feat: runtime metric API

[nyannyacha]

What kind of change does this PR introduce?

Feature

Description

This PR exposes an API to get runtime metrics.

Note: This API is only exposed in the main worker.

Note 2: The number of pending requests is the difference between the number of handled requests and the number of received requests, so I didn’t include it in the metric.

Usage

serve(async () => {
    ...
	if (pathname === '/_internal/metric') {
		const metric = await EdgeRuntime.getRuntimeMetrics();
		return Response.json(metric);
	}
    ...
})

Sample output

{
    "mainWorkerHeapStats": {
        "totalHeapSize": 11730944,
        "totalHeapExecutable": 524288,
        "totalPhysicalSize": 11165696,
        "totalAvailableSize": 1508889368,
        "totalGlobalHandlesSize": 16384,
        "usedGlobalHandlesSize": 10144,
        "usedHeapSize": 10273032,
        "mallocedMemory": 278632,
        "externalMemory": 79991,
        "peakMallocedMemory": 139480
    },
    "eventWorkerHeapStats": {
        "totalHeapSize": 11468800,
        "totalHeapExecutable": 262144,
        "totalPhysicalSize": 10174464,
        "totalAvailableSize": 1509473792,
        "totalGlobalHandlesSize": 16384,
        "usedGlobalHandlesSize": 9504,
        "usedHeapSize": 9473440,
        "mallocedMemory": 278632,
        "externalMemory": 79991,
        "peakMallocedMemory": 173088
    },
    "activeUserWorkersCount": 1,
    "retiredUserWorkersCount": 2,
    "receivedRequestsCount": 17,
    "handledRequestsCount": 17
}

[laktek]

@nyannyacha Is it possible to squash the stamp commits? Will keep the commit history clean :)

[nyannyacha]

@laktek hold a moment 😋

[nyannyacha]

@laktek done

[github-actions]

🎉 This PR is included in version 1.35.0 🎉

The release is available on GitHub release

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