dawn/node: Work around NodeJS brokenness with printing long strings.

Attempting to print a long string can cause output to go missing.
Split long strings up into 4k chunks.

Change-Id: Ibcb07459bd8fb4a1a11b6f8db41c8378274a6d09
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/95940
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Ben Clayton <bclayton@google.com>

src/dawn/node/binding/GPUDevice.cpp

@@ -41,6 +41,53 @@ namespace wgpu::binding {
 
 namespace {
 
+// Returns a string representation of the WGPULoggingType
+const char* str(WGPULoggingType ty) {
+    switch (ty) {
+        case WGPULoggingType_Verbose:
+            return "verbose";
+        case WGPULoggingType_Info:
+            return "info";
+        case WGPULoggingType_Warning:
+            return "warning";
+        case WGPULoggingType_Error:
+            return "error";
+        default:
+            return "unknown";
+    }
+}
+
+// Returns a string representation of the WGPUErrorType
+const char* str(WGPUErrorType ty) {
+    switch (ty) {
+        case WGPUErrorType_NoError:
+            return "no error";
+        case WGPUErrorType_Validation:
+            return "validation";
+        case WGPUErrorType_OutOfMemory:
+            return "out of memory";
+        case WGPUErrorType_Unknown:
+            return "unknown";
+        case WGPUErrorType_DeviceLost:
+            return "device lost";
+        default:
+            return "unknown";
+    }
+}
+
+// There's something broken with Node when attempting to write more than 65536 bytes to cout.
+// Split the string up into writes of 4k chunks .
+// Likely related: https://github.com/nodejs/node/issues/12921
+void chunkedWrite(const char* msg) {
+    while (true) {
+        auto n = printf("%.4096s", msg);
+        if (n == 0) {
+            break;
+        }
+        msg += n;
+    }
+}
+
 class DeviceLostInfo : public interop::GPUDeviceLostInfo {
   public:
     DeviceLostInfo(interop::GPUDeviceLostReason reason, std::string message)
@@ -88,12 +135,14 @@ GPUDevice::GPUDevice(Napi::Env env, wgpu::Device device)
       lost_promise_(env, PROMISE_INFO) {
     device_.SetLoggingCallback(
         [](WGPULoggingType type, char const* message, void* userdata) {
-            std::cout << type << ": " << message << std::endl;
+            printf("%s:\n", str(type));
+            chunkedWrite(message);
         },
         nullptr);
     device_.SetUncapturedErrorCallback(
         [](WGPUErrorType type, char const* message, void* userdata) {
-            std::cout << type << ": " << message << std::endl;
+            printf("%s:\n", str(type));
+            chunkedWrite(message);
         },
         nullptr);