rstream: Pass read count to read events

This is necessary to keep events in the same order received from the OS.

2 files changed, 16 insertions, 10 deletions

diff --git a/src/nvim/event/rstream.c b/src/nvim/event/rstream.c
index 94853f616a..0a720bb852 100644
--- a/src/nvim/event/rstream.c
+++ b/src/nvim/event/rstream.c
@@ -114,7 +114,7 @@ static void read_cb(uv_stream_t *uvstream, ssize_t cnt, const uv_buf_t *buf)
       // Read error or EOF, either way stop the stream and invoke the callback
       // with eof == true
       uv_read_stop(uvstream);
-      invoke_read_cb(stream, true);
+      invoke_read_cb(stream, 0, true);
     }
     return;
   }
@@ -124,7 +124,7 @@ static void read_cb(uv_stream_t *uvstream, ssize_t cnt, const uv_buf_t *buf)
   // Data was already written, so all we need is to update 'wpos' to reflect
   // the space actually used in the buffer.
   rbuffer_produced(stream->buffer, nread);
-  invoke_read_cb(stream, false);
+  invoke_read_cb(stream, nread, false);
 }
 
 // Called by the by the 'idle' handle to emulate a reading event
@@ -158,7 +158,7 @@ static void fread_idle_cb(uv_idle_t *handle)
 
   if (req.result <= 0) {
     uv_idle_stop(&stream->uv.idle);
-    invoke_read_cb(stream, true);
+    invoke_read_cb(stream, 0, true);
     return;
   }
 
@@ -166,19 +166,21 @@ static void fread_idle_cb(uv_idle_t *handle)
   size_t nread = (size_t) req.result;
   rbuffer_produced(stream->buffer, nread);
   stream->fpos += nread;
-  invoke_read_cb(stream, false);
+  invoke_read_cb(stream, nread, false);
 }
 
 static void read_event(void **argv)
 {
   Stream *stream = argv[0];
   if (stream->read_cb) {
-    bool eof = (uintptr_t)argv[1];
-    stream->read_cb(stream, stream->buffer, stream->data, eof);
+    size_t count = (uintptr_t)argv[1];
+    bool eof = (uintptr_t)argv[2];
+    stream->read_cb(stream, stream->buffer, count, stream->data, eof);
   }
 }
 
-static void invoke_read_cb(Stream *stream, bool eof)
+static void invoke_read_cb(Stream *stream, size_t count, bool eof)
 {
-  CREATE_EVENT(stream->events, read_event, 2, stream, (void *)(uintptr_t)eof);
+  CREATE_EVENT(stream->events, read_event, 3, stream,
+      (void *)(uintptr_t *)count, (void *)(uintptr_t)eof);
 }
diff --git a/src/nvim/event/stream.h b/src/nvim/event/stream.h
index eaf4b010f5..c6baac0db7 100644
--- a/src/nvim/event/stream.h
+++ b/src/nvim/event/stream.h
@@ -14,10 +14,14 @@ typedef struct stream Stream;
 ///
 /// @param stream The Stream instance
 /// @param rbuffer The associated RBuffer instance
+/// @param count Number of bytes to read. This must be respected if keeping
+///              the order of events is a requirement. This is because events
+///              may be queued and only processed later when more data is copied
+///              into to the buffer, so one read may starve another.
 /// @param data User-defined data
 /// @param eof If the stream reached EOF.
-typedef void (*stream_read_cb)(Stream *stream, RBuffer *buf, void *data,
-    bool eof);
+typedef void (*stream_read_cb)(Stream *stream, RBuffer *buf, size_t count,
+    void *data, bool eof);
 
 /// Type of function called when the Stream has information about a write
 /// request.