refactor: split out last h1 specific code from core

lib/dispatcher/client-h1.js

@@ -742,6 +742,40 @@ async function connectH1 (client, socket) {
       resumeH1(client)
     },
     destroy () {
+    },
+    busy (request) {
+      if (socket[kWriting] || socket[kReset] || socket[kBlocking]) {
+        return true
+      }
+
+      if (client[kRunning] > 0 && !request.idempotent) {
+        // Non-idempotent request cannot be retried.
+        // Ensure that no other requests are inflight and
+        // could cause failure.
+        return true
+      }
+
+      if (client[kRunning] > 0 && (request.upgrade || request.method === 'CONNECT')) {
+        // Don't dispatch an upgrade until all preceding requests have completed.
+        // A misbehaving server might upgrade the connection before all pipelined
+        // request has completed.
+        return true
+      }
+
+      if (client[kRunning] > 0 && util.bodyLength(request.body) !== 0 &&
+        (util.isStream(request.body) || util.isAsyncIterable(request.body) || util.isFormDataLike(request.body))) {
+        // Request with stream or iterator body can error while other requests
+        // are inflight and indirectly error those as well.
+        // Ensure this doesn't happen by waiting for inflight
+        // to complete before dispatching.
+
+        // Request with stream or iterator body cannot be retried.
+        // Ensure that no other requests are inflight and
+        // could cause failure.
+        return true
+      }
+
+      return false
     }
   }
 }

lib/dispatcher/client-h2.js

@@ -133,6 +133,9 @@ async function connectH2 (client, socket) {
     },
     destroy (err) {
       session.destroy(err)
+    },
+    busy () {
+      return false
     }
   }
 }

lib/dispatcher/client.js

@@ -598,37 +598,12 @@ function _resume (client, sync) {
       return
     }
 
-    if (client[kHTTPContext].version === 'h1') {
-      if (socket[kWriting] || socket[kReset] || socket[kBlocking]) {
-        return
-      }
-
-      if (client[kRunning] > 0 && !request.idempotent) {
-        // Non-idempotent request cannot be retried.
-        // Ensure that no other requests are inflight and
-        // could cause failure.
-        return
-      }
-
-      if (client[kRunning] > 0 && (request.upgrade || request.method === 'CONNECT')) {
-        // Don't dispatch an upgrade until all preceding requests have completed.
-        // A misbehaving server might upgrade the connection before all pipelined
-        // request has completed.
-        return
-      }
-
-      if (client[kRunning] > 0 && util.bodyLength(request.body) !== 0 &&
-        (util.isStream(request.body) || util.isAsyncIterable(request.body) || util.isFormDataLike(request.body))) {
-        // Request with stream or iterator body can error while other requests
-        // are inflight and indirectly error those as well.
-        // Ensure this doesn't happen by waiting for inflight
-        // to complete before dispatching.
+    if (!client[kHTTPContext]) {
+      return
+    }
 
-        // Request with stream or iterator body cannot be retried.
-        // Ensure that no other requests are inflight and
-        // could cause failure.
-        return
-      }
+    if (client[kHTTPContext].busy(request)) {
+      return
     }
 
     if (!request.aborted && client[kHTTPContext].write(request)) {