JSContextLock::JSContextLock(JSGlobalContextRef ctx) noexcept
#if WITH_FBJSCEXTENSIONS
: ctx_(ctx),
globalLock_(PTHREAD_MUTEX_INITIALIZER)
{
WTFThreadData& threadData = wtfThreadData();
// Code below is responsible for acquiring locks. It should execute
// atomically, thus none of the functions invoked from now on are allowed to
// throw an exception
try {
if (!threadData.isDebuggerThread()) {
CHECK(0 == pthread_mutex_lock(&globalLock_));
}
JSLock(ctx_);
} catch (...) {
abort();
}
}
Value Value::fromDynamic(JSContextRef ctx, const folly::dynamic& value) {
// JavaScriptCore's iOS APIs have their own version of this direct conversion.
// In addition, using this requires exposing some of JSC's private APIs,
// so it's limited to non-apple platforms and to builds that use the custom JSC.
// Otherwise, we use the old way of converting through JSON.
#if USE_FAST_FOLLY_DYNAMIC_CONVERSION
// Defer GC during the creation of the JSValue, as we don't want
// intermediate objects to be collected.
// We could use JSValueProtect(), but it will make the process much slower.
JSDeferredGCRef deferGC = JSDeferGarbageCollection(ctx);
// Set a global lock for the whole process,
// instead of re-acquiring the lock for each operation.
JSLock(ctx);
JSValueRef jsVal = Value::fromDynamicInner(ctx, value);
JSUnlock(ctx);
JSResumeGarbageCollection(ctx, deferGC);
return Value(ctx, jsVal);
#else
auto json = folly::toJson(value);
return fromJSON(String(ctx, json.c_str()));
#endif
}
