[wasm] Port thread-related APIs for no thread platform

This change ports the thread-related APIs for the no thread platform by
adding no-op implementations. Note that WASI is going to support threads
in the near future, so this does not guard by `TARGET_OS_WASI` but by
`!SWIFT_CORELIBS_FOUNDATION_HAS_THREADS` to make it easier for future
WASI + threads support.

Author: kateinoigakukun

CoreFoundation/Base.subproj/CFInternal.h

@@ -654,6 +654,36 @@ CF_INLINE int _CFRecursiveMutexUnlock(_CFRecursiveMutex *mutex) {
   LeaveCriticalSection(mutex);
   return 0;
 }
+#elif TARGET_OS_WASI
+// For wasi-libc without pthread support (_POSIX_THREADS), just assume that it's single-threaded.
+typedef struct {} _CFMutex;
+#define _CF_MUTEX_STATIC_INITIALIZER {}
+CF_INLINE int _CFMutexCreate(_CFMutex *lock) {
+  return 0;
+}
+CF_INLINE int _CFMutexDestroy(_CFMutex *lock) {
+  return 0;
+}
+CF_INLINE int _CFMutexLock(_CFMutex *lock) {
+  return 0;
+}
+CF_INLINE int _CFMutexUnlock(_CFMutex *lock) {
+  return 0;
+}
+
+typedef struct {} _CFRecursiveMutex;
+CF_INLINE int _CFRecursiveMutexCreate(_CFRecursiveMutex *mutex) {
+  return 0;
+}
+CF_INLINE int _CFRecursiveMutexDestroy(_CFRecursiveMutex *mutex) {
+  return 0;
+}
+CF_INLINE int _CFRecursiveMutexLock(_CFRecursiveMutex *mutex) {
+  return 0;
+}
+CF_INLINE int _CFRecursiveMutexUnlock(_CFRecursiveMutex *mutex) {
+  return 0;
+}
 #else
 #error "do not know how to define mutex and recursive mutex for this OS"
 #endif
@@ -677,7 +707,7 @@ typedef uint32_t os_unfair_lock_options_t;
 static void os_unfair_lock_lock(os_unfair_lock_t lock) { pthread_mutex_lock(lock); }
 static void os_unfair_lock_lock_with_options(os_unfair_lock_t lock, os_unfair_lock_options_t options) { pthread_mutex_lock(lock); }
 static void os_unfair_lock_unlock(os_unfair_lock_t lock) { pthread_mutex_unlock(lock); }
-#elif defined(_WIN32)
+#elif defined(_WIN32) || TARGET_OS_WASI
 #define OS_UNFAIR_LOCK_INIT CFLockInit
 #define os_unfair_lock CFLock_t
 #define os_unfair_lock_lock __CFLock

CoreFoundation/Base.subproj/CFPlatform.c

@@ -1628,6 +1628,8 @@ CF_PRIVATE int asprintf(char **ret, const char *format, ...) {
 extern void swift_retain(void *);
 extern void swift_release(void *);
 
+#if SWIFT_CORELIBS_FOUNDATION_HAS_THREADS
+
 #if TARGET_OS_WIN32
 typedef struct _CFThreadSpecificData {
     CFTypeRef value;
@@ -1806,6 +1808,7 @@ CF_CROSS_PLATFORM_EXPORT int _CFThreadGetName(char *buf, int length) {
 #endif
     return -1;
 }
+#endif // SWIFT_CORELIBS_FOUNDATION_HAS_THREADS
 
 CF_EXPORT char **_CFEnviron(void) {
 #if TARGET_OS_MAC

CoreFoundation/Base.subproj/CFRuntime.c

@@ -1194,9 +1194,13 @@ void __CFInitialize(void) {
         DuplicateHandle(GetCurrentProcess(), GetCurrentThread(),
                         GetCurrentProcess(), &_CFMainPThread, 0, FALSE,
                         DUPLICATE_SAME_ACCESS);
-#else
+#elif _POSIX_THREADS
         // move this next line up into the #if above after Foundation gets off this symbol. Also: <rdar://problem/39622745> Stop using _CFMainPThread
         _CFMainPThread = pthread_self();
+#elif TARGET_OS_WASI
+        _CFMainPThread = kNilPthreadT;
+#else
+#error Dont know how to get the main thread on this platform
 #endif
 
