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#ifndef Performance_h

#define Performance_h

#include "Common.h"

namespace tns {

class Performance {

public:

// Installs the WHATWG Performance API by evaluating internal/performance.js

// with a bag of natives {now, timeOrigin}. Must run after Events::Init

// (Performance extends EventTarget) and after ErrorEvents::Init (observer

// failures are reported through it). Evaluated once per isolate during

// Runtime::Init, for main and worker isolates alike; each isolate carries its

// own time origin.

static void Init(v8::Local<v8::Context> context);

// Milliseconds elapsed on this isolate's performance timeline: monotonic and

// zero at the time origin. Native producers of JS-visible timestamps (a

// future requestAnimationFrame) must read the clock through here instead of

// sampling one of their own, so every such timestamp shares

// performance.timeOrigin as its base. Returns 0.0 for an isolate with no

// runtime.

static double NowMillis(v8::Isolate* isolate);

// Wall-clock milliseconds since the Unix epoch at the isolate's time origin,

// on the same base as Date.now(); this is performance.timeOrigin. Returns

// 0.0 for an isolate with no runtime.

static double TimeOriginMillis(v8::Isolate* isolate);

private:

static void NowCallback(const v8::FunctionCallbackInfo<v8::Value>& info);

};

} // namespace tns

#endif /* Performance_h */