}
static void unlock(MutexHandle &mutex) {}
static bool try_lock(MutexHandle &mutex) { return true; }
static void unsafeLock(MutexHandle &mutex) {}
static void unsafeUnlock(MutexHandle &mutex) {}
};

struct ReadWriteLockPlatformHelper {
static constexpr ReadWriteLockHandle staticInit() { return nullptr; }
static void init(ReadWriteLockHandle &rwlock) {}
static void destroy(ReadWriteLockHandle &rwlock) {}
static void readLock(ReadWriteLockHandle &rwlock) {}
static bool try_readLock(ReadWriteLockHandle &rwlock) { return true; }
static void readUnlock(ReadWriteLockHandle &rwlock) {}
static void writeLock(ReadWriteLockHandle &rwlock) {}
static bool try_writeLock(ReadWriteLockHandle &rwlock) { return true; }
static void writeUnlock(ReadWriteLockHandle &rwlock) {}
};
}

#endif