ensure that fast timers and native timers are set properly

lib/dispatcher/client-h1.js

@@ -129,9 +129,17 @@ let currentBufferRef = null
 let currentBufferSize = 0
 let currentBufferPtr = null
 
-const TIMEOUT_HEADERS = 1
-const TIMEOUT_BODY = 2
-const TIMEOUT_KEEP_ALIVE = 3
+const USE_NATIVE_TIMER = 0
+const USE_FAST_TIMER = 1
+
+// Use fast timers for headers and body to take eventual event loop
+// latency into account.
+const TIMEOUT_HEADERS = 2 | USE_FAST_TIMER
+const TIMEOUT_BODY = 4 | USE_FAST_TIMER
+
+// Use native timers to ignore event loop latency for keep-alive
+// handling.
+const TIMEOUT_KEEP_ALIVE = 8 | USE_NATIVE_TIMER
 
 class Parser {
   constructor (client, socket, { exports }) {
@@ -163,36 +171,38 @@ class Parser {
   }
 
   setTimeout (delay, type) {
-    this.timeoutType = type
-    if (delay !== this.timeoutValue) {
+    // If the existing timer and the new timer are of using different timer
+    // (fast or native) or have different delay, we need to clear the existing
+    // timer and set a new one.
+    if (
+      (type & USE_FAST_TIMER) !== (this.timeoutType & USE_FAST_TIMER) ||
+      delay !== this.timeoutValue
+    ) {
+      // If a timeout is already set, clear it with clearTimeout of the fast
+      // timer implementation, as it can clear fast and native timers.
       if (this.timeout) {
         timers.clearTimeout(this.timeout)
         this.timeout = null
       }
 
       if (delay) {
-        switch (type) {
-          case TIMEOUT_HEADERS:
-          case TIMEOUT_BODY:
-            // Use fast timers for headers and body to take eventual event loop
-            // latency into account.
-            this.timeout = timers.setFastTimeout(onParserTimeout, delay, new WeakRef(this))
-            break
-          case TIMEOUT_KEEP_ALIVE:
-            // Use native timers to ignore event loop latency for keep-alive
-            // handling.
-            this.timeout = setTimeout(onParserTimeout, delay, new WeakRef(this))
-            this.timeout.unref()
-            break
+        if (type & USE_FAST_TIMER) {
+          this.timeout = timers.setFastTimeout(onParserTimeout, delay, new WeakRef(this))
+        } else {
+          this.timeout = setTimeout(onParserTimeout, delay, new WeakRef(this))
+          this.timeout.unref()
         }
       }
+
       this.timeoutValue = delay
     } else if (this.timeout) {
       // istanbul ignore else: only for jest
       if (this.timeout.refresh) {
         this.timeout.refresh()
       }
     }
+
+    this.timeoutType = type
   }
 
   resume () {