1 files changed, 97 insertions, 0 deletions
diff --git a/lib/timers.js b/lib/timers.js
new file mode 100644
index 0000000..5782217
--- /dev/null
+++ b/lib/timers.js
@@ -0,0 +1,97 @@
+'use strict'
+
+let fastNow = Date.now()
+let fastNowTimeout
+
+const fastTimers = []
+
+function onTimeout () {
+  fastNow = Date.now()
+
+  let len = fastTimers.length
+  let idx = 0
+  while (idx < len) {
+    const timer = fastTimers[idx]
+
+    if (timer.state === 0) {
+      timer.state = fastNow + timer.delay
+    } else if (timer.state > 0 && fastNow >= timer.state) {
+      timer.state = -1
+      timer.callback(timer.opaque)
+    }
+
+    if (timer.state === -1) {
+      timer.state = -2
+      if (idx !== len - 1) {
+        fastTimers[idx] = fastTimers.pop()
+      } else {
+        fastTimers.pop()
+      }
+      len -= 1
+    } else {
+      idx += 1
+    }
+  }
+
+  if (fastTimers.length > 0) {
+    refreshTimeout()
+  }
+}
+
+function refreshTimeout () {
+  if (fastNowTimeout && fastNowTimeout.refresh) {
+    fastNowTimeout.refresh()
+  } else {
+    clearTimeout(fastNowTimeout)
+    fastNowTimeout = setTimeout(onTimeout, 1e3)
+    if (fastNowTimeout.unref) {
+      fastNowTimeout.unref()
+    }
+  }
+}
+
+class Timeout {
+  constructor (callback, delay, opaque) {
+    this.callback = callback
+    this.delay = delay
+    this.opaque = opaque
+
+    //  -2 not in timer list
+    //  -1 in timer list but inactive
+    //   0 in timer list waiting for time
+    // > 0 in timer list waiting for time to expire
+    this.state = -2
+
+    this.refresh()
+  }
+
+  refresh () {
+    if (this.state === -2) {
+      fastTimers.push(this)
+      if (!fastNowTimeout || fastTimers.length === 1) {
+        refreshTimeout()
+      }
+    }
+
+    this.state = 0
+  }
+
+  clear () {
+    this.state = -1
+  }
+}
+
+module.exports = {
+  setTimeout (callback, delay, opaque) {
+    return delay < 1e3
+      ? setTimeout(callback, delay, opaque)
+      : new Timeout(callback, delay, opaque)
+  },
+  clearTimeout (timeout) {
+    if (timeout instanceof Timeout) {
+      timeout.clear()
+    } else {
+      clearTimeout(timeout)
+    }
+  }
+}