 #if TARGET_OS_WIN32

CoreFoundation/Base.subproj/CFUtilities.c

@@ -927,8 +927,13 @@ static void _populateBanner(char **banner, char **time, char **thread, int *bann
     bannerLen = asprintf(banner, "%04d-%02d-%02d %02d:%02d:%02d.%03d %s[%d:%lx] ", year, month, day, hour, minute, second, ms, *_CFGetProgname(), getpid(), GetCurrentThreadId());
     asprintf(thread, "%lx", GetCurrentThreadId());
 #elif TARGET_OS_WASI
-    bannerLen = asprintf(banner, "%04d-%02d-%02d %02d:%02d:%02d.%03d [%x] ", year, month, day, hour, minute, second, ms, (unsigned int)pthread_self());
-    asprintf(thread, "%lx", pthread_self());
+    _CFThreadRef tid = 0;
+    // When pthread API is available from wasi-libc, use it. Otherwise use the dummy value.
+# if _POSIX_THREADS
+    tid = pthread_self();
+# endif
+    bannerLen = asprintf(banner, "%04d-%02d-%02d %02d:%02d:%02d.%03d [%x] ", year, month, day, hour, minute, second, ms, (unsigned int)tid);
+    asprintf(thread, "%lx", tid);
 #else
     bannerLen = asprintf(banner, "%04d-%02d-%02d %02d:%02d:%02d.%03d %s[%d:%x] ", year, month, day, hour, minute, second, ms, *_CFGetProgname(), getpid(), (unsigned int)pthread_self());
     asprintf(thread, "%lx", pthread_self());

CoreFoundation/Base.subproj/ForSwiftFoundationOnly.h

@@ -412,6 +412,10 @@ typedef unsigned long _CFThreadSpecificKey;
 typedef pthread_t _CFThreadRef;
 typedef pthread_attr_t _CFThreadAttributes;
 typedef pthread_key_t _CFThreadSpecificKey;
+#elif TARGET_OS_WASI // WASI without pthreads
+typedef void *_CFThreadRef;
+typedef void *_CFThreadAttributes;
+typedef void *_CFThreadSpecificKey;
 #endif
 
 CF_CROSS_PLATFORM_EXPORT Boolean _CFIsMainThread(void);
@@ -423,6 +427,7 @@ CF_EXPORT CFHashCode __CFHashDouble(double d);
 CF_CROSS_PLATFORM_EXPORT void CFSortIndexes(CFIndex *indexBuffer, CFIndex count, CFOptionFlags opts, CFComparisonResult (^cmp)(CFIndex, CFIndex));
 #endif
 
+#if SWIFT_CORELIBS_FOUNDATION_HAS_THREADS
 CF_EXPORT CFTypeRef _Nullable _CFThreadSpecificGet(_CFThreadSpecificKey key);
 CF_EXPORT void _CFThreadSpecificSet(_CFThreadSpecificKey key, CFTypeRef _Nullable value);
 CF_EXPORT _CFThreadSpecificKey _CFThreadSpecificKeyCreate(void);
@@ -431,6 +436,7 @@ CF_EXPORT _CFThreadRef _CFThreadCreate(const _CFThreadAttributes attrs, void *_N
 
 CF_CROSS_PLATFORM_EXPORT int _CFThreadSetName(_CFThreadRef thread, const char *_Nonnull name);
 CF_CROSS_PLATFORM_EXPORT int _CFThreadGetName(char *_Nonnull buf, int length);
+#endif
 
 CF_EXPORT Boolean _CFCharacterSetIsLongCharacterMember(CFCharacterSetRef theSet, UTF32Char theChar);
 CF_EXPORT CFCharacterSetRef _CFCharacterSetCreateCopy(CFAllocatorRef alloc, CFCharacterSetRef theSet);

CoreFoundation/CMakeLists.txt

@@ -99,6 +99,10 @@ else()
   add_compile_definitions($<$<COMPILE_LANGUAGE:C>:DEPLOYMENT_RUNTIME_C>)
 endif()
 
+if(Threads_FOUND)
+  add_compile_definitions($<$<COMPILE_LANGUAGE:C>:SWIFT_CORELIBS_FOUNDATION_HAS_THREADS>)
+endif()
+
 # TODO(compnerd) ensure that the compiler supports the warning flag
 add_compile_options($<$<COMPILE_LANGUAGE:C>:-Wno-shorten-64-to-32>)
 add_compile_options($<$<COMPILE_LANGUAGE:C>:-Wno-deprecated-declarations>)

Sources/Foundation/CMakeLists.txt

@@ -150,6 +150,11 @@ add_library(Foundation
   WinSDK+Extensions.swift)
 target_compile_definitions(Foundation PRIVATE
   DEPLOYMENT_RUNTIME_SWIFT)
+if(Threads_FOUND)
+  target_compile_definitions(Foundation PRIVATE
+    SWIFT_CORELIBS_FOUNDATION_HAS_THREADS)
+endif()
+
 target_compile_options(Foundation PUBLIC
   $<$<BOOL:${ENABLE_TESTING}>:-enable-testing>
   "SHELL:-Xfrontend -disable-autolink-framework -Xfrontend CoreFoundation"