src: use string_view for report and related code

Use `std::string_view` for process.report code and related
code, drop a few unnecessary `std::to_string` calls,
and use `MaybeStackBuffer` instead of `MallocedBuffer`,
all in order to avoid unnecessary heap allocations.

PR-URL: https://github.com/nodejs/node/pull/46723
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>

1 files changed, 29 insertions, 33 deletions

diff --git a/src/node_report_utils.cc b/src/node_report_utils.cc
index b8f32beb20..516eac22dc 100644
--- a/src/node_report_utils.cc
+++ b/src/node_report_utils.cc
@@ -83,36 +83,33 @@ static void ReportEndpoints(uv_handle_t* h, JSONWriter* writer) {
 // Utility function to format libuv pipe information.
 static void ReportPipeEndpoints(uv_handle_t* h, JSONWriter* writer) {
   uv_any_handle* handle = reinterpret_cast<uv_any_handle*>(h);
-  MallocedBuffer<char> buffer(0);
-  size_t buffer_size = 0;
+  MaybeStackBuffer<char> buffer;
+  size_t buffer_size = buffer.capacity();
   int rc = -1;
 
   // First call to get required buffer size.
-  rc = uv_pipe_getsockname(&handle->pipe, buffer.data, &buffer_size);
+  rc = uv_pipe_getsockname(&handle->pipe, buffer.out(), &buffer_size);
   if (rc == UV_ENOBUFS) {
-    buffer = MallocedBuffer<char>(buffer_size);
-    if (buffer.data != nullptr) {
-      rc = uv_pipe_getsockname(&handle->pipe, buffer.data, &buffer_size);
-    } else {
-      buffer_size = 0;
-    }
+    buffer.AllocateSufficientStorage(buffer_size);
+    rc = uv_pipe_getsockname(&handle->pipe, buffer.out(), &buffer_size);
   }
-  if (rc == 0 && buffer_size != 0 && buffer.data != nullptr) {
-    writer->json_keyvalue("localEndpoint", buffer.data);
+  if (rc == 0 && buffer_size != 0) {
+    buffer.SetLength(buffer_size);
+    writer->json_keyvalue("localEndpoint", buffer.ToStringView());
   } else {
     writer->json_keyvalue("localEndpoint", null);
   }
 
   // First call to get required buffer size.
-  rc = uv_pipe_getpeername(&handle->pipe, buffer.data, &buffer_size);
+  buffer_size = buffer.capacity();
+  rc = uv_pipe_getpeername(&handle->pipe, buffer.out(), &buffer_size);
   if (rc == UV_ENOBUFS) {
-    buffer = MallocedBuffer<char>(buffer_size);
-    if (buffer.data != nullptr) {
-      rc = uv_pipe_getpeername(&handle->pipe, buffer.data, &buffer_size);
-    }
+    buffer.AllocateSufficientStorage(buffer_size);
+    rc = uv_pipe_getpeername(&handle->pipe, buffer.out(), &buffer_size);
   }
-  if (rc == 0 && buffer_size != 0 && buffer.data != nullptr) {
-    writer->json_keyvalue("remoteEndpoint", buffer.data);
+  if (rc == 0 && buffer_size != 0) {
+    buffer.SetLength(buffer_size);
+    writer->json_keyvalue("remoteEndpoint", buffer.ToStringView());
   } else {
     writer->json_keyvalue("remoteEndpoint", null);
   }
@@ -120,42 +117,41 @@ static void ReportPipeEndpoints(uv_handle_t* h, JSONWriter* writer) {
 
 // Utility function to format libuv path information.
 static void ReportPath(uv_handle_t* h, JSONWriter* writer) {
-  MallocedBuffer<char> buffer(0);
+  MaybeStackBuffer<char> buffer;
   int rc = -1;
-  size_t size = 0;
+  size_t size = buffer.capacity();
   uv_any_handle* handle = reinterpret_cast<uv_any_handle*>(h);
-  bool wrote_filename = false;
   // First call to get required buffer size.
   switch (h->type) {
     case UV_FS_EVENT:
-      rc = uv_fs_event_getpath(&(handle->fs_event), buffer.data, &size);
+      rc = uv_fs_event_getpath(&(handle->fs_event), buffer.out(), &size);
       break;
     case UV_FS_POLL:
-      rc = uv_fs_poll_getpath(&(handle->fs_poll), buffer.data, &size);
+      rc = uv_fs_poll_getpath(&(handle->fs_poll), buffer.out(), &size);
       break;
     default:
       break;
   }
   if (rc == UV_ENOBUFS) {
-    buffer = MallocedBuffer<char>(size + 1);
+    buffer.AllocateSufficientStorage(size);
     switch (h->type) {
       case UV_FS_EVENT:
-        rc = uv_fs_event_getpath(&(handle->fs_event), buffer.data, &size);
+        rc = uv_fs_event_getpath(&(handle->fs_event), buffer.out(), &size);
         break;
       case UV_FS_POLL:
-        rc = uv_fs_poll_getpath(&(handle->fs_poll), buffer.data, &size);
+        rc = uv_fs_poll_getpath(&(handle->fs_poll), buffer.out(), &size);
         break;
       default:
         break;
     }
-    if (rc == 0) {
-      // buffer is not null terminated.
-      buffer.data[size] = '\0';
-      writer->json_keyvalue("filename", buffer.data);
-      wrote_filename = true;
-    }
   }
-  if (!wrote_filename) writer->json_keyvalue("filename", null);
+
+  if (rc == 0 && size > 0) {
+    buffer.SetLength(size);
+    writer->json_keyvalue("filename", buffer.ToStringView());
+  } else {
+    writer->json_keyvalue("filename", null);
+  }
 }
 
 // Utility function to walk libuv handles